Notes from the Sandbox ...

Customizing VCarve Pro and PartWorks - January 2008

Well I know it’s been too long since my last installment, and I have a bit of a backlog of ideas to write about. I’d like to detail how I use VCarve Pro and my ShopBot to work with the RTA (Ready-to-Assemble) fittings, but there is something else I need to explain first. I’m going to show how you can customize the VCarve Pro (and PartWorks) postprocessors to get the specific outputs you want, then next time I’ll describe how I use these modified postprocessors to create toolpath files for handling sheet materials including using RTA fittings and the auxiliary drill head. So this installment is pretty much useless to you unless you use VCarve Pro or PartWorks, but it seems many ‘botters are using or are interested in these excellent programs so here goes.

It seems too few people realize that the VCarve Pro postprocessor files are text files which can be edited with any text editor program. (To clarify, PartWorks is the same program as VCarve Pro, but it comes with only the ShopBot postprocessors. For the purposes of this article, PartWorks and VCarve Pro are identical, with on exception which I’ll get to.) Our friends at Vectric are understandably hesitant to encourage us to fiddle with the postprocessor (.pp) files, since if you make a mistake it could lead to ruined material, broken tooling, damaged machinery, and/or personal injury. So please don’t tell them that I’m writing this, but if you are reasonably comfortable with editing .sbp files and understand what the various ShopBot commands look like and how they perform you should be able to successfully modify a .pp file to your liking.

First, be very careful when modifying a postprocessor file as every character makes a difference and the results can be unpredictable. Be sure to keep a copy of the original postprocessor file, or, as I do, save the edited file under a new name so the original file is kept unchanged. You can make the modifications in any text editor including the ShopBot text editor. The postprocessor files are found in the “Program Files\VCarve Pro 4.0\PostP” folder on your hard drive. You can name the new file whatever you want – the name of the file will not affect the performance or even be visible while using VCarve Pro. For simplicity’s sake I’ll use as an example the “ShopBot_alpha_Arc_inch_router_control.pp” file – others may vary slightly but should be similar enough to follow along. Open the file and familiarize yourself with the layout and contents. Any line that begins with a “|” or a “+” character is a comment line and is there for information only. So you can see the first paragraph is a list of the authors of and contributors to this postprocessor file and the dates on which their contributions took effect. Go ahead and add your own name, date and the changes you are making so you’ll have a record of your work. Just remember each comment line has to start with a “|” or a “+”

Just after the first section of comments is the line:

POST_NAME = "Shopbot (arcs)(inch)(alpha_control)(*.sbp)"

Whatever type is between the quotation marks in the above line is what will appear in the postprocessor drop-down menu when you go to save a toolpath file in VCarve Pro. I suggest changing it to something short, sweet, and descriptive, such as “Plywood” or “RTA fittings”. You do not need to include the (*.sbp), but don’t forget to leave the quotation marks. (Here is the exception for PartWorks users – you will have to have the name “Shopbot” included somewhere between the quotes.)

The next several paragraphs are used by VCarve to set variables which will be used later in the file. I have no idea what most of them are for but some of them are obvious and if you are sure that they will not be used in the final postprocessor file than you may safely delete them. For instance, if you do not need to set the spindle speed from within the resulting .sbp files, you can delete the following section:

 +------------------------------------------------

 + Spindle Speed

 +------------------------------------------------

var SPINDLE_SPEED = [S|A||1.0]

If in any doubt about any line or section, just leave it be, it won’t hurt to leave it in.

Farther down the file you’ll find a section that begins with this:

+---------------------------------------------

+ Start of file +

---------------------------------------------

begin HEADER

followed by a bunch of commands and/or comments. Whatever follows the above will appear at the beginning of each file which is output using this postprocessor. Since I use a master file to call all my sheet cutting and drilling files in the proper order and to control things like cutting speeds and turning the router on and off, I simply delete this entire paragraph for most of my .pp files. But if you want any particular commands or comments to appear at the start of each file, this is the place to make that happen. Notice that each line starts and ends with a quote mark [ “ ] which will not appear in the resultant files but cannot be left out. Note also that this is where the commands are generated that send the tool to the “home” position at the beginning of each toolpath file, so if you want to eliminate that pesky feature (like I did) just delete the line:

"J2,[XH],[YH]"

Here’s a hint: If you replace everything after “begin HEADER” with the simple line:

“C5”

Then the command C5 (Custom Cut 5) will appear at the start of each .sbp file output with this postprocessor. You can then save any standard start-of-file commands as a Custom Cut file (Custom5.sbc) and it will be run as a subroutine by each file before starting the cutting moves.

Next, look for the section that starts with:

begin FIRST_FEED_MOVE

"M3,[X],[Y],[Z]"

Let me digress here for a moment. One of the benefits of learning how to modify the postprocessor files is the ability to create .sbp files that perform a specific task or function at each vector location in your drawing, instead of the cutting action which VCarve thinks it is creating. Specifically, if you use a Drilling toolpath on a group of circles, you can substitute the code of your choice in lieu of a Move command in the postprocessor file where VCarve thinks it is going to drill a hole. For instance, you can use the CC or CP commands to drill a hole with a spiral plunge, the C# command to invoke a custom cut file, or even the FP command to run a particular file at each hole location on your drawing. This last sentence is the key to my technique for machining holes for RTA fittings with VCarve Pro, which as I said I intend to cover in more detail in my next installment.

So back to our file. The following line is the move command that will be generated for each required move. If you are just tweaking your router or spindle .pp files to adjust the headers and footers you’ll probably want to leave this alone, but to change the function dramatically try replacing this entire line:

"M3,[X],[Y],[Z]"

with:

"FP, RTA fitting.sbp,,,,,2" (0r substitute the name of the file you want to run at each hole location.) Don’t miss the five commas followed by “2” – that specifies that the named file will be run in 2D offset mode.

