ER Colletts – will they hold my plug?

[Jim O’Connell 1Participant @jimoconnell1]

Do I need one

[Jim O’Connell 1Participant @jimoconnell1]

I am thinking of getting an ER collet for my mini lathe. I am new to lathes so please bear with me.

I have a 20mm stainless plug and the head is 25mm.

I want to grip the 25mm head and machine the screw part

Problem with the 3 jaw chuck is it is hard to center the plug.

Would the ER collet help!!! Any advice please

[Thor 🇳🇴Participant @thor]

Hi Jim,

If you want to grip a 25mm diameter rod you will need an ER-40 collet system, may be something like this, from ARC. You could of course use a 4-jaw independent chuck.

I made an ER-32 chuck for my smaller lathe and I am satisfied, but ER-32 collets only go up to 20mm.

Thor

 

Edited By Thor on 01/09/2016 17:27:16

[Nigel BennettParticipant @nigelbennett69913]

I think it unlikely that anything short of an ER40 size collet would do – ER32 has a maximum diameter of 20mm. If your 25mm head is very short, then an ER collet would not be a good plan as it would distort badly and not grip well – unless you fitted a short 25mm disc in the far end as well.

I don't think ER40 collet chucks are readily available for mini lathes. (ER collets really are for cutting tools only, not material, despite what people – including me – actually use them for.)

In your case, I would fit a piece of material in the 3-jaw chuck and BORE it out to 25mm. I'd mark it against jaw No. 1 and remove it, cut through one side of it to make a split collet and then use that to hold your parts.

[Tony Pratt 1Participant @tonypratt1]

You would be better making the whole thing from scratch, but it's obviously your decision.

Tony

[Bob Brown 1Participant @bobbrown1]

Soft jaws machined to suit is an option, I use soft jaws when I want to hold a part true and have some strange jaws from holding loco wheels etc.

 

 

Edited By Bob Brown 1 on 01/09/2016 17:45:38

[JasonBModerator @jasonb]

As Bob says soft jaws or the 4-jaw unless you have masses of them to make.

If you want to go the collet route then 5C will do you nicely

[AjohnwParticipant @ajohnw51620]

There are ER40 collet chucks available with certain recess sizes. Not sure of the size of the reces on a mini lathe

**LINK**

I would have thought that a 4 jaw which may have come with the lathe and a purchase of a decent DTI would be a better investment for one offs.

John

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[John ReeseParticipant @johnreese12848]

I made a backplate to fit an ER 32 collet chuck to my 10K South Bend. I already had the collets for my mill. I am very satisfied with this setup. One shortcoming of the ER or other collets primarily designed to hold tools: they do not work well when the part or tool does not extend through the full length of the collet. To hold extremely short work you can make a plug the same size of the work to fit the back end of the collet.

[Frances IoMParticipant @francesiom58905]

when you say ‘machine the screw part’ just what are you trying to do – for example shortening a screw thread is easier with a lantern chuck which for a single thread size is no more than a simple block bored to sufficient depth to accept the threaded item leaving enough of the screw part projecting through a hole (possible threaded) as needed with some form of additional tightening into the block to stop the head rotating

[Jim O’Connell 1Participant @jimoconnell1]

What I want to do is put a spring recess 10mm wide by 1mm deep in the plug that screws down on the spring.

I have the 2 flute end mill to do the job. Just looking for a quick way to center the plug in the chuck or whatever.

Have a good few to do!!!

[Tony Pratt 1Participant @tonypratt1]

Posted by Jim O'Connell 1 on 01/09/2016 19:41:52:

What I want to do is put a spring recess 10mm wide by 1mm deep in the plug that screws down on the spring.

Reminds me of Professor Stanley Unwin.

Tony

[JasonBModerator @jasonb]

I'm wondering why your 3 jaw is not good enough for this.

Is it that the 25mm head is quiet short so the end of the thread can wobble if the work is not being held perfectly true across the head.

Are the plugs turned or forged in which case the thread may not be true to the head anyway.

Also what length is the threaded part in relation to the head, if ther is not much length to grip and/or the thread is long there is a risk of the work moving as the cutter makes contact.

All three of these could be solved by Frances' method

[Frances IoMParticipant @francesiom58905]

20mm dia thread is quite large – maybe one simple scheme is to get 20 hex nuts for that thread gluse these to a piece of same 10mm sq bar on their sides just far enough apart to allow the complete screw to fit in and then be screwed thro the leading nuit – a second screw then tightened to lock 1st and the 10mm bar mounted at centre height in toolpost and the 10mm cutter in a holder in headstock and proceed slowly to mill 1mm deep

Edited By Frances IoM on 02/09/2016 08:35:18

[DustyParticipant @dusty]

Split collet, Turn and bore a piece of material with the O.D.just larger than the head. Mark where No1 jaw is positioned on the job and part off to length. Hacksaw through the new collet along it's length midway between where two of the jaws will come. Clean up the saw cut on the inside. Put your plug into the collet place it back in the 3 jaw with the head on the inside of the chuck making sure you line up No1 jaw and your previously made mark. job done. While this is not deadly accurate it is simple and effective and works on keeping the screw concentric.

