MT2 vs. B&S #7 Collets on Bridgeport M-head

First, let me say this is a great looking forum and I am glad I found you all!

I have an Old Bridgeport Round-Ram with an M-head that I am working to get set-up and I was looking at the collets that I got with the mill and it came with a mixture of MT#2 and B&S #7 Collets.

Now, looking at the collets they look VERY similar in size and shape and both seem to fit into the mill without much issue. I do not have a drawbar for the mill yet so I have not been able to use any of the collets with an end-mill to verify if the B&S #7 collets are correct but I do have a MT2 chuck that does snap in place and seems quite tight.

So, can anybody advise if the Mill is supposed to be a MT2, which I am guessing it is, will I hurt anything if I use the B&S #7 Collets? Can someone advise just how I can verify which of the two systems are the correct ones for this mill?

The "M" head was available with either #2 Morse taper or B&S #7. There is a difference in the taper per foot.
Check this out:
http://www.lathes.co.uk/bridgeport/page10.html

I would get some "Prussian blue" or as some call it "high spot blue". and coat the spindle bore. Place a collet in the bore and see how much gets marked. The collet with the fullest marking is the correct one. I hope that they have not been using both styles of collets in your machine. This would tend to wear the spindle bore from incomplete contact either at the outside or inside depending on collets.

If you've never used Prussian blue, you can buy it at most art stores. Wear some rubber gloves when using is, it does not wash off. To apply to the spindle bore, I'd probably use a cotton swab to reach inside. It takes very little to leave a mark. Don't glob it on like grease.

JR

Thanks for the reply and I will try this.

I don't think the B&S collets had been used with the mill as they look new in every way. I know the previous owner of the mill had compiled quite a few of the accessories that came with the mill but he discovered the mill took way too much room of his basement before he ever got it running. I am still trying to figure out what I have and how to do the Phase 3 thing still...

Cheers!
QB

Quarterbore,

It would have depended on what drawbar was originally on your mill.

The #2 Morse taper would have had an overall length of 18 3/16" and the #7 Brown would have been 19 11/16".

If you have any more questons, please give me a call at (800)906-0012

Dee

Hint: If you don't want to locate prussian
blue to check this, there are two other
alternatives that work as well:

First is some lipstick. Just raid your
wife's purse and don't get caught.

The other one is to simply mark the outside
of the collet with a a sharpie pen. Use
blue if you want to simulate that old-timey
feeling! :^) But that gives a nice thin
coating that will show contact very well,
it will wipe right off where there's
metal-to-metal.

Take the incorrect collets and sell them
or trade them for other goodies.

Jim

Quarterbore said:

Thanks for the reply and I will try this.

I don't think the B&S collets had been used with the mill as they look new in every way. I know the previous owner of the mill had compiled quite a few of the accessories that came with the mill but he discovered the mill took way too much room of his basement before he ever got it running. I am still trying to figure out what I have and how to do the Phase 3 thing still...

Cheers!
QB

Click to expand...

I’ll buy the bs 7 if u don’t need them. Ken in Gardner Ma. Nine78 three02 four223 thanks

Id be surprised if you couldn’t feel which one fits right vs rocking since they have .008in/in of difference in taper.

Guys,

Pay attention to the last date posted to this thread. April 2004!!!!

Quarterbore has not posted since that day. Has not been seen since that day.

Ken