Graziano 12S

For doing cleanup like you've shown, I refreshed the spindle on my little Atlas with reamers. It was spooky, but easy, and the results were very good.
 
Will definitely proceed cautiously. I have a whole bunch of stuff to do before I start worrying about collet runout.
 
i would be worried about high spots in the spindle, low spots usually don't cause a lot of problems
i would consider grinding
i would think that reaming would not produce as accurate a taper, if the tailstock was even slightly out of alignment
the same reason a hole is often bored to size, after drilling
maybe i'm overthinking it
 
I ordered a pair of import reamers. I'll have at least a month to figure out what to do with them if anything.

It seems to me that a light reaming of the spindle bore would be ok--there's plenty of surface to guide things. It would be dependent on how good the alignment is to the tailstock as the tailstock alignment would be critical to the success I'd think. Gonna do some more research before I do anything.
 
ACHiPo said:
I'm not sure. I've done some searching and haven't found any information on how to refurbish a headstock taper. There's a decent video showing reaming a tailstock, and there are carbide reamers available to purchase, so that seems to be the way to go. It seems like it would make sense that reaming it in-situ would be the best way to maintain precise alignment.
Click to expand...
Reaming it will clean up the taper, but it will not center the taper. Grinding it would be the best way to get it cleaned up and spinning true, but is fussy work to get right, and should ideally be done mounted to the lathe. Depending on the extent of damage, the taper may end up too big to be useful with standard tooling. If so, it might be possible to grind an oversize opening of a useful size and shape for semi permanently mounting a custom insert, mounting the insert and then grinding it to the original standard size Morse taper. If the damage is not too deep, simply grinding it to clean up the taper should be sufficient.
 
Bob,
Thanks. If the taper is already centered and the damage is ~0.010” but overall averaged correctly, I was hoping the reamer would clean it up and improve accuracy/precision.

Here are a few thoughts:
1. Put drill rod in a good collet and measure runout. If it’s sub-0.001” leave it alone. If it’s above 0.001” take the next step.
2. Set the compound for MT 5 angle and put a tenths indicator and measure the perturbations.
3. Is there a way to do a precision stone and just clean up the high spots?

Evan
 
ACHiPo said:
Bob,
Thanks. If the taper is already centered and the damage is ~0.010” but overall averaged correctly, I was hoping the reamer would clean it up and improve accuracy/precision.

Here are a few thoughts:
1. Put drill rod in a good collet and measure runout. If it’s sub-0.001” leave it alone. If it’s above 0.001” take the next step.
2. Set the compound for MT 5 angle and put a tenths indicator and measure the perturbations.
3. Is there a way to do a precision stone and just clean up the high spots?

Evan
Click to expand...
Hoping is like guessing. Indicate it and see what you have. Reamers follow whatever already exists. Precision stones work by having a plane with lots of flat cutting edges that clean up whatever sticks up above the surface, then quit cutting when the work surfaces high points match the stone. Making a MT precision stone seems like quite a reach to me. A tool post grinder could do a good job of cleaning your existing taper. I have a nice one if you want to try it, but it might run out of travel when using your compound to traverse it.
 
Did the best I could to characterize the spindle bore, and was pleasantly surprised. Really need a profilometer to accurately assess the ridges, but using a Tesa 0.0001" indicator with my compound set at 1.5°, I scanned the MT5 bore as far as I could with the compound (~1"). I was getting fluctuations of <+/- 0.0001" as I scanned from out to in the flat portion of the taper at 4 different radial positions about 90° from each other. It looks rougher than that, and if I had a stylus instead of a ball I would read greater fluctuations, but the ball should be close to what the 5C adapter "sees". I checked run out in a few different distances from the nose and the indicator barely moved as the spindle turned--maybe 0.00001"?

I cleaned the spindle bore and collet adapter a few times with WD40 until the paper towel didn't remove any black stuff. I slid the collet adapter into the spindle and gave it a thump with the heel of my hand. I was pretty happy with how firmly it "stuck" which I take as another positive indicator.

I indicated a few different distances from the nose of the adapter and again got maybe 0.0001" to 0.0002" total movement of the indicator.

I used the collet closer tube that came with the lathe to try to manually close a 1/2" collet on a 1/2" drill. It spun the collet adapter in the spindle nose. It's pretty clear now how the spindle got scored.

I decided to try out the pneumatic collet closer that came with the lathe. It's a bit leaky, but seems to basically work and clamps the collet, firmly holding the 1/2" drill. Rotating the spindle with the indicator on the drill shaft I'm seeing about 0.0005" - 0.0007" fluctuation. This seems decent, although it's only about 1/4" from the collet nose, so runout would obviously be a lot worse further from the nose.

Gonna need to make a few parts for the collet closer. This lock ring that secures the bearing for the collet closer is pretty messed up, both the cavity for the spanner and the threads.
IMG_0295[1].JPG
 
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