Do the same thing where the file says:

begin FEED_MOVE

M3,[X],[Y],[Z]"

Now the resultant .sbp file will move the machine to each hole center location, and run the indicated ‘RTA fitting.sbp’ file (or the file or commands of your choice)

If you’ve made it this far you can probably decipher the rest of the postprocessor file. For my RTA and drilling postprocessors there are no “arc” moves – or any other type of moves needed so I just delete the entire rest of the file. If you are just tweaking your cutting postprocessor you can adjust what happens at the end of each saved .sbp file in the section just after the line:

begin FOOTER

Again, substituting the original lines of code with a C# (or FP) command will let you run a standard end-of-file routine at the end of each .sbp file.

Once you are reasonably sure you’ve correctly modified your way to a new, improved postprocessor file, save it with a .pp extension in the same directory mentioned above. Then open VCarve Pro (or PartWorks). The software actually scans each postprocessor file upon opening, so if there are any obvious syntax errors you will get an error message right up front, with a line number that corresponds to the line number in the .pp file, which gives you a place to look for the problem. If the software starts up OK, then try saving a toolpath using your new postprocessor. Make sure to check out the first few resulting .sbp files with a text editor to be sure there are no surprises, and run the first few files in preview mode just to be sure. Since I started using my modified postprocessors I rarely if ever have to edit or even check my .sbp files before running them. Here’s another tip: you can delete or move to a new folder all the .pp files for any machine you don’t currently own and don’t expect to own any time soon. Do the same for any stock .pp files you won’t use, such as metric files if you only work in inches. That way when you go to select a postprocessor file in order to save a toolpath you’ll have a custom menu of all your own .pp files with no unnecessary extras. (You can restore the original .pp files by re-installing VCarve Pro.)

Sample files: The attached files are meant as samples only, although you can use and/or modify them as easily as the ones which come with VCarve Pro. For each .pp file, I used VCarve Pro to toolpath a simple drawing consisting of four small circles placed at 2,2; 2,4; 4,2 and 4,4. For the RTA Only file I used a Drilling toolpath with the depth of cut set to zero; the resulting .sbp file runs my “RTA fitting.sbp” file at each hole location.

For the Custom Cut file I used the same four circles but a Profile toolpath and a .5” depth of cut. The resulting .sbp file has a C5 command as the Header and a C6 command as the Footer, with the typical machine output in between. If you use the C#, format you can use Custom Cut files with 2-digit numbers and keep your single digit numbered Custom Cut files for use with the keyboard. [Download sample files]

Almost There - August 2007

Why not use the ShopBot for all my panel cutting? Mainly because I’m just not there yet with my software, panel hold-down system or spindle.

That was me about a year ago. I’ve been purposely taking baby steps towards using the Shopbot for all my sheet cutting needs as I pretty much have to do it all myself and any time spent on R&D or machine maintenance/improvements is time I can’t spend producing cabinets (read: earning a living). As I wrote last October, I started with the vacuum table, which has been a huge success. Not that I’m not already thinking about improvements and what I might do differently next time, but it works well as-is, and my only regret is not taking the time to install a decent vacuum table sooner. But shortly after writing the installment detailing how I was purchasing pre-ripped and edgebanded melamine strips for my closet client, I made the plunge and tried machining a couple of small jobs entirely on the ‘Bot. Well, to get right to the point, I haven’t looked back. Even though I still lack full-featured software that can take my designs from “screen to machine” I already find it so much easier and more productive to do all my cutting and machining on the ShopBot than on the tablesaw/linebore/etc. that I now have a hard time imagining cutting a full sheet of plywood or melamine on the tablesaw.

So, of the three obstacles I mentioned, the hold-down system is taken care of, and I’m still using a Porter-Cable router – it’s loud and the bearings need regular replacement but it gets the job done. I’m getting much closer to being ready to order a spindle. That leaves the software. I’ve had several inquiries from folks who want to know if I’ve found a program that works for me, but unfortunately I still don’t have a real good answer for them. We all know there are numerous programs out there that will set you back as much or more than the cost of the Shopbot, and quite frankly, if I found one tomorrow that would work for me in every situation it would be worth the price of admission by saving me hours on every job. It’s not so much the cost of the software alone that is holding me back, but the time investment required to evaluate all the options out there and then to get up to speed on whichever one I choose. Just as the purchase price of the Shopbot doesn’t tell the whole story of how much it costs to get one up and running and get familiar enough with it to make it profitable, the time required to decide which software to buy and then learn how to use it would cost me as much or more than the cost to buy it. So for the time being I’m using my trusty DesignCad to manually draw and nest my parts and VCarve Pro to create the toolpaths for each sheet. As with anything, the more I do it the faster I get. I’ve saved a library of drawings so I can quickly bring up a drawing that has all the parts required to build a typical cabinet, arranged in such a way that I can easily stretch all the horizontal parts to correspond to the width of the cabinet, then cut and paste those parts into a drawing that represents blank sheets of material. I find that I can nest those parts onto the sheets as well as if not better than most nesting programs I’ve seen, although I admit it will take me longer than a decent nesting program would take. I created a macro for DesignCad that automatically exports each layer of each sheet into a separate .dxf file for importing into VCarve. The process of creating the toolpaths in VCarve is so repetitive (and so reliable) that I showed my 13-year-old daughter how to do it and now (when she has the time) she takes care of that part of the process for me.
 

