PM-1660TL

Matt is not around to consult with, but I suspect it must be a MT7 taper as well. Curiously, the manual says " 3. D1-6 Camlock MT#6 Spindle "
but that would not make any sense.
 
Just think out loud here. The spindle taper is not a morse taper but the inner sleeve is an MT4?
Okay, 1/19.18 is just a morse taper angle of 1.49°.
 
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I was all ready to buy a Morse Taper #7 dead center. I planned to use the part of the dead center that has the exact same outer dimensions as my reducing sleeve, but cut to length to allow for a 60° nose at an appropriate working length. The idea here is to just have a solid dead center (i.e. no reducing sleeve). Not that there’s anything wrong with reducing sleeves!

However, I took a close look at the dimensions of the reducing sleeve, and I saw that a 7MT dead center would only be able to be pushed in (to the spindle nose) for only 1/2” until the dead center reached the point where it couldn’t go in any further.

I HAD thought that the supplied reducing sleeve may have been a shortened “MT7 outside and MT4 inside” socket (or collet). This is NOT the case because the smallest diameter of an MT7 (2.7500”) can only be pushed in to the spindle nose for a distance of 1/2”.

I now believe that the outer dimensions of the reducing sleeve supplied with the PM-1660TL do not correspond to a shortened 7MT shank. It MAY have the same ANGLE of taper as an MT7, but most of the length of the reducing sleeve has a diameter that is too small to be found on a #7 Morse taper.

I just bought a 12” length of 3” diameter cold rolled 1018 ($66 delivered), and I will attempt to make a dead center. I will copy the outer dimensions of the reducing sleeve and then extend that taper angle out several inches to a 60° tip. Not my first choice of material, but it fits my budget.

Cliff Notes version: This lathe appears to have a spindle nose with custom dimensions, perhaps because in order to obtain a 2.55” spindle through hole, 6MT is too small and 7MT is too big.
 
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@erikmannie I'm late to the discussion (I think I've read it druing it's early posts) my apologies if I've repeated another post.

I use a machined centre in my 3 jaw instead of a centre in the headstock taper. I just chuck up a piece of steel in the chuck and turn it to 60 degrees. every time I need it again I just re-cut the 60 degree by a few thou. It must always be perfectly concentric with the rotation, unless your headstock is very loose.

This process takes about a minute each time - less time than it takes to remove the 3 jaw chick...
 
erikmannie said:
I have watched most of Joe Pie’s videos several times. He is amazing! As I recall, I was reluctant to try the “threading away from the headstock” because I think he turned his threading tool upside down. Until I get more experience, I want to keep those forces pushing down on the carriage. I’m sure it’s fine to pull up, however.
Click to expand...
He has 40+ yrs doing it, it is easy.
 
Dabbler said:
@erikmannie I'm late to the discussion (I think I've read it druing it's early posts) my apologies if I've repeated another post.

I use a machined centre in my 3 jaw instead of a centre in the headstock taper. I just chuck up a piece of steel in the chuck and turn it to 60 degrees. every time I need it again I just re-cut the 60 degree by a few thou. It must always be perfectly concentric with the rotation, unless your headstock is very loose.

This process takes about a minute each time - less time than it takes to remove the 3 jaw chick...
Click to expand...

So it sounds like this machined center has a straight or hexagonal shank. I have done this using a dead center with a straight shank in a 3J, and it worked perfectly.

The main reason that I bought a face plate is because I prefer to do stuff like machinists did a long time ago (before there were good chucks!).

Since there are no time machines, this is as close as I can get to traveling back in time.

History is fun:

 
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