Pultra 10mm Collet Blocks

This topic has 28 replies, 11 voices, and was last updated 7 April 2026 at 11:53 by bernard towers.

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5 September 2019 at 15:33 #19453
Phil P
Participant
@philp
Pultra 10mm Collet Blocks
Advert

5 September 2019 at 15:33 #427627
Phil P
Participant
@philp
OK I know this is a long shot, but before I set to and make some, has anyone come across any commercially available ones.

What I am talking about are the four and six sided blocks to hold collets, they are typically available for ER and 5C etc.

Those are too bulky for my needs, and I would like a set to take my 10mm Pultra 1770 collets for doing really small work on the Boley jig borer. I have every imaginable size and shape of collet, so it makes sense to use them on more than one machine.

Thanks

Phil
5 September 2019 at 17:19 #427649
Michael Gilligan
Participant
@michaelgilligan61133
I've seen nothing commercially available, recently, Phil

A few years ago RDG did have a few 'bench' collet holders for 10mm Pultra collets, but I missed out

Hearsay was that they were specials made for BAe, but I don't know for sure.

If you do locate any, do please let me know.

MichaelG.
5 September 2019 at 18:03 #427665
Bazyle
Participant
@bazyle
I've only ever heard of them for 5C. I kept suggesting to the late John Stevenson that he make some for 3C since there are so many of those collets around for Boxfords. 6, 8, 10mm sizes would also be logical developments of the theme.
5 September 2019 at 18:19 #427668
Phil P
Participant
@philp
As I suspected.

The only thing I have managed to find is on this website, he calls it an upright collet holder but it is not really what I am after.

**LINK**

Looks like I will be making my own then.

Phil
5 September 2019 at 23:04 #427703
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Phil P on 05/09/2019 18:19:34:

As I suspected.

The only thing I have managed to find is on this website, he calls it an upright collet holder but it is not really what I am after.

**LINK**

.

That's very similar to the one I mentioned … useful, but not what you are looking for.

You presumably want something more like the ones I pictured on this thread from 2017:

**LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=131257&p=2

MichaelG.
5 September 2019 at 23:52 #427706
Phil P
Participant
@philp
Yes Michael

That's the sort of thing, in fact I have just this minute finished drawing a set up in Solidworks 3D CAD.

Watch this space !!

Phil
6 September 2019 at 11:14 #427754
Phil P
Participant
@philp
OK, if anyone is remotely interested, here are my Solidworks drawings in JPG format.

Just bear in mind that I have not actually made them yet, so they may possibly change.

The plan is to bore the 10mm collet hole and taper in the square and hexagon raw materials, then use a mandrel to hold them in the dividing head to finish the flats to size on the milling machine.

Phil
6 September 2019 at 11:18 #427758
Michael Gilligan
Participant
@michaelgilligan61133
Many thanks for sharing that, Phil

MichaelG.
6 September 2019 at 11:25 #427760
JasonB
Moderator
@jasonb
The one thing I'm always wary of with the 5C blocks is that when you use them vertically they are stood on the end of the collet as it and the nut stick out the end, not a problem with ER blocks.

I wonder if this could be avoided if the block were made a little longer and a recess cut for a "nut" that could be tightened with a two pinned spanner so nothing stuck out the back. Possibly make a second larger flanged nut too for when you want that to act as a stop as discussed previously in Michael's linked thread.
6 September 2019 at 11:34 #427764
Phil P
Participant
@philp
Jason

Fair comment.

I have made the nut so it is machined on both sides and also so that the collet cannot poke out of the end for that very reason. I did wonder about a recessed nut, but thought it over complicated the design.

Phil
6 September 2019 at 11:38 #427765
Michael Gilligan
Participant
@michaelgilligan61133
Posted by JasonB on 06/09/2019 11:25:04:

The one thing I'm always wary of with the 5C blocks is that when you use them vertically they are stood on the end of the collet as it and the nut stick out the end, not a problem with ER blocks.

I wonder if this could be avoided if the block were made a little longer and a recess cut for a "nut" that could be tightened with a two pinned spanner so nothing stuck out the back. Possibly make a second larger flanged nut too for when you want that to act as a stop as discussed previously in Michael's linked thread.

.

[my emboldening]

Jason: If you scroll down Phil's recently linked page: **LINK**

http://www.wefalck.eu/mm/tools/attachments/attachments.html

… to 'Upright Collet Holder'

You will see that's exactly what was done [albeit on a much smaller scale than 5C]

MichaelG.
22 November 2021 at 16:34 #572486
malcolm hollins
Participant
@malcolmhollins96641
Hi Phil

I have some Pultra 10 collets so I am interested in making the collet blocks'

The problem I have is getting the correct size taps to make the nuts for the collet.

