What size chuck key?

[Michael WildeParticipant @michaelwilde12011]

1/4″ or 9/32″?

[Michael WildeParticipant @michaelwilde12011]

I’ve just received a Bernard 4 jaw chuck that I bought on ebay, minus a chuck key. Its the ’34m’ 6″ model that has the words “made especially for the Myford Ml7 lathe.”

I’ve used a piece of 1/4″ square bar to remove the jaws and give it a good clean, polish and lube. The square bar was quite a sloppy fit in the square hole and, on measuring it, found it to be 0.280″.

This works out at 9/32″, is this the right size as it seems a bit of an ‘odd-ball’ size? or is the sloppy fit on the 1/4″ bar right?

If anybody has this same chuck and wouldn’t mind giving their chuck key a quick measure I’d greatly appreciate it!

I’m just trying to see if its worth buying one on ebay (1/4″) or making an ‘odd-ball’ size. Also, what to make it from? I can get off-cuts of quite tuff stuff from work (we call it durehete, used a lot in the power generation industry).

Thanks in advance

Mike

Edited By Michael Wilde on 09/02/2011 23:00:20

[David Clark 13Participant @davidclark13]

Hi There

Buy a 5/16 or 3/8 in. one from Ebay, Five minutes on the grinder and you have a 9/32 one.

regards David

 

 

[Dave TointonParticipant @davetointon92281]

Michael,

I’d suggest you just turn one up!!! Must be one of the easiest turning jobs with a tee handle to suit. I made one out of mild steel and it has lasted years.

Regards

Dave Tointon

 

 

[NJHParticipant @njh]

Hi Mike

 

I’ve just checked my Myford 6″ PB 4 jaw. The socket measures 7.74mm and the key. which is a loose fit in the socket, is 7mm AF. Both chuck and key are in as new condition.

 

Regards

Norman

 

 

 

[Gordon WParticipant @gordonw]

As mentioned before, a good source of square bar, in seemingly good quality, is old door locks, varies between 5/16″ and 8mm, can beefiled to suit if needed.

[Author]

Posts