ER25 collets to hold square material

It is not too difficult to mathematically determine how much packing would be needed under one jaw of a 3 jaw chuck to hold square stock centrally, based on square root of 2. I have done this on occasions. Another method I have used it to machine the corner off one of two short pieces of steel angle to achieve the same result.

What's the purpose of the tap collet?

.

Holding taps ... [for threading holes]

Presumably intended for more specialised machines than most of us have ... but I can see it being very useful in a tailstock on the lathe.

MichaelG.

While the collet holds the tap the square feature provides positive drive. This is important when machine tapping, especially on CNC mills, as the spindle speed, depth of cut, feedrate and thread pitch are intertwined. It all goes pear-shaped if the tap slips or moves axially.

Andrew

Ian, you might be interested in this solution for holding taps:

http://mikesworkshop.weebly.com/improved-chuck-for-taps.html

Mike

I see.

I have a Harrison and have found that if you wind the tailstock out until it comes off the screw then it has around 2" of free back and forth movement but won't rotate due to it still being on the key. This is perfect for tapping threads on the lathe.

Are other lathes not like this?

Chris,

My point was that the 'Tap Collet' is likely to hold the Tap more accurately and securely than any alternative. ... Thus reducing the risk of breakage, and increasing the likelihood that the tapped thread will be the correct size.

How do you hold your Taps in the Harrison ?

MichaelG.

Edited By Michael Gilligan on 31/01/2015 15:58:04