I’ve worked out a pretty good system for creating clean, consistent parts from most sheet materials. I’m mostly cutting ¾” two-sided melamine-coated particleboard, but I use the same techniques for veneered MDF and plywood. First of all, I use a ¼” compression spiral router bit which leaves clean surfaces on both the top and bottom faces of the board. I could easily cut all the way through in one pass, but if I do I’ll have a problem when I get to the last few parts of each sheet. Since they won’t have the hold-down force of the entire sheet to keep them still, they would shift and lose the vacuum seal. So I cut everything in two passes. The first pass leaves a “skin” of .02” – just a little more than the melamine coating. The entire sheet is cut with this first pass before the second pass cuts through the material and .012” into the spoilboard. In addition, I have to take into account that the machine, like all things mechanical, has just a little bit of “give” to it, which can mean that two identical parts might not end up identical depending on several factors. First is that a climb cut can yield different results than a conventional cut, since climb cutting has a tendency to pull the bit away from the part during cutting while a conventional cut tends to pull the bit towards the material. We’re not talking a lot of difference, but it’s enough to notice and it’s not hard to compensate for. Secondly is that in order to minimize waste and sawdust, I want to place the parts as close together as possible on the sheet. So, when cutting the first part the bit is fully engaged in the material for the entire cut, but when cutting the adjacent part the bit is mostly traveling in the kerf that was cut for the first part. This creates a different amount of sideways force on the bit which can also leave a noticeable difference in size between the two parts. So what I do is leave an allowance of .02” on the first pass (the first pass cuts the part .02” oversize on all sides), using a climb cut to make sure the bit is not being pulled towards the part. Then once all the parts have been roughed out slightly oversized with the first pass, the second pass cuts the parts free from the sheet, to the final correct size, using a conventional cutting direction. This technique yields uniform, proper-sized parts since the sideways force on the bit is consistent on all sides of all the parts.

A few more details complete the story. On all but the smallest parts I’ve found that I can space the parts .30” apart – that’s .25” for the bit diameter, .02” allowance for the finish pass on each part, plus an extra .01” to make sure that the first part’s first cut, which is the climb cut, does not encroach on the adjacent part’s .02” allowance. I also place parts no closer than .30” to the edge of the sheet, to be sure to remove the factory edge and not cut into the stops which I’ve bolted to the edge of the table to aid in sheet placement. For smaller parts such as rails which are typically only 4” wide and can be less than 20” long in some cases I leave a full inch between them and the next closest part. This leaves a skeleton of waste material surrounding each small part which helps keep those parts from moving during the final pass. If I had a more powerful vacuum system I probably would not need to do this. It’s worth mentioning that even with a pretty decent dust collection system the kerfs tend to stay full of sawdust even after the second pass is complete. This is due to the fact that the compression bit has only a short upcut segment on the end and is mostly comprised of downcut geometry. Although it leaves more dust on the table to be cleaned up between sheets, it works in my favor to preserve the vacuum seal even towards the end of the second pass. As for cutting speeds I’ve found I can run the router at 6ips for both passes for about the first 15 sheets or so, then once the bit has some wear on it I have to slow the first pass down to 4ips or the router sounds like it wants to bog down a bit. I’m hoping once I upgrade to a spindle I’ll be able to maintain the faster speed if not increase it some. I can usually get 25 sheets or more from a bit, which I then save for less demanding cutting like raw MDF or thinner materials. For veneered MDF I keep the speed at 4ips from the start as the router doesn’t like the faster speed in the denser MDF core. Also, any machining such as pockets, grooves, holes, etc. is done before the parts are cut out from the sheet to ensure that the parts cannot move during the machining process.

A sheet of closet parts ready for edgebanding.  All machining except for edgebanding is done on the Shopbot – grooves, holes, notches, cutouts – whatever.

Meet My New Friend, Cam - June 2007

When I built my vacuum table I knew there would be items which would not lend themselves to being held down with the vacuum, so I incorporated T-tracks into the table. Not being sure how I was going to use them, I figured I’d come up with various hold-down devices as the need came up. Well I’m pleasantly surprised to say that my first such device is an unqualified success. It’s a cam-powered lever that bolts to the T-track using an aluminum hub. The hub has a flange that keeps the whole assembly tight to the table while allowing the plywood lever to pivot. It only takes a small amount of offset in the cam – 1/16” seems to be plenty – to create enough force to crush the edge of the workpiece.

The easiest way to describe how it works is to show you a few of the set-ups I’ve found useful over the past few months.

Close up of cam lever in action. The lever is made from Baltic Birch Plywood.	The cam action generates enough force to crush the soft mahogany. The shim protects the edge of the door but is not needed for clamping.
It sure is nice when the size of the workpiece matches the T-track layout.	A Cypress door jamb is machined for hinges using cam levers and stops which are bolted to the edge of the table. A plywood strip spreads the clamping pressure, especially at the end where the workpiece doesn’t reach the T-track, but care must be taken not to make the caul too wide or there can be a tendency for the workpiece and caul to “hinge” where they meet and rise off the table.
The working parts. The fixed wrench makes adjustments quick – a half-turn to loosen the nut, slide the lever up tight to the workpiece, and another half-turn to re-tighten. Then rotate the handle away from the workpiece to tighten the cam. It takes longer to describe than to do.	Working prototype of the screw-down version, using a bushing and fender washer instead of a hub. Also a good way to try the system for yourself using hardware store parts and some scrap plywood.
The final screw-down version – a little smaller and lower profile, with a smaller hub and hole sized for a screw - had no problem securing these solid wood parts for edge notching.  The entire jig took only minutes to staple together and is itself being held to the table with the vacuum system.	Don’t try this at home!  I should have used the screw-down version, but I hadn’t made them yet – so I improvised.
It was nice not having to run the vacuum for hours while these keystones were being machined.	Securing a large slab for surfacing.  This is the application that prompted me to create the cams in the first place.  The slab is from a local tree that fell over after Hurricane Ivan passed through a few years ago.
Gravity probably would have sufficed as a hold-down method on this one, but why take chances?

As you can see I've come up with new uses for these cams on almost every job. I used to use all wood versions of these and just put a screw in the center, but the center hole would wear out making the cam unreliable, plus it required screwing multiple holes into the table.  The aluminum hub can be bolted (or screwed) tight to the table without wearing out and the plywood handle is still free to pivot but will not lift. The T-track versions work great and are easy and quick to adjust but they take a little creativity sometimes when the workpiece doesn't fit the track spacing. For smaller parts, I made a jig with 2 fences that I can screw a couple of cams down on, then I can use the T-track to bolt the jig down to the table.  I designed a smaller version of the hub that works well in this application.

