# Craftsman 101.07381 headstock alignment



## fast204 (Jan 26, 2018)

Hello all. I have an alignment question. My 12" craftsman lathe had a babbit bearing headstock, the bearings were shot so I replaced it with a timken roller unit. I have found that when turning ods I have a .002" taper consistently. The larger diameter being on the tailstock end of the work piece. I have wear on the ways but have tested at different spots with the same result. 
Is it safe to assume the headstock needs to be trued? How do I test this? And can it be done?

All work was done without the tailstock.


----------



## markba633csi (Jan 26, 2018)

I have the same problem on my little 6" and like you I have swapped heads also.  I don't know if the factory hand-fitted each head to bed but I suspect it may be a batch issue.  
Only way to correct it is to carefully remove material on the headstock boss that engages with the bed such that the headstock will rotate toward you (clockwise if you are looking down on it)  a tiny amount to bring it back to perfect alignment, the resulting gap on the diagonal corners would have to be filled with epoxy or similar.  How much patience you got? 
Mark S.


----------



## fast204 (Jan 26, 2018)

I have a good bit of patience and some time. I was hoping it might be a matter of loosening the 3 bolts from headstock to bed and torqueing them in a different pattern but I'm open to explore the option.


----------



## westsailpat (Jan 26, 2018)

A easy quick check , mount your face plate on the spindle , put a indicator in the tool post and drag it along the face plate .


----------



## fast204 (Jan 26, 2018)

If I can find the face plate I will try that. Would it work the same indicating the left and right face of my 3 jaw chuck??


----------



## Bob Korves (Jan 26, 2018)

.002" taper over what distance?  Without the stock being supported by a tailstock center, deflection caused by tool pressure can push the work away more the further you get from the headstock.  If that is what is happening, you are seeing workpiece deflection, not a lathe error.  Adding a tailstock center can help, or not, the tailstock has to be set up to be in line with the spindle axis of the lathe or it will cause its own errors.  What kind of stock (size, material), and what kind of tooling setup do you have when making the cuts?


----------



## fast204 (Jan 26, 2018)

Using hand ground hss small nose radius. Cutting anything from 1/2" 1018 cold rolled bar to 1 1/2" 6061. Have even done some brass bar stock. Still seem to be getting this .001"_.002" taper. Always bigger on the tailstock side.


----------



## fast204 (Jan 27, 2018)

The .002" taper is over roughly 3".  After work tonight I ran an indicator over the face of my 3 jaw chuck. I'm getting a .0045" error from operator side to the rear of the lathe (motor side). 

I removed the chuck and indicated the face of the spindle. From front to back was less than .0005". TIR is basically 0.000. I moved to the farthest point of the spindle where the step is and had the same results. ?  I wonder if it is the worn bed or the even more worn second hand chuck.


----------



## cjtoombs (Jan 27, 2018)

The headstock on my 12" Atlas/Craftsman was on crooked from the factory.  I made a test bar on another lathe and use that with a dial indicator on the carriage to measure it.  I had to do some filing on the indexing ledge that mates with the lathe bed.  This involved a lot of removing the headtstock, filing a bit, reinstalling it and checking the test bar until it was right.  It was a bit of a pain, but it can be done.


----------



## fast204 (Jan 27, 2018)

Or maybe I'm looking at the results wrong. The spindle seems to be dead on but the measurement with the chuck on puts it roughly .004" out on the motor side of the lathe. This would have me cutting a taper that is larger on the chuck side of the work being held?


----------



## Round in circles (Jan 27, 2018)

I think I'm right when I say .... 
Make sure the cutting  tool is held tight in the tool post & that the tool post is locked tight on the cross slide  ( some times the tool post rotates a fraction ) Then make sure your saddle gibs are also set correctly  a loose saddle can  give some wacky  turning results .
If all these are hunky dory .....
 First ensure that the tailstock gibs are correctly set & that the tail stock slides freely when  unclamped & the way is cleaned & oiled  but not too easily when only very lightly clamped up .

