Mori Seiki SL-3 turret alignment question

isaac338 · Oct 14, 2017

I've noticed some things with my lathe that point to a turret being radially misaligned (oversize drilled holes etc). I indicated it per the manual I have, indicating an OD turning pocket in the turret in X, and it's straight to .0005 across its length. However, if I sweep a boring bar holder, they're consistently .003-.004 out in Y.

I would assume this points to the holders not seating properly (burr, chip, whatever), but it's consistent on every holder in every position, which looks more like turret misalignment.

When I got the machine it had some damage indicative of a massive crash, so I fully expected the turret to be way out of whack, so why are my readings like this?

Anyone have any thoughts?

ewlsey · Oct 14, 2017

Your curvic coupling is out. Your spindle may also be out. You need to do a full alignment.

isaac338 · Oct 14, 2017

ewlsey said:
Your curvic coupling is out. Your spindle may also be out. You need to do a full alignment.

Yeah that's what I figured.. I guess I just don't know why the straight pockets indicate fine but the boring bar holders are out. I suppose any error in the straight pockets would be amplified farther out where the holders are..

Anyways looks like I have some measuring and tapping to do.

ewlsey · Oct 14, 2017

Which way is it out in Y? If it's low, it could be wear in the X axis (or Z axis for that matter). If the spindle is out of alignment you can get all kinds of strange readings.

isaac338 · Oct 14, 2017

It's high. The machine doesn't seem to have tons of wear, it just had some spindle drive problems and crash damage when I bought it. It was hit hard enough to break things so I wouldn't be surprised if the headstock moved a lot.

I'll start with checking level and aligning the headstock and going from there I guess. Thanks for your input.

Bill in PA · Oct 14, 2017

A turret alignment is normal maintenance. The parts book will show you where the taper pins are located. On my SL-1 the pins are behind the turret. I think they are in front on the larger machines. Some say ream and put new pins in, some say leave the pins out. I left them out last time I aligned the turret.

The turrets get knocked high when run into the chuck.

It's an easy fix.

Bill

isaac338 · Oct 15, 2017

They're behind on the big ones, too. You've got to remove the turret disk, loosen the bolts and pull the pins, put the turret disk back on to indicate, then take it off to tighten things up. Sounds like one hell of a process.

litlerob1 · Oct 15, 2017

If it's the first time, it's a bitch. But it is normal, and should not be considered damage, it's adjustment or tuning. BEFORE you deal with the turret, make sure the headstock is right though. You get into the turret think you have it all lined up, still have problems, figure out it's the headstock, fix that, then have to align the turret again.

R

isaac338 · Oct 15, 2017

I turned a 2" bar over 2.5" and measure about .0011 of taper, so just under five tenths per inch. I suppose the headstock is a bit out. Are any of you guys familiar with adjusting it on an SL-3?

I can see the headstock mount bolts but I'm not sure which are the jack bolts and I'd really obviously not like to make it worse than it already is.

litlerob1 · Oct 15, 2017

isaac338 said:
I turned a 2" bar over 2.5" and measure about .0011 of taper, so just under five tenths per inch. I suppose the headstock is a bit out. Are any of you guys familiar with adjusting it on an SL-3?

I can see the headstock mount bolts but I'm not sure which are the jack bolts and I'd really obviously not like to make it worse than it already is.

Yep, first take the Chuck/Closer off. Run an indicator on the taper of the spindle and the face of the spindle and see where that is. It should be listed in the maintenance manual, I would guess .00005" for each would be the limit for error, but that is an old lathe soooooo?

Usually (not always) what happens is the Chuck has barely moved in the spindle . But that means there is somewhere that it is allowed to move (dings, trash, used condoms whatever get in there). So a thorough inspection of the mating surfaces is critical. If you are getting excessive TIR in the taper and face, then you need to ask someone more gooder than me.

R

ewlsey · Oct 15, 2017

That's not horrible, but you'd like it to be less than .001 per foot. Typically there are 4 or 6 hold down bolts and 2 pairs of push pull screws. The hold down bolts will be big, like M16 or M20. The push pulls will be M8 or M10. You may need to remove the sheet metal over the spindle to get access to all of the bolts.

isaac338 · Oct 15, 2017

ewlsey said:
That's not horrible, but you'd like it to be less than .001 per foot. Typically there are 4 or 6 hold down bolts and 2 pairs of push pull screws. The hold down bolts will be big, like M16 or M20. The push pulls will be M8 or M10. You may need to remove the sheet metal over the spindle to get access to all of the bolts.

