Question for Richard King on lathe alignment.

mcostello

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Glad to see Your presence here, Richard. I have seen the videos from Abom, Keith Rucker and the others and have learned much from them. I would like to attend a class in the future, just cannot do one now.

Here is the first question, I am asking here to make this part of the public record as it may help Someone else.

I am having a problem with a 15"x50" Clausing Colchester that I bought 2 years ago. The history is unknown. The problem I am having is when I first got it it was turning a taper of .010-.012 in 2 inches. I have done all the tuning and adjusting that I can think of and the taper is now down to .002-.003 in 1 inch. If I use the tailstock and turn a shaft down with the two collar method I can get a taper of .0005 in 12 inches telling Me the machine is aligned with the tailstock reasonably well.
If I try and move the headstock to take the taper out, the taper remains constant. I measured and moved the headstock a total of .022 and the taper remains constant, and the tailstock then does not align up anymore. I used a straight shaft and put the headstock back into alignment with the bed and tailstock. I suspect the bearing in the front of the spindle is loose and cannot seem to find anything with a dial indicator to support this. I had the spindle apart and the bearing looks like new with no wear apparent. Colchester uses a spring setup on the outboard end of the spindle to account for heat expansion, I have plenty of adjustment left and the way it's made I can take a prybar and move the spindle out toward the tailstock about 1/4".
How do I proceed? My next step seems to buy another bearing at Ebay cost of $800 or from Clausing for $3000. Trying to not make a big expensive mistake.
 
Try setting up an indicator at the end of a short piece of stock then take a cut just inboard of where the indicator is touching, see if the spindle is deflecting
Certainly don't purchase any new parts just yet until you determine for sure what the problem is
 
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I am not Richard but I would get an accurate test bar that fits the taper of your spindle and evaluate head alignment from that, without involving the tailstock, using indicator on the compound.

Rotate spindle and check runout on test bar in several places to make sure bar and taper is inline with actual spindle center. You may need to average readings or position bar at midpoint if there is runout.

See if top and front of bar are in line with the bed by moving carriage. If runout was detected earlier, rotate bar to midpoint of runout before checking.

If everything about the headstock is inline, then mount the test bar between centers and check for tailstock alignment.
 
MachPete99, I have done all that with no success. Will try a cut with the indicator this afternoon. Tried taking a cut with an indicator on the cross slide with no movement.
 
the end play in any headstock should be no more than .001-.002 there has to be a take up on it.
 
A quick simple cheap test bar is to buy a piece of Thompson hard shafting for linear bearings. Say a piece 1" dia x 12-18" long. McMaster Carr has it and not badly priced. I bought one recently 12" long. It is dead straight and round. Chuck it up in your 4-jaw and get it running true.
don't have to be real tight. Indicate at chuck and at end and get it under 0.0005" TIR. Then, with indicator attached to your carriage, check movement in the 2 O'clock position or top dead center on the test bar. Move carriage back and forth from the chuck out and back again. Do this a couple of times. Make note of readings, high-low and at which end of the test bar. Next, check it at the 9 O'clock position a check.

This will tell you how much wear you have in the bed, provided you have the bed leveled without twist in it. You don't care about bed lengthwise level, just cross wise. Older lathes will develop wear regardless what you do. Older lathes were not taken care of like one would do in a home shop environment. So you wind up with this inherited problem that's going to take a great deal time and money to correct and fix.
 
Do you mean that spring is doing/applying the pre-load to the headstock bearings? And the headstock does not seat/lock onto the ways? Instead, can it be pivoted for alignment?
 
The 1/4" is way to much in my opinion too. I would adjust that up like Kern suggests and run the head for a 1/2 hour and check it again. The rule of thumb on spindle bearing temp is if you lay your hand on the spindle head and it's hot but not so hot it burns, that about the right temp. That's around 140 to 150 F. There is no way the factory would leave 1/4" as no bearing would expand that much. I just spent an hour looking for info on a Clausing 1550 lathe. I found one on Vintage Machinery and one on Grizzly as grizzly has a lot of clone machines.
http://vintagemachinery.org/pubs/181/16416.pdf and http://cdn2.grizzly.com/manuals/g0709_m.pdf

Neither says anything about how to adjust the spindle bearings. but from my experience you tighten the spindle up until it doesn't move. The Clausing manual looks like there are springs on a collar as you said. I would bet the adjustment nut or nuts on the spindle until the collar plate is up against the shoulder on the spindle. Then there is still room for the springs to tighten or spring back when the spindle gets hot.

In The Grizzly manual page 67 it says to run the machine at high speed for 20 min and make the adjustment and have zero backlash.

Check that out and then lets talk about how to align the headstock. Do you have the original Clausing Manual? Tell us what it says? Did you take any pictures or take notes when you removed the spindle the first time? how did you arrive to the setting the spindle the way you did?
 
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The spindle is held tight by the springs, the adjustment nut is tight with more threads not being used. No matter how long the lathe is used the bearing makes no discernable heat, stays cold. I have ran the lathe for 4 hours at a stretch. As an aside the lathe is leveled with a Starrett precision level, I attempted to put some bias in the machine by putting a .005 shim under a corner to see if it changed something, it did not change anything. Tried all the corners that way. I have a copy of the factory manual and tore the spindle out for a visual inspection, nothing evident. The springs are the only way to hold the spindle back into the front bearing. The outboard bearing is a roller bearing, the spindle is not held between 2 cone and cup bearings.
The way I aligned the spindle was to use a collet with a straight ground shaft and average any indicator readings to find the center of rotation. It drills straight, centers line up.
I tried Markba633's suggestion and mounted an indicator on a shaft while cutting. With the 1" shaft sticking out 5" deflection was hard to read with the vibration but seemed to be around .001.
Thanks for the help and keep the suggestions coming.











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What is the machine serial number and model. If you could scan the pages showing the spindle drawing and show us or snap a picture and send me a text picture. It just doesn't sound right to have that much play in there. I'll call a friend and see if he has ever replaced the spindle bearing in one. When you put the bar in the spindle did you try to lift the bar or did it have and side movement with an indicator? I'll send you my phone number and email.

Did you buy the machine new or used? Did the spanner nuts look like they had been removed before? Were the Allen cap screws look like they had been removed before? Paint in the socket? I figure the spindle is loose and thats why you can't get good finish and alignment. I would bet you have read and re-read the instructions in your manual on How to align the head-stock and tail-stock and you still get taper I would look at the spindle is loose. Plus if you ran it 4 hours at top speed you should have seen temp change.
 
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