ER25 collet chucks that fit a myford spindle nose

I'm thinking of buying one of these to save making one. There are several suppliers and I wonder if any offer one with a light interference fit on the spindles register rather than being a clearance fit?

John

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Best bet is to make or use a chuck backplate and turn register to fit the backplate. If you use a larger backplate you could add holes in the diameter to take a tightening rod.

It's to go one a Dore Westbury for a milling chuck so back plates wont fit in well.

I could always treat one I buy as a casting kit but wondered if any had been made properly.

John

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Only by serendipity, I would think, John.

I'm pretty sure there is some tolerance on the dimensions of [even] the Myford register.

... a guaranteed 'light interference fit' would probably require selective assembly.

MichaelG.

Edited By Michael Gilligan on 19/10/2015 14:00:50

I was thinking of getting one from Chronos but they were out of stock so as a stop gap purchased one on ebay nwith MT2 and draw bar found it suited my needs so will not be getting the screw on one.

H

The one I bought is pretty tight on the register of my S7. Unfortunately it was also slightly eccentric so I had to skim the collet taper - fairly hard steel but doable with a TC tip. I use a taper fitting one in my Sharp mill which has a 2MT as well as a Myford nose. I've made a couple of ER 25 chucks since, no problem provide you can cut a 1.5 mm thread.

HTH

Rod

if there is a problem with them I thought the best option would be to re machine the register and add a sleeve. That could be done while the collet end is holding a piece of turned bar so should work well providing the collet is ok.

The Chinese do seem to work to this sort of tolerance on some parts such a chuck to spindle plate fitting.

John

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I suppose it all depends on what tolerance your Dore Westbury was machined to.

Could be well out compared to a Myford ?

John W1

You do not want a slight interference fit. If you manage to get it on the nose I doubt you will ever get it off again without serious damage to your lathe. Interefernce is exactly what it says The male is larger than the female part even size for size would be an improbable task. In order for something to pass over another item there must be some clearance albeit minimal.

I've been taking chucks of my Boxford and putting them back on along with a light interference fit for a number if years now.

JS make a good point. The DW seems to be made a just over a thou over size but I really need to check the cal of the mic to be sure of that.

Just have and my trusty ancient Starrett agrees with the digital one. 1.2 thou.

John

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Looks like you've hit lucky, John

Just buy one that's the sliding fit most people use, and it wll be interference on your regisiter.

MichaelG.

It might not go on Michael. I know from one of the suppliers that they did have some problems with them. That must have been several years ago. Be interesting to see if it's been improved.

Out of interest I do have an ML7 spindle from when I reconn'd one. The register is bang on 1.250" even via the vernier on the mic.

John

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as a fellow Dore Westbury owner and user, John's thread is of considerable interest to me especially as my Myford collets are all to imperial sizes.

i have a special head for the disposable carbide 1/4" dia shank cutters. i was lucky enough to get a further supply of these cutters at the Bristol ME exhibition last year.

cheers,

julian

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Quite so, John ... That was the reason behind the comments in my first posting.

Perhaps the ideal would be to buy a tight one, and /lap/hone its register to give the 'fit' that you want.

MichaelG.

I was fortunate, the collet chuck I bought was fairly tight and this was not an issue.

I have standardised on ER32 for both lathe and mill and am selling the Myford collets - I think the ER32s are far superior and 32 instead of 25 gives even more versatility.

I think this is a good solution for me.

I often use an ER16 2 morse collet holder on mine or 2 morse collets from arc euro. They do part sets for milling. The draw bar thread is too big for a DW so I either drill and fit a tapped sleeve to suit or add a short length of all thread with tapped hole to suit the DW draw bar. So far I have managed with the all thread. They are just loctited in place. I use the ER16 holder because it's easier to see what going on especially with small cutters.

I want to try a much larger cutter so am going to try ER25 and the myford fitting should be stronger than 2 morse plus less projection. I've no idea if the mill will handle a 100mm face mill. If not back on ebay and try another size.

The sort of fit that is needed is something of the order of 0 clearance to some 1/10 thou interference. The nearest standard I am aware of is ansi light interference fit number 1 but lathe registers are generally bang on size.

John

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I have the british made one at Rotogrip link on my wish list at the moment, but have other more basic things to get yet before a collet system.

By all accounts on here they seem to be helpful people there, perhaps worth a call to see if they could check fit?

it arrived from Warco. It's a should fit but doesn't fit size. A Myford spindle 1/2 thou under size goes in but is noticeably loose.

Measurements suggest it's register bore is 1.8 thou over size but a plus 1 thou oversized register wont go in cleanly. Neither will the milling spindle.

A 2/10 thou oversized myford spindle nose on a dividing head does just about go in cleanly. A Myford chuck is a touch tight on that. The mechanical advantage of the thread is needed to get it on - ideal.

Via a mic on the OD and a ball end mic to check thickness there is some taper in the register hole, circa 7/10 thou over a distance that shouldn't matter and the register isn't central to the OD. Not that this matters but maybe the thread isn't concentric to the register. That would explain the fit being a bit strange. If I check with blue which isn't that easy this seems to be the case.

Grrrrrrrrrrrrrrr

More measurements tomorrow. Another explanation could be that the hole isn't round.

John

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Set a myford spindle on a V block on my surface plate with the holder on it. Measurement errors less than 1/2 thou over the chuck length and double that checking run out further from the chuck. The V block is about 2/10 thou out.

Run out of bar at the nose of the collet holder circa 0.005" and double that 2" from the end of the chuck.

I rotated the collet to check that and didn't see anything to suggest the claimed when I bought them 0.0005" is incorrect. The high spots on the test bar hardly changed.

If I locate the test bar in the collet and stick that in the V block there is negligible run out on the register. What's there might be due to the collet or the chuck. It's around 3/10 thou.

The screw thread must be off centre. I can't think of any other way of checking that. It must tip the entire holder when it's fitted on a spindle. That would also explain things not going in that should.

John

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John

Forget about checking a test bar held in the collet it is only telling you that the test bar is running out. Put the collet holder on the lathe and check the angle of the collet holder for run out (that is the part of the holder that the collet registers on) if that is running out then you have a case for replacement. If you are pulling the spindle round by hand ensure your bearings are properly adjusted, if anything they should be slightly tight.