CNC Foam cutter/Router conversion

[skyborne98]

I am currently building a foam cutter similar to the one pictured here http://www.8linx.com/cnc/cnc.htm. However I also need a wood router for light ply and Balsa. I was thinking of building a cross member between the two vertical towers, to make it into a gantry. to hold my rotozip and or trim router.

Please note that mine is not going to be clamped to the work surface rather it is permanently mounted, to keep everything as rigid as possible.

What do you guys think of this? The idea is to build rc airplanes/rockets and gliders.

[harryn]

The designer / builder of the foam cutter in the link is a very creative guy. He did a nice job of taking what he could find locally and making it work to do what look like (to me) nice foam cuts.

If you add some cross braces for both fixed distance and moving gantry parts and a bit more frame, it might be ok for a light duty cutter. (2 axis movements) If you are going to try to add a 3rd axis, it will probably vibrate around way to much even for foam work.

There is a comment in his build, esp since he is using drawer slides - you need to keep them absolutely clean or it will be a mess - fast. With a hot wire, there is not much dust. With a rotating cutter, there is a lot of dust and vibration. This will be a push for that design.

I am still building my first DIY router project, but it is the electronics + motors + misc. small motion parts that really became a big cost driver for me - not the more obvious items like the support framework.

[skyborne98]

LOL, the reason i wanted to retro fit the existing design is due to the electonics costs and not wanting to duplicate electronic package purchases.

I have to agree with you about the concerns with the slides being an issue, but if i use a vac system nextto the cutter, do you think it would still work, with renforcement of the upright?

[harryn]

I really do not know the answer. Maybe if you describe your goals a bit more, someone else will know.

Example
- balsa - 1/4 in thick flat stock - just cut it in two parts.
- drill some holes in a line approx xxx size in balsa with a spacing of yyy and a precision of 0.1 inches

Good luck

Harry

[vulcom1]

I have also built a foam cutter similar to the one on the web site. I wanted to do what you are thinking of and combine them and save the separate electronics. What I am going to do and purchased so far is 3 steppers with more power and build a separate setup. My motors are on plugs on the case so it is a matter of reconnecting and using different software.
I don't think the towers are sturdy enough to support the router or dremel with the stepper for cross travel without a lot of movement. Just my opinion.
John.

[High Seas]

I am kinda in the same BOAT - well sort of. I wanted to build a foam hot wire cutter. Had already a 3 axis Xylotex setup - so I bought a second 3 axis card. Then I started integrating the 2 cards and power supply into a separate stand alone control box.

It took more time to find the box I liked to do the job - but finally did. Got it nearly all wired up -- but not yet fired up. And it was time to head back to sea.

I have some shots of the guts if interested too - I'll have to find which drive they're on.

My plan is to have one control box and move from 3 axis to 4 axis as I have space in the "factory" for only one up at a time. So I standardized on Xylotex and pacsci bipolar - all the machines have motors and I plug and play - the plan anyway.
Hope thats some help for you.
Jim

[skyborne98]

My basic goal is just to cut wings and formers for my self and friends. Materials that i will be dealing with will be .25in Balsa and 3/16th plywoods.

Machine doesn't have to be fast, just accurate to .01 inches.

I have hand cut several scratch built models, but I detest doing that part of the build process, so I want to take my computer skills and assist wit the tedius part of building scratchbuilt models.

I fly both RC Gas and TD sail planes (Thermal Duration Gliders). So I have a need for both foam and balsa CNC machines.

[vulcom1]

I am also into RC and scratch build a lot and know your problem. I used 2 drawer slides on each base and 2 on each tower. It also has a bearing running on the inside of each tower that stops the tower from pulling to the middle. I have not looked at the possibility of joining the towers and using another stepper but will do a little head scratching to see if I could do it. It has to come apart easily.
What do you do with the steppers in the towers? Run them in parallel as I think they have to be in sink or your cross rail will get screwed up.
Will see if I can find some pic's of mine. I changed computors so not sure where I have them.
John

[skyborne98]

Thanks for the feedback, it looks like you have the my idea correctly in mind. I also was worried about keeping the multiple steppers controlled, but figure if I can do a 4 axis foam, it shouldn't be hard to add another axis.

I do see that retro fitting my foam cutter will cause increased accuracy issues, since I have 2 x axis and 2 vertical axis steppers to deal with, not to mention the y axis that needs to be added.

Maybe if I could figure out a simple way to disconnect one side of the x axis from one of the towers , i wouldnt need a larger driver board(s) and eliniate binding caused by out of synch issues. I could further lock the vertical axis and use a stepper in the center of the gantry to set hieght of cut. (this could even be a manual setting since I am just cutting balsa and light ply).