For a little background on how I got some hubs to try out, check this post from the TalkShopBot forum.  Many thanks to Shawn Fennell for making the first sets of hubs for me.  So how can you get a set?  Make your own using these specs (pdf version or dxf version), have some turned by a local machine shop or do what I did – work something out with Shawn.  Actually, for those who would rather buy than make, send me an e-mail – if there is sufficient interest we’ll make enough for everyone.  You can also make a half-decent screw-down version using a bushing and a fender washer instead of the aluminum hub.  For light cutting such as V-carving several 'botters have modified the concept to use pegs and holes instead of the aluminum hub.  See here for an example.

I figured I’d have designed a bunch of different hold-downs for the T-track by now, but so far the cam levers have handled just about everything that wasn’t suitable for the vacuum or just being bolted directly to the T-track.  It’s proven to be a simple solution that works.

Closets - March 2007

So my other psychic bid involved a query from a local closet outfitter – he’s a one man show who installs closet shelving similar to the big national companies you are probably familiar with. Two of his brothers own a commercial cabinet shop and had been providing all the shelving, but they had sold their shop and he needed to find a new supplier. Now I’m no stranger to melamine, and frankly, the idea of volunteering to handle a mountain of the stuff every year does not appeal to me, but something else did. I figured if I could outsource most of the cutting and edgebanding, I could use the ShopBot for all the machining. If I could create a system to process the closet parts that almost anyone could follow, then I could get almost anyone to do the actual work. In a nutshell, it has almost turned out that way.

I had done a small job using RTA (ready-to-assemble) fittings – the ones that come with all that flat-packed “furniture” where the end-user assembles it themselves with a screwdriver – and I know that the big closet companies use them routinely. My prospective customer was screwing all his parts together – even though his brothers’ commercial casework shop had a high-dollar CNC machine, they couldn’t be bothered to program each of his jobs so they were just providing him with generic line-bored parts – holes all the way up and he could use whichever ones he wanted on each panel. I told him I could do at least as well to start with and eventually work out a way to custom machine each panel for the RTA fittings, shelves and hardware.

The closet program was one of the driving reasons behind building my vacuum table and adding the air drill, both of which I completed last summer just as we were finalizing our first few orders. Once the ShopBot was ready, I spent close to 40 hours writing a bunch of part files that would process each of the pieces needed to build a closet – side panels, shelves, rails and drawers. I started with what was needed for the first few jobs, then added options and features as they were required. It turned out not to be too hard to implement the RTA fittings pretty early in the process. It’s now six months later, and it has grown into what I would call a suite of files including “master” files that allow the operator to choose which type of part to machine and enter all the pertinent information.

So what I do is buy bundles of melamine (a bundle is around 40 sheets) and have it ripped to our standard sizes and edgebanded. Now if I were back in the old shop with multiple employees and a nice panel saw I could easily rip and band these parts in-house and save some money, but with just me and a helper and my 10” tablesaw usually covered up with regular cabinet work, that’s just not an option. So I ended up renting a storage space down the street and filling it up with 4”, 12” and 16” rips of edgebanded melamine, plus drawer material and some hardware. We go grab whatever we’ll need for the next few jobs and start machining. For side panels we put the full 8’ rips on the ShopBot, where they get cut to length and drilled on one side, then flipped over and drilled on the other side. For shelves and rails, we cut the edgebanded rips to length on the tablesaw, then use the ShopBot to machine the ends for the RTA fittings. I know we could be machining these parts out of full sheets and just edgebanding them, and I may move in that direction someday, but for now this system works well, mainly because there’s no programming required for each job (and it’s easier on my poor old edgebander).

It’s a pretty simple system that can be used by any reasonably intelligent person to fill a closet order without my having to do much of anything. It’s not exactly at the point where it runs itself; I’m still spending several hours a week tweaking the files, overseeing the production, training operators, etc., but we are consistently producing well-fitting parts, and the sales, design and installation are all handled by someone else. I certainly can’t say the whole program has been free of problems (in fact I’m saving up a few of the problems for a future installment) but it has become a nice little part of my business. As a side benefit, it has caused me to evaluate how I process parts through the shop, and I’ve been able to streamline my regular cabinet production by using some of the techniques I developed for the closet jobs.
 

One of the test assemblies during the initial R&D stage. We soon switched from the zinc fittings to white plastic, which are less expensive and seem to work better.

Each side panel is placed on one half of the table where it gets cut to length and drilled on one side, then flipped over onto the other half of the table to be drilled on the other side. The operator starts at one end of a wall, enters the critical dimensions and a code corresponding to what type of drilling pattern is needed, and the machine drills all the appropriate holes for one section of closet.

Shelves are placed on one end of the table to have one end machined, then slid to the other end of the table to have their other end machined. It seems a little labor intensive, but it goes quickly and there is no need for programming or other compensation for the length of the part – all shelves get machined the same way regardless of length.

For the rails we use a mask to block the airflow through the open area of the vacuum zone.

Orders come in via e-mailed PDF plans and elevations, and stacks of finished parts are picked up by the client. I never have to leave the shop.

Psychic Bids - January 2007

In the venerable card game Bridge, bidding follows a carefully proscribed set of rules and formulas, in order to provide accurate communications and allow partners to reach the most advantageous contract. Deviating from these rules is liable to provoke the ire of one’s partner and opponents, and cause the bidders to wind up with a losing hand. But every so often a Bridge player will make what is referred to as a “Psychic Bid”, where something unusual spurs the player to make a bid that is not logically indicated, because of an unexplained but strong feeling that it’s the right way to proceed. I mention this because in the last year or so I have had two opportunities to bid on jobs that on 99 days out of 100 I would have turned down outright, but which for some unexplained reason I was moved to follow up on, with successful results.

