Lathe issues .........please help .

Hello Practical Machinists ,

Its been a while since I have posted on this board but am in hopes you folks could help me sort out my lathe issue . I bought a big dirty Ebay lathe a long time ago , got it running a while back and haven't used it a whole lot and what little use I have had has been short pieces .

The issue : It cuts on a .03 taper at 3 feet !

My findings : I clocked up the ID of tail stock at head stock ( +- .0005 ) , indicated bed rails with carriage but still this big old girl is in and out like a fiddlers elbow .
- placed a long piece of material in , took parallel cuts at the ends on piece and adjusted tail stock to suit . Still the dia. is not constant .

I am up to my ears in local work - I would like to hear your thoughts . BTW its been machine leveled .

todays results :

All I have is a 6" precision ground bar thats approx. 3 " in dia. & chucked it up in 4 jaw , indicated both end diameters and face with interapid then did a carriage sweep along z axis . I then loosened bolts on head stock and adjusted it to to give me a less than .0005 along Z axis .

Next I brought tail stock in and indicated it , adjusted tail stock to suit horizontally and added .029 shim to to achive +- .0005 sweep on ID of tail stock .

After that I placed a 3 ft bar in lathe and made a cut . Still its cuts on almost a .025 taper . If I adjust tail stock over I can achive a +- of .008 over 3 ft .

I leveled my lathe with a 12" starrett machinist level and a 10 " Mitutoyo master level but the part where the tail stock needed .029 to come onto head stock center tells me that this old girl has alot of miles on her .

your thoughts

Scott

Do you have three foot long cuts you need to make?

If the lathe cuts .030 over three feet between centers, move the tailstock on it's base to correct.

If that doesn't do it.

Take the twist out of the bed.

CalG said:

Do you have three foot long cuts you need to make?

If the lathe cuts .030 over three feet between centers, move the tailstock on it's base to correct.

If that doesn't do it.

Take the twist out of the bed.

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Sure do CalG ..........how would I go about taking the twist out of the bed ?

That's a crowning lathe! It's for machining crowns in conveyor pulleys

It must have some very visible bed wear near the headstock? Run the carriage way back on the bed (onto the less used part) and rig up a long arm to suspend an indicator from, and indicate the bed for two or three feet, and see how much drop you get, and if it is a real drop, then the indicator should show a rise back up again when it gets to the unworn area under the chuck. If the bed wear is real, I don't think any amount of fiddling is going to make it cut straight anywhere except way down the bed somewhere.

Also check the carriage for slew when you reverse directions on it. A small amount of slew is normal, maybe .0005 to .001", but I've seen lathes with cracked saddles that had extreme slew factors. If the carriage had worn out Turcite underneath, its a crap shoot about how bad it could be.

If you don't have a manual for the lathe try to get a copy. You may be overlooking a minor detail.
Check all fasteners you are able to reach for proper torque. Especially the ways, bed, etc.
If you floor is flat, try bolting the lathe to the floor.
Does your temp inside the shop vary much?

What a drag .........

I seen something like .025 drop earlier today when indicating the top of bed . So I guess this is what makes a good machinist " being able to turn out a quality part off a worn out lathe " .

Something tells me that I am going to be spending alot of time getting to know this machine before any quality parts are made .

Thanks for the reply

bradinNC said:

If you don't have a manual for the lathe try to get a copy. You may be overlooking a minor detail.
Check all fasteners you are able to reach for proper torque. Especially the ways, bed, etc.
If you floor is flat, try bolting the lathe to the floor.
Does your temp inside the shop vary much?

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I do not know the manuf. , no name plates are visible . Temp is pretty constant from the wood stove but will check all fasteners in the morning .

cheers

windsormw said:

What a drag .........

I seen something like .025 drop earlier today when indicating the top of bed . So I guess this is what makes a good machinist " being able to turn out a quality part off a worn out lathe " .

Something tells me that I am going to be spending alot of time getting to know this machine before any quality parts are made .

Thanks for the reply

Click to expand...

Make a good Machinist from using a worn out lathe ??????????????????
It would Piss me off.

The lathe is a good lathe it is a wacheon made in korea it is a copy of the mori seiki. They were rebadged under several names like Webb, Royal, there is also a version that was made in Tiawan called a cadillac it is a decent lathe as well, pretty sure you have a wacheon. The beds are hard so all the wear should be in the carriage. Is it a gap bed and has the gap been taken out?

jrmach said:

Make a good Machinist from using a worn out lathe ??????????????????
It would Piss me off.

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I have passed the anger stage jrmach ........just looking for a solution at present .

kpotter said:

The lathe is a good lathe it is a wacheon made in korea it is a copy of the mori seiki. They were rebadged under several names like Webb, Royal, there is also a version that was made in Tiawan called a cadillac it is a decent lathe as well, pretty sure you have a wacheon. The beds are hard so all the wear should be in the carriage. Is it a gap bed and has the gap been taken out?

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Wow , your good !

Indeed the ways are hard and no the segment is still in position .

did you use the cross slide lock?
Joe

Has the gap ever been removed? if it has there is a good chance that may be the problem, if it has been removed you will be able to feel the edge on the ways, if it has not been removed the paint will be intack and there should be no edge. That is a very good lathe so I would not give up on it, they are 50 grand for that size of lathe right now.

kpotter said:

Has the gap ever been removed? if it has there is a good chance that may be the problem, if it has been removed you will be able to feel the edge on the ways, if it has not been removed the paint will be intack and there should be no edge. That is a very good lathe so I would not give up on it, they are 50 grand for that size of lathe right now.

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I just got my kids to bed so I'll have to check out segment in the AM . Could you explain a little bit more Kpotter ? The segment is never suppose to be removed ? Whats the purpose of having it if thats the case ?

Thanks for the great replies PM's

A removable gap, is a piece of the lathe bed that can be removed so you can increase the swing of the lathe for a short distance.

If the gap has been removed check that it is fully seated and not proud to the rest of the ways.

They can be removed but it is a very bad idea, I have never seen one go back dead flat. Having the lathe level is super important, just a side note how does the spindel sound, is there any play?

Where did you get the genius idea to screw with the headstock?

I can tell right now that most of what you are doing is just wrong, I bet everything you have done is making things worse. it was better before you fucked with it.

So how man hours you have into this 30 minute job?

keep listening to people about headstocks, twist in beds and gap removal and installation. Once you have screwed up on all of it twice you will know the machine very well.

Ha ha ha , happy learning. In glad you will never touch my lathes.

oldbikerdude37 said:

Where did you get the genius idea to screw with the headstock?

I can tell right now that most of what you are doing is just wrong, I bet everything you have done is making things worse. it was better before you fucked with it.

So how man hours you have into this 30 minute job?

keep listening to people about headstocks, twist in beds and gap removal and installation. Once you have screwed up on all of it twice you will know the machine very well.

Ha ha ha , happy learning. In glad you will never touch my lathes.

Click to expand...

That's fukin cruel.
To the OP,what the oldbiker says, rings truth.The Headstock should of been left alone,especially if not %100 sure of WTF your doing.May I suggest at this point to look in the phone book for help.You could end up chasing a rabbitt here for a long time now.

You need to forget that bullshit about a level. You added .029 at the tailstock because a level said to? That machine could cut perfectly at any angle if left alone.