Could you give me the Tap size and where could I get the Taps from.

Cheers

Malcolm
22 November 2021 at 20:41 #572517
david bennett 8
Participant
@davidbennett8
Posted by malcolm hollins on 22/11/2021 16:34:43:

Hi Phil

I have some Pultra 10 collets so I am interested in making the collet blocks'

The problem I have is getting the correct size taps to make the nuts for the collet.

Could you give me the Tap size and where could I get the Taps from.

Cheers

Malcolm

Be careful here. Pultra 10mm collets are not the same as Pultra10 collets, which are probably 8mm collets.
22 November 2021 at 20:53 #572518
JasonB
Moderator
@jasonb
If you are making the same as Phil's then the thread size is on the drawing . M10 x 1 which is quite common as it is a spark plug thread

The 8mm collets have a thread 0.268" dia x 40tpi, I think I have seen this size tap somewhere as several collets use the thread. Shouldalso be able to single point them on the lathe with a small tool.
19 June 2022 at 06:27 #602309
Colin D
Participant
@colind
Phil P — thanks for posting your excellent and very clear drawings.

I am thinking of making a pair of these collet blocks, and maybe a third one in a cylindrical form. Can I ask – did you make them, and did you make any changes that were advantageous?

I was thinking of using Jason's idea of making recessed nuts, for instance.

Thanks

Colin
19 June 2022 at 08:04 #602315
bernard towers
Participant
@bernardtowers37738
I am in the process of making some er16 blocks so they can be used in the sherline. My only complaint with my er25 blocks is that I find them a bit on the short side a problem I hope to get over when doing the er16 version.
4 April 2026 at 10:05 #843137
Phil P
Participant
@philp
Sorry for the late reply, I have only just seen this.
I did make the collet blocks and have found them very useful.
4 April 2026 at 18:04 #843215
Dell
Participant
@dell
I just made the Hexagon one because I can use it for square as well i used it today.so the pictures are screen shots.
4 April 2026 at 19:51 #843225
Bazyle
Participant
@bazyle
Is the block just jammed onto a taper mandrel for the flycutting?
4 April 2026 at 21:40 #843237
Nigel Graham 2
Participant
@nigelgraham2
Jason:

Are the collets generally metric?

The 8mm collets have a thread 0.268″ dia x 40tpi, I think I have seen this size tap somewhere as several collets use the thread. Should also be able to single point them on the lathe with a small tool.

That’s 17/64″ X 40, or over such a short distance, not 6.8 X 1mm?

The nearest standard is 9/32 X 40tpi ME but whether that would work properly I wouldn’t like to say.

Is the Pultra collet also that used on the BCA jig-borer? Mine has only a few collets with it.
4 April 2026 at 22:36 #843246
Phil P
Participant
@philp
Pultra collets are not the same as a BCA (I have both) Pultra are 10mm diameter, BCA are 11mm diameter and much longer, they are like hens teeth to find as well.

I loctited the collet blocks to parallel shafts for the flycutting operation.

Another thing that might not be obvious, the nut to draw the collet into the block was machined to be truly parallel on the two faces and deep enough so that the collet does not protrude right through. This means that the collet block can be used vertically in the machine vice sitting nice and square on the nut’s outer face.

Phil P
5 April 2026 at 08:46 #843290
Michael Gilligan
Participant
@michaelgilligan61133
Nigel

Just to expand on Phil’s note

The BCA collets were basically Lorch ‘long series’ and when made by Crawford were designated 55

MichaelG.
5 April 2026 at 10:09 #843309
JasonB
Moderator
@jasonb
On 4 April 2026 at 21:40 Nigel Graham 2 Said:

Jason:

Are the collets generally metric?

The 8mm collets have a thread 0.268″ dia x 40tpi, I think I have seen this size tap somewhere as several collets use the thread. Should also be able to single point them on the lathe with a small tool.

That’s 17/64″ X 40, or over such a short distance, not 6.8 X 1mm?

Last time I looked 40tpi was about 0.635mm pitch not 1mm, short or long distance it ain’t going to fit.
5 April 2026 at 11:20 #843329
Phil P
Participant
@philp
If you need watchmakers lathe collet dimensions look here on the “Lathes” website. Bottom of page.

https://www.lathes.co.uk/watchmaker/index.html

Phil P
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