Autolock/Posilock chucks

[stevep]

Can anyone give me instruction on the correct way to fit a milling cutter to an Autolock or Posilock collet chuck? (I think the Posilock, which is actually what I have, is a low cost version of the Clarkson).

I don't know how far to scew the cutter into the collet before tightening the nose piece.

Thanks....Steve

[Jo]

I was always taught to wind the cutter in level with the back of the holder and then back it off half a turn or so.

The backing off is to enable the point at the center of the body to push down on the cutter in the collet and hence close it around the cutter, whilst maintaining maximum thread engagement between the collet holder and the body.

Jo

[jackrae]

It might not be the official way but this is what I do
with the tool loose in the collet I hand tighten the nose nut
I then wind the tool into the collet until it makes contact with the centring stud
I then wind off the nose nut half a turn
This allows the tool to be tightened a bit more which effectively extrudes (pushes) the collet into full contact with the nose nut
Then tighten up the nose nut with the proper spanner with a gentle knock from a copper or hide mallet

By ensuring the tool is in intimate contact with the centring stud there is no possibility of it winding into the tool holder and so having the effect of reducing the cut depth during a cut.

happy swarfing
jack

[Deleted]

Hi
According to the instructions with my clarkson 's' type chuck, you assemble the collet and the end sleeve - until the flange meets the face of the body. You then screw the cutter in until it becomes tight, I presume hand tight, then you give it a final tighten with the spanner. It does stress that the sleeve should be in contact with the end face of the body.
To remove, you undo the sleeve half a turn and then unscrew the cutter, if the replacement cutter is the same size, you then tighten the sleeve until it contacts the body, screw in a new cutter and the lightly lock the sleeve as previously instructed.
I hope this helps
Regards
Trevor

[jones]

Hey Steve,
I have one of these collet chucks and the way I was taught was to put the collet in the chuck and hand tighten. The cutter is then screwed into the chuck and finally it is tightened with the spanner. This gives repeatable cutter changes. Pretty much exactly as trevor describes.

Andrew Barber

[stevep]

Many thanks to everyone that posted a response. The logic seems sound - putting the collet into the body and screwing on the nosepiece ensures that the dog-clutch drive to the collet is fully engaged.

Then screwing in the cutter until it meets the "centre" ensures a consistent depth of insertion, and the final tighten of the nosepiece makes sure everything stay where it ought to.

Once again, many thanks.....Steve

[Steve M. W]

Well done Stevep just the question I was about to post

Steve

[SteveW]

Guys,

There's a bit on these things in this week's ME. The correspondent is adamant that it's not necessary to fully tighten the end mill into the collet but it is essential that the front closer nut fully contacts the body of the chuck.

The point he makes is that if the cutter isn't held it'll turn until it contacts the point and then further turns will tighen it in the collet which ain't going to go anywhere because it's held by a fully closed nut, i.e. start cutting with a loose cutter and it'll self tighten cus it's an "auto-lock" chuck.

He counters a previous letter by suggesting that any more than a 1/4 turn on the nut with an over tighened 6mm cutter will stuff the cutter's thread.

[steammadman]

Stevep , is correct , but , during my time at the local tech college i have seen
a few "ham " fisted students leave the locking ring too far down,put a cutter
in the collet tight up to the center,and then tighten up the ring with too much
enthusiasm and split the thead on the end of the cutter, RESULT, cutter
.
"cream crackered"


ok for we instructers though, they still work ok in plain collets

[stevep]

Just a post-script for everyone. I used all the advice, and noticed something interesting, which I don't believe anyone has mentioned. This is that the collet is actually loose in the body when the nosepiece is screwed up. So it's not until the cutter is screwed in, and against the internal centre, that the collet actually comes into contact with the inside of the nosepiece.

I found that after screwing the nosepiece on by hand (not even firmly), and then screwing the cutter into the collet, I was unable to move the nosepiece very much at all when "nipping" it up. Clearly, this means that any further tightening can only happen (as has been described) by the cutter rotating slightly, causing the collet to be pushed harder into the inside of the nosepiece, also causing it to close on the cutter.

Cheers....Steve