Its a German made Optimum approx. 26 inch center distance. I was running the power feed at high speed, turning a wood bowl, and let the carriage hit the work. Everything works, but the carriage handwheel is hard to turn and not smooth - worse closer to the chuck, where it happened. Everything looks normal (rack, gears, etc.), and the power feed works fine. I haven't checked parallelism or anything yet. Where should I start?

On Fri, 25 Apr 2014 01:17:00 -0700 (PDT), robobass
wrote:

Its a German made Optimum approx. 26 inch center distance. ...

I assume you have a lead screw and nut in the carriage. Sence the
problem is not aparent away from the point of impact, that leads me to
believe the gearing is OK. Same thing with the nut in the carriage.
I'd look to bent/deformed area in the lead screw. Might be able to use
an old fashion file to true it up again.

Just guessing, need to see it to know for sure.

Karl

It's not in the screw, based on that the screw/half nut isn't engaged when I turn the hand wheel. The roughness is spread over a hand breadth of travel. Rack maybe? If I'm lucky I suppose.

On Sat, 26 Apr 2014 00:35:06 -0700 (PDT),
wrote:

It's not in the screw, based on that the screw/half nut isn't engaged when I turn the hand wheel. The roughness is spread over a hand breadth of travel. Rack maybe? If I'm lucky I suppose.

I'm guessing that you've already checked all surfaces on the ways for
damage and roughness, then ruled that out.

Yes, it sounds more like swarf between the ways and saddle. Try
flooding the ways with light machine oil, loosening the saddle gibs
and running the carriage end to end. It can float out the debris.
Otherwise, you might have to pull the carriage to clean out the swarf.

--
Stoop and you'll be stepped on;
stand tall and you'll be shot at.
-- Carlos A. Urbizo

I'm guessing that you've already checked all surfaces on the ways for

damage and roughness, then ruled that out.



Yes, it sounds more like swarf between the ways and saddle. Try

flooding the ways with light machine oil, loosening the saddle gibs

and running the carriage end to end. It can float out the debris.

Otherwise, you might have to pull the carriage to clean out the swarf.


Yeah, I'm thinking of pulling off the carriage and doing a cleaning and inspection on that end. I only got the 20 year old machine recently, so it would be good to have a look in there anyway. There is play in the gibs.

I loosened the screws on the rack and re-tightened them. I saw no movement. Now the tight spot has disappeared, but the handwheel turns roughly all along the rack. Maybe I bent the gear shaft or the bearing behind the handwheel. I might try replacing the gears and bearing, but a good cleaning and adjustment of the saddle seems like the next logical step.

"Just having the half-nuts disengaged doesn't guarantee it is not
the leadscrew. Bend it just enough and it will bow to drag on one half
of the open half-nuts, thread crest to thread crest. Certainly worth
checking out."

Don, I checked the leadscrew with a dial indicator. Luckily it's still perfectly straight!

On Sun, 27 Apr 2014 01:57:08 -0700 (PDT), robobass
wrote:



I'm guessing that you've already checked all surfaces on the ways for

damage and roughness, then ruled that out.



Yes, it sounds more like swarf between the ways and saddle. Try

flooding the ways with light machine oil, loosening the saddle gibs

and running the carriage end to end. It can float out the debris.

Otherwise, you might have to pull the carriage to clean out the swarf.


Yeah, I'm thinking of pulling off the carriage and doing a cleaning and inspection on that end. I only got the 20 year old machine recently, so it would be good to have a look in there anyway. There is play in the gibs.

With them adjusted properly? Not good, indicates wear.


I loosened the screws on the rack and re-tightened them. I saw no movement. Now the tight spot has disappeared, but the handwheel turns roughly all along the rack. Maybe I bent the gear shaft or the bearing behind the handwheel. I might try replacing the gears and bearing, but a good cleaning and adjustment of the saddle seems like the next logical step.

Time to pop that baby apart and look for scrape marks, bent items,
dragging rollpins, chewed gears, bad thrust bearings, swarf, etc.


"Just having the half-nuts disengaged doesn't guarantee it is not
the leadscrew. Bend it just enough and it will bow to drag on one half
of the open half-nuts, thread crest to thread crest. Certainly worth
checking out."

Don, I checked the leadscrew with a dial indicator. Luckily it's still perfectly straight!

Have someone shove the carriage back and forth while your fingertips
are on the leadscrew. (This type of thing is really hard to do by
yourself. DAMHIKT) If you feel vibration, it's likely hitting.

--
If government were a product,
selling it would be illegal.
--P.J. O'Rourke

On 2014-04-26, wrote:

It's not in the screw, based on that the screw/half nut isn't engaged
when I turn the hand wheel. The roughness is spread over a hand breadth
of travel. Rack maybe? If I'm lucky I suppose.

Just having the half-nuts disengaged doesn't guarantee it is not
the leadscrew. Bend it just enough and it will bow to drag on one half
of the open half-nuts, thread crest to thread crest. Certainly worth
checking out.

Just one of many possibilities, of course.

Good Luck,
DoN.

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