PM-1660TL

[erikmannie]

I was threading 1/4-20 with the cold rolled steel this morning. The first thread I made turned out poorly (bent one in photo), and then I bent it while putting on a final chamfer.

So I finally got a good one (straight one in chuck shown below). The safety groove is ridiculously long because one time I mistook the cross slide handwheel for the carriage handwheel & accidentally cut into the work.

 

[erikmannie]

My RPM when threading was 105, which was almost too slow. I was flooding the work with CF.

My Shars thread screw micrometer has always worked nicely.

I think I’m going to get a hold of some hex and form some metric threads for fun. I still have never made metric threads.

 

[mattthemuppet2]

that's some pretty crazy stick out there - 3-4x diameter is a good rule of thumb

 

[erikmannie]

that's some pretty crazy stick out there - 3-4x diameter is a good rule of thumb

I definitely had it supported the whole time! I took the live center out to test the nut.

I always use a center if stickout exceeds 3.5X the diameter.

 

[erikmannie]

I sent an email to PM to ask about putting an MT6 dead center in this spindle.

The through hole looks to be a straight 2.55” all the way through, but all dimensions of an MT6 taper are less than 2.5” (see screenshot).

The PM manual says that the headstock spindle taper is MT6, but I think that the manual is also shared with a PM-1440TL.

I will be finding out the answer to this because I bought a 14” diameter D1-6 face plate that has a 3” center hole. I have not been able to figure it out how I will get a dead center in the spindle.

PM supplied a reducing sleeve with the PM-1660TL that accepts an MT4 dead center. I have used that sleeve with the chucks, and that worked fine. Unfortunately, this reducing sleeve is less than 3” in diameter, so I will not be able to put it in the center of the face plate like I did with the chucks.

I am very curious as to how this problem will be solved. Maybe I will have to machine a reducing sleeve (with an MT4 or MT6 taper on the inside) that can slide in the 3” center hole of the face plate.

 

[erikmannie]

I wonder if chucks and face plates have a taper in the center hole.

I have always slid a Morse taper dead center in to the center hole of a chuck, and it worked fine.

I have also converted a tapered dead center into a straight shank and then clamped that straight shank in to a chuck, but you’re not doing that on a face plate.

Here are some pictures of the face plate that I have coming. I can’t tell if the center hole has a taper:

 

[erikmannie]

Now it would appear that spindle through holes are always straight, so the only place to grip a dead center would be on the chuck, face plate, dog driver or backing plate.

 

[davidpbest]

My PM lathe has a MT spindle nose. Beyond the taper, the spindle bore is straight walled.

 

[AlanB]

The pm-1660 description implies that the adapter fits into the internal taper of the spindle. Have you tried that?


Spindle:

• Spindle Mount D1-6 Camlock Quick Change
• Internal taper of Spindle (With included reducing sleeve) MT 4
• Spindle bore 2.55” in. diameter (will pass a 2.500″ piece)

 

[erikmannie]

My PM lathe has a MT spindle nose. Beyond the taper, the spindle bore is straight walled.

“Spindle nose” explains it all! Only tonight did I learn that the spindle bore (what I have been calling a “through hole”) is straight walled.

Until this moment, I did not realize that a spindle nose exists, and that is why I kept asking about the taper in the center hole of a chuck, dog driver, backing plate or face plate.

I have been doing it wrong. I have been trying to put Morse taper dead centers in the center hole of my chucks.

Live & learn.