Mill spindle runout

In an earlier post I did mention how to check to see if the spindle is bent. I would check this first before I did anything else.

You are half way there with your set-up above.

Also if the run-out on the taper test bar is getting progressively larger away from the spindle nose then this will also point to a bent spindle, but, it will also point to a Morse taper that is not true to the spindle centre-line, i.e. at an angle.

To check the quill bearing registers set one bearing inner face on a circular parallel, (Old ball bearing outer races are good for this). Using your DTI clock the exposed bearing inner face. You are only interested in the face alignment with this test.

In the vee blocks rotate the quill to check for run-out of the outer bearing diameter registers. Mark any high spots on the outside of the quill with a magic marker pen.

If the run-out is the same magnitude and in line then do not worry.

If the run-out is 180 degrees opposite then you have a problem. It is salvage-able but only if you have the equipment.

If the faces are out then it is a case for setting up in the lathe with a fixed steady and skimming the face or faces. This set-up will also allow you to bore the bearing diameter register oversize and insert a sleeve to correct the 180 degree problem.

Regards

Gray,

If, as a last resort,I were to have to make a new spindle, I would machine the socket first and then machine the spindle around that. The soft blank arbors, I mentioned earlier, would be used as one centre for the workpiece.

When you have got your head around Graham Meek's advice re proving whether the spindle is bent and whether the morse taper is axially correct, but off centre, I wonder if a sensible and cost effective option, will be to change the bearings for taper rollers.
I believe it was a mod sometimes done using Timken Timken 15578/15520 TS Single-Row Taper Roller Bearing 1x2.25x0.6875 inch. This wouldn't directly help you, as everything would still run off-centre.
If you have a look through the various catalogues and websites, such as this one you should be able to find one with the correct OD, and a larger ID, say 1.0826"/1.125" x 2.25"
https://simplybearings.co.uk/shop/Taper-Roller-Bearings-Taper-Roller-Bearings/c1_5459/index.html?selection=Tapered+Roller+Bearings+Cup+and+Cone+Assemblies

You could then sleeve the bearing surfaces on the centre spindle, and run it between centres.
This would allow you to re-machine where the bearings sit, and thus have them concentric with the morse taper and Myford chuck register.

I have lots of documentation, recovered from the old Dore Westbury Yahoo group before its demise.
PM me your full contact details, and I can burn it to a CD/DVD, or maybe zip it up into a large file for one of the free file transfer services.
I'll not reproduce it here for copyright reasons.

p.s. an alternative way of seeing what's not concentric might be to use your lathe.
If it has a Morse headstock, get an MT2 blank arbor, fit directly in the headstock taper, via a size adaptor sleeve if need be.
Take a light skim off the outer stub, to make sure that it is concentric and axial.
Hold this newly finishes stub in your independent 4 jaw, and dial it in with your tenths clock.

You now have an MT2 taper, on which to sit your DW inner spindle. Your clock can now sit on the cross slide/saddle and move up and down the DW spindle to give you an idea what's happening.

This arrangement could also be used for re-machining the aforementioned sleeves, and might even allow a slight correction if the female taper is very slightly off axially.

Bill

Edited By peak4 on 13/09/2022 13:40:10

Following on Graham's observations, when I made my DW mill back in the 1970's I rejected the first part machined spindle as the Morse taper was not in line with the part and rear centre axis so if I had carried on and ignored this issue when I applied the tail stock centre to support the part it would have flexed said part and created in effect a bent spindle when machined. they were surprised I picked up this fault but precision engineering is my profession so these things get noticed, the spindle was replaced with a correct part and I suppose some one else got the faulty one?

Tony

To make sure that any error is in the spindle and not the MT arbor fitted would be to mark the spindle and tool and then refit the tool at 180 degrees to its original position. If the error is the same, it is the spindle and if it changes, the tool is suspect.

