PDA

View Full Version : Myford Spindle Thread?



Arnak
08-27-2005, 06:38 AM
Hi Folks,

Could some kind person tell me the core diameter of the Myford 1 1/8" spindle thread?

I need to make an internal thread for an adaptor.

Thanks,

Arnak

JCHannum
08-27-2005, 07:50 AM
An easy way to determine hole size for tapping or threading Imperial threads is to divide 1 by threads per inch and subtract from the major diameter.

If pitch is 8; 1/8=0.125", hole diameter is 1.00".

With Metric threads, simply subtract pitch from diameter.

I don't know the Myford pitch, except that it is a non-standard. Guy Lautard was selling a tap with the Myford pitch for making accessories.

Arnak
08-27-2005, 09:03 AM
Thanks JC,

That's brilliant!

Arnak

GRH
08-27-2005, 10:31 AM
According to Guy Lautard
Myfords made from 1946-2000
had a 1-1/8" x 12 TPI thread and it was a 55 deg included angle (British Standard Whitworth) It was a RH thread. I would suggest if you have any other chucks, faceplates etc. for this lathe just measure
what they was bored to (I.D.) and duplicate.
I also would using 3 drill shanks as wires
measure my spindle and make a threaded gage
to duplicate the spindle so when you bore and thread a new casting you will have a way of knowing if it will go onto yor spindle.

Graeme



[This message has been edited by GRH (edited 08-27-2005).]

Arnak
08-27-2005, 02:09 PM
Thanks GRH, I'll do that.

It's an unusual job, I have a Vertex dividing head with a Myord sized spindle but I have a spare 4" Warco chuck!

So I am attempting to make a bush with a Myford 1 1/8" centre thread and a Warco outside thread as an adaptor...

A new chuck is just too expensive.8-((

Regards,

Arnak

GRH
08-27-2005, 06:48 PM
Amak
Would it not be a better solution to make a new back plate for the chuck or is the chuck used on other equipment??????
How do you propose to remove the adapter from the chuck??????
A couple of things to consider.
Graeme

Arnak
08-28-2005, 04:48 AM
Hi Graeme,

Yeah, I did think of the new backplate.

I did get a blank cast iron one threaded with the myford thread but I wasn't sure that I could get it running correctly enough.

Then I decided that to get it running really true I'd need a myford spigot to hold it first.

That led me to the idea that if I could make a spigot with a myford thread then I could just as easily make a theaded adaptor which hopefully would have both of the threads fully parallel as they would both be turned in the same sitting. 8-)

The back plate on the chuck can then stay on the old chuck and the adapter screwed in. Then if I need to use the chuck on the other smaller lathe I can just remove the adaptor!

Well that's the plan, wether it works well enough I'll have to see.....

Either way it's good practice for turning internal and external threads. <g>

Regards,

Arnak

Norman Atkinson
08-31-2005, 12:43 PM
Can a Limey Bastard copme in?

The Vertex dividing head in the Uk is sold with a Myford "nose". Got one!
However, it comes with a faceplate which will take a lathe chuck.

One firm sells chucks to go with the Vertex set up.

Again, part machined Myford backplates are available from many UK stockists.

OK?

Norman

Arnak
08-31-2005, 01:09 PM
Hi Norman,

Thanks for your input.

After an abortive attempt to make a reducing bush I did indeed manage to make an arbor with the Myford thread then turned the supplied face plate to fit my Warco 4" chuck!

So i got there in the end thanks to all the folks help...

Regards,

Arnak

Norman Atkinson
08-31-2005, 03:11 PM
Sorry, Arnak- I didn't reckon that you were from the Principality.

I could have probably given you a more 'local' answer.

Something says to me that this Myford thread isn't quite the "bastard" thread which most of us suppose.
Instead of doing it at 55 degrees- why not assume that it is 60.

Now start thinking laterally.
So this is a SAE Fine but with a Whitworth 55.

Following on with a bit of lateral thought, who the hell cares about the thread?
It's the register that matters.
That is a straight inch and a quarter for 7- 16ths. The nose- before we start fiddling is an inch and 5/8ths and 3/16ths.

Amazingly simple- but I have never seen the relationship in print before.

Norman