The first was just about a year ago, when I received a somewhat cryptic e-mail asking if I could handle a rush job involving assembling and veneering some curved parts which turned out to be a prototype pair of high-end audio speakers. Now if this request had arrived on any other day last year, I would simply have been too busy to even consider taking on another job, especially a rush job. But as it happens I was enjoying a rare break after a long period of being slammed with work, and the job I was working on was not time-critical. So I took the bait and said I could squeeze in a 2 or 3 day job, charging for my time and material.

Well, it turns out the parts I was being asked to veneer were still being fabricated, in Oregon, about 3,000 miles away, as that was the only place this poor client, who lives 15 miles away, had found that was capable of producing this product for him. He was quick to point out that they were using a 5-axis machine, which I found curious since his product could easily be produced with a 3-axis machine – my ShopBot.

However, once I saw the final specs and photos, I started to wonder what I had gotten myself into. The speaker faces were a single, tall sculpted wave form, with recessed openings which would be nearly impossible to veneer after machining. I’ve long ago given up on veneering with contact cement, so unless I can use clamps or a vacuum bag I won’t touch it, and I started to get a headache trying to figure out how to veneer the sides of all those openings. So it occurred to me that if I inlayed solid wood into the opening area, then veneered over it, I could rout through the veneer, exposing the solid wood and eliminating the problem.

But that lead to a dilemma. I was 98% sure my proposed method would work, but the client was already paying for the parts which he had ordered from Oregon, and he was short on time – the finished product had to ship in 3 weeks in order to make the annual Consumer Electronics Show – a debut for which he had been preparing for months if not years, and was heavily committed to financially. He was not likely to be open to changing course that dramatically with so much at stake. But I had no intention of getting bogged down in an impossible veneering project, and at this point he was expecting me to do the work. The Oregonian parts were due in 3 or 4 days.

So for reasons I still don’t quite understand, I took the plunge. I put out a call for help on the ShopBot Forum, and in a few hours I had the 3D toolpath I needed to machine the wave pattern. I laid out the details in DesignCad, and got to work. I spent most of a weekend ignoring my family, laying up MDF, inlaying solid Maple, machining the wave, veneering the face, and routing the openings. Sure enough, my method worked like a charm. By the time the client came to the shop to meet for the first time (we had been communicating solely by e-mail up to that point, and I had no deposit or firm commitment from him to give me the job) I had a completed, veneered sample.

The first full set of speakers in production.  Each finished speaker is 5’ high, and consists of three of the curved faces that made up the sample.	Final machining of one complete speaker face.  This set is made with Cherry veneers and solid wood.  The long opening is for a “ribbon” tweeter.
A detail shot of the Cherry wood peeking through from under the veneer.	After spraying the ends with dye stain, I stacked the boxes up to stain the sides.

When the client saw the sample, I didn’t have to say anything. He knew immediately that I was capable of producing the quality work he was looking for, and that my method of construction was equal to if not better than what he had designed and ordered from Oregon. He gave me the go-ahead right then, even though the parts from Oregon had yet to arrive. Turns out it was a good thing, too, because the long-awaited parts were completely unusable – poorly machined, ill-fitting, and damaged in shipping. I’ve now completed 3 sets of speakers for this client, with total billings exceeding $20,000, all at my regular hourly rate plus expenses. If not for the ShopBot and my psychic bid, I might never have even answered his e-mail.

I’ll have to tell you about my other psychic bid in a future installment.

One sixth of a finished set of speakers, ready for hardware.

Vacuum Table ... ultra! - October 2006

A few months ago I replaced the worn out plywood and MDF table which came with my ‘bot (the demo model from the 2004 IWF) with a custom-designed 8 zone vacuum table. There has been a lot of interest in vacuum tables recently, and since I posted a few pictures of my newly upgraded setup on the TalkShopBot Forum I’ve received several questions and requests for more info, so I thought I’d share some details. Now that it’s been in service for more than a few jobs I can safely say it works well, however keep in mind I designed this system to suit my particular needs so your mileage may vary.

I started by laminating a piece of ¾” 4x8 Baltic Birch Plywood with 2 sheets of “brown backer” laminate, which I figured would help minimize changes in moisture content and help stiffen the plywood. It also made the surface non-porous, which would come in handy as the plywood serves as the bottom layer of my vacuum platen, and with the laminate layer on top of the plywood I don’t need to worry about losing vacuum through the bottom of the platen. I then bolted the plywood to the steel cross supports using countersunk holes, but not before carefully checking the limits of travel of the machine so that I was sure both my router and my drill unit would be able to traverse the entire length of a 96” (or 97”) sheet. By moving the gantry all the way to one end and then the other and making note of the tool locations at each extreme I determined there was only about ½” of leeway as to where I could bolt the plywood down and still have full machining capabilities with both tools. The table ended up only about ¼” off center from the cross supports in the X direction. In the Y direction I determined that by centering the table on the cross supports I had the maximum flexibility to reach the edge of the workpiece with the router and would still be able to reach the entire sheet with the air drill, which is offset from the router about an inch in the Y direction.

So now I had the plywood bolted down and in the proper position. I measured the locations of the steel cross supports and drew them in my CAD drawing of the table, to be sure my plumbing holes, T-track and such would not conflict. This allowed me to lay out my vacuum zones, plumbing, and T-track locations. The fun was just beginning.

Gluing the MDF platen down in four pieces - the first piece is done, the second is being glued (using a melamine cover to block the airflow), and the third piece, shown upside down, is ready to go.

