Rather than bury this in the back of my original radius cutter I decided make this its own separate post. I hope it ok Jon and DIY'er.
The original was based around the only rotary table I had, my monster 10" that has got to weigh 100# and I'm just getting old to toss around that much steel. One of the many problems with the old setup was it was almost impossible to center quickly and easily and having only one rotary table made it so if I was cutting convex or concave I had to switch the cutter and the work positions. I found on eBay these cute little 3" rotary tables for $35ea(!) and decided it was time to revise the whole idea and give each arm its own table and mount everything on one 80/20 rail. That would make everything much lighter and easier to align. In this process I also realized I needed to be able to make domes. So I got another rotary table to mount the work on. This was a test run so I've still got to work out the mount for work rotating table. It's just clamped right now. The first cut was 24" radius, the max I could cut on this rail with the work arm that is on it right now. That proved to be to big a radius. I repositioned the work arm pivot to 19 1/2" and that was just right for the forming I was doing.
The next improvement would be to make bigger hand wheels for all three r-tables and make a mounting block for the work rotating table so I can offset it to the cutter to do compound radii. Thats something I didn't realize until I finished this experiment. Man I love this 80/20 stuff it's just like erector sets when I was a kid and if I don't like it I can just take it apart and try something else. And like with the arms and main rail I still have a 10' piece I've not cut up yet so I can disassemble and use the parts on longer pieces. Wish I'd had this stuff years ago.
I like your improved design and the ease of experimenting with the 80/20 Inc. - T-slotted aluminum framing systems. As you say, it is like a erector set for building machining systems. Can you post a few more close-up photos of your Radius Cutter V2.0? This is very interesting way to prototype and be able to turn it into a shop tool.
I have been looking at the small 3" rotary tables listing on eBay and good to know that is what you used. I but bought a 4" rotary table from JTS Machinery & Supply Co. for $60 and was surprised at the accuracy and smoothness of operation. I want to add a stepper motor to make a programmable indexing plate for cutting small gears. I think using the T-slotted aluminum framing systems would make a great frame with minimal machining.
Thank you for sharing your version 2.
Thanks. I would be glad to post some close ups. What exactly should I concentrate on? It's pretty easy to take it apart. Take to clamps loose and crank the adjusters to the end and pull the rails out of the linear bearings. The 3 parts, the work arm, cutter arm, and base, and then store them. The base rail is perfect for this kind of setup because it makes it easy to change radii. That was another problem with the original design. And you're right, it's far easier to prototype with this stuff than doing from scratch.
I think if you are looking for precision you would be pretty dissapointed by those little r-tables. But for me it was way easier to buy them than make them from scratch. I wasn't looking for precision out of them, I was just needing the geared rotation. It takes me so long to make something as it is I have to balance my time vs $$$. The weird thing about these tables is the mounting base slots are not centered to the table. I'm not sure why but I had to make my mounting plates take that offset into consideration because I wanted everything centered on the rails. This way if I wanted to change from convex to concave, just center the arm and lock it and unlock the cutter arm and go. That proved tough to do with the old setup.
It could be different now, but last I checked with the 80/20 site I didn't see to much machinery being made with it. I have seen DIY CNC router tables and that where I got my stash. I guess they had retired their CNC router and we're going to toss the 80/20 frame after they had taken all the goodies of it! Luckily the kid who worked there took it home and then decided to dump it on CL. Score, touchdown
I first viewed your photos on my phone. I am now viewing the same photos with my full size monitor and can see the details and no real need for additional photos. I guess at $30 per rotary table there might be some QC problems but you made it work. Do you use some type of driver connection with a cordless drill to run the rotary table handle on the rotary table that turns the circular parts? This would be similar to what we sometimes do when running the lathe compound in and out for smoothly machining tapers.
Thank you for the ideas.
I was thinking about some kind of driver as I was turning those silly little handles. Probably some kind of coupler setup for a variable speed drill would be the down and dirty for especially work rotating table. It's the hardest to get to and depending on how I'm doing the cut the one that has the longest cut runs. If I was going to build something for the two arms I think I'd go with 1:1 bevel gears and have a straight rod and ball handle like on a drill press or like my Souix valve grinder. That would offer a good mechanical advantage and fast articulation. And when I think about the arm and handle would not foul each other in use. I don't know if I wish I would have thought about that before or it's a good thing I didn't because I'd probably still be trying to figure those out
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