 

Edited By Dusty on 02/09/2016 09:45:56

[Jim O’Connell 1Participant @jimoconnell1]

Posted by JasonB on 01/09/2016 19:48:49:

All three of these could be solved by Frances' method

Whats the Frances method???

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Frances IoM on 02/09/2016 08:34:48:
20mm dia thread is quite large – maybe one simple scheme is to get 20 hex nuts for that thread gluse these to a piece of same 10mm sq bar on their sides just far enough apart to allow the complete screw to fit in and then be screwed thro the leading nuit – a second screw then tightened to lock 1st and the 10mm bar mounted at centre height in toolpost and the 10mm cutter in a holder in headstock and proceed slowly to mill 1mm deep

Edited By Frances IoM on 02/09/2016 08:35:18

.

Jim ^^^ is the method described by Frances

[Frances IoMParticipant @francesiom58905]

Michael – surpised you didn’t just look up Latern chuck in Tubal Cain’s great book about workholding in lathe (pity that the photo in the reprint are so badly reproduced tho) – my ‘nutty’ suggestion was I guess a very cut down version of same as given size of thread and small diff in sizes between head + thread thought that any scheme relying on other than pressure on head was probably doomed – and tapping a 20mm dia thread seems rather hard work

[SillyOldDufferModerator @sillyoldduffer]

Posted by Jim O'Connell 1 on 01/09/2016 19:41:52:

What I want to do is put a spring recess 10mm wide by 1mm deep in the plug that screws down on the spring.

I have the 2 flute end mill to do the job. Just looking for a quick way to center the plug in the chuck or whatever.

Have a good few to do!!!

Hi Jim,

Is this what you are trying to produce? If so, how deep in mm is the head that needs to be gripped?

Ta,

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Frances IoM on 02/09/2016 16:37:58:
Michael – surpised you didn't just look up Latern chuck in Tubal Cain's great book about workholding in lathe (pity that the photo in the reprint are so badly reproduced tho) – my 'nutty' suggestion was I guess a very cut down version of same as given size of thread and small diff in sizes between head + thread thought that any scheme relying on other than pressure on head was probably doomed – and tapping a 20mm dia thread seems rather hard work

.

Why would I do that, Frances ?

The question was specific, so I answered it.

MichaelG.

[Frances IoMParticipant @francesiom58905]

my initial suggestion and that ‘endorsed’ by Jason was the classic lantern chuck – the 2nd scheme, tho obviously a version of the chuck idea both reversed the roles the cutter (now held in headstock) + work and replaced a chuck by a cut down linearised scheme – ok same basic principle hold the screw at correct orientation to cutter by pressure on the head

[Michael GilliganParticipant @michaelgilligan61133]

Frances …

Pardon me for trying to help !!

There was clearly a misunderstanding by Jim regarding "the Frances method", so I simply pointed him to your most recent post.

MichaelG.

.

Edit: I presume that Jim is capable of reading back through the thread, to appreciate your previous contributions.

Edited By Michael Gilligan on 02/09/2016 18:18:36

[Jim O’Connell 1Participant @jimoconnell1]

Posted by SillyOldDuffer on 02/09/2016 16:38:08:

Posted by Jim O'Connell 1 on 01/09/2016 19:41:52:

What I want to do is put a spring recess 10mm wide by 1mm deep in the plug that screws down on the spring.

I have the 2 flute end mill to do the job. Just looking for a quick way to center the plug in the chuck or whatever.

Have a good few to do!!!

Hi Jim,

Is this what you are trying to produce? If so, how deep in mm is the head that needs to be gripped?

Ta,

Dave

Yes. This is what I want to do. The head of the plug is 4mm X 25mm and the treaded part is 15mm X 20mm long

[Frances IoMParticipant @francesiom58905]

Jim to return to your original post – have you got any nuts for the thread (is it a standard thread eg M20 – do you know what the thread is?)

[AjohnwParticipant @ajohnw51620]

The grip length of an ER40 collet is too long really for holding 4mm x 25mm accurately. It's the main problem with this style of collet.

If I had a lot to do I suspect I would make something to hold them first. That could simply be a recess in something that was a snug fit using grub screw to hold them in place but you may have to avoid marking them so the screws would need some thought. Soft solder ends maybe. Or some steel plate on a surface plate. Drill a hole through it, slit into the hole from one edge, drill and tap a hole through the edge to clamp it up. Mount on the lathe face plate with the clamp screw tightened a touch and then machine the recess for the screw heads.

Soft jaws are another option and maybe normal a normal 3 jaw chuck with the jaws reversed. That way you will have a square on face to press the head up against. If you rotate the work by hand just as the jaws close on it things generally will run as accurately as the chuck does. There is a bit of a knack to doing that though. A small chuck will do this sort of thing easily. Big ones too if the part is big enough. It may be feasible to machine up a split ring if that's the case. You may find that you can't get the part out if you do that though.

Rotagrip stock soft jaws but be prepared to spend a while fitting them to the chuck by hand with a file. I think they are deliberately made a touch over size. Getting them to a really good fit usually takes me 1/2 hr or so being very careful to find out what aspect needs relieving. They only need thou's removing as well.

John

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