Er32 chuck for Fortis lathe

[sean logieParticipant @seanlogie69385]

[sean logieParticipant @seanlogie69385]

Been a while since I've had time for my wee workshop ,so today I decided I would make the er32 chuck I've wanted for a while now ,so I used a chunk of stainless I had ,probably not ideal but it's what I had . It's not perfect but it's accurate where it matters . I put a tenths indicator on the inside of the collet taper and it barely moved which kinda surprised me a bit 😁 but I'll take it . The only negative is the cheapo collet set I bought have 0.002 run out ,I tested using three different sized carbide End mills in the collects. .

[Martin ConnellyParticipant @martinconnelly55370]

ER chucks were developed for holding tooling and for most cases the runout you have would be fine. Home workshop users have started to use them for workholding and this may then give unacceptable results. If you have a 4 jaw independent chuck you can get the runout required for what you are doing if it needs to be lower and as a compromise, if you want to also use your ER collets, you can mount a collet holder in a 4 jaw chuck. A square ER32 collet chuck may be your next piece of tooling to make or buy. They are also useful for holding round parts in a vice for milling so not limited to one infrequent use.

Martin C

[sean logieParticipant @seanlogie69385]

The run out I have in the er32 collet is good enough for what I do . It’s true that you get what you pay for . I do have a four jaw independent. I wanted to make er32 chuck to use/have and also as an exorcise to see if I could make something that had to be accurate ,up till now I’ve just been mucking about . 😊 I have a square block er32 holder which is a very handy piece to have .

Sean

[EmgeeParticipant @emgee]

Hi Sean

Have you modified the collet closing nut in some way as all of my ER collet nuts wrap around the front face of the collet which hinders working close to the collet face.

Does the nut still engage the slot in the collet to assist removal ?

Thanks, Emgee

[Michael GilliganParticipant @michaelgilligan61133]

Well-spotted, Emgee

Whatever that modification might be, it could be useful !!

MichaelG.

[JasonBModerator @jasonb]

Or more likely the nut has just been tightened down a bit on the empty collet which makes it stick out.

Same 12mm collet one with a cutter the other tightened down a bit by hand with nothing in it

Edited By JasonB on 11/11/2018 11:04:59

[Michael GilliganParticipant @michaelgilligan61133]

[sean logieParticipant @seanlogie69385]

Emgee I’ve not made any alterations to the nut ,the release of the collet works the same as the original. It pops out like it should 😉 . The collet is a beautiful fit .

Sean

[egaParticipant @ega]

sean logie:

For 'tis a jolly good lathe!

Here is my shop-made version showing also a GHT-inspired dividing attachment for use with milling and drilling spindle:

Not obvious in the photo but I have made the chuck body long enough to be able to work up close despite the gap.

[sean logieParticipant @seanlogie69385]

My old Fortis is a bit rough around the edges but it’s accurate enough for me 😉

Sean

[egaParticipant @ega]

Posted by sean logie on 11/11/2018 14:00:04:
My old Fortis is a bit rough around the edges but it's accurate enough for me 😉

Sean

Tony Griffiths gives them a good write-up as you are no doubt aware.

[Clive Brown 1Participant @clivebrown1]

Don't necessarily put the run-out down to your "cheapo" collets. I made a similar ER25 chuck and at first had a few thou. run-out, similar for all my collets despite the taper running true. I thought that this might be due to making the screw-thread a wee bit too tight, so took off a shaving. Sure enough, the run-out reduced to less than a thou. at which I'm quite happy.

Clive

Edited By Clive Brown 1 on 11/11/2018 14:33:07

[Russell EberhardtParticipant @russelleberhardt48058]

I was thinking the same Clive. The nut should centre itself on the front of the collet, not on the thread.

Russell

[sean logieParticipant @seanlogie69385]

Food for thought gents .

Sean

[egaParticipant @ega]

Posted by Clive Brown 1 on 11/11/2018 14:31:53:

Don't necessarily put the run-out down to your "cheapo" collets. I made a similar ER25 chuck and at first had a few thou. run-out, similar for all my collets despite the taper running true. I thought that this might be due to making the screw-thread a wee bit too tight, so took off a shaving. Sure enough, the run-out reduced to less than a thou. at which I'm quite happy.

Interesting point; my Quick Step Mill with ER20 spindle came with a rather loose collet nut. The designer/manufacturer may have had the same idea in mind.

[EmgeeParticipant @emgee]

After checking further all Emco made ER25 collet chucks I use have the front of the nut extended to always be about 2mm in front of the collet face .
The other makes including Schaublin (RH front in pic) do allow almost flush facing if in the lathe.

Emgee

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