Although I had been planning (and dreaming about) the new table for some time, I hadn’t figured out how to bond the MDF layer that would serve as the vacuum platen to the plywood/laminate sandwich. But I had been scouring the Forum regularly for ideas and sure enough Brady Watson came through with his idea about a one-piece platen/spoilboard. I modified his idea for the next step. After scuff-sanding the brown laminate with a handheld belt-sander, I used the Shopbot to rout holes for my Fein vacuum hoses where the larger holes for the 2” PVC plumbing would eventually go. I then cut the MDF platen into 4 quadrants, and routed a simple grid into one face of each quadrant. By flipping the MDF and placing it over the table with the routed grooves down, I was able to securely glue the platen to the table, one quadrant at a time, using polyurethane glue and the Fein vacs hooked up to 2 holes per quadrant. (If you use polyurethane glue, use it sparingly – just enough to wet the surface. A short piece of baseboard or crown molding makes a great glue spreader.) I followed this with a border of solid hardwood glued and clamped to the underside of the table, all the way around the perimeter. I figured this would add stiffness, make clamping easier (not that I expect to do much clamping with the new vacuum table, but you never know, right?) and make it easier to attach stops securely to the edges of the table.

A strip of edgebanding between the platen quarters blocks air from leaking between zones.

The vacuum grooves are cut and hardwood edging is being glued to the underside of the perimeter.

Once the layers were built up, I used the ‘Bot to trim all four edges of the table, being careful about the location of the cross supports. I then surfaced the MDF platen flat, routed the grooves for the T-track and the vacuum grid, and enlarged the holes to fit the 2” PVC. [My PartWizard .art file for the grid and track. To download, right-click this link and save file to your computer.] I secured the T-track using epoxy and screws. I’ve only had a need for the T-track once in 3 months, but I expected it to be one of those things that while only used occasionally makes life much easier when it does get used. It did complicate the design and construction (as well as adding to the cost), so I suppose you could leave it out and still have a mighty nice vacuum table, but knowing the variety of tasks I use my machine for I’m glad I went to the trouble and expense. I have some ideas for hold-downs, which once I get a chance to fabricate them will make the T-track much more valuable to me. A note of caution – the T-track results in my having little or no vacuum on the last couple of inches of table at each end. So far I have not found this to be a major problem, but it is something I have to keep in mind.

The three layers, ready for trimming. The gap in the MDF will be enlarged and filled with T-track.

I held my breath while the cutter trimmed the edges, oh so close to the steel cross supports.

While I was planning and working on the table I was laying out the PVC plumbing and the 16 valves (!) which are the key to my 8-zone system. I do a fair bit of repetitive work on pieces much smaller than 4’ x 8’, so it was important to me to be able to alternate between two zones – while the machine cuts a part, I can be preparing the next part to be machined on the other end of the table. So my system is designed to be used with two vacuum motors, each with a manifold and 8 valves. Fitting and gluing up the pipe and valves was quite an exercise – there are a lot of small parts and fittings, all glued up into one rather large assembly, so it took some planning to figure out what order to assemble the parts in and how to keep everything aligned. The final part of the plumbing system involved connecting the Fein vacs to the manifolds. As it turned out, I had a 2” shopvac hose from a recently retired (read: worn out) old wet-dry vac, which fit perfectly into the Fein outlets and the 2” PVC “T” fittings. A couple of vacuum gauges allow me to monitor the holding power, which is substantial. I finished up with an MDF spoilboard, which I surfaced on both faces to facilitate airflow.

The PVC was made up in two large subassemblies. It was a bit of a pain, but it works.

Shop-made pipe hangers for the longer runs to the rear zones.

I shimmed the PVC in place, centered in the hole, then sealed it up.

The completed plumbing system. Some day I may add wood handles to make the valves easier to operate.

2" Shop-vac hose connects the motors to the manifolds. Vacuum gauges let me know how much holding power I have to work with.

So how well does it work? In a word, great! The freedom to place almost any flat workpiece on the table, hit a switch and start cutting is empowering. No more screwing workpieces down and keeping fingers crossed that I put the screws in the right places. No more time wasted creating and running an extra toolpath to locate “safe-screwing” spots. No more clamping the corners of a sheet and running around the machine moving clamps as the parts are cut up. My confidence level increased and set up times decreased substantially. As a bonus, many cuts are cleaner and more chatter-free as the workpieces are securely held at every spot, not just where I put screws or clamps. I can now concentrate on tooling, feed speeds, and cutting strategies instead of worrying about how to hold the workpiece while cutting. Many smaller tasks are now cost effective, whereas previously it would have taken longer to secure the workpiece (and work around the clamps and screws) than it would take to do the task by hand. In short, adding the vacuum table has proven to be one of the most effective upgrades I could have made.

Done. Ready to start cutting!

I knew the T-track would come in handy sooner or later.

Not a Square Corner - June 2006

Here’s a project I completed earlier this year, which if not for CAD and the ShopBot might have had me running screaming from the customers’ house. This was for long-time clients who own an unusual home characterized by round and curved walls, many of which are made of solid stone. The challenge was to update the bar in the photo with modern cabinetry.

I convinced the clients that filling the angled cabinets with angled drawers, even though they would lose the triangular spaces between the cabinets, would provide better access to the contents of the cabinets. I’ve made angled drawers before (before I started using the computer for all my drawings), but these were more complicated. Each angle was unique due to the freehand curve of the wall. Using the computer for laying out the cabinets and drawers made it easy to determine the length and angle of each component, not to mention how and where to mount the drawer slides. Part of the CAD drawing showing the cabinet and drawer construction. Dimensions and angles are but a few clicks away.

I used the ShopBot to cut out all the angled parts, namely the cabinet tops and bottoms, the drawer bottoms, and various spacers for between cabinets and around the curved paneled wall (which we kept as a backer for the new Basswood paneling, another unique feature of the rest of the home). I also used the ShopBot to make a 1/4” plywood template to lay out on the bare subfloor to verify the cabinet locations and to help the plumber determine where to rough in the new water supply and drain pipes.

The cabinets were not that unusual, except for the angled bottoms.	Even with no two angles the same, the drawers fit the cabinets just right. I hated telling the customer that the computer did all the hard work.

To fit the zinc bar top to the rock wall, I used the ShopBot to cut a template of the bar top out of ¼” plywood. I fitted the plywood template to the rock with a scribe, jigsaw, utility knife, and file, then used the ShopBot to probe the scribed end of the template. I sent the bar top fabricator a .dxf file of the bar top, including the scribed end, and several weeks later a crate arrived with the already fitted zinc-covered bar top, ready to be set in place. Sweet.

