Adjusting A Taper Bore

savarin

savarin

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I've cut a tapered bore for an er collet.
I blued the collet and twisted it in the bore (with a rod in the collet)
The blue wore of approx half way leaving the bottom half of the collet untouched.
I am assuming that means the top of the bore is too narrow and the bottom half is too wide.
If I adjust the angle a tiny smidge more so that its now 8.0+smidge degrees is this going in the right direction?
 
If I followed you correctly, yes, you would turn your compound clockwise. Be careful if you are using that collet as a master angle checker. That collet could have a bad angle on it.
 
good point I will use three of them.
 
When I cut an ER collet bore,I put a piece of drill rod in a collet and chucked it between centers. I then adjusted my compound angle until a indicator read "0" traveling the length of the collet. As a backup, I figure the length of the sides of the triangle formed here and use an indicator to check my setup.


Edit: if the collet fits too loose on the drill rod put a hose clamp LIGHTLY snugged on the front of the collet. It will hold it .
 
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Thanks Mark I have read that before but forgot all about it so I left sufficient material to enable me to sneak up on it.
 
Verify that your cutting tool is truly on center, otherwise you'll cut a flared taper. When I made mine (ER40) I wound up sanding and lapping the taper until it fit the collets.
 
T Bredehoft said:
Verify that your cutting tool is truly on center, otherwise you'll cut a flared taper. When I made mine (ER40) I wound up sanding and lapping the taper until it fit the collets.
Click to expand...
Are you referring to the tool height here? If so, and the height is slightly above or below center, will it change the angle?
 
Hmmmm, I must check that as I altered the bit so it may now be off.
By golly you learn a lot on this forum.
Tom, how did you lap it?
 
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