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See if this is it.
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So the not-great sketch below shows a 3D part I'm trying to make. I can visualize it, but I have no idea how to go about drawing or programming this in BCC. I have V23, and have used it only for 2.5D so far.
This would be about 2" in diameter, and maybe .500" deep/thick. It's meant to act sort of like a face gear as part of an indexing mechanism, where there would be two of these meshing against each other.
Suggestions? I realize 3D milling this with a ball end mill isn't going to be exact, but that's OK, I can go back with a regular mill to clean up the corners.
For those interested, the application is an idea I have for a simple automatic toolpost for a 7x mini-lathe. The idea is that there'd be some kind of stiff spring holding the two halves together, and a 4-position tool holder mounted to the top. A shaft with a worm drive and a gear motor would be used to rotate the top gear while the bottom one was fixed in place.
I'm thinking the gradual ramps would provide enough advantage that I could drive it against the spring pressure, and save the trouble of a lock/unlock mechanism. The vertical faces of the gear would provide rigidity in the X and Z planes, and the mechanism should index pretty repeatably without needing to be precise about the degrees of rotation.
I have no idea how well this would work in practice, but the concept seemed good enough to be worth a try. While comments on the concept are welcome I'm mostly interested in learning how to draw/program this geometry in BCC
See if this is it.
Look like the clutches out of a Mercury outboard motor.
http://www.kirkcon.com/
Ive never drawn in BCC. What i do is do all my drawing and nesting in AutoCAD and then open it in BCC for programming. In AutoCAD or similar program, that would be quite simple with basic 3d knowlegde.
Sorry that i dont have a good answer about your BCC drafting. But i recommend doing your drawing in another program first.
Wiley, if I had Autocad I'd do the same thing. Unfortunately I don't have the spare couple thousand $ laying around for it.
Burrman, once again you are the winner. That video was exactly what I was trying to do, and with a little bumbling, I seem to be making progress.
The one thing I couldn't get to work was the "skin" surface. I used the 4-edge surface instead, and it looked right, so I am going to see if that does what I want it to. I also had a little trouble with the solid operations, I changed the order of things slightly so that I subtracted the core before joining all the pieces, and it seems to have worked.
Now I have to figure out how all of the 3D milling options work. I do have the version with the Z-level roughing and equidistant offset. Since I am working on a very small X2 tabletop mill I will need to go gently. For reference this is 2" in diameter and the deepest part is .25". I generally go about .050" DOC for roughing, half for finish, unless I don't care about accuracy in which case I can do 50-100% more. It's not fast but it beats a file and sandpaper!
You may want to look at the slice radial toolpath.. The options should be easy to see as the inner and outer dimensions... This path will leave the ramps vertical faces cut angularly though, so i followed it up with a profile op on the face to get a clean, direct cut line.Originally Posted by sansbury
Did you mean Slice Spiral? Radial seems to cut from X0Y0 straight out like the hands of a clock, spiral gives me a pattern more like your pic. I'm thinking that could be good to rough it out and then use a single equidistant offset pass to smooth the faces out.
No, I used a radial... it does go in and out from the center like the hands from a clock... It has the option to limit the inner and outer start/end points... The spiral will go around in a circle (Like a helix) I felt the little short moves from inside to outside would be a better cut on that type of surface, Though the vierticle walls (Where the face drops from high back to low) will need a second op to staighten them out. but I'm not much of a machinist either
Drawing it is not so hard, but if you want to machine that part, it would require 5 axis' & a fishtail cutter I think..
http://www.cnczone.com/forums/cnc_wood_router_project_log/125895-my_diy_cnc_cnc2011_%3B.html
@hub Luckily I don't (think I) need perfection here. I can face off the vertical faces and the flats left at the bottom shouldn't be an issue, since I'll be making both sides they should mate properly.
FWIW, I think I could make this "perfectly" using a rotary table as a C axis, tilted at a fixed angle in the B axis, and a regular endmill. There are no undercuts, and the angles are all constant. It would be easy enough to hand code. A 5th axis would just eliminate the setup, at the cost of a 5-axis machine and CAM
For that matter, I could just set the piece up in a vise and index it manually. I'm doing it 3-axis because I think it will be easier, and as an experiment in true 3-axis milling which I haven't done.
I was thinking the way in pic1. A regular endmill with the part fixed at an angle would result in pic2. Would that be ok?
http://www.cnczone.com/forums/cnc_wood_router_project_log/125895-my_diy_cnc_cnc2011_%3B.html
Ah, you are right. #1 is what I want as the purpose of this is to provide a face to prevent backdriving. I can get there if I don't mind having a small flat at the bottom, which I don't think will be a problem.
#2 might be "good enough" though. I'd have to try it. If I can have a large clamping pressure, then it might be rigid enough. Ideally the edges would have an undercut to make backdriving/lifting completely impossible, but that would require special cutters.
So I'm going for the simplest approach first, and seeing how it works in practice. For all I know, there may be other more serious flaws in my approach aside from the face gear
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