ER25 collets to hold square material

Are ER25 collets to hold square material (say 1/4" or 3/8" available at a sensible price.

Thank you.

Ian

Not as far as I know. However Harold Hall did an article in MEW sometime ago about making square collets to fit normal ER collets. I made some & they certainly work. Have a look on his site I`m sure there is a reference to them on it.

Alan

Here is the page on Harold's site.

MichaelG.

It's not beyond the realms of possibility that you could get someone to electrostatically machine a square hole in a standard collet.

Neil

Slightly off-topic, because they wouldn't suit holding square bar-stock; but I was interested to see these ER "tapping collets"

MichaelG.

Still off topic but seeing Michaels post, I did a search and found these floating tapping collets.

John

This will be regarded with horror- I have held square stock , 6 &7mm, in the nearest round collet. May have to just knock the corners off. Not really accurate but made some small model gun axles like that.

Thanks to all for your replies.

I spotted the tapping collets some where else & very nearly brought one. but now I've seen the drawing of the ones you found Michael I can now see it would not be suitable.

I will go down the Howard Hall method ( Thanks Alan) nice little project for a Winters afternoon !

Just to explain what I need them for. I have just finished (nearly) building a Bonelle T & C grinder I Have used an ER25 collet chuck with a straight shank in the work head & needed a method to hold square HHS to grind as lathe tools.

Thanks again

Ian

As has Gordon, I have no problem holding square stock in ER32 collets for machining. Accuracy is pretty good in my estimation. Obviously the 4 jaw has to come out for exact stuff.

Mick

My 4-jaw self centering chuck works very well for this application.

Steve

Ian,

You`re very welcome. At the time when Harold did the original article in MEW I didn`t have any ER collets though I was seriously contemplating getting them but didn`t know which size to purchase.

Studying the article & the prices of 5C square collets convinced me to go for ER32 collets mainly because they were larger than ER25 so I could make shall we say bigger square collets ( & also by the way Rectangular collets) than would be possible in the smaller sizes of ER collets.

I used 12mm Sq steel bar for my collets, cutting 4 x 90mm lengths cleaning the inside 2 faces before stacking & loading in the four jaw & turning the OD to 23.5mm. I then faced off the end & turned a length of 40mm down to 19.5mm dia. I then turned a groove to accept a circlip at the shoulder. Removed 4 jaw, fitted ER chuck with 20mm collet, fitted first embryo collet into said chuck & repeated above. I then parted off in the centre of the 23.5mm dia & cleaned up the faces of the 2 embryo collets. I then stamped each jaw 1,2,3 & 4 so that I could keep the jaws in the same position in relation to each other.

I repeated the above a few times so I`d have ready made blanks if I required different sizes. Must admit they have come in very handy

Alan

Pleased Alan that you are making good use of the idea. I like your suggestion that they can also be made to take rectangular material. I will add that idea to my web pages if thats OK, that is of course if I can find time!

Harold

No objection whatsoever Harold, by all means go ahead. Hope you are enjoying your retirement !! I know I am.

Alan

I has used both square and hexagonal bar in ER32 collet without problem. Do not use big force on ER collet to hold the square/hexagonal bar and take light cut each time to required size.

There's a simple emergency solution with is to turn up a collar that is bored to be a good fit on the corners of the stock you're using and then slit it with a hacksaw. The collar can be held in a chuck or a collet.

Just for information- my ER collets are all 8 segments, first time I've counted them. So OK for square , not good for hex.Whilst counting them I noticed one or two rags and burrs so cleaned them up. Also checked the axles I had made from square- 6mm square to 5mm dia.at each end. There is no noticable problem, no doubt a dial gauge or similar would show some.

Edited By Gordon W on 25/01/2015 10:44:11

Gordon W has it sussed out, if the square stock can be squeezed into whatever collet, then just tighten it up and go for it. You can buy collets for square bits of material, but they are a bit on the spendy side, best just use what you have, lot's cheaper and they work on either round or square stock.

.

Graham,

Given that the original question was specific to ER collets ...

Can you please let us know where these are available ?

Thanks

MichaelG.

It is not too difficult to mathematically determine how much packing would be needed under one jaw of a 3 jaw chuck to hold square stock centrally, based on square root of 2. I have done this on occasions.