Boley 8mm collet nut

I have a Kerry 1324 lathe and use ER32 collets in a 4 Jaw chuck.

I have 15 Bolely collets so I want to make a Collect block out of round bar that I could fit a Bolely collet and use it in my Kerry. Er32

I have never cut a internal thread so I do not think I could cut such a small thread using a Single point tool.

The thread required is 0.275" x 40tpi .

Where can I buy a tap of this size?

Look at a 9/32" x 40 ME Tap. could be close enough ? 0.275 is 7mm so maybe a metric 0.6 pitch if such a thing is made ?

Hi Malcolm.

Tracy tools do a 9/32" - 40tpi tap for £3. It's onlty 6 thou oversize, probably closer than you could cut that thread as a novice.

https://www.tracytools.com/taps-and-dies/model-engineering-taps-dies/9-32-x-40-tpi-me

If you have done external threads before then you could make a tap or use a die to make a tap

Or buy the correct tap on e-bay, there are some listed

Edited By JasonB on 29/11/2021 09:19:04

RGD used to sell them, look in the watch makers section of their catalogue

Roy

I have ordered the taps from Tracytools £3.00 plus £3.00 postage.

I will make a nut and see if it works O.K.

RGDtools tap at £17.95 seems a bit of an expense when I only want 1 nut.

Received my 9/32" x 40tpi Taper Tap today.

Drilled a 6.5mm hole in a piece of aluminum to test the tap and tapped it.

A Boley Collet screwed on , the collet can be moved up and down a bit but can be tightened up O.K.

Need to wait for my Metric reamers now then I can make a Collet Block.

Ordered 6.2mm drill which is the correct size for the tap.

I hope it takes the slop out of the next tapped hole.

If you find you need to hold small items in a 4 jaw chuck an ER16 chuck on a parallel shank will work for a lot of the things you want to do. You haven't said what the target sizes are but I suspect the collets you are trying to make use of are for specific diameters and may go smaller than the ER collets but the ER collets would add to what you can do with your 4 jaw chuck and existing collets. Something to consider in the future maybe.

Martin C