I can see the 6 hold down bolts, and at the top there are two sets of bolts, one at each end of the headstock casting, and in each set is a SHCS and a set screw next to each other. I'm assuming the SHCS is the pull screw and the set screw the push? I can post pictures if it's easier.

It seems straightforward then, loosen the hold down bolts, push or pull the headstock fore or aft with the bolts, tighten everything down, take a test cut, repeat.

isaac338 · Oct 15, 2017

litlerob1 said:
Yep, first take the Chuck/Closer off. Run an indicator on the taper of the spindle and the face of the spindle and see where that is. It should be listed in the maintenance manual, I would guess .00005" for each would be the limit for error, but that is an old lathe soooooo?

Usually (not always) what happens is the Chuck has barely moved in the spindle . But that means there is somewhere that it is allowed to move (dings, trash, used condoms whatever get in there). So a thorough inspection of the mating surfaces is critical. If you are getting excessive TIR in the taper and face, then you need to ask someone more gooder than me.

R

Makes sense - I need to pull the chuck and clean it up anyways so I'll do that before I move the headstock around.

Thanks.

isaac338 · Oct 16, 2017

Ok, I've been playing with aligning the turret and am having trouble interpreting what I'm seeing.

If I line up a stick tool holder by jogging in X, I can get it within a tenth or two. But, if I then indicate a boring bar holder, I'm high by .003-.004.

If I get that holder lined up and then indicate another, I'm high by .003 or so.

I've stoned the mount faces and holders and made sure they're pretty clean; is within .003 as good as it's gonna get? Should I just mount a few holders and average the error between all of them?

Also, it's worth noting that these readings are repeatable so I don't think the curvic is moving around when I index the turret.

ewlsey · Oct 16, 2017

How are you indicating the boring bar station? I wonder if you are seeing some indicator sag. That will make it look high.

I prefer to mount the indicator to the chuck and use a test bar in the boring bar station.

isaac338 · Oct 16, 2017

Clamping the stem of an Interapid in the chuck jaws and indicating inside the pocket of the holder. I was using an indicator holder but decided minimizing overhang was probably better.

For the stick holders I was using a tenths indicator on a holder, but that shouldn't sag since it's stationary, I'm assuming.

Vancbiker · Oct 16, 2017

I've seen machines that the turret assembly to X slide mounting surface was "raised" around the bolt holes by crashing. Then when you lined up a "stick tool" pocket the ID holders were high. Might be what you are seeing too.

litlerob1 · Oct 16, 2017

isaac338 said:
Ok, I've been playing with aligning the turret and am having trouble interpreting what I'm seeing.

If I line up a stick tool holder by jogging in X, I can get it within a tenth or two. But, if I then indicate a boring bar holder, I'm high by .003-.004.

If I get that holder lined up and then indicate another, I'm high by .003 or so.

I've stoned the mount faces and holders and made sure they're pretty clean; is within .003 as good as it's gonna get? Should I just mount a few holders and average the error between all of them?

Also, it's worth noting that these readings are repeatable so I don't think the curvic is moving around when I index the turret.

There is a part of me that wants to say .003"!!!!! on a 30 year old machine!!! leave it alone and run with it.

There is another part that says, while you are in it, you may as well do it right. USER DISCRETION

Nothing is perfect including the Hirth! After time things wear. But if I were in Utah and you were in Canada on the East side of the Continent, I would guess that it is the tool blocks and Turret mounting surfaces that are giving you error. The "bolt on" type tool blocks have a lot of potential for mis-mounting, wear on the alignment keys, and raised holes like the Biker said.

It is more important to me to have the ID tools on center than it is to have the OD tools on center. (that's just me) But I build some really small parts.

R

spock · Oct 17, 2017

You may want to also keep in mind that on a 30 year old SL3 (I have one), you probably have quite a bit of wear on the ways, increasing as you get closer to the chuck. May not come into play with what you are doing now, but when you finish and go to set your grid shift.......

isaac338 · Oct 17, 2017

I agree guys.. it is an old machine so I'm going to try to get a few holders within .002-.003 and call it good.

Thanks for all the tips!

Mori Seiki SL-3 turret alignment question

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