ML7 - Apron Slack

Hello everyone,

This is a Myford ML7 I have been using and spending my nights on getting it serviceable and turning accurately. It has been usable but I do think I have a large source of inaccuracy with this issue.

With the saddle locked, there is a lot of play in the lead-screw. So facing off, or any diameter turning I believe this is going to impact my results. My gut feeling is that this amount of play is unacceptable.

To my understanding, I think it could be worn apron bushes. I don't like asking to be spoon-fed, but I'm twenty years old and have no-one to ask (my grandfather was the tool maker, he passed away ten years ago). I attended one of the last fitting and turning short/interest 'courses' in my country a year ago but that's using Taiwanese equipment and learning general procedures.

I would appreciate any help. PS. I love this forum. So much knowledge to consume and particularly on Myfords, so I'll be sticking around .

Also, the video doesn't really show it as a large amount of play but it is more than what it looks like.

Aaron

Edited By JasonB on 10/03/2015 12:02:41

Hi Aaron

I don't have one of these myself but hopefully someone who does may be able to advise on the specifics. Ideally they would be able to give you a copy of the servicing manual in PDF format.

There are likely to be several causes contributing to the backlash you are seeing. As I think you are suspecting, the leadscrew itself needs to be adjusted so that it doesn't move left to right under load - this would presumably be where the handwheel is fastened. Hopefully somebody will confirm that. The gib screws on the saddle (and also the cross and top slides) need to be adjusted so that the saddle remains square to the bed (ie it's not too loose) and finally, the leadscrew and half nuts themselves are bound to have some wear. You can't do much about the latter short of replacing one or both of them but it's probably not an issue unless you plan something really precise and critical.

For facing off, you should think about tightening up the saddle lock so that the saddle movement along the bed is stiff or even fixed, For lengthways turning, you mainly need to take care not to forget about that backlash if you are threadcutting. Generally I think you'll find most people don't rely on the dials much, particularly for lengthways measurements and instead use calipers or digital readouts to measure what is actually happening. Moving the saddle when turning would normally be done with the apron handle, not the leadscrew, so in most cases the backlash wouldn't be a problem.

A good starting point would be to adjust all the gib strips and any other sources of backlash. Looks as if you will be able to do this as you reassemble your machine. Giving it a good clean and keeping it clean and lubricated is a good idea obviously.

Hope you have fun with your machine! You do realise of course that you should waste no time acquiring milling machine, drill, welding gear, hand tools etc etc - it's a life's journey!

Murray

Hi Aaron.

If the leadscrew itself is moving longitudally then the leadscrew handwheel needs some adjustment to reduce the end play. This just entails tightening the Nylock nut on the end until the play disappears. If the play is between the half nuts and the leadscrew then the halfnut are out of adjustment (they are not closing enough). There is a screw adjust on the bottom half nut. The half nuts also could be full of muck so a strip and clean may be a good idea as this will also stop the nuts closing properly onto the leadscrew.

For this proceedure see

http://www.model-engineer.co.uk/forums/postings.asp?th=75192

regards Martin

Hello and welcome to the forum

The red knob handle on the left of the saddle is not a saddle lock it is the threadcutting half nut engagement lever. The saddle lock is (probably) the bolt head on top of the saddle to the right of the cross slide which is visible in your video. This should have a small plate on the other end of it that the bolt pulls up against the underside of the ways to pull the saddle down and fix it.

The slop you are showing in the video doesn't matter at all and is perfectly normal.You can sometimes reduce it by some of the adjustments but it isn't important to running.and accurate work.

Hello Aaron,

Both Bazyle and Martin are correct, the saddle lock is the hex headed bolt on the right hand rear wing of the saddle and clamps a plate up under the rear shear of the bed.

The slack in the half nuts, the lever you have been using could well be from muck trapped in the nuts preventing them from closing fully onto the leadscrew. Cleaned and adjusted the problem goes away.

Regards

Brian

+1 for Martin's comment about the lock nut (called the Simmonds nut in the manual) on the right hand end of the leadscrew.

Tightening this a bit should remove much of the slop but you do need some end-float otherwise it'll be too tight.

As Bazyle says though any backlash will be taken up when the carriage is being driven by the leadscrew so you do not need to worry too much on that score and when facing lock the carriage with the saddle lock.

HTH

Jon

I would like to repeat the advice I have given many times to new owners of Myford lathes - buy a manual.

Myford manuals are freely available and are comprehensive.

Or you can join the Yahoo Myford User Group and have a look at the manual for free before buying (in the Files section). Here: **LINK** will find it.

Also an article on adjusting the half-nuts, and much much more.

There seemed to be a lot of play in your half-nuts, so another vote for cleaning and adjusting these.

Am I right in thinking you are not in the UK?

Phil

.

... ML7 freely ...

MichaelG.

Hi Aaron,

It appears from your video clip that grease may have been injected into what are the oiling points at the ends of the leadscrew and possibly the saddle also. If this is the case, it would be prudent to dismantle these parts, clean and degrease and lubricate with the correct oil.

You already have been given sound advice regarding cleaning the half nuts and adjusting the leadscrew end float; so if you carefully follow the exploded diagrams in the manual and maybe take photo's at every stage of stripping down, re-assembly is quite straightforward. The correct method of adjusting the 4 gib screws on the front of the saddle is on page 29 of the manual.

Good luck.

Gordon.

If it's a later lathe there will be a long, thin grubscrew that adjusts the spacing of the half nuts in the lower nut. This is to make sure they repeatably close by the same amount. The nuts should NOT completely close and a small amount of backlash is acceptable as cutting and driving forces should always be consistently in the same direction for any operation.

Assuming you get rid of any end float in the leadscrew and clean it up and there is still excessive backlash, you may need to back off that grubscrew a little, but don't over do it, if the nuts clamp the leadscrew enough to remove all backlash it will just cause excessive wear.

Neil

Hi Everyone,

Apologies for the late response - it was a killer week at work.

Thank you everyone for your responses, there's a lot of basic things to learn and I am glad you took the time to help me. You are right about the grease, Gordon. My Dad thought that was the right thing to do after vaguely been shown years ago and never having much interest. I will disassemble it further, and clean it all up and do some tweaking. I got the pdf manual now, and ordered a hardcopy of Ian Bradley's.

I've bought some spanners because over the years shifters have ruined many of the nuts. I might replace them just because it urks me to see them all rounded. I am from Australia. Amazing work on this website, you guys are an inspiration.

Kind regards, and many thanks,

Aaron