aligning the holes in the back of a chuck.

savarin

savarin

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My new 4 jaw chuck has 4 8mm fixing bolts on the back but the holes do not go all the way through so I cannot use a transfer punch.
I need to transfer the hole centres on the chuck to the back plate so I can drill them.

1) How can I do this accurately?

My first thought (only one actually) is to turn down some 8mm bolts to a sharp point and hope they are centered, screw them into the chuck, ensure they only protrude sufficiently to touch the plate after the back register engages, say 1mm.
Give a light tap of the chuck body so they mark the soft plate. BUT, how can I get them out again?
File 2 flats and hope a pair of needle nose pliers can grip them?

2) Do the socket bolts securing the chuck to the back plate have to be counter bored to sink the heads flush or can they be left proud?
 
You really need an 8mm Transfer punch here Charles. The bolt idea will work though. Locate the first hole, drill and tap it and put a bolt in it to hold the BP to the chuck.. Now punch the other holes, they will be perfect. I would counterbore for the bolt heads. I have never seen any that weren't.

"Billy G"
 
I've used the method you described with success but the plate was open and I could remove them from the back (slotted) South bend says to use chalk to transfer the holes If I can find the PDF i'll post it. Also if needed can you disassemble the chuck to lay out the backplate holes? HTH
 

Attachments

  • chuck adapter.pdf
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You need a set of these.
IMG_0536.jpg

The body that stores them has a hex end to spin the transfer punches in and out of the holes.
Should be easy enough to make a set in 8mm.
Greg

IMG_0536.jpg
 
Bill Gruby said:
You really need an 8mm Transfer punch here Charles. The bolt idea will work though. Locate the first hole, drill and tap it and put a bolt in it to hold the BP to the chuck.. Now punch the other holes, they will be perfect. I would counterbore for the bolt heads. I have never seen any that weren't.

"Billy G"
Click to expand...

I cant use a transfer punch as there are no through holes for it.
Definitelt will counterbore the fixing holes though.
 
f350ca said:
You need a set of these.
View attachment 91770

The body that stores them has a hex end to spin the transfer punches in and out of the holes.
Should be easy enough to make a set in 8mm.
Greg
Click to expand...

Thats what I was thinking of Greg, thanks.
What is their real name?
 
You really have to love this forum, The exact answers you need at the speed of light.
Thanks Guys.:thanks::applause:
 
Haven't got a clue what they're called. Don't use them often but sure are handy when you need them. The ones I have range from a number 8 to 1/2 inch in course thread.

Greg
 
Transfer screws.

Tom
 
Without a thru hole the only way to go are the Transfer Screws Charles.

"Billy G"
 
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