Morse Taper Slipping between Drill Chuck and Tailstock

[stupoty]

Interesting, I assumed all mt had tangs. I know my mt4 tail stock does.
What’s the limit on an mt4?
1” on a mt1? Eeeech.

some one had mentioned a while ago that the tangs are uncommon on lathes , I have no tang slot on my MT3 tail stock.

I tend to tap the end of the drill with a soft hammer to make sure they are seated (not tiny ones)

 

[macardoso]

Maybe I'm the crazy one here, but I've drilled a 1" hole in steel (1/4" starter hole) on my lathe using a silver and deming bit going into an MT2 taper. I had no slippage at the taper and it cut beautifully. The only issue was the keyless drill chuck got so tight it required a strap wrench to open it up.

If I am going to be cutting hard, I'll seat the taper with a nice whack from a deadblow.

 

[SLK001]

The tang is NOT for anti-rotation, but is for being able to remove the drill. You should seat a MT2 device with a smart push into the socket. Before you do this on your lathe, BE SURE THAT YOUR TAILSTOCK CAN EJECT YOUR DRILL BEFORE YOU SEAT IT!!! A Morse taper needs to extend beyond the small diameter end to engage the ejecting projection. If it doesn't, you will have to disassemble your tailstock to remove the drill.

 

[Packard V8]

Standard range for MT
#1 - up to 1/2"
#2 - 1/2" to 3/4"
#3 - 3/4" to 1"
#4 - 1" to 1-1/2"

That larger than standard drills exist in various MTs is not proof it's good practice to use them. One may buy 1" round shank drills to use in a 1/2" chuck, but it's not best science.

I have a friend with a decent quality Taiwan lathe who has damaged the holding power of the tailstock by repeatedly drilling oversize holes with a 1/2" chuck in the #2MT. We're going to have to buy a reamer to clean it up enough to hold as it did when new.

jack vines

 

[macardoso]

Standard range for MT
#1 - up to 1/2"
#2 - 1/2" to 3/4"
#3 - 3/4" to 1"
#4 - 1" to 1-1/2"

That larger than standard drills exist in various MTs is not proof it's good practice to use them. One may buy 1" round shank drills to use in a 1/2" chuck, but it's not best science.

I have a friend with a decent quality Taiwan lathe who has damaged the holding power of the tailstock by repeatedly drilling oversize holes with a 1/2" chuck in the #2MT. We're going to have to buy a reamer to clean it up enough to hold as it did when new.

jack vines

Thanks for sharing that information! Did you have a source you used to find this? I'd like to look up more info.

 

[erikmannie]

Super helpful responses! I do appreciate it.

 

[SLK001]

Thanks for sharing that information! Did you have a source you used to find this? I'd like to look up more info.

I just went to the original source.

 

[extropic]

That's useful information but the source, in the USA, is ASME B94.11m-1993. You can purchase a copy here.

ISO 3291:2016 is the standard elsewhere. Both specs are probably functionally interchangeable regarding taper shank drills.

 

[Dabbler]

In my experience, on a suboptimal set up like a normal lathe with some wear, the practical values are less. I'd rather be careful than ruin my tailstock. Just my view. As I said, I've seen some ruined tailstocks that needed replacement of the quill or re-reaming to get them to work again.

-Most of my MT#2 drills are in the 1/4 - 3/8 range. I think I have a 7/16 one. My MT#3 drills used to max out at 5/8. I just acquired a 15/16" MT drill to do some aluminum for a project.