Have you tried adjusting the tailstock adjustment screws after slackening off the main tail stock clamp  .
To get rid of the large end of the taper at the tailstock end move the tail stick a tiny smidgeon towards  the back of the lathe then turn up a six inch test piece & check it .
 You'll usually find that you will get different trueness  the further you move the tailsotock away from the head stock .
So make up a set of 3, 6 .9 ,12 ,15 " etc test bars so that you can quickly adjust to true  when you need greatr accurate turning over the  changed distances


----------



## fast204 (Jan 27, 2018)

Round in circles,
The taper experienced is without the tailstock engaged. The other mentioned tips are helpful. I have been making sure to lock the gibs down while turning.


----------



## westsailpat (Jan 27, 2018)

I think you are on to it fast204 , the 0 to .004 on the chuck is a indication of the misalignment . What is the dia . of the chuck ? The spindle snout is too small of a dia. to help .


----------



## fast204 (Jan 27, 2018)

The chuck is 6".


----------



## westsailpat (Jan 27, 2018)

OK , I would  get it dialed in and see how that works . The bigger the distance the easier it will be to get dialed in .


----------



## fast204 (Jan 27, 2018)

Now the thousandth dollar question.... What's the most effective way to do this. An earlier post by cjtoombs seems the only logical way to get it done although labor intensive I don't see another option. Any options are on the table. Short of sending it out of course. 
Thanks


----------



## markba633csi (Jan 28, 2018)

First thing would be to take the headstock off the bed and inspect where it engages with the bed; see if there's a burr or debris there. Then reassemble and test again.  If trimming is needed it will be a very small amount so go slow. Having a collet and a test bar would speed things up since you wouldn't have to remount the chuck each time.
Mark


----------



## fast204 (Jan 28, 2018)

I removed the headstock, with a bit of self dissapointment found a good deal of grease and a few metal chips crammed into the headstock. Cleaned everything with degreaser then lightly stoned all mating surfaces. 
The next cuts had me in the same boat. Out about .002" over 2.00 inches. I removed the headstock and took 3 light strokes with a fine file on the back left and front right, followed by a light stoning. 

I never removed the test piece of 6061 1 1/4" stock. The headstock was placed in position and snugged  while using a dial indicator to offset what I had measured by .0015" roughly. 

By the time I got that done it was movie day with the family. Once I get the boy to bed I will repeat the test and post results.


----------



## markba633csi (Jan 28, 2018)

Sounds good, just lather, rinse, repeat. When the error starts to diminish you'll have a better idea how much more filing is required
Mark
ps actually, let me correct that: when your arm starts getting tired, you're about halfway done.


----------



## fast204 (Jan 30, 2018)

Well you were not kidding. 2 nights spent with a fine file an even finer stone and I'm getting to the point where the finish of the test passes is playing a part in the readings.
I believe its safe to say I went .0005" to far. 

I know for the purely hobby work I do this far exceeds what I need but my OCD kicked in so I will continue down this road for a bit.

I did find I am able to manipulate about .001 +- depending on which bolt I torque first. I have a feeling this is introducing some twist but I'm not sure how or what direction.


----------



## wa5cab (Jan 31, 2018)

By the way, no one has yet mentioned checking the bed for twist with a machinists level.  The bed doesn't actually have to be level in order to work OK but it does have to be straight.  And a level is the cheapest way to do that.  Under $150 for an acceptable grade of level versus over $10K for anything else.


----------



## fast204 (Jan 31, 2018)

I took your advice maybe a year ago when we spoke about building the bench it sits on and borrowed 1 from a machine shop I had worked at. My new one purchased from msc is in the mail. I will double check now that I have removed the headstock and remounted as many times as I have.


----------



## wa5cab (Jan 31, 2018)

OK.


----------

