Myford

any experiences with myford screw on er 25 collet holders

Hi, I had an er 40 collet set on my miller with a 4 morse er 40 collet holder. I found this very useful, so i decided to use said collets on my Myford ML7 Tri-Leva. I obtained a backplate and a backplate mounting er 40 collet holder, machined it up and now have the best of both Miller & Lathe, and large size collets.

Terry.

I bought an ER 25 screw-on collet chuck from one of the usual suspects at a show ( I can't remember which). It was very tight on the register and had about 2 thou runout. I ended up re-turning the taper with a new sharp QC TC tip and is acceptable now. My advice would be to buy the backplate mounting type.

cheers

Rod

Hi

I too have an ER25 screw-on collet chuck for my Myford. It SHOULD be a tight fit on the register! The secret is to get the alignment right and it will screw on easily. Put an appropriate collet in the chuck (say 12mm) and a similar piece of round bar in your tailstock chuck but don't tighten the collet. Slide the chuck along the bar and you will find it is aligned and will screw on easily. I've checked the run-out on the inside taper of my chuck - it's better that 1/2 thou. Chuck & collets are SOBA - I'm pleased with them.

Regards

Norman

P.S. Quick test before as I was called for supper! I have tried again with arather better st-up using a test indicator and the run- out is barely perceptable. I'm even more pleased!

N

Edited By NJH on 18/09/2012 20:11:22

Norman,

Not so tight that you can't snug it up to the register face with the spindle lock on and a tommy bar in the chuck. The issue was that there was no relief at the corner and it interfered with the slight radius on the myford spindle face/register corner. A bit of work with a grinding point in a Dremel sorted that out but there was still a disappointing amount of run out. I'm pleased you have got a good one, as we know, quality control is often the issue with these less than premium makes.

cheers,

Rod

Ah Rod - well yes that is too tight!

When I first got mine I thought it would never go on but, having thought it through, and applying the alignment method described, it was quite a relief when it did so quite easily. I suspect, as you say, that there may well be "variation" in some makes. However an ER collet chuck of some variety is very useful and affordable - compared with the cost of a set of Myford No2 MT collets!!

Cheers

Norman

Edited By NJH on 18/09/2012 21:33:53

I bought one made by the brand that is not intoxicated and it was a (way too) tight fit and it had considerable run out, worse than a knackered three jaw. I ended up cutting my losses and pitching it in the bin. I then bought the version sold by Myford for Myford where they tell you to machine the small back plate supplied fitted on your spindle before bolting the taper section to it. It's beautifully made and spot on from a cocentricity point of view. The moral of the tale being, you get what you pay for.

Edited By Chris Trice on 18/09/2012 22:18:20

Hi search this forum for ER32 Collet Chuck --- there are a lot of posts on this matter

**LINK**

I bought from RDG and was very pleased with the result

John

Make one yourself. Turn the taper in situ and it will be spot on, mine (ER32) is better than I can measure, 1/10 thou.

Personally I would avoid the backplate type as there is an aditional interface which can introduce errors.

Russell

Russell,

Sound advise if you are able and confident enough to do one.

Many reading this forum are not and rightly or wrongly are either frightened or do not have the time.

Back plate mounting ones, whilst adding an addition interface as you say, can be beneficial in that you can adjust the mounting to zero any run out, something you cannot do with a fixed system bought off the shelf.

John S.

I don't have a Myford, but the spindle nose on my Dore Westbury emulates the Myford one. I had a set of ER25s, so I bought a screw-on collet chuck from from RDG. I've been very happy with it; no more hammering away on the drawbar to free off MT2 collets. That said, zero runout isn't quite so important for a milling cutter as it is on a lathe.

Russell suggested making your own, but that would involve making up a dummy spindle nose to test the thread and register for fit. A compromise might be to buy one and if necessary re-bore the 8 degree taper (16 degree included) on the lathe.

Andy

Problem with that Andy is that bought ones are generally hardened and ground. As John points out, one piece ones have no way of fine tuning and you're relying on the accuracy of your spindle and the manufacurers quality control (which can vary greatly) to get it right where a separate backplate machined in place on your particular lathe is as concentric as it's possible to get plus the option to correct for manufacturing faults in the taper section. It's quick and you only have to do it once.

I bought an ER25 collet holder for my Myford Super seven from Chronos about a year ago, it has a run out of about 2 thou (measured on the taper). Chronos replaced it free of charge very quickly. The replacement was much better, but still had a run out of almost 1 thou. I set the top slide to the taper angle using a DTI and the collet holder as the reference, and then used a carbide boring tool to skim the inside of the taper. The collet holder now has no discernable runout.

Carbide tools are much harder than most people seem to realise, it is quite possible to machine most "hardened" steel with them. I succesfully machined the ends of a set of hardened ballscrew spindles for my CNC mill conversion using inserted carbide tools.

Chris

My other ER25 chuck, which incorporates a flange to match the flanged spindle of a Chinese lathe, needed its taper skimming true, Chris. I had no problem doing that on the lathe with an HSS tool.

The Myford-style one on my miller doesn't seem to be hardened, either, if the scratch I've just put on its outer rim with an old drill bit is any guide. But they may vary between manufacturers or batches.

Andy

True.

The other problem of course is that truing the main taper doesn't correct the small taper in the cap which will (presumably) still be off because the threaded section will remain out of true. In practice it probably doesn't make a lot of difference (or does it?) but I question the value of an accessory bought primarily for it's implied superior accuracy if you have to remachine it. They should all be spot on within stated limits or they're not worth the metal they're made of.

Edited By Chris Trice on 20/09/2012 11:24:35