Hello from Swindon

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Hello from Swindon

This topic has 6 replies, 4 voices, and was last updated 7 May 2019 at 19:48 by Peter Silson.

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6 May 2019 at 17:02 #407971
Peter Silson
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@petersilson33479
Hello

In a rush of blood to the head I went and bought myself a 1946 Myford M type lathe with the plan of making a few parts for my old motorcycle. The good part is, that when I got it home, it powered up and actually cut metal however the bad part is that I have found some things that need serious attention before I can do anything useful with it. Unfortunately my knowledge of lathe mechanics consists of vague recollections from "workshop practice" as part of my electrical engineering training somewhen last Millennium so I am in need of some help please.
The headstock, tailstock, leadscrew and drives seem to work fine however when I took the carriage apart I found the threads in the cross-feed to be (for want of a proper engineering term) knackered. The cross-feed lead screw seems reasonable but the thread in the saddle is virtually non-existent (picture 1). My first question is – can the saddle thread be repaired or is the saddle scrap?

The tool slide drive is also sloppy but the thread in the slide block seems to have a removable bronze nut fitting (picture 2). Is this bronze insert standard or a previous repair and could a similar thing be done for the saddle thread?

I'm sure I will find lots of other issues but this is a start.

Pete
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6 May 2019 at 17:02 #40530
Peter Silson
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@petersilson33479
6 May 2019 at 19:30 #407998
David George 1
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@davidgeorge1
Hi Peter welcome to the forum I have an M Type just a few years younger than yours and yes you can make a bush to repair the cross slide bush like the one on the top slide. Is the thread in the lead screw ok as that is a bit more involved. I have done a few mods to make the M Type a little easier to use they are in my albums to look at. If you need any further info drop a message. Just where in the country are you based as it helps to suggest supliers etc.

David

Edited By David George 1 on 06/05/2019 19:34:05
6 May 2019 at 22:45 #408023
Peter Silson
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@petersilson33479
I am based near Swindon Wiltshire (UK) just north of the M4. It would be nice to find somebody local who's brains I could pick regarding this lovely old machine.

My level of skill on a lathe only runs to turning an odd spacer and maybe a thread or two. I certainly don't have enough expertise or tools to tackle a job like bushing and threading the cross-slide lead screw nuts myself so am looking for advice/suggestions as to who might be able to take on this sort of job for me. Are these Acme or square cut threads?

The main carriage lead screw looks fine to me and, when I ran the lathe, seemed to move smoothly with little or no backlash – although not under any huge load.

Pete
7 May 2019 at 06:11 #408036
Hopper
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@hopper
Hi and welcome to the forum from another M-type owner. Can't help you with making parts as I am on the other side of the world but there are quite a few M-type owners on here. The latest issue of MEW actually contains two articles featuring M-types – David George's making a sine bar and yours truly's turing worm threads. We are taking over the world one job at a time.

The threads on the M-type leadscrew and cross slide and top slide screws are all square threads, not Acme. Your main leadscrew in the pic above looks good, but the brass half-nut looks typically worn. Good enough to be going on with but not great. There is a trick to replacing that with a threaded brass sleeve soldered into position in the bored out half-nut lever that can be done.

If you have more money than square thread cutting skills, a new cross slide screw and a matching nut could be sourced using Myford ML7 Acme-threaded items but some machining would still be required to make the conversion. The Myford nut has a flange with two retaining screw holes on the end so you would have to bore out the cross slide and then drill and tap two screw holes to hold the Myford sleeve nut in place.

But you might be able to buy a suitable square thread tap from Tracy Tools to make a brass sleeve nut like the one on your topslide in the pic. You'd still have to bore out the slide to fit the nut.
7 May 2019 at 15:43 #408095
Howard Lewis
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@howardlewis46836
If you are happy to depart from the original specification, modifying to take Myford 7 Series Leadscrews and nuts may be a good idea.

The ML1,2 3 and 4 Leadscrew is Right handed, from memory, although 8 tpi, like the 7s, BUT which are Left hand. So you would need Leadscrew and Half Nuts. And setting up a gear train may be simpler, but you would need to use the tumbler reverse, if your lathe has this fitted. Also for a really fine feed, you would need to use the tumbler reverse, ro move the saddle towards the headstock.

The Cross and Top Slide Leadscrew are the early MLs are 12 tpi, (According to Lathes UK ) so converting to ML7 parts will rid you of the 80 division dials with their " not quite a thou" divisions, and give a sensible increment.

Howard
7 May 2019 at 19:48 #408128
Peter Silson
Participant
@petersilson33479
Posted by Hopper on 07/05/2019 06:11:11:

The Myford nut has a flange with two retaining screw holes on the end so you would have to bore out the cross slide and then drill and tap two screw holes to hold the Myford sleeve nut in place.

Much as I dislike spending out for a new part costing nearly as much as the lathe did, this might be a job I can do myself – a couple of questions though:

1) Is the sleeve nut located purely by the flange screws or does the hole bored in the saddle also have to be an accurate size or position. i.e. would drill and ream be sufficient for the hole?

2) The current cross-slide lead screw appears to be 1/2" 10 t.p.i. with a 5/16" shaft through the cross-slide whereras the ML7 is 3/8" 10 t.p.i. Is the Myford shaft also 5/16" so I wouldn't need to alter the cross slide itself?

3) I am assuming that the existing handle can be fitted to ML7 lead screw – it appears to be longer in the pictures.

I am not trying to rebuild the lathe at the moment – I just want to get it working sufficiently well to allow me to learn how to use it. Maybe a lttle later, when I have learned some of the basics, I will have a go at making things like lead screw nuts. Another slight issue is that, because this is the only lathe I have got, I need to get it working before I can make the parts to fix it. Chicken and egg?

Pete
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