M20x1.5 to 1"x8tpi

[Leo]

I was wandering if anyone knew where I could find an adapter for an m20x1.5 spindle on a lathe to a 1"x8tpi Chuck. I have bought a hardly used Elektra beckum ( metabo ) HDM 1000 for 100 euros, but will need an adaptor for it.

Thanks for any info.

Leo

 

[dickm]

Tricky one, that. The difference in diameter would only be just enough to accommodate the male and female threads. Would be very surprised if there was anything "off the shelf" to fit, so it's probably a case of finding a friendly engineer.

 

[Leo]

Thanks Dick,

I think that's going to be the only way I can go.

Waiting for a reply from Phill Irons first, then, if no joy, off to find an English speaking engineer, not easy over here..............

 

[katellwood]

Leo

I used to have a hdm 1000 and had a backing plate made for a three jaw engineering chuck. If I can dig it out you are more than welcome

In addition I think I have the original screw on drive

 

[Leo]

Katellwood,

That would be fantastic, obviously I would pay for the p&p.etc. if you would do that for me. I will have to think of something to send you, in return........hhhhhhhhhhhhhhhhhmmmmmmmmmmmm eerrrrrrrrrrreeeeeeeeerrrrrrrrrr ????? but what ??

 

[NetBlindPaul]

Leo,
One thread on top of another you would have about 0.027", 27 thou (about 0.67mm) between the root of the 1" & the crest of the 20mm!
You'll really need either the adaptor offered above, or an extension effectively!

 

[Leo]

Thanks Paul, I thought it was a little, little to have holding a chuck. Is it possible to rethread a chuck ?? Probably a stupid question, but if I don't ask, I'll never know.

 

[NetBlindPaul]

Yes you could probably change the thread in the chuck, i.e make bigger, IF you have enough "meat" there.
It is probably soft cast iron.
Don't know the chuck "in person" myself, so i can't comment in detail.

 

[Leo]

Thank you very much for the help and information !

Leo

 

[CHJ]

Leo, if you have to have an adaptor made, a threaded sleeve bored out and tapped/cut to 20mm dia. x 1,50 mm pitch(ISO metric fine) with a 33 X 3.5mm external thread is a possibility, this could be bonded to your lathe spindle and would give you a standard thread for the European Norm. for chucks and avoid the problems of increased overhang of the normal extender type adaptor.

Unfortunately this made to the required accuracy is likely to cost a fair percentage of your lathe outlay.

Here is an old copy of Axminsters listing of standard lathe spindle noses which may be of interest.

 

[Leo]

More great info. thank you Chas. !!

I have found that my adapter ( 3/4 x 16tpi ) fits very well into the screw on drive, but the 3/4 x 16tpi chuck will not fit the spindle. My question is this, if it's that close, would it just be easier to rethread the spindle to 3/4 x 16 tpi. Sorry but I know absolutely nothing of these things and live a long way away from decent info. If this is possible, could I buy the thingy and do it myself ?? never done this sort of thing before, but it is not easy to get anything done over here.

Sorry to drag this on so much. !!

Leo

 

[NetBlindPaul]

Leo,
Now I AM confused, how have we ended up with a 3/4"x16tpi please?

 

[Leo]

Paul,

I am so sorry, I looked through the posts above and realised that I had not mentioned this. I thought that I had !!

You try to help people and they mess you around like this ! My fault totally !!!!!!!!!!!!!!!!

My record power chuck is in fact a vicmark that RP. sold a while ago, ( they told me today ) this had an adapter ( home made, not by me ) to fit onto a 1" x 8tpi. spindle. This was so jammed on that it was impossible to get off, I have got it off after a year of trying...........few. The chuck itself is 3/4 x 16 tpi. I had an old 3/4 x 16 tpi adapter, that I tried on the spindle and in the screw on drive. Did I make any sense at all here ???

This mistake, on my behalf, has confused matters and I am very sorry for that. I am now sat in the corner chastising myself with a wet Kipper.......sorry.

 

[9fingers]

Be careful if you get an adaptor made or try to make one yourself.
It is a turning job that demands accuracy.
The thread is purely a means of holding the chuck onto the mandrel. there should be a plain collar behind the thread which has a precise flat face and an accurate diameter.
It is these two surfaces that are used to ensure that the chuck is mounted concentrically and will run true without wobble or vibration
The adaptor has to pick up on the mandrel register and have its own larger register to fit your chuck/faceplates etc

Bob

 

[Leo]

9fingers,

I must admit that my chuck with the adapter on, did not run exactly true, now I understand why, it was home made by someone, not me.

Thank you for the info and advice.

Leo

 

[CHJ]

Be careful if you get an adaptor made or try to make one yourself.
It is a turning job that demands accuracy.
The thread is purely a means of holding the chuck onto the mandrel. there should be a plain collar behind the thread which has a precise flat face and an accurate diameter.
It is these two surfaces that are used to ensure that the chuck is mounted concentrically and will run true without wobble or vibration
The adaptor has to pick up on the mandrel register and have its own larger register to fit your chuck/faceplates etc

Bob

That's why I posted the link to the "standard" nose dimensions Bob,

...., if it's that close, would it just be easier to rethread the spindle to 3/4 x 16 tpi. ...

It may be possible, 3/4" (19.05mm) is is slightly under 20mm so there is enough diameter, however the thread pitch (16 tpi =1.587mm) is slightly different and there is a mis-match over 1" (25.4 mm) of 1.4mm, almost I metric thread pitch. Over a short distance you might get away with it.

But as Bob has said this needs cutting with accuracy and would need to be done on a metal lathe and not with a hand held Die.

Problems associated with the register collar can often be overcome with a simple slim stepped collar as long as it's a good fit on the existing spindle

 

[Leo]

Thank you Chas,

Looks like a bigger job than I expected !!!!!

 

[dickm]

Sorry, I'm getting a bit confused here too (doesn't take much at my age ). What is the "native" thread of the chuck, that is, the thread into which you screwed your adapter? It sounds as if it is larger than 1", and many of the chucks that take inserts have a common thread (it's usually something metric and odd). If it's one of the standard ones (which I'd expect it to be) then it's quite possible there is a commercial adaptor out there to fit it and your 20mm nose.
As others have said, it's a precision job if you need to make an adapter, but I've done one or two for my Mystro, so it's not impossibly difficult if you have access to a metal lathe, or know someone who has and can drive it well.

 

[Leo]

Hi Dick,

The native thread is 3/4 x 16 tpi. and the adapter is 1" x 8 tpi. so I could use two adapters I suppose, if it came to it.

Leo

 

[NetBlindPaul]

Leo,
So the chuck has a 3/4" x 16 tpi male thread?
The lathe has an M20 x 1.5mm female thread?