I have a couple of test bars,one about 7" long and the other 12" with MT2 ends and centres, bought for the lathe. They are both more accurate than my measuring equipment. Very useful also for testing Morse tapers, but care must be taken freeing them from the taper for fear of damaging the centre at the end.

Edited By old mart on 13/09/2022 14:28:32

Hi Steve

Looking at your latest video it is clear that the bearing seats
on the shaft are not round.
Just watch this video here it may be of some use

https://www.youtube.com/watch?v=tE6m1aBfN5A

Some of the suggestions on this thread have not taken into account
this in your opening posting,
-----------
"The spindle doesn’t have a very good finish (home made obviously). But I’m
not in a position to remake it as it’s too long for my lathe."
-------------------
With that in mind it would seem pointless to even try to re-machine
this spindle.
-----------
This part of Tony Pratt's posting struck a chord with me

"when I made my DW mill back in the 1970's I rejected the first part machined
spindle as the Morse taper was not in line with the part and rear centre axis so
if I had carried on and ignored this issue when I applied the tail stock centre
to support the part it would have flexed said part and created in effect a bent
spindle when machined."
--------------------------
I think that you have to go back to the way the Dore westbury kit of parts
were supplied, Most of the major parts of the machine are already made and
finished to complete the machine some additional work mostly drilling
and tapping holes for assembly .
Some parts like the Quill and spindle are only part made ,my own spindle
supplied as a piece of bar stock with through hole for the draw bar
and pre-machined 2 morse taper and centered 2 morse taper plug ,it was
obvious from the start that the through hole about 15 inch in length had been
drilled from each end as the junction could be easily seen by looking through.
Being a complete beginner at this then, i did not fully realize the significance that
this would have and as you may guess the taper runs out in an axial direction.
Nearly 40 years on correcting this would be a simple job.

Your shaft seems to have many errors so much so it would be easier to
remake the shaft ,as you have a lathe that is too small you could consider
just making the lower part and the spline upper part as two parts and
using loctite to join them together. I think the biggest problem you may face
is first drilling a through hole through a piece of barstock of about 7 1/2 inches
on a lathe that is only 12 1/2" between centres, if you could manage to do that
and set up each end of the through hole and turn the centre seating, this
cutting from an old book shows how the rest could be done using a sprung
dog centre and fixed steady.

John

Edited By John P on 13/09/2022 17:06:49

As regards making a new spindle the socket would be the last thing to do in my book. There is always a very good chance with the amount of material being removed that the new spindle will distort due to the locked up stresses in the bar stock. Far better to rough out and finish machine such an item.

This is how I made the spindle below,

Regards

Gray,

.

Nice to see the material specification in that post of your, John

“crucible steel spindle forging” … those were the days !!

MichaelG.

Posted by Michael Gilligan 13/09/2022 20:08:05

Nice to see the material specification in that post of your, John

“crucible steel spindle forging” … those were the days !!

MichaelG.
--------------------------------------------------
Hi Michael,

Was from a re-print of an original book that was published
in 1920's useful method for the OP as his lathe is short on
centre distance.

Later on a similar illustration for finishing still using
the same setup sprung type centre and fixed steady which
is useful for finishing if you have such a thing.

Thanks to everybody who has taken the time to post and try to help me solve my problem.

Yesterday I acquired a new 0.0001 DTI gauge, and I thought I would redo the measurements with that. So I cleaned up everything, got rid of the mag chuck, and used a proper M&W surface gauge. Most frustratingly, I got completely different results. Luckily, in the right direction. What I learned was:

According to the new set up, the bearings on the spindle are within a reasonable tolerance
The MT2 test bar also seem to be giving reasonable and consistent readings along its length

Lessons:

1) Tenths are really, really small, and the slightest knock or piece of dirt, or burr, will make a significant difference to the readings, as it should.

