My DIY rack clamps

Post Reply
msimpson
Site Admin
Posts: 3176
Joined: Tue Mar 30, 2004 6:19 pm

My DIY rack clamps

Post by msimpson »

I just posted a piece about my DIY rack clamps. While I am using them on my plasma CNC prototype, I have tested them on my KRMx02 and they work great.


You can see them here:
http://www.kronosrobotics.com/rack-clamps/
baysale976
Posts: 494
Joined: Mon Dec 31, 2012 11:07 am

Re: My DIY rack clamps

Post by baysale976 »

Michael,
it warms my heart to see you making your own components. It just galled me to pay the kind of money they were asking for simple pieces of aluminum, so (as you know) I made almost everything myself. While I do agree that most folks building a KRMx02 don't have their own milling machine and lathe, this clamp is a perfect example of what can be done with hand tools alone.
msimpson
Site Admin
Posts: 3176
Joined: Tue Mar 30, 2004 6:19 pm

Re: My DIY rack clamps

Post by msimpson »

I have a few other things in the works as well. For one, I have been playing with R&P drive reducers.

The latest ones I have are working very well, but I need to make some design changes. I am using a 14.5 pressure angle rack and while it works, its not as smooth as a 20 degree pressure angel rack. The problem is I cant get the a ready made pinion, so I have to by the pinion stock and cut them down myself and tool a section for a couple grub screws.

You can see them here:
http://www.kronosrobotics.com/motor-reducer/
baysale976
Posts: 494
Joined: Mon Dec 31, 2012 11:07 am

Re: My DIY rack clamps

Post by baysale976 »

Nice. Belt drive is definitely the way to go, for vibration, smoothness, noise. And it is a mechanical fuse so the gear teeth don't break off.

Delrin may end up being stiffer than Corian. Aluminum, of course, even more so. 1/8" is likely thick enough for that. Still, performance is right where you need it.

I've attached my cheapskate answer to a turnbuckle. You can't see the nut on the bottom piece. That's aluminum flashing material, plenty strong for the purpose and easy to work (cuts with scissors). Just tighten the screw to adjust.
Attachments
IMG_0305.jpg
msimpson
Site Admin
Posts: 3176
Joined: Tue Mar 30, 2004 6:19 pm

Re: My DIY rack clamps

Post by msimpson »

Do you mean belt drive on the reducer? If so its the only way to go if you want to keep backlash down to near zero. On my original design I used a belt drive system instead of the R&P. They dont scale well. The longer the belt the more it stretches and thus you get a lot of wiggle. On top of that as you change the tension on the belt, you have to re-calibrate the machine.

I wanted to design a reduction system where you could pop in what ever main gear you want. This would allow you to select the torque/accuracy/speed to suit the kind of use you will be doing with the machine. For example the one I am using has a 2.5:1 reduction. Thats a good range for a router/plasma. If I were going to be cutting a lot of aluminum I would try for a 5:1.

Also once I get things ironed out, I will switch to aluminum. Its much cheaper using scrap Corian than it is to use aluminum to work out the kinks.

Is that a CNCRouterParts R&P drive? If not where did you get the main gear/pinion?
baysale976
Posts: 494
Joined: Mon Dec 31, 2012 11:07 am

Re: My DIY rack clamps

Post by baysale976 »

Yes, belt drive on the reducer. You are spot on about belt drive instead of R&P.

That's a CNCRouterParts pinion and gear set (and belt) with my own chunk of aluminum and some 'fancy' lathe work. I have a 4-jaw chuck and know how to use it... :wink:

IIRC they sold those as spare parts, or maybe it was an upgrade kit? The pivot bolt is from McMaster. I mean, it's just a couple of holes in a metal plate.
Post Reply

Return to “General CNC”