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Simple and easy method of checking wear on lathe bed ways

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dlkuzara

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#1
I've found the easiest way to check how much wear is on a lathe bed is to use the tail stock ways as the reference. Since the tail stock ways usually have minimal wear, those ways can be used as a reference for the carriage ways, which can have significant wear, usually over a span of a foot or so near the spindle. In the case of my '40's Wards lathe (made by Logan), the ways were not flame hardened, probably due to "value engineering" to keep the costs down, and had over 20 thousandths dip in both the V and flat ways. I eventually found an almost new bed ($90) which solved the problem.

To measure the wear, I move the carriage to the extreme left, fasten a 1/10th thousandth dial indicator base to the tail stock, put the indicator point on the way to be measured and slide the tail stock from end to end measuring how much dip is on the carriage way. There is usually minimal wear on the right side carriage ways and you can watch the needle dip right where you would expect the wear to be. It works well for both the flat way and the V way. I measure the V way at the 50% point. It is critical that the indicator base does not move while measuring the V way. As such, a magnetic base is not sufficient, mostly because of the thick paint used on castings, so the best method I found was to C-clamp the indicator base to the tail stock.

Last week I used this method to check the ways on a 12X36 Enco for a friend, which indicated about 6 thousandths max droop. As a result the dealer knocked $500 off the price while learning how to measure the wear on the ways.

My original intent, before I found the pristine base, was to set up a grinder to reshape the bed ways on the Wards lathe, (stripped down, of course) again using the tail stock base as a platform for the grinder, but I never got that far, so at this point it is just theory.
 

Charles Spencer

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#2
There are, no doubt, some theoretical or professional reasons why this isn't accurate. However to me it seems that you have come up with a simple and quick way to check used equipment.
 
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#3
It gives you a "ball park" indication of wear of bed ways. With harden and ground ways it somewhat holds true. A word of caution, this is not always the truth! I've seen and dealt with lathes that the tailstock ways had just as much wear as the carriage ways had. The only real way to check for the amount of wear in the bed ways, other than putting the bed on a planer or surface grinder, is to make a fixture that has a 3-point arrangement that would guide on the non-worn portion of the bed adjacent to the bed ways. And I'm not talking about using the Kingway fixture that rides on the ways. Ken
 

dlkuzara

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There are, no doubt, some theoretical or professional reasons why this isn't accurate. However to me it seems that you have come up with a simple and quick way to check used equipment.
At the beginning I bought a 24" parallel and used feeler gages to check the ways. The tailstock ways had almost zero wear which gave me the idea for using them as the reference. The tailstock method verified the 24" parallel method, however I believe the tailstock method is faster and more accurate plus there is no need for the very expensive parallel.
 

tq60

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The easy way is move the carriage close to the chuck and tighten down the lock gently then loosen it just enough to move the carriage.

Now work back and forth while checking by tightening the lock to get the lowest spot and here it can move just a bit and stop.

You now can loosen a bit and move it until it stops and this will give you a wear pattern.

When you get past the wear it will slide easily to the end.

How much wear...?...

Say 1/2 turn and we are just making things up and too lazy for math but the idea...

Remove the bolt for the carriage lock and count the threads per inch.

From this determine how far it moves per turn.

Now determine how far that 1/4 turn would be.

A micrometer is nothing more than a precision c clamp with accurate scale to indicate how far you turned it so the theroy works but is not as precise but can be an estimate.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 
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At the beginning I bought a 24" parallel and used feeler gages to check the ways. The tailstock ways had almost zero wear which gave me the idea for using them as the reference. The tailstock method verified the 24" parallel method, however I believe the tailstock method is faster and more accurate plus there is no need for the very expensive parallel.
I disagree. You need something there, like a precision straight edge or camelback straight edge preferred, to verify that the tailstock ways are reasonably flat and straight. Not knowing that, still leaves that "fuzzy" number in the back of your head. I guess it depends on how accurate are you looking for? Machine tool accuracy when it left the factory, no. Good enough for us H-M, yes! Ken
 

KBeitz

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#7
Cheap and dirty.... Shoot a laser beam across the bed and slip a feeler under the beam...
 

MSD0

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#8
Wouldn’t the tailstock just follow the dip (to some extent anyways)?
 

KBeitz

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#9
Some.... Not all lathes have a different part of the bed wayx that the tailstock rides on...
 

Richard King 2

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#10
I have been telling folks to do something similar for years. The TS ways under the chuck and on the far right are seldom worn. Have to stone the dings off under the chuck first. Then dismantle the tailstock base and use it as a "sled" to mount a mag base and indicator the bed from this platform. But you need to first take the twist out of the bed by setting a precision on the TS base sled and then put an equal amount of weight on the leveling screws. Then starting on the check end zero level, use a magic marker to draw exactly where the level was sitting on the base. Try to pic it up and lift it up and over the saddle and go to the tail stock end. adjust the bed to zero the level. This may take a few tries as the bed twists up by the chuck. Then check the tailstock ways as they will be worn in the middle. I have someone knocking on my door....be back later. Please renew Ken's membership... I am sure he regrets what happened.
 

bhigdog

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You guys got me wondering about my LeBlond 13" Regal. It's precision leveled so should not be twisted. To check the bed ways wear I used a length of flat ground stock laid edge down on the ways. Stock showed no bow when checked for flatness on a granite surface plate. Max wear was .002 about 6" from the chuck by feeler gauge. .002 gauge lite drag, .0025 gauge was tight. Simple check and way close enough for what I do................Bob
 

Richard King 2

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#12
A simple way to check for twist is to set a level on the top of saddle wings when the saddle is up as far as you can crank it to the left and slide a feeler gage under the low side until it reads level. Then crank the saddle to the right and stop every 6" and see what happens.
 

markba633csi

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#14
Regarding the procedure in post #1 : A more comprehensive test would be to remove the carriage completely
M
 

warrjon

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#15
When I bought my 1967 Colchester (It was not installed just sat on the floor of a machinery dealer) I checked for way wear by moving the saddle to to the left nipping the saddle lock so there was just drag and moved the saddle to the right. The saddle got tight but I could still move it so I guessed the wear was minimal.

When I had the lathe installed and adjusted. Just for the hell of it I put a mag base on the cross slide at the front then the rear over the ways and indicated off the tailstock spindle, using the saddle to move the tailstock, measured 0.02mm rear 0.03mm front.
 
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