Steel to make a collet chuck

[P JParticipant @pj36746]

[P JParticipant @pj36746]

Hope I’ve posted this in the right section – it’s my first post.

I’m looking to make an ER32 collet chuck for my lathe. I’m considering EN8 mild steel. My lathe has a 1 7/8” x 8 spindle so I’ll need to form an internal thread on the new chuck and an external thread for the collet nut. Am I on the right track with EN8 or might there be a better choice?

Pat

[Thor 🇳🇴Participant @thor]

Hi Pat,

Welcome to the forum. I made an ER 32 chuck for my small lathe using mild steel. I have used the chuck often for several years without problems. With the use I have I guess the collet chuck will last longer than me.

Thor

[colin hawesParticipant @colinhawes85982]

I have made several collet chucks using mild steel. One of them at my club has had quite a lot of use with no problems. Colin

[EmgeeParticipant @emgee]

Hi Pat

EN8 is a good choice but if new to machining you may find it more difficult to obtain mirror finish and crisp threads because it can be a tough material.
EN1Apb will be the easy material route and may suffice for occasional workshop use.

I would suggest buying a closing nut is worthwhile, especially the ball bearing type.

Emgee

Edited By Emgee on 12/01/2023 18:36:42

[old martParticipant @oldmart]

Welcome to the forum, PJ, I would agree with Emgee about the choice of steel if you can get some. What lathe do you have?

[P JParticipant @pj36746]

Thanks for the warm welcome and for the suggestions.
I have a South Bend 13 from approx 1942 and an Elliot Victoria V2 mill. I’m in the UK

I’ll look into EN1APB to see if it, or equivalent, is available here.

Pat

[duncan webster 1Participant @duncanwebster1]

I'd buy a flange mounted collet chuck and make a backplate for it, a lot less work. Photos of mine available if required

[Peter Simpson 3Participant @petersimpson3]

My go to choice of metal supplies are M-Machine in Darlington. They do EN1APB. other suppliers are also available.

[P JParticipant @pj36746]

Posted by duncan webster on 12/01/2023 21:39:52:

I'd buy a flange mounted collet chuck and make a backplate for it, a lot less work. Photos of mine available if required

Always open minded but I think I’ll struggle to find an 1,7/8” backplate ready threaded so I’ll still have to machine it.
What I’m proposing will be from a single slug of 2.5 x 3.5” steel. Turn the thread to fit the spindle thread, mount it, then turn the ER32 end. I have a spare ER32 nut so won’t need to buy anything else.

Pat

[P JParticipant @pj36746]

Posted by Peter Simpson 3 on 12/01/2023 21:44:29:

My go to choice of metal supplies are M-Machine in Darlington. They do EN1APB. other suppliers are also available.

Thanks Peter

[HuubParticipant @huub]

I have made several collet chucks and Hex holders from 42CrMo4, CK45 and mild steel. They all will last longer than the lathe (or me).

I prefer making my own collet chucks because it is my hobby, it is cheaper and most of all, wen made on the lathe the chuck is used on, the runout can be far better then when buying a top quality chuck.

[JellyParticipant @jelly]

I would strongly suggest a pre-hardened alloy steel for long term durability and accuracy.

709M40 (EN19 in old money) is widely available in U condition, and 826M40 (EN26) in W condition. West Yorks Steel will sell you both for delivery, via phone or email.

Those letters refer to the tensile strength and hardness as supplied, you would need to turn them with carbide, but the results are usually very good.

 

Personally I would be inclined to use 080M15 (EN32), do the threaded elements with an allowance for shrinkage, turn to near finished shape, then heat treat myself over a long soak time so the core normalises and the exterior case hardens to a decent depth, then hard turn the register and taper to final size with a CBN insert.

This, obviously is a more complex undertaking, but certainly not beyond the ken of an enthusiastic amateur; if you're curious I can explain in more detail.

Edited By Jelly on 13/01/2023 11:59:04

[Neil LickfoldParticipant @neillickfold44316]

7075 Aluminium works well too. It is harder than mild steel, and gives a great finish and chips well, so becomes quite easy to cut on home sized machines.

[samuel heywoodParticipant @samuelheywood23031]

I'd be tempted to get a few small samples to try before you start the project proper.

See what works for you.

My novice take on different steels is as follows: (bear in mind i'm using home ground toolbits so my geometery may be way off for the material in question.

EN1 leaded, didn't like, 'smeary', marks easy, unlikely to buy again.

EN3~ much better, machines nicely (though a web search suggests it's not so good to machine as EN1) Does seem rather prone to rust however.

EN8~ like others have said, difficult to get a really good finish (at least for a novice like myself) You can tell when cutting it's noticeably harder than mild steels.

EN16T~ (T stands for tempered) Turns quite nice, just from the cutting sound you can tell it's quite hard, gives a good finish, odd colour, yellowy. I blunted a hss threading tool trying to put a thread on it. Probably did something wrong.

EN24T~ My internet research suggested i would have a hard time machining this with hss tools.

Now either i got burned, or the interweb is wrong.

Yes it's quite hard,(but seemed less so than EN16 ??) hss did the job~ beautiful finish, nice shiny silver colour Probably my favourite steel to date.

[peak4Participant @peak4]

I bought a length of EN19 to make an ER25 based spindle for my Quorn tool and cutter grinder, but not got around to it yet.
I did however get asked to make some spacers for a friends motorcycle special, and used some of the bar for those.
Very nice finish using carbide, albeit on my larger Warco GH1330.

I bought a set of collets and a chuck from a chap who was selling off his workshop.
Amongst the items were a couple of very well made parts that he'd machined from hydraulic rams.
John (AKA Bogstandard, RIP) recommended the rams for this sort of job, but luckily had a local supplier; a company who refurbished rams and sold off bent or damaged parts etc.; you just need to get past the hard chromed layer on the outside.
I've no idea what material they are, but it seems to work well.

Bill

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