How to make a reducing sleeve for a spring collet

[Ivan SchuchParticipant @ivanschuch53451]

I have an Elliot mini borer and have not been able to find any metric #00 collets for it. The largest collet I have is 1/2”. Is a reducing sleeve a feasible option? What is the easiest way to make them?

 

[DC31kParticipant @dc31k]

Please could you state your question more clearly. You say “the largest collet I have…”, which implies two things – that you have more than one collet and that something you have is less than 1/2″.

What size of tooling do you want to hold? What collets do you actually have?

ER collet holders are available on a straight shank. You will have to look in a place more geared towards the US market, but you will find one with a 1/2″ shank (CTC Tools out of Hong Kong is a reliable suppler). The slight disadvantage is that the holder will eat up headroom.

You call it a reducing sleeve, with the logic that it goes in the collet and makes its gripping size smaller but an alternative might be an ‘expanding’ sleeve that goes onto the tooling to make it bigger. Drill/bore/ream the inside to suit the tool’s shank diameter and loctite the tool in. That way, the sleeve does not need any ability to compress (it does not need to be split). A 13″ length of 1/2″ diameter silver steel would make many sleeves and has an OD made to an acceptable standard.

[JasonBModerator @jasonb]

Two options if you have a 1/2 capacity collet.

1. Make a parallel bush 1/2″ dia with a “top hat” flange on the end say 2mm thick, ream 6mm right through. Cross drill and tap this for a grub screw then you can use the FC-3 throw away cutters from 1mm to 6mm. It’s a bit shallow on the thread but should do the job. If head room is not an issue then make it more like a side lock cutter having a 1/2″ shank and a larger say 3/4 ” x 1″ long head that will then give a better depth of thread for the grub screw

2. Turn a similar sleeve bored/reamed to the shank size you want, for metric 4mm, 6 and 10 will do for most. Set it up horizontally and with a slitting saw cut three or six slots along its length. Two or five not quite all the way through, the last all the way through. I’ve used reducers like this upto 20,000rpm, just don’t get too greedy with the depth of cut

[Howard LewisParticipant @howardlewis46836]

My incvlination, to asapt a 1/2″ collet to hold metric stock, would be to turn a sleeve 1/2″ OD, hold in the 1/2″ collet and drill ream for the Metric size stock, and then make one longitudinal slit, and deburr.

It is possible that the bore will close slightly.

Put the Metric material into the bore, and hold in the 1/2″ collet.

Howard

[Howard Lewis]

On Howard Lewis Said:

…turn a sleeve 1/2″ OD, hold in the 1/2″ collet and drill ream for the Metric size stock, and then make one longitudinal slit, and deburr

Maybe we should give some thought to any limits on that procedure. If, for example, he wants to hold a 3mm shank cutter, the wall thickness of the split sleeve might be excessive. In that case, it might need a partial slit on the opposite side (Gucci version would have a relief hole first for stress relief) to give it a bit more flexibility.

[Ivan SchuchParticipant @ivanschuch53451]

Thank you all for the replies, I really appreciate your help.

I have a 1/4 and a 3/8 collet as well as some obscure small sizes. I would like to use 6, 8, 10mm cutters. The collets do not fit in my lathe.

i will try a combination of your proposals.

For 8 and 10mm: Side lock bush with larger head and grub screw.

For 6mm: 3/8 Silver steel sleeve with 1 or more slits. I’m concerned with concentricity so will set it up in the 4 jaw for drilling.

Ivan

 

 

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