Hello All,
Another long time lurker turned builder. I've read just about every post over the last couple of months (and some many more times than once) and have found the Zone to be an absolutely fantastic resource and wonderful community. Thanks to all the contributors.
Now on to the deep end of the pool into which I have jumped. Against all good advice I built big. Hopefully the attached pic works. My plan was to 1) CAD up my design 2) build the mechanicals 3) go for help. So now I'm at 3.
A bit of background to the project for everybody:
Construction: 7Ply plywood for moving gantry parts. Cold rolled steel tubing for all bearing surfaces. All bearing blocks are skate bearings in a 120' configuration... so 6 bearings per block. Dimensions X: 7ft, Y5ft, Z18"... workable area is 4ftx5.5ftx15". Table base is made of mdf with I joist stringers. Spindle is a 2-1/4hp makita router.
Purpose: above and beyond the fun of tools - I'm hoping to have a machine that is capable of producing 3D wooden scultpure pieces... hence the large Zaxis (Also a faroff dream to use it to produce a classic wooden boat)
Results to Date: well, I'm reasonably happy with the mechanicals, all the axii move very nicely with very little finger pressure. Its a lot bigger than I envisioned... but this wouldn't be the first project that got out of hand. I've put in 1/2" 13tpi plain old threaded rod on the Z and Y axis... this leads to some questions below. The rigidity seems very good given the materials, even with the Z fully extended it takes a good shoulder to deflect the spindle. (Sorry for the scientific measure)
Design goals: This prototype will hopefully work and perform to reasonable accuracy (don't really need absolute accuracy so long as relative accuracy is there for sculpting) and at a reasonable speed. I hope to be able to cut finishing passes at 100"/min. Eventually I'd like to evolve to proper linear slides, aluminum framing, etc etc. At that point I'd like to be in the 200-300 "/min category.
Questions Questions
Q1: Is this monster going to move... and what will it take. My uniformed guess/design notion was something like the camtronics 600 oz/in package or what DaSigntist is using on his machine. Is this pie in the sky given my 100"/min wish, and 200-300 "/min dream?
Q2: What are my options for drive mechanism?
The threaded rod on the Y and Z works reasonabley well - I can turn the Y to 500 rpm no problem... at 1000 rpm (using my drill to power the rod) the whip is nasty. I'm experimenting with tensioning the rod between the end supports although I think my rod has some bow in it from the store. So at 500 rpm I'm around 40"/min which is going to kill me on the finishing passes. I'll post another msg to this thread with a few thoughts I had plus picture. Basically I'd like a reasonably quick system that is fairly cheap... I'm going to test it on the X axis. I'm considering a timing belt set up, or a chain drive setup (cheapest), or a wire rope drive setup. I can always fall back to cheap threaded rod and low "/min performance. As a target, I'd like to get the X drive set up for 150 bucks.
So that's where I'm at to date. Thanks all for the inspiration. All comments/criticism/suggestions most welcomed. Oh yeah, I'll be completely disassembling what you see in the pic (for painting/alignment) so feel free to offer suggestions that take me back to square one.
Thanks all.
AJ |