Frederic Testard Critter Shed

[Bernd]

Tom Wilson's mention of using a Cricut machine to do his building reminded me of the yearly Challenge Build that started the New Year and ended Tax Day, April 15th on the Railroad Line Forum. I had picked to do a scratch build project from the list of subjects. A sketch was done by a member, Frederic Testard. Another member used the sketch to make up drawings. He was kind enough to send me a set for my HOn30 quarry line to service the electric locomotives. I used a router/engraver CNC for a part of the structure that used a Cricut cutter holder. I did use a milling cutter to do some of the cutting. Before I got the Comgrow Robo router/engraver CNC I was looking at the Cricut. What I didn't like was that the software is Cloud based and you needed to be connected to the internet to use the software. A big turn-off for me in using CNC machines at home.

Fredrick's Sketch of the Critter Shed



In that set of plans there where two sheds with different dimensions. Plan "A" was a small version. Plan "B" was the larger version.



And George's drawings of the critter shed.



I redrew the drawings from George's larger version in CAD because I needed a DXF file for the CAM program. Once all that prework was done it was time to fire up the ROBO router and have at it.

I had built a rock bin from Plexiglas and I wanted to experiment with thinner Plexiglas. I had found some .120" thick Plexiglas I had laying around. I also had some .062" 3 ply Birch plywood. So, I'm making two critter sheds.



The walls of the engine shed came first.



Here I'm trying a technique I've seen on U-tube that guys use to hold things together. It's double-sided tape. I put a couple of strips down on the plywood, then peeled off the backing and placed it on the machine table.



This is what it looks like with the backing pulled off.



Next it is placed on the machine bed and the machine is homed and the "start button" is pushed.



One wall done.



One minor mistake and one major "could have been disastrous" mistake. The mistake is the window. Apparently, I didn't set the depth of cut right for the tabs on that particular window. More on this later. The "almost disastrous" is when the door was cut through. It came out and it got caught between the cutter and one of the sides. Those were a few seconds of pants pooping excitement. Luckily, it didn't break the cutter.





And 12 minutes later it's done. Now comes the fun part. Getting the parts off. I've never used double sided tape of this nature before. it's used to hold carpets down and boy does it stick to anything you apply it to. It was a major battle getting the parts off.



Next came the harrowing experience of removing the larger part of the sheet leaving the cut-out parts till last. I've never worked with such tenacious tape in my life. I now understand why one video I watched the guy swore he'd never use double sided tape again. There is another method to use that makes the use of painter's tape and CA glue with a hardening accelerator. I'll use that sometime in the future.

Here I'm carefully getting underneath the part to pry up the finished parts.



And here's the major disadvantage to using such sticky tape. Thin sections can get easily get broken trying to get them un-stuck. That part of the wall got broken off. It'll be glued back together again during assembly of all the walls.



Pulling this stuff was no fun.



The red arrows point to the "tabs" that were supposed to be left on the parts so they would not come flying out when cut through. Chalk that one up to "programmer error". Same goes for the window in the red square. The proper height for the tabs was not set correctly.



Next up was the Plexiglas version of the walls. Here it the first cut. A couple of seconds after I took the picture the cutter went "Bing". Yup, broke the cutter.



Third cutter was the charm.





All done. Those two cutters gave up their lives for the test run on Plexiglas on the ROBO router. I discovered that I was running the machine to slow. It did well at 8000 cutter RPM and 4 inches a minute feed rate. It sounded like the machine was going to blow up any minute. I expected the cutter to break at any moment too. This was pants pooping times two. It made it through. Now came the task of pulling the parts off the table. Yup, going to try the painter tape and CA glue the next time around.

A quick tape job using painters' tape to see what the finished engine shed part of the critter shed looks like.



That's it for now. More to come tomorrow night. I also have to find my pictures of the Cricut Kinfe holder I made for the Robo engraver/router.

Bernd