PDA

View Full Version : Handling backlash when boring on M/D



nheng
03-24-2005, 05:31 PM
I was considering building a nice, compact, power downfeed for my mill/drill when it suddenly struck me that it has an atrocious amounts of backlash.

It seems to me that to implement power downfeed, you've got to take positive measures to all but eliminate the backlash.

Has anyone been there and done that? Den

IOWOLF
03-24-2005, 05:39 PM
I was thinking of doing that to mY m/d before I got my index mill.

I was going to use an electric hospital bed screw drive unit, it is like a small electric hydrualic cylinder.

nheng
03-24-2005, 05:51 PM
That's a good idea.

I was thinking of cheap and simple, using the existing rack but hadn't thought about bypassing it with a different drive. And I guess it doesn't need to be a very long screw.

A plastic nut clamping a screw would remove all backlash.

torker
03-24-2005, 06:35 PM
Den...I don't know if you saw the power feed I built for my mill/drill but mine has no backlash issues. If you have the gearing right it holds constant load on the quill. Yours may be really loose so it could be a problem. If you have around 130 to 150 to 1 reduction it will likely overpower the backlash anyway.
http://img.photobucket.com/albums/v210/torker/155fbcc7.jpg
Russ

nheng
03-24-2005, 06:47 PM
Russ, The downward feed pressure prevents backward travel but the quill has play relative to the micrometer dial, doesn't yours (maybe the return spring is compensating for it)?

Unrelated to the original question, I've got a small (400:1) dc gearhead motor and will probably have a fast shuttle up/down rocker switch (since the handwheel is gone) and a pot to control feed rate for normal operation.

[This message has been edited by nheng (edited 03-24-2005).]

torker
03-24-2005, 07:01 PM
Den, sounds like you are on the right track. I've bored a few 2 1/2" holes in 1" thick "mystery metal" that was pretty tough. Had no problems with backlash. And, yes..my handwheel probably has the usual amount of backlash. I'll check it later but I'm sure it's a lot. I have a forward/reverse switch on mine and a pot as you say. Very nice setup. The rapid return is nice!
Russ