Repairing an MT2 socket

[rwm]

Yesterday I spun a drill chuck in the MT2 tailstock of my lathe. It caused galling in about the middle of the taper and raised some metal. Now the tapers won't seat correctly. I can not get in there to sand it down smooth. How can I fix this? I was think about buying an MT2 reamer and lightly running it in by hand? What is the best approach here?

While we are at it...how can I prevent this?

Robert

 

[34_40]

I'd think you are on the right track. Maximize the internal surface area will increase grip ( Friction) and help stop further slippage / damage.

 

[ghostdncr]

Having been here myself, I'll throw out what advice I can. First, I'd pull the spindle from the tailstock to gain unfettered access. Next, strike some out-of-the-way surface with a file to determine of your spindle is hardened. If it is, it will not play well with a reamer. If it is soft enough to cut with a file, I would try removing the worst of the standing metal with a small file, just to minimize the localized cutting load the reamer will experience when first encountering these areas.

If the spindle is hardened, I'd remove the standing metal with a diamond file until the taper seats correctly and call it done.

Going forward, you may consider cleaning both tapers with alcohol or acetone before seating. That will throw quite a lock on most tapers!

 

[Tozguy]

Yes always have the MT2 tapers clean, dry and in good condition, but ...
when there is an application where high torque is applied and/or the cutting action tends to pull the taper out, consider using an additional means of holding the torque, such as a dog or wrench, as insurance.

 

[ghostdncr]

Yes always have the MT2 tapers clean, dry and in good condition, but ...
when there is an application where high torque is applied and/or the cutting action tends to pull the taper out, consider using an additional means of holding the torque, such as a dog or wrench, as insurance.

I've never considered adding a dog to my tailstock, so thank you for the inspiration. You can bet that project will unfold in the near future!

 

[rwm]

Yes always have the MT2 tapers clean, dry and in good condition, but ...
when there is an application where high torque is applied and/or the cutting action tends to pull the taper out, consider using an additional means of holding the torque, such as a dog or wrench, as insurance.

Can you elaborate on that? How would I use a wrench to hold the chuck?
In my application the material was "grabby" and pulled the chuck out then spun it. I have a feeling that the material in the bore is actually from the chuck taper and is deposited in the female part. I believe my spindle is harded. I was hoping that a reamer could scrape it off without taking off any of the hardened spindle. Does it make sense that could happen?
R

Edit:
Update. My tailstock spindle does not appear to be hardened. I removed it but it is very hard to get to the damage. There is a raised circle half way down the bore. I think I am going to have to confront it with a reamer. Thanks for all the ideas. I will wipe down with acetone next time.
Robert

 

[rwm]

I took your suggestion but she is not happy about it:

(otherwise boring thread without pics....)

 

[Bob Korves]

First, cause no further harm. Using files or abrasives, only touch parts of the socket that are actually damaged. Leave the good areas untouched! Yes, it does take patience. Follow the excellent advice in the posts above. Do not use a roughing reamer. You can use a standard MT reamer to LIGHTLY dress the taper after the high spots have been removed by careful stoning or filing. Round India stones and/or curved end jewelers or riffler files can get in there and only touch the damaged areas. If the quill is truly hard, stones will be about all that will touch it. Removing the quill from the tailstock is a very good idea. You can get in a comfortable position with the work padded in a vise and see what you are doing. The advice about using dogs in the future to avoid doing it again is excellent. If the lathe is one that still has new parts available, you might consider buying a new quill, but it would likely need to be fitted to the tailstock bore. And probably $$$...

 

[Bob Korves]

You can put the dog on the drill itself, which also stops it from spinning in the chuck.

 

[Tozguy]

Robert, holding the torque can be done directly on the drill bit, or on the chuck arbor. I would not hold the chuck itself.
It might mean that you have to cut flats for a wrench where possible. If you have a photo of your set-up we might have a suggestion or two. Have any vise grips?

In my application the material was "grabby" and pulled the chuck out then spun it.

In my books it is worth grinding the drill bit for the material at hand to reduce or avoid the tendency to pull out. I prefer just about any challenge other than fixing a galled taper. And there might be two tapers to worry about, the JT taper on the chuck and the MT taper in the TS.