2) It’s incredibly important to turn the spindle in the V blocks very gently and carefully

3) When a large, rapid jump occurs on the DTI dial, it is probably not due to a wear situation, more likely due to some manual or physical anomaly with the set up

4) just because a measurement shows up in a particular area of the test piece, does not mean that that area is the source of the measurement anomaly. The source of the anomaly may well be elsewhere (for example at the other end of the spindle)

5) in my case, the shoulder between the spindle shaft and the nose was not machined to a completely sharp right angle. I believe that this pressing up against the V block was causing a lot of the anomalous measurement.

So with everything clean and carefully deburred with emery paper, and the shoulder of the nose of the spindle away from the V block, I am getting much better results. Here is a New Video showing the new measurements.

After everybody coming up with sage advice on remaking the spindle, I am hoping that in fact it is acceptable. Opinions on the video would be welcome. To be honest I’m feeling pretty stupid at the moment! But I guess that’s why I posted it in the beginners forum, working at tenths is not easy, and obviously requires a lot of experience, and I am definitely a beginner at it.

I also mentioned before that once any preload is put on the bearings with the preload nut, the bearing will not turn easily. What I have discovered, is that that is in the horizontal position only. When I hold the quill in a vertical position, the bearings all run freely. However, in the video I have tried to illustrate a tiny amount of play that seems to exist, I am not sure whether this is play in the upper race bearing, or whether it is between the race bearing and the quill. The lower race bearing is a very firm fit in the quote and requires quite a lot of effort to get it out. The upper bearing on the other hand, is an easy push fit, and there may well be a tiny amount of play there.

Thanks again for all the help everybody. Any further comments on what I should do next would be very welcome. It’s a journey!

Steve

Edited By Steve355 on 14/09/2022 09:51:35

Your latest figures are excellent, within 0.001" tir. That will be plenty good enough for home use. If the cutter shanks end up more than that, it may be possible to find the sweet spot between the spindle and collet holder by trying different positions and the one that gives the minimum runout can have alignment marks on the tooholder and spindle end. When you repack the washed bearings with lithium grease, leave at least 50% air space between the spindle and quill bore.

 The bearing preload is best adjusted until the spindle gets just warm after running fast for about 15 minutes, slacken the preload very slightly if it feels hot.

Edited By old mart on 14/09/2022 20:04:04

The upper bearing on the other hand, is an easy push fit, and there may well be a tiny amount of play there.

If it is actually able to move, use of loctie ‘bearing fit’ grade would stabilise the bearing within its seating pocket.

The upper bearing in a two bearing mill spindle has to be able to move to allow the preload to be adjusted.

Now that you have the spindle cartridge sorted out, how much clearance is between the spindle and the bore that it runs in.? In my case it was around 0.07mm of clearance. I got the outside of the spindle flash chromed and lapped the OD down , hindsight I should have ground it. The upper section was not true to the lower section so it needed a small amount of honing to get it corrected. Now the spindle runs true better than 0.01mm over its 100mm stroke. So ai am very happy with it. It's no Bridgeport but is very repeatable. I am still getting it sorted for the shims and levelling to get it as best I can to the table run out. The mill I am using has a rise and fall table, with some irregularities in the table assembly. But is very repeatable when wound up, and locked or unlocked, is not changing the height of the table. Mine has a tapered bearing on the bottom of the spindle and a angular contact for the top bearing. Some replace the top angular contact with taper bearings, while others recommend replacing the bottom taper roller with a higher precision angular contact bearing. To get better precision from the spindle, the bearing housings need to be as round as the tolerance that you are trying to get the spindle to run to. So if you are looing for roundness from the spindle of 5um 0.005mm, the spindle bore in general will need to be round to 0.0025mm and the same with the spindle shaft as well. It does not take long and trying to get things really correct become a serious amount of work to achieve , along with the price of the bearings etc. I have added the extra spindle cartridge bearing support on the bottom of the casting as well. It did not change the linear runout of the quill, but when it locks in place using the flexure clamp, the quill movement at the end of its travel is less than 0.01mm , again, I am very happy with that.