Screw cutting advice ml7

Hello,I'm after some advice,I'm about to start a screw cutting job on my myford ml7,it's regarding using the little dial gauge.Silly question but when you engage the dial on a specific number I notice it's not that easy to select it bang on each time sometimes I may catch it after,but difficult to catch it in the same place each time,is this normal or maybe something needs adjusting or what people think? Thanks in advance.

Hello von dutch,

Try packing it out on the mounting stud with washers of selected thickness, you will find one that gives it a decent match.

Regards

Brian

First two questions 1 is your machine Imperial or metric 2 are you cutting imperial threads or metric ?

Do the lines on the rotating dial line up precisely with the mark on the body when the half nuts are fully engaged? If they are not you need to adjust this with washer’s on the mounting stud. Providing they do Line up you should start engaging just before, and I do mean just before, the chosen line comes up to the fiduciary line on the body. Lastly what speed are you running at? Higher speed makes it difficult up to almost impossible to facilitate engagement.

John

It is an imperial machine and I will be cutting an imperial thread,I will be running it slow as I don't want to scrap my part,I'll try some washers also,so in answer the the lines must exactly line up ?,you also have to "coax" the leadscrew engage lever sometimes as it won't just drop in every time(I don't want to force it) is that just normal wear I take it ?

Possibly the halfnuts and associate mechanism need a good clean and oiling - in any case, it wouldn't hurt to do it.

Rob

Do I need to remove the apron to inspect/clean the half nuts or can you remove nut on lever and get to them that way?

Hmmmm,I have just read on another post,I also have this issue,when I engage the lever the leadscrew does deflect a little as well,when i got the lathe the leadscrew was loose I had to tighten a few things up I don't what went on before

I'd remove the apron. However, it sounds more like you may have an alignment problem - slacken off the leadscrew bush mountings at each end, wind the carriage to the extreme left, engage halfnuts, tighten left hand mounting. Repeat for the right hand end. This should help get things aligned a bit better so the leadscrew doesn't deflect.

Rob

I shall try that thanks for your advice.

Hi von dutch, Sorry been out all day but to answer the above -- no the lines don't have to line up exactly but its easier if they do [and simple with shim washers] - but if they don't you need to know and remember where to drop in the half nuts and of course it will alter depending on whether you are cutting right to left or vice versa.

Regarding the operating lever being maybe stiff or similar it certainly sounds as though some maintenance is required as GSCowboy suggests. I would remove the apron inspect the half nuts for damage or wear then clean and lube everything, amazing how much crud gets in there ! Also re-align the leadscrew as GSC says. The lever should move easily and smoothly.

John

Right update I've had the apron off and inspected the half nuts full of crud some small bits of swarf stuck in there and some nasty old grease,stripped cleaned.Pleasntly surprised to see apart from a small burr there was little wear on them,reassembled the lot and it is a lot smoother,and the lever engages now with little effort,but am still finding it very difficult to fully engage the lever and catch it on a line it's as if something catches if I move the saddle handle a bit I can fully engage the lever but then I've missed the line 🤣 I did try another washer on the thread dial.Is it like a timing thing do I need to remove the apron again and re-engage on the leadscrew in a different place until it does freely drop the lever or am I reading to much into it🧐🙄

There is nothing to prevent you from stopping the motor, winding the handle along until your lines line up then putting the half-nuts in before re-starting the motor, if you're worried about engaging it in the wrong place. It's slow and it might be hard on the motor starting cap but it would save you from trashing a part or crashing the lathe.

I have somewhat similar problems on my ML7 with engaging the half-nuts, and if it doesn't engage neatly I kock it straight out of wherever it has stopped and try the next number or iteration.

It is just possible to clean and lubicate the mechanism fairly well without removing the apron, by taking the lever off and operating pins out. The lower half-nut can then be winkled out downwards. I washed the remaining innards with liberal squirts of WD-40 (which is not a lubricant), wiping what I could with a small brush and paper towels from under the apron; then lubricated the lot liberally with oil. It helped but I still have that trip effect so will examine the indicator alignment as suggested above - for which thank you.

I note suggestions to "re-align" the leadscrew. Any axial adjustment will simply take up end-float on the screw itself, and although that might help, it disguises the real mis-alignment.

Instead the half-nuts are adjusted by a small screw with lock-nut on the end faces of the apron.Not the lead-screw.

If you think about it the relative position along the machine of the saddle and screw is not important so adjusting the lead-screw will merely kick the saddle down the road, to paraphrase...

What matters is the mutual alignment of the two half-nuts, then the alignment of the indicator marks so they agree with the half-nuts and the screw.

On mine the stud holding the cam to the apron was working loose in the apron thread, and that won't help matters, by introducing a lot of slop.

So to make the leadscrew sit agreeably with the half nuts at the same time as the dial engages on a line you adjust this with washers on the stud then ( I have 2 fibre ones on at present)?,out of interest it must be possible to align it all smoothly on such a well made machine? Or do you still have to jiggle it about?!

Right another update I'd like to thank the above people that gave advice on my post,it would appear with a strip and clean of apron and half nuts along with setting the dial with washers spaced on the stud it now appears to be engaging everytime on the line and engages smoothly with no catch or bind .Very happy will cut thread on a test piece but feel more confident now thanks again people's very useful information 👍👍👍🤗

Absolutely, I was talking about a radial adjustment - or to be strictly accurate, a vertical adjustment (unless the mounting brackets were packed out or skimmed* to add a horizontal component) - so that engaging the halfnuts would not deflect the leadscrew.

Rob

* - do NOT do this

Hi von dutch,

If the thread tool is held in the tool post and mounted on the compound slide, adjust the slide to suit the mark

on your dial,

I use a piece of threaded rod to mount the thread start indicator, with a nut either side. Easy to adjust.

Good luck, Bear..