The finished product. In the foreground are glass doors on each cabinet end. Wedge-shaped glass shelves utilize the space and allow the client to show his shot glass collection.	Angled drawers take some patience and brain power, even with computer assistance, but the results are worth it. No more bending down to reach into the backs of those awkward shaped cabinets.

The most challenging part of the job was the curved wood backsplash. I built a full-sized form using pieces cut with the ShopBot from some scrap leftover from a previous job. Then using a pre-kerfed material called Timberflex and layers of 1/8” bending plywood I glued the layers together using 3” stretch wrap to secure the assembly against the form. The angled returns at each end almost had me stumped. I tried to figure out some way to hold the giant horseshoe-shaped piece of Basswood-veneered spaghetti up to the miter saw, then finally dug out an old crosscut handsaw I was given years ago by a distant relative in the tool business. I was able to handsaw the joints close enough to clean them up with a sharp handplane. Once the ends were sawn off I cut the matching miters on the short return pieces normally on the chop saw.

Bricklaying the form for the wooden splash. The sizes of the pieces are dictated by the sizes of the scraps on hand in the shop.	Building up the splash. Stretch-wrap holds the first few layers together and to the form while the glue dries. The inner layer is already veneered with Basswood. A solid Basswood cap will be added once the layers are built up.	The hardest part of the whole job. It’s hard enough to get a reference from a curved workpiece, but when it’s difficult to handle as well it can be the stuff of nightmares. A handsaw saved the day.

If I implied earlier that not having the computer and the ShopBot would have made this job difficult if not impossible, I was exaggerating a little. Curves and angles have been part of construction and cabinetmaking since long before computers came on the scene. In fact, the first round room I ever built cabinets for was in this same house. One of the first jobs I did for these clients was over ten years ago, when I replaced the cabinets in their semi-circular, rock-walled kitchen – sound familiar? Except that was when I was just starting out with CAD, and of course all the parts had to be cut out by hand using full-sized templates and a fair bit of guess work.

Let’s just say I can personally attest to the fact that the new way is much easier and less prone to errors.

Here’s to a safe and happy July 4th for everyone.

 

It's Not the Equipment - May 2006

A sliding table attachment, overarm guard, dust collection and outfeed tables give this basic cabinet saw flexibility and convenience.

Like most cabinet shops, the bulk of my work can be broken down into cutout, other machining, assembly and (sometimes) finishing. The heart of my shop (and I suspect most others) is the tablesaw. While I miss the sliding table panel saw I had in my previous, larger shop, I don’t miss the monthly payments at all. I’m currently using a Jet cabinet saw, with an Excalibur aftermarket sliding table attachment and an overarm guard/dust extractor. The sliding table attachment is absolutely critical for being able to make square cuts easily on large or long pieces, and I have found it to be very reliable for maintaining squareness of cuts. The overarm guard seemed like an optional accessory at the time, but it improves safety and eliminates the sawdust from being thrown at my face while cutting to the point that I now cringe when using another saw without one. (I know too many woodworkers who have to remove their shoes to count to ten.) It also raises and swivels out of the way easily for those operations where it would interfere, which makes it much more likely to be used for the next operation than a guard that has to be removed and re-installed. The lack of a scoring blade is a definite disadvantage, one that I overcome as best as possible by keeping blades sharp and the saw well-tuned. While the tablesaw does most of my cutting out, I also have a dedicated miter-saw station, bandsaw, and of course the ShopBot for those cuts that the tablesaw can’t handle effectively. Why not use the ShopBot for all my panel cutting? Mainly because I’m just not there yet with my software, panel hold-down system, or spindle. I hope to make that transition to mostly automated panel processing over the next year or two (and to document the good, the bad, and the ugly in this column as I go – so stick around!). But even so the tablesaw will always have an important place in the heart of my shop.

The rest of my panel processing equipment includes an antique Brandt edgebander (from 1992, but still going strong) and a Blum line boring/hinge boring machine, which will be used less and less for line boring as that operation is moved to the ‘Bot. Most of my panel joinery is done with a pneumatic stapler and particleboard screws, but I also use a Kreg pocket screw machine and a DeWalt biscuit joiner when appropriate.
 

This wide-belt sander makes quick work of processing wide panels, and makes a tedious job tolerable. The panels were surfaced on the ShopBot to make them flat before sanding.

For solid wood machining, I have the basics: 6” Powermatic jointer, 15” Jet planer, 18” Jet bandsaw, a shop-made router table, and plenty of hand tools. But I do have one other machine that has revolutionized my work almost as much as the ShopBot: a 36” widebelt sander, an entry-level model made by Timesavers, called a Speedsander. For both veneered panels and solid wood, it has made a previously tedious job tolerable and profitable. I’ve found that by using the ShopBot to surface wide or glued-up boards, and the Speedsander to smooth them, I can easily work with slabs or edge-glued panels up to 36” wide. It even has wheels so I can move it out of the way between uses.

I’ll tell you about my veneer press some other day – that may get its own installment here one day soon.

But in the end it’s not the equipment or tooling that produces results in the shop, it’s what we do with them. When I first started out (back in the parents’ basement) I made some pretty nice pieces using not much more than an old radial-arm saw and a Craftsman router mounted upside down under a piece of plywood. What the shop full of goodies does is let me produce quality work easily and efficiently – which allows me to stay in business and feed my family.

More Work in a Day - March 2006

How would you like a raise? I knew that would get your attention. Well, I realized a few years ago that there were two basic ways I could make more money doing woodworking, which as we all know is not the easiest way to make a living. I could either charge more for the same product (and then have to work harder to make the sale) or I could figure out how to get more work done in a day. Maybe it’s just laziness, but I am constantly thinking about how I can accomplish the greatest amount of work with the least amount of effort. I’ve identified two areas which seem to have the biggest potential for eliminating wasted effort and streamlining production.

