A Learning Adventure in the Workshop

First attempt at a "raster-like" CNC photo engraving

This weekend I made my first attempt at a "raster-like" photo-engraving into wood using my home-built CNC mill.  My previous photo-engravings with the CNC used the "vector" method of using software to define the "edges" of color zones in the image and only engraving these edges into the wood, sort of like a black and white line drawing.  For the "raster-like" method, every inch of the image gets "cut" into the wood by the CNC's cutter using lawn-mower-like back-and-forth passes.  The darker the color of each photo pixel, the deeper the cut's plunge.  Therefore, if you are using a "V" style bit in the CNC, the deeper the cut also translates into a slightly "wider" cut as more of the "V" enters the wood with depth.  This method results in a more photo-like result with much more detail than the vector method, but it is also harder to do and slower.

For this first attempt, I used a 9"x14" piece of mahogany ply mounted to the CNC's table, and a carbide Dremel 1/4" V-bit.  I generated the g-code of the image of the "Big Ben" clock tower, using the trial version of the Vectric PhotoEngrave software that I download from their website.   The software was intuitive, and produced a g-code file that easily imported into TurboCNC on my CNC's PC with no errors. 

The CNC ran for almost 3 hours, and engraved the photo very well, but most of the detail of the image was not visible because I apparently used a "V"-bit that did not have enough width at the top...i.e., the changes in depth did not cause enough changes in width of cut to be easily visible.

Therefore, I will buy a bit with either a 60-degree or a 90-degree point and try again....

So, my first attempt at raster-engraving met with mixed results...time to try again.

Auriou Rasps

Another of my mini-product reviews...

I bought an Auriou rasp (click here for Auriou at Highland Hardware) and it is another of those tools that shows you that you've never really used a rasp if you've only used modern ones.  Modern machine-made rasps are almost useless, for years I've thought that rasps were an awkward, poor substitute for good-old sandpaper.   Well, try a "new" hand-cut rasp from Auriou, or an old hand-cut rasp and you will realize why cabinetmakers of old used these things all the time.  They can cut wood in a controlled fashion and leave a clean tear-out free surface.

Mahogany Trim

Last night I made the 54"-long front and rear solid mahogany trim pieces for the laminated desktops.  After I routed 1/8" radius round-over edges on a 54"x29/32" mahogany board, I ripped four strips to 3/4"x29/32"x54"  pieces for the trim edges.

Also, I removed a 1/16" from the thickness of the mahogany blanks for the breadboard ends.  This will compensate for the laminated tops only being 29/32" thick and not a full inch in thickness.

Next, I will mount the trim pieces to the desktops and then cut the desktop ends to prepare them to mount the breadboards.

Saw Guard Change

I moved the tablesaw around in the shop last night so that I had enough room on the in-feed and out-feed sides of the saw to cut the 54" x 29" laminated panels to final size.   Also, I had to remove my modified overarm blade guard from the saw.  I got the guard used from eBay a few years ago, and to modified it fit the Dewalt saw (it was made for a Delta saw), I needed to build a custom mount out of metal bits and plywood.  It works great, but the custom mount limits the ability to move the fence on the saw past 24".  Too small to cut the panels for the desks.

So, I replaced my modified overarm blade guard with the "Shark Guard" parts that I was not using (I've only been using the splitter parts from the Shark Guard till now).  I think I will stick with this arrangement from now on, rather than remounting the overarm guard.  It may go back on to eBay. I want to keep the full-capacity of my saw available.

After the saw guards were reconfigured, I cut the laminated panels to size.  They look good.

Desktop Lamination

I've laminated the 1/4" mahogany ply to 3/4" baltic birch ply to form the main body of the two desktops.  I used standard wood glue and a ton of clamps. The glue should be fully cured by tomorrow and then I will cut them to final size and begin to make the solid mahogany front and rear edges for the top and cut the tops for the solid mahogany breadboard ends.

The final thickness of the laminated top is only about 7/8 of an inch.  I was shooting for a full 1", but of course the finished thicknesses of the birch and mahogany plys are thinner than their full 1/4" and 3/4" dimensions due to the nature of manufactured ply now-a-days (finish sanding at the factory reduces the thickness).  So, I think that my original design thickness of the breadboard ends (1 and 1/8") needs to be reduced to only 1."   I only want the breadboard ends to be about 1/8" proud of the rest of the top.   I will re-plane the breadboard ends to remove another 1/8". 

