Stud for tool post on Myford lathe

This is a request for information from Myford lathe owners.

Since ARC launched the Model 000 Wedge type Quick Change Tool Post, we have recieved questions from several new and exisiting customers about fitting this QCTP to their Myford lathe.

As a result, with assistance from Tim Stevens and others, we prepared the modification kit to allow customers to fit the 000 QCTP to their Myford ML7.

We are confident that the kit is suitable for the ML7, however we are uncertain if the kit will be suitable for fitting onto the Super 7 or any other models of Myford.

If you are an owner of a Myford lathe, other then an ML7, and if you are able to offer any information on the subject, I will be grateful if you could please have a look at the fitting instructions pdf here. It shows the original Myford toolpost stud which has a 7/16" thread. I need to know if all or which other Myford lathes have/share the same stud as a component.The picture below shows the original stud fitted to an ML7, next to the stud supplied in the modification kit:

Any information anyone can provide would be very much appreciated, and it will help us to provide correct guidance to anyone who has a Myford, other then an ML7.

Thank you.

Ketan at ARC.

Ketan,

The kit should also be compatible with the ML7R

... this uses the ML7 top-slide.

MichaelG.

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for using the forum for customer input.

Ketan,

The small-bore (headstock spindle) Super 7s used the same toolpost stud as the ML7. Can't say for the later large-bore machines.

Ketan, what diameter is the ML7 stud on the parallel shank portion?

On my big bore S7 it's 11.1 mm / 0.437 inches. Is that the same?

Sounds like 7/16" to within half a thou to me.

Neil

Many people avoid fractions these days, they're seen as quite vulgar you know,

Michael and Robbo, Thank you both for the information.

John H, I will check this when I get into the office. It does sound like 11.1125mm / 7/16"/0.4375" as you and Neil has mentioned. If so, then it seems that it will probably be okay for the big bore S7 too. If it is different, I will report back. Thanks for the information.

Thank you for your help guys.

Ketan at ARC.

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Starting the day with an oxymoron

Some fractions are completely vulgar!        Sorry Ketan, this is supposed to be a serious thread.

Edited By Robbo on 21/05/2016 09:15:38

Hey John,

Just measured it, and depending on where I measure on the parallel, the measure is between 11.11 to 11.14, so for me, it is reasonable 'to presume' 7/16" nominal.

Thanks again.

Ketan at ARC.

The one I have is a fairly tight fit* in the Myford hole - just as tight as the original which came out.

* I rely on the advice of a Norton engineer who said 'There are just three sorts of fit, a press fit, a push fit, and a p*ss fit, son, and this is none of them'.

Cheers, Tim

Hi Ketan,

I fitted a QCTP to my Super 7 last year. It wasn't the type you described, I bought it from Chronos and it was made by Shorba (India). The S7 had the 4-way tool post and had the detent pawl plate attached by three countersunk screws. This was removed and kept with the original tool post.

The Chronos QCTP wasn't supplied with a new bolt, just the body and the tool holders. It was a generic type not specifically intended for the Myford lathes, so I can't complain. I made a new center bolt to suit with a 12mm diameter as that was the hole in the body.

The one thing I discovered is how the original center bolt had caused the top of the top slide to become belled upwards. I had to take a tiny bit off the top face to correct this as the body would not sit down flat and it moved under a heavy cut until I corrected this problem. After that it was fine!

The amount I had to remove was minimal, probably less than 0.25mm, but without this modification it was always going to be a problem. The Chronos QCTP is bigger in footprint than the one you show so it may not be a problem with yours.

The thickness of the S7 top slide is a bit marginal and the counter bored hole also weakens the top of the casting a bit. As long as not too much stress is put on the casting it should be fine, but too much Sunny Jim could be a problem.

I would recommend that anyone changing to the QCTP check this problem, before fitting the new parts, by applying a straight edge to see if the mounting surface is truly flat.