The first involves analyzing the flow of work through the shop and figuring out areas where small changes can save steps or eliminate operations. Here’s an example: My edgebander does a decent job but the end trimmers leave something to be desired; they often chew up the end of the tape or cut it cleanly but not flush to the substrate. I would have to block sand the ends of every part before assembly to clean up after the machine. So it occurred to me that if I edgeband the 8’ long rips before crosscutting the parts to length, the tablesaw would cut the edgetape and the substrate simultaneously. So now not only is every end cut perfectly without my even having to think about it (let alone hand sand each and every one), but it turns out it’s more efficient to handle the 8’ rips instead of keeping track of multiple parts and which edges get banded, etc. So there were additional savings beyond what I had expected.

An entire kitchen worth of cabinet parts stacked up, primed, and ready for lacquer, lets me finish before I’ve even begun!

But it gets better. I often find that the streamlining is an incremental process, where one improvement leads to another until after a while the entire production method looks little like it did before the process began. For instance, I always finish the banded edges of my frameless cabinets to match the doors, so that any edge that shows through cracks between doors or next to a door blends in. Initially that involved masking every cabinet after assembly, a time consuming job no matter how you do it. Well I noticed that I could finish the edges of the shelves by stacking them up and just finishing the stack of edges, and only have to mask the top shelf in the stack. So I had the breakthrough idea of stacking all the parts and finishing all the edges in a big stack before assembling the cabinets! Maybe some of you have been doing this for years and I’m just a little slow, but for me this was a huge time-saver. No more masking!! I really patted myself on the back for that one. But then I realized that if I was edgebanding the long rips before crosscutting, why not stack up the 8’ rips and prefinish the entire job before crosscutting the parts? Between this change and many others I have reduced the time it takes me to produce a set of cabinets from weeks to days, and increased my bottom line tremendously.

Sign of a sick mind? Maybe, but one which knows where all its tools are. With this wheeled cart, everything I’m likely to need can be rolled over to anywhere in the shop.

The second area worth looking at involves set-up times. I’m talking about the amount of work you have to do before you can actually turn on a machine or pick up a staple gun and start stapling. This might not apply as much in a large production shop where the workflow doesn’t vary from day to day, and each station or machine does the same thing, day in, day out; but in a custom shop we might be building melamine kitchen cabinets one week, a veneered bedroom suite the next, and who knows what after that, all in the same space and with the same equipment. If it takes 15 minutes to clear off the router table before you can put a bit in it you aren’t getting paid for that 15 minutes. So I’m always looking to minimize set-up times, and I’ve found a couple of ways to do that. First of course is to have the shop itself organized to minimize steps and to allow each machine to be used without having to do any re-arranging. That’s pretty basic stuff. But a less obvious step is to stock each machine or area with the tools and materials needed to maintain and operate it efficiently. For instance, my ShopBot is located at one end of my shop, and my assembly area is at the other end. So I constantly found myself walking back and forth across the shop to fetch a sanding block and bench brush to clean the platten off – now the ShopBot has its own sanding block and brush dedicated to that end of the shop. I haven’t bit the bullet and stationed a cordless drill at the ShopBot yet, but that’s a logical next step. I also try to organize each station or area so that tools and supplies are easily accessible, and I can see at a glance if anything is missing or needs to be replenished.

The other method I use to minimize the cost of set-up times is to combine jobs and organize workflow to get as many jobs or as much material through a machine or operation while it’s set up for a particular task. Even though my tablesaw is always ready for cutting, it takes at least a few minutes (or more) to get ready to cut out a large job. I’ll often cut and edgeband parts for any small jobs in the cue at the same time as a larger job, then set those parts aside for later assembly. That way I’ve essentially eliminated the set-up time on those operations for the smaller jobs, on which the set-ups often take as long as the operation itself. It’s the same thing as picking up milk on the way home instead of going back out to get some later.

I think next time I’ll highlight some of the machines I use regularly to keep product going out the door and sawdust in the bin. But this column is here for you so if there’s anything you’d like to see here just let me know.

First Report - February 2006

Why the sandbox? That’s my wife’s pet name for my shop – a place full of my toys, where I get to make all the rules – heck, I don’t even have to put the toilet seat down. The name is fitting, I suppose. Most of the time I’m fortunate in that being in the shop feels more like playing rather than working. So who am I and why an I writing this?

Maybe I can answer both questions at once. I’ve been involved in woodworking for (gulp) 25 years. I started by doing odd carpentry jobs while working out of my parents’ basement (at least they let me sleep upstairs). I managed to work a few furniture projects in, a couple of which weren’t bad for a beginner (the others were bad). After a brief attempt at college (I almost became an electrical engineer – whew, that was close), my springboard into life in the real world was a two year stint studying under Ian Kirby, a traditionally trained woodworker, writer and teacher, during which time I earned a foundation of woodworking theory, hand and machine tool use, drawing and design that I am still building on today.

This brief period of exploration and enlightenment was followed by many years of blundering, missteps and mistakes – at least that’s what it felt like some days. Since 1988 I’ve been self-employed building custom residential cabinetry, built-ins and furniture, beginning with a single helper and growing steadily to as many as 10 employees, and (sparing you many agonizing details here) now have come full circle to a shop attached to my house, with a single helper.

So what’s different about that compared to working out of my parents’ basement? Well, other than having a much better equipped (not to mention better lit) shop, the difference is that (gulp) 25 years of experience. In those years I’m watched a lot of good ideas turn out to be not so good, seen some changes (mostly improvements) in how things are done in a woodshop, and learned a few techniques that make my job easier and keep the phone ringing. While it’s impossible to teach experience, I’m happy to share some of what I’ve found along the way in the hopes of helping those who are not as far along the path to avoid some of the pitfalls I’ve fallen into; and since I think I still have a ways to go myself I also hope to bounce some ideas off of y’all and maybe pick up a new trick or two along the way.

Now, it’s back to my sandbox…