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 Post subject: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 11:54 am 
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Location: Miami
I am still dithering on the issue of replacing my old Clausing vs. putting an ELS on it. I thought I was sure I wanted a different lathe, but now I'm having second thoughts.

Can anyone give me (or direct me to) a really sound way to check the wear on an old lathe? I've seen people say fairly dumb things, like "look at the ways," but I can't detect .003" of wear just by staring. I've read that the screws and half-nuts wear inside the machines, and that wouldn't be obvious from the outside. And for all I know, the hardened ways might be the last things to show wear.

Yesterday I put calipers on the lead screw, checking the diameter at both ends. I figured a worn lathe would have a lead screw that was narrower near the chuck. I couldn't find any difference. I've read that cross slide screws get "hourglassed," and I assume that means they get worn in the middle, screwing up accuracy as you go across a piece. Should I check that by taking the cross slide apart, or is it sufficient to face a wide part and see how flat it is?

I really want to have at least one electronic lathe, whether it's the tiny Big Dog or something bigger. There are too many cool things about electronic control to pass up. I don't think I'd want to put ELS or CNC on a really nice 14" lathe, though. I'd be afraid I was butchering it. If the Clausing gets messed up, it's not a big deal. I could part it out for more than I paid. If it's not too worn to do good work, maybe ELS is the answer.

This is a tougher choice than I anticipated. It's stupid to take on projects you are not likely to be able to handle in a reasonable amount of time, and that's the main reason I would hesitate to convert a lathe. It's also stupid to waste money on machinery that limits what you can do, and that also makes me want to get a different lathe. Finally, it's stupid to blame your tools instead of improving them and enhancing your skills, so that's a good reason to fix the Clausing. So I'm balancing the stupidity of each course of action against those of of the others.

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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 12:40 pm 
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I've been fooling around with the calipers. The keyway in the lead screw is .008" bigger up near the chuck. Going by feel, the backlash in the cross slide seems to be about 0.034". The backlash in the compound feels like about .017". I can move the apron when the half-nuts are engaged. Haven't measured the movement.

Edit: looks like the apron will move about .026" when the half-nuts are engaged.

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"A man who can't handle tools is not a man. You're disgusting." -- Willy Loman, in Death of a Salesman


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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 12:54 pm 
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Joined: Sun Jun 27, 2010 10:43 pm
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Location: pendleton or
i have seen machines with a lot of wear still turning out acceptable work in a repair environment, not harolds precission world. :lol:
if you can find a copy, machine tool reconditioning could be a good book to explore.


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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 1:02 pm 
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The seller told me it looked like it had seen "very little use." I have to wonder what that means, to a machine dealer.

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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 1:48 pm 
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I found out how to measure the bed wear. I put an indicator on the apron and put the tip on the flat way where the tailstock rides. Presumably this flat area has zero wear near the chuck, since you can't really get the tailstock up there. I got a figure of 0.003". I think it might have gone higher, but there is a limit to how far I can push the apron with the chuck and indicator in the way.

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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 2:04 pm 
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Location: Phoenix, AZ
SteveHGraham wrote:
The seller told me it looked like it had seen "very little use." I have to wonder what that means, to a machine dealer.

It means that it runs without too much banging or whine, and that the wear is not visible to the naked eye from 20 feet away in dim light. Oh, did you think the dim light in all such places was just an accident? ;) Caveat emptor was never more appropriate, except maybe at a used car lot. With a few exceptions, there's usually not much difference really...

As for determining and quantifying wear, that is a VERY long discussion with lots of dissent.

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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 2:09 pm 
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Well, I got this from ______, and I trusted his reputation.

Edited to remove dealer's name.

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"A man who can't handle tools is not a man. You're disgusting." -- Willy Loman, in Death of a Salesman


Last edited by SteveHGraham on Fri Dec 30, 2011 4:19 pm, edited 1 time in total.

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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 2:32 pm 
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From what I've heard, he's one of the good ones. There are a few out there. The guy I hang out with locally is also a good one. I've seen him tell a new guy who thought a machine was a "good project" and was wanting to buy that he really should look for something else. Basically talk the guy out of the sale. But we've got a few others here that would put sawdust in a differential to quiet it for sale...

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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 3:20 pm 
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I decided to edit this and remove most of the details of my bad experience with the guy who sold me my lathe.

My experience with him was not very good. He was rude when I pointed out that he had sold me a 5936 instead of a 5914, and he did not offer to cover all of the shipping to take it back.

*Stuff Deleted*

Primarily, though, my problems with the lathe were caused by my own lack of knowledge. I think the wear is beyond what he implied, but the main problem is that it's just not the best choice for my needs, regardless of condition. I can't blame him for that.

*Stuff Deleted*

I guarantee you, if Grizzly had sent me the wrong lathe, a truck would have been dispatched to take it back, free of charge.

Never deal with anyone who won't take a credit card. That's one lesson I learned. If someone refuses to take credit cards, it's a good sign that they have had so many dissatisfied customers, they are no longer willing to risk charge-backs. I saw what I thought was a little-used Clausing for a low price, and I got all excited and decided to take a chance. That was stupid. If it had been American Express, I could have cancelled the charge and let him come get the lathe.

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"A man who can't handle tools is not a man. You're disgusting." -- Willy Loman, in Death of a Salesman


Last edited by SteveHGraham on Fri Dec 30, 2011 4:23 pm, edited 1 time in total.

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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 3:36 pm 
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Joined: Fri Dec 22, 2006 5:41 pm
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Location: Lewes, DE
Hi There,

I dealt with Joe a few times and he is alright. Maybe a little
on the optimistic side perhaps when it comes to his merchandise
but most sales people are.

Are you judging "backlash" by your dials on the cross feed and
compound? Remember, they are "direct reading" dials and are
calibrated double the movement of the screw. Hence, .034" of
cross slide backlash measure with the dial is actually only .017"
of real movement.

Measuring bed wear via the dial indicator on the saddle and the
button of the tailstock flat way isn't an accurate way to tell real
wear. It is just an indicator that there is some wear. It all depends
how the wear is distributed. If the .003" wear is "straight down" wear,
the impact on accuracy is negligible. But wear isn't usually "straight
down." So, it depends on whether the saddle is moving in or out as
it is moving down due to the wear.

The pressures created during machining push the saddle down and
away from the work so, the wear usually is not just down, but also
slightly away from the work. Also, the flat way of the saddle doesn't
usually wear as much as the prismatic way of the saddle because
the pressure of cutting is transmitted more to the front prismatic way
than the rear flat way. And the two side of the prismatic way don't
usually wear evenly either. The inside portion wears more than the
outside portion.

All this means is the .003" measurement isn't just downward movement
but is an indication of a compounding of movements.

Good Luck!
-Blue Chips-
Webb


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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 3:47 pm 
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Thanks for the info. You're right; on the cross slide and compound, I did not account for the fact that they measure diameter, not radius. Thanks for pointing that out.

I don't know how I'd measure the sideways motion of the apron. Maybe put an indicator on it and turn something?

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"A man who can't handle tools is not a man. You're disgusting." -- Willy Loman, in Death of a Salesman


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 Post subject: Re: Measuring Lathe Wear
PostPosted: Fri Dec 30, 2011 4:20 pm 
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On reflection, I decided to remove the name of the business from this thread.

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