ER25 collet chucks that fit a myford spindle nose

[AjohnwParticipant @ajohnw51620]

Given how fine the thread in the nut is Dusty you may be right but I think it will be ok. I aught to check what grade and type the piece I have is. It should be one of the tensile grades suitable for back plates etc.

I had wondered about using E8M but will give the cast iron a go. The thread for the nut will be chased for a very precise fit.

John

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[DustyParticipant @dusty]

John

EN8m would be a good alternative. Personaly I would not go with the cast iron, it is an awfull lot of work to find in a couple of months that the thread has not stood up to the task. I do not know what your experience is and I might be teaching you to suck eggs, if so I am sorry, but when you machine the nose on which to mount the chuck blank, for machining the taper, make sure the thread is a relaxed fit. That way you should ensure that the blank chuck is located on the machined register and back face and is not influenced by the thread.

Edited By Dusty on 31/10/2015 20:57:58

[AjohnwParticipant @ajohnw51620]

I have a 3 morse Myford dummy nose Dusty. It's handy as both my dividing head and miller have myford spindle noses. I also have a Myford grip true to use with it. The thread and register will be fitted to an ML7 spindle I happen to have. That end can be done in one setting and I will cut the thread with a machine chaser.

As far as the register goes I will be aiming for a few 1/10 clearance max – one of the reasons for preferring cast iron. With that it's possible to have it fitting so close that it will tend to coin the surface of the register without it locking up.

John

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[DustyParticipant @dusty]

John

The accepted way to machine this would be by turning and screwcutting a nose on a length of bar held in a four jaw. By all means try to use your morse taper nose, but, if there is any flicker of runout do not use it. Any error at that end will be maginfied by the time you get to the front of the chuck and even more so by the time you get an inch or so from the collet. Do I know what I am talking about? as an ex toolmaker and special purpose machine builder I would hope so.

[AjohnwParticipant @ajohnw51620]

Tell you what I'll stick my test bar in the morse socket and test the run out 125mm from the end of the socket. Boxfords spec is better than 0.001 thou per foot but they always seem to be a lot better than that. Mine was. Maybe some one used the usual trick to true it up. I've mentioned on here several times that a pure spindle nose runout measurement is useless.

Actually I will have to do that again anyway as I need to take my lathes headstock apart to undo something I did as a bit of an experiment that hasn't worked as well as I thought it might. I greased a part that is normally oiled to prevent the bearings from warming up. It has. Sounded like a good idea but it's better as it was.

The 3 morse plus myford nose was turned up on the lathe anyway so in real terms is no different to what would be achieved via a chuck other than rotational orientation. If I did that it would be with the 3 jaw as it would rather difficult to use it again once it was taken out – and who knows the spindle might be slanting up anyway.

If you are thinking of making one you might find the choice of material used here of interest. It wouldn't be mine for the reason I outlined.

By Harold Hall

**LINK**

Me. They spent 3 years training me as a tool maker plus 6 months of machine tool design and a further 6 months on other things. And yet more after I finished my apprenticeship.

John

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[Michael GilliganParticipant @michaelgilligan61133]

Posted by John W1 on 01/11/2015 22:38:40:

Boxfords spec is better than 0.001 thou per foot but they always seem to be a lot better than that.

.

Wow !!

MichaelG.

[AjohnwParticipant @ajohnw51620]

Posted by Michael Gilligan on 01/11/2015 22:44:18:

Posted by John W1 on 01/11/2015 22:38:40:

Boxfords spec is better than 0.001 thou per foot but they always seem to be a lot better than that.

.

Wow !!

MichaelG.

LOL. You should get your self a decent lathe Michael. Boxford provided test report sheets with all of them real ones too.

There are or rather have been better about. I used a DSG guaranteed to be better than 1 1/2 thou between centres which must be circa 5ft. I couldn't measure any at all over 3ft. Not much chance of finding one that hasn't been worked to death now. Mounted on adhesive pads. I shudder to think what the cast iron box type stand weighed in at let alone the lathe itself.

John

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[AjohnwParticipant @ajohnw51620]

John

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[Michael GilliganParticipant @michaelgilligan61133]

Posted by John W1 on 02/11/2015 00:04:57:

Posted by Michael Gilligan on 01/11/2015 22:44:18:

Posted by John W1 on 01/11/2015 22:38:40:

Boxfords spec is better than 0.001 thou per foot but they always seem to be a lot better than that.

.

Wow !!

MichaelG.

LOL. You should get your self a decent lathe Michael. Boxford provided test report sheets with all of them real ones too.

.

John,

I assume that you missed the intention of my Devilish Smiley

But: On the remote chance that you actually believe what you wrote; I would be very interested to know how you checked your runout to be better than one millionth of an inch at one foot. … Do you have an UltraViolet Interferometer, or what

MichaelG.

.

P.S. … The 'picture' in your follow-up post is not loading … If it's the Boxford certificate, I would love to see it.

[AjohnwParticipant @ajohnw51620]

I used quantum theory Michael not involving the cat by utilising certain aspects of string theory.

Can't correct that typo now.

The test certificate did load up when I posted. Here it is

When I had the lathe the bearings were loose causing around 0.002" taper over 6". There is also very slight oval wear in the bearings now so this time when the head is stripped I am going to bite the bullet and replace them. Hope it doesn't mess things up.

John

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[Michael GilliganParticipant @michaelgilligan61133]

Thanks, John

Back to Earth now.

MichaelG.

[Author]

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