Checking My Nuts

[EdK]

Since the mill power feed is on hold until a bigger lathe dog arrives, I decided to try to find out why my mill table has so much slop in it. I took the table off to look at my nut. Couldn't see much with all of the grease and oil on it so I removed it from the saddle and cleaned it up the best I could with denatured alcohol. The threads are worn so bad they look like pointed threads instead of acme or trapezoid threads. No wonder there's so much slop in the lead screw. The good thing is that the surface where the nut mounts on the saddle is a ground surface, unlike the raw cast iron surface that was on my lathe cross slide. I doubt replacement parts are available since the mill is 6 years old but I'll contact Enco and see what they say. Otherwise I might try Grizzly and see if they have something that might work. I haven't even tackled the cross feed which should be in worse shape since it seems to have the most slop in it.

The lead screw measures about .941" according to my micrometer. It's 10TPI and the closest acme thread to those specs would be a 15/16 x 10 TPI. That's a rare bird. The closest metric lead screw would be a 24M x 2.54, another rare bird.  

Bummer, time to start searching for parts.

Ed

         


         

[Highpower]

(02-15-2015, 05:53 PM)EdK Wrote: The lead screw measures about .941" according to my micrometer. It's 10TPI and the closest acme thread to those specs would be a 15/16 x 10 TPI. That's a rare bird. The closest metric lead screw would be a 24M x 2.54, another rare bird.  

Bummer, time to start searching for parts.

Ed

That is a bummer Ed. You may be facing the same problem I ran into with my lathe tail stock.  Enco said the shaft was discontinued and no longer available. (Of course.)  I had the local experts in town http://www.roton.com/ scratching their heads for awhile when I walked in looking for a replacement length of shaft. Turns out my tail stock lead screw had a metric diameter but had a ANSI/ASME thread pitch. 

So I wound up going to a slightly larger ASME diameter shaft and nut and machined a new shaft.

[EdK]

I wish I knew for sure if it's metric or imperial.

Ed

[PixMan]

I hear there's a guy over in central MA who willingly makes new replacement screws and nuts for his friends' machines for the cost of material and shipping.

And he sometimes forgets the material part if it's already on hand and didn't cost him anything.

You should try and find that guy, though I hear he's a bit of a pompous arse.

[Dr Stan]

Given you have imperial dials with one full turn equaling 0.100" you probably also have a metric diameter with an imperial pitch, 10 TPI. There is a acme threaded rod manufacturer somewhere near Minneapolis/St Paul or in a town in Wisconsin on the lake from whom I've purchased odd ball V form and acme threaded rod and nuts. Just cannot remember the name of the company.

In any case I recommend you switch to 1"-10 acme rod and make or purchase the appropriate nuts. If you cannot find precision threaded rod, if you do not already have a DRO on the mill now would be and excellent reason.

[EdK]

Thanks for the thoughts guys. I'm going to see what Enco says and then go from there. The lead screw looks to be in good shape so I'd only need new nuts.

Ed

[f350ca]

Same as Willie ran into, my compound I had to fix was metric dia with english tpi to get the dials right. Might want to have a close look at it, it could well be a metric thread form cut at 30 deg as mine was.

[EdK]

(02-15-2015, 08:17 PM)f350ca Wrote: Same as Willie ran into, my compound I had to fix was metric dial with English tpi to get the dials right. Might want to have a close look at it, it could well be a metric thread form cut at 30 deg as mine was.

How would you measure the angle of the thread?

Ed

[PixMan]

(02-15-2015, 08:37 PM)EdK Wrote:

(02-15-2015, 08:17 PM)f350ca Wrote: Same as Willie ran into, my compound I had to fix was metric dial with English tpi to get the dials right. Might want to have a close look at it, it could well be a metric thread form cut at 30 deg as mine was.

How would you measure the angle of the thread?  

Ed

Only two ways I can think of. One, an optical comparator is the quickest and likely most accurate. I don't have one of those either. Yet.

Other than that, grind a HSS tool at 29º and one at 30º and see which fits better?

If you send me both parts I can make a nut to fit the otherwise good screw.

Or, take this opportunity to fit a ballscrew? Or is that "as casting pearls before swine"?

[Dr Stan]

This may be the company I've used in the past:

http://eandrmfg.com/