Myford ML 7 Top Slide

Hello! Im in the process of rebuilding the top slide on my 1954 Myford ML7.

I have it in bits and the tool clamp stud is bent and very tired looking

I'm thinking the semicircular section taken out of the base of the stud

and the corresponding drilling out of the underside of the topslide

are incorrect It looks to me as though the pin that stops the tool post from turning has sheared through and never been replaced

From the otherside I could only get two of the three grubscrews out, half the head of one having broken off. Its now jammed in place

I have two questions

Is the body of the top slide salvageable? or is it too far gone

What are the grubscrews for? to ensure the tool post is perpendicular to the top of the topslide?

I cannot answer the first question, but the grubscrews are filling the holes which are used to locate the ratchet of a 4-way tool post. They keep out your frass.

Make a new stud that's a tight fit in the counter bore, and drill a new hole for the anti-rotation pin. That could be a cap head screw.

Or you could move into the twentieth century and loctite the new stud in place.

You don't need the ratchet for the toolpost.

Edited By Nick Wheeler on 15/09/2023 22:40:26

The three tapped holes are to hold the ratchet for the indexing 4 way tool post. I’ve just been making George Thomas’s indexing tool post which employs a larger diameter stud in a slightly different position so I rebored the hole and resurfaced the seating to suit. I went for a light press fit but you could use a retaining compound. In George’s version the post is clamped tight by a nut under the tool post block which takes no part in readjusting the position once assembled. Have a look in his  book.
You could bore yours out slightly larger and make a stud with a larger flange and larger dia for the length through the casting. Retain with a pin or loctite.

regards Martin

Edited By Martin Kyte on 16/09/2023 08:42:58

Edited By Martin Kyte on 16/09/2023 08:43:59

I can't immediately recall the thread on the stud, but when I converted my S7 to non-topslide I just bought a corresponding HTS hex head bolt from my favourite supplier.

I took the topslide off because it's flimsy and I wanted to make sure the QCTP worked repeatably, so there's a dowel pin in the hole at the bottom left of the block to stop it deflecting (which was one of the issues with the original slide. I haven't missed the slide at all but I do use CNC so there's nothing it would do for me.

From memory, the stud is 7/16 BSF.

The anti rotation pin would have gone into a hole that was drilled once the stud had been pressed into the Top Slide.

Having made a new stud, and pressed it into place, it would be an idea to drill another hjole (Opposite to the current one? ) and to fit a new anti rotation pin (Rollpin? )

As already said, the three small tapped ho;les secure the ratchet wheel for the four way tool (If one is fitted ) It is too easy to lose the pawl or the spring from the toolpost when it is removed!

Howard

To remove the broken grubscrew, try using a "left handed drill " There are such things! With a bit of luck it will bite in and start to unscrew the grubscew.

The thread is probably BA. At a wild guess, 2 or 4 BA.

DON'T be tempted to try using an Easyout. TOTALLY misnamed.

If the worst came to the worst, if the remains can be got out, but the thread is damaged, it could be restored by drill and tapping oversize and fitting a bush, tapped to original size.

This might entail some reassembly, machining and hen stripping down again.

The surface should clean up with careful use of emery on a file. Any slight removal of metal will be compensated for when setting the tool height.

HTH

Howard

Many thanks to everyone for the input. I dont have the 4 way post so I'm just going to put the two existing grubscrews back in when I've cleaned up and replaced the tool post