Myford ML7 1956 back gear removal

Hi,

I have two broken back gear teeth on a lathe that I have just purchased. Myford ML7 1956 model. The Myford parts manual has a socket Countersunk screw (2BA x 1/2 inch). My model has a flat faced washer with a small hole. I have checked that this is a small allen screw at end of shaft, possibly holding the end cap. This appears very tight so I have not forced allen screw to remove. Can anyone confirm that I need to remove this to release back gears. Lever etc has been removed and shaft is free in housing.

Regards

Neville New Zealand

Hi Neville, welcome to the forum.

Although I can't answer the question because I don't own a Myford, broken teeth due to using the wrong method to remove stuck chucks is a common problem. With luck me bumping the post will get a qualified Myford owner on the case.

Dave

http://www.lathes.co.uk/myford/index.html

This website may help, quite a good reference.

Yes, as you say it's a 2BA socket-head countersunk screw (& washer) that retains the gears on their spigot - it has a (ridiculously) small socket, so you'll need a well-fitting Allen key.. ..Good luck!

Socket size of that screw is 1/8" Allen Key on my 1949 ML7. Regards

A hammer type impact driver with a well fitting bit is the best way of shifting it. The same problem happens with disc brakes that are held onto the hub with a counter sunk screw. They grip extremely well!

If you use an allen key (with or without a cheater bar) be prepared for it to let go with a bit of a bang and mind where your knuckes are.

I think I wouldbe giving that 10 seconds with the blow torch then having a go, if you could do it without scorching nearby paint. A quick blast of heat works wonders with long-tight screws and bolts.

Hi to all providing valued advice.

I used a new Allen key following diogenes11 advice and gave it a bit of force and it came loose, indeed with a it of a bang as Mark suggested. I will now look to replace 21/56 back gear as it has two teeth missing.

Has anyone run a bead of weld and then lathed and milled new tooth or best to get new cluster?

Kind regards

Neville in New Zealand.

If you can get a bead to stick (the gears are cast iron) then it'll be fine to re-machine the teeth - an alternative would be to pin & braze / maybe even dovetail & Loctite in a small block and turn to size / form new teeth on that - so yes, in principle nothing wrong with repairing - I think there may be others on the forum who have done it..

Perhaps worth making the obvious point that the weld deposit needs to be machinable ie not hard.

I have salvaged a number of cast iron gears having missing teeth with inserted implants, brazed in and then reshaped to the tooth profile

Regards

Brian

Admittedly it was a S7 but ME carried an article on one way to resolve this issue. Graft a new 21T onto/into the 56T or vice versa ! It worked for me well. Noel.

Noel's suggestion is probably the best in the absence of a replacement compound gear set. If doing a weld repair, use a high nickel rod (98%) and preheat the gears to 3-400°C. The weld deposit will be easily machinable and the HAZ will not be brittle (Did the feed years on a Royal 10" shaper this way)

I tried that with an unknown rod previously used on an exhaust manifold, which it did fine.

No pre-heat, run a bead then another on top (only 16dp) mount the gear cutter on the mill and ----- knock knock etc killed the cutter. Can't really file it either, grinder took forever. So yes you can weld it with the right rod or else... The rods work at a lower current than steel ones, but in the UK 99% nickel rods are £8 for two rods, then you need a cutter £20 ish. Assuming you already have an arbor to mount it on, a stick welder and a dividing head.

Or.

As Noel is suggesting. You get another 21 tooth gear with matching DP and PA, trepan out the centre, turn all the teeth off the busted gear to match the id of your new/old gear ring and loctite 603 the two together.