Make Magazine

I've found a new magazine that I really like.  Its called "Make."  Make is hard to describe, but basically its "Popular Mechanics" for techno-geeks or gizmo DIYers.  It comes out four times a year in almost book-like form (similar to a National Geographic magazine in size and print quality), and is filled with mostly for-fun articles about gadgets and gizmos that can be built in your workshop if you have the time, patience and talent to do it.

Now, these are NOT "how to install a new sink in your bathroom" DIY articles, these are "how to build an RC lawnmower with a hybrid gas-electric motor" type articles...yikes!  I love it.  These people make my CNC-driven Etch-a-Sketch machine look normal.

Mail-order source for hardwood plywood

The mahogany ply that I ordered for the Greene & Greene desktops arrived yesterday from Bristol  Valley Hardwood in New York State.  I am very pleased with the quality and price of the wood. Including shipping, it was cheaper than I could find it locally, and they were able to ship pieces via UPS that were large enough for my purposes (I needed two 31" by 55" pieces).  I bought two 4' by 8' pieces (which UPS would not ship), and Bristol cut them for me to 1" larger than my final needed size so that UPS would ship them.  This saved me from the expense of truck rate shipping.  I will use the cut-off pieces that were left over for other projects in the future.

Bristol has a wide range of different  furniture grade ply as well as regular lumber packaged for shipping.  I'll add Bristol to my bag of tricks for when I need good hardwood ply going forward.

RoboAngus EAS (Etch-a-Sketch)

I finished the RoboAngus EAS (Etch-a-Sketch) side project this weekend.  I got the idea from Jeff Epler and Chris Radek's website and figured that it would be easy to adapt the controller and software from my Wood Turtle project to make my own version of the EAS CNC...it was...it only took me two hours for the complete build.   It runs using TurboCNC software and two stepper motors.

My innovations to this project were:

• the removable rubber cups that attach the motors to the knobs on the EAS using only friction.  Use of these rubber cups for the attachment allows you to remove the Etch-A-Sketch easily without tools...just pull.  I just drilled a 1/4" hole in the middle of a standard rubber chair leg end bought from Home Depot.  I then pushed a 1/4" by 2.5" bolt through the hole and used a nut to tighten it on.  Then I used a 1" length of automotive vacuum line to attach them both to the stepper-motor axis.  Works great and pulls off in a second.

• the use of a stuffed monkey as the operator (wink)

The above photo shows my son's name "Mason" drawn by the RoboAngus EAS. You can see the device is really only stepper motors mounted in plywood and attached with the bolts and rubber cups.

The photo below shows the rubber chair end mounting device described above.

Mike Burton's book "Veneering: A Foundation Course"

I read Mike Burton's book "Veneering: A Foundation Course" (ISBN 0806928557) last night after buying it used from Amazon.com (it is out of print).   Excellent book of practical knowledge on veneering.  I don't agree with his concepts of safety as presented in the Introduction of the book (says he doesn't use safety glasses and holds breathe against dust), but everyone is free to take whatever risks that they think are acceptable!

I can't wait to try some of his veneering methods.  Hightly recommended.

Veneering will have to wait...

Happy New Year!

Over the holiday weekend, I managed to complete all of the plywood patterns for the G&G desks, and planed the wood for the breadboard ends.  I also built a simple jig to make pattern-routing safer on my router table and then used it to make the first of the drawer fronts.  I am going to pattern route the breadboard ends and the desktops because they need to fit together "perfectly" because of the cloud-lift details on the corners...any gap will show up badly. So, that means the patterns need to fit together perfectly.  I spent a bit of time today perfecting them, and they are now ready for use.

I also noticed that when I drew the plans I made the top panel 29 3/8" wide and it should be 29 3/4" wide.  Glad I caught this error in my plan.

I found a source that sells mahogany ply on-line and will ship it to me full-size (eliminating the need for seems in the veneer), so I am going to do that instead of learning to veneer on this project.  Since I do not want fancy "figure" in the wood on this desk tops (G&G needs simple lines), veneering would be over-kill.  I returned the veneer sheeting to Woodcraft today.  Veneering will have to wait for another project.

I did learn A LOT (via the web and books) about veneering in the past week or so, and I really want to experiment with it soon anyway.  Check out the Joe Woodworker site for excellent info on veneering.  I want to build one of Joe's vacuum presses someday soon.  I ordered the basic veneer tool and adhesive package from Joe so that I can experiment with veneering when I get a chance.