Collets in Super 7 tailstock

[JohnHaine]

Has anyone made a Myford spindle nose thread on the end of the tailstock barrel?  I would like to be able to fit Myford collets to the tailstock to hold larger drills etc.  The diameter of the barrel is larger than the od of the threaded spindle nose so there should be enough meat for a thread.  Carefully applying a file to the metal suggests that it isn't very hard.  Any advice or experience welcome!

[John Rudd]

What size of drill were you thinking of?
IIRC the ML 7 has an MT2 in the tail.....why not sleeve for bigger sizes to MT3?     

I have a Chester 9*20 that has an MT2 taper, I use a 13mm chuck with blacksmith drills up to 25 mm....if I need bigger holes then switch to boring.....

Depends on what you are doing?

[JohnHaine]

It's not so much size as grip that I want, as well as not having the build up of misalignment between taper shank, chuck and drill.

[Jonny]

You will have exactly the same misalignment no matter what you do.
Gripping power, have you seen what a good quick release chuck (not Asian) will hold along the lines of Metabo yet alone a keyed Jacobs chucks.
Gripping power of keyed chuck is more than ER where cutters constantly drop, I am often too idle too change 15 secs and mill with a cheap keyed chuck.

[Meldonmech]

 
          I have built a Myford collet holder for my cutter grinder, it works well and holds all my cutters positively. The screw cutting of the barrel was straight forward. My barrel was mild steel. I cannot for see any problems, your tail stock barrel must be 1.125 inch dia. to take the thread. Seems quite a good idea.

                                                                                           Good luck   David

[JohnHaine]

When I say grip I mean between the tailstock barrel and the taper!  Too often I find that large drills dig in slightly then the arbor starts rotating in the barrel.  Thai is partly because the arbor supplied with the large keyless chuck I have is not quite the right taper.  But given I have mt2 collets it is a shame the only place I can't use then is in the tailstock.

Though the od of the barrel is slightly less than 1.125, it's still larger than the crest diameter of the Myford spindle nose thread so it should be possible to cut a thread.  You don't need the usual 1.125 register for a collet closer.

[JohnHaine]

Just to get back on topic, what I am asking really is:

Has anyone cut a thread on the end of a Myford Super 7 tailstock barrel to allow them to fit the Myford collet closer to clamp a myford collet?

I know that the diameter is OK, the main concern is if the steel is machinable.  I don't want to start and find that it's too hard and make a mess.

[Meldonmech]

Hi John

                      Try filing the barrel with a fine cut file, generally if you can file it you can thread it.

                                                                                       Cheers David

[JohnHaine]

OK, thanks David.  I tried a file and it seemed OK, so I will give it a try.  Will have a trial run on some scrap stock first I think!  If it works I'll post some photos (if it doesn't I'll keep very quiet!).

Cheers,

John.

[racer-john]

   
JohnHaine
 You're being very quiet!

[JohnHaine]

Haven't psyched myself up to it yet!  First I need to find out why my previous attempts at cnc threading on my lathe didn't work; then do a trial run to prove to myself I can cut a Myford thread; then dismantle the tailstock and do it for real!