Not all MT2 are equal

[Ed McDonnell]

I use oneway live centers on my wood lathes. I have attachments I've bought / made over the years that could be pretty handy on the metal lathe for some pen making operations.

The oneway live center is MT2. The tailstock on my Microlux 7x16 is MT2. MT2 is MT2....right?

I put the oneway live center in the Microlux tailstock and spent the morning getting some work done. This afternoon I tried to remove the live center from the tailstock. No way. It was stuck but good.

Not wanting to risk stripping the threads on the tailstock leadscrew trying to unwind it out I switched to plan B. Tried some strap wrenches to see if I could break the live center loose by twisting. No go.

I tried some levers between the quill and live center body to see if I could pry it out. No go.

There is no thru hole or knock out bar for the tailstock. I had to disassemble the tailstock and remove the quill, so I could try using one of my transfer punches to pound the live center out of the tailstock quill.

A rubber mallet wouldn't do the job. A regular hammer didn't have what it took (made some nice sparks off the transfer punch though). I had to break out the BFH. 3 Lbs of hammer swung with some emotion behind it did the job.

Looking at the MT2 taper on the oneway live center, it is a lot longer than the MT2 tapers on my metalworking gear. Being longer, it is also skinnier at the end and inserts a lot farther into the quill. In any case, I won't be using it on the metal lathe again.

But, this leaves me wondering if a MT2 on a metal lathe is different than a MT2 on a wood lathe? Or was it just an unfortunate mismatch between my oneway livecenter and the microlux tailstock.

Ed

 

[BKelley]

Ed.

M2 is M2!! I have run into this same problem. The difference being the length, the taper is the same. It is a shame the tailstocks do not have a thru hole for knock-out.

Ben

 

[Ed McDonnell]

I think I figured out what my problem was. The oneway style live centers have thru holes. The thru hole on a genuine oneway live center is large enough for the microlux tailstock leadscrew to enter it. This means the leadscrew can't pop out the live center when the quill is backed up. Cranking harder just jams things up.

I also have a oneway clone livecenter that came with my PM3520 wood lathe. The thru hole on that is smaller than the genuine oneway by about 0.02". That's small enough that the tailstock leadscrew won't go in. The clone popped right out.

Next time I'll just have to remember to use the clone (or put a plug in the hole of the genuine oneway).

Ed

 

[randyrls]

Looking at the MT2 taper on the oneway live center, it is a lot longer than the MT2 tapers on my metalworking gear. Being longer, it is also skinnier at the end and inserts a lot farther into the quill. In any case, I won't be using it on the metal lathe again.

But, this leaves me wondering if a MT2 on a metal lathe is different than a MT2 on a wood lathe? Or was it just an unfortunate mismatch between my oneway livecenter and the microlux tailstock.

Ed

Ed; The MT2 spec has the maximum size, minimum size, and taper, and a length of about 2.5". There are "short" tapers, and "tang" types among others. These are the specs for MT tapers

 

[Rich L]

I have a MT2 dead center that presents the same problem in that the tailstock screw won't reach it to pop it out. Two solutions:

1) make a shallow wedge out of aluminum to place between the back shoulder of the center and the nose of your tailstock. If you didn't really hammer the center in your tailstock then this should pop it loose. Again, if you're not really whacking on it, don't worry about the shock to the center bearings. Next time don't set it so hard - since it's a live center, you don't need to. Or, you could make some other more complex collar that you could pound on in a more axial direction. A lot of old drill presses that used taper shank drills used a wedge that was pounded through a slot in the spindle to extract the tapered drill bit.

2) Make a small solid spacer so your lead screw can push it out. Next problem is extracting the spacer if you can;t just leave it in there. Make it out of steel so a magnet can get it out.

Just some ideas ... I use the wedgy.

Cheers,
Rich

Ps - like Ben says, MT2 is MT2 but far be it for MTBs (machine tool builders) to be consistent in their application of such things.

 

[alamocdc]

I had an MT2 issue that deals with my Delta midi wood lathe (or my old 15" Craftsman - can't remember now). I bought a dead center either from The Little Machine Shop, or Enco (can't remember that either...LOL!) and it wouldn't seat into my headstock. Turned out it was too long. Not by more than 1/4", but that was enough. I introduced it to my grinder and it worked fine after that. So I look for short MT2 pieces now.

 

[Ed McDonnell]

Randy - Thanks for the link to the MT specs.

Rich - Thanks for the ideas. I think the solid spacer / plug idea is the way I'm going to go. Plan A is to see if I can thread the back of the live center so that I can screw in a solid spacer / plug. If I can't thread the live center end, then Plan B would be to use a magnet to retrieve the plug from the quill (if I can't machine it with a snug fit and it tends to fall out).

The good news is now that I've got a metal lathe I can make the plug / spacer myself!

How did I ever get along without a metal lathe?

Billy - I learned my lesson too. Now I know to look for solid ends on any MT2 for my metal lathe.

Ed

 

[rherrell]

I cut down all my live centers so I can insert them with the tailstock all the way in. Then I drill and tap the end of it for a socket head cap screw, now I can adjust the screw so it "pops" out just before the quill bottoms out.

 

[Ed McDonnell]

Hi Rick - Using a SHCS seems like cheating when I can make a custom threaded plug on the lathe. :biggrin: Using a metal lathe is new enough to me that I still find making something as simple as a threaded plug fun (and amazing!), plus I still can learn a lot doing it.

Ed

 

[randyrls]

As an addendum; *SOME* MT2 tapers will have a threaded hole in the base of the taper to attach a drawbar so the taper will not come out if inserted into the head stock. Being chased around by a spinning chuck and drill bit isn't fun!

 

[rherrell]

Hi Rick - Using a SHCS seems like cheating when I can make a custom threaded plug on the lathe. :biggrin: Using a metal lathe is new enough to me that I still find making something as simple as a threaded plug fun (and amazing!), plus I still can learn a lot doing it.

Ed

You're exactly right, I was the same way when I first got a metal lathe.:biggrin:

I made EVERYTHING I could think of...even if I didn't need it! Great way to learn.:wink: