Acceptable wear on leadscrews and nuts.

Not really a beginner but a lot to learn. I have just purchased an ML10 and wish to put it in good order. What is the acceptable wear on lead screws and nuts (Both the main lead screw for thread cutting etc and those on the carriage.)

I also don't seem to have the oil gun for the headstock, best place to buy one?

On my other lathe, an ML7,the oilers have been broken (not by me!). I believe the original ones were made by Adams(?). I have heard uncomplimentary stories about more modern replacements, so which are best to buy and a lead to the company?

Andrew

It can be argued that wear and backlash on the carriage lead screws is not a problem since you are likely to be approaching the work piece from only one direction and should be checking progress as you go. There are lots of factors that affect the resulting diameter when turning down to size as well as lead screw wear, such as workpiece deflection, tool tip wear, tool tip height (if it is not quite right) and depth of cut.

Wear on the screw cutting lead screw will show up as uneven threads but only if you are cutting long threads. It would take major wear to produce noticeably uneven pitches in a thread that is only 6mm or 1/4" long. If your intention is to make your own long lead screws with good precision then wear in the lead screw will be a problem.

If there is enough wear to make you thing the half nut threads are likely to shear then replace the half nuts otherwise I think you can use it and not worry unless you need to do a long thread that requires precision. Does the lead screw have the option of swapping it end for end as some lathes do to put worn sections where they are least used?

Martin

With many lathes there is an adjuster on the leadscrew half nuts so they don't close completely - as Martin says this is because they usually only travel one way and swarf stopping them closing completely is more likely to have a bad effect on repeatability.

Myford didn't fit these to the series 7s, but there may be one on the ML10 and they are easy to retro fit.

What does become a problem is if you have on very worn section and need to cut long accurate threads such as lead screws. If you only cut shorter threads then unless the half nuts are about to let go you should be OK.

For the cross-slide it is more important as if it stops you being able to rely on the accuracy of the dials you have a problem, although fitting a DRO can help.

Neil

Adams oilers here

http://www.adamslube.com/Oilers_Main/

Oil guns here

http://www.lathespares.co.uk/myford-oil-lubrication?zenid=ormpm5ofgjbp7asd4blf3ujpq7

You can check wear on all of the leadscrews on an ML10 with the handles. One turn moves one thread pitch so say there is a 1/4 turn play there is that much clearance. The majority of any wear will be in the nuts but some parts of the lead screws tend to get much more use than others as most lathe work is generally under 6" long and has fairly low diameters. That tends to make the bed and cross slide wear in certain areas as well.

Play on a new lathe ? I'd say circa 10% of a turn. Might often be less might be more. My boxford has about 20% on the cross slide and at that level of wear shows tightening when the cross slide is wound right out but I do set mine fairly tight well in. I'd expect a bit more play on the main lead screw than on cross slides. Compound slides don't usually see much use so can give and idea of what it might have been new. About 10% on my Boxford.

It is possible to get some idea of wear in the screws by measuring the back play with the slides in various positions. The screws need to be nice and cleanly lightly oiled with the usual grade of machine oil. Not thick heavy stuff or grease.

The usual eventual problem screw cutting is severely worn nuts or some not forcing them to engage rather than feeling them into mesh. Myfords and others are worse in this area as the screw is also used for feeds so gets used a lot more often.

I suppose I might get concerned if there was 50% or more play in the cross slide but I doubt if the thread in the nut would be likely to strip under load even with that much. Lead screw wear for normal turning shouldn't really matter. Cut sizes should be based on what the previous one actually took. No oh it's 0.005 too big so take a light cut. If dread to think a lathe needs that size of cut to get a decent finish make sure the ones before are of a similar size so that what is actually removed can be measured.

Jam nuts as per Neil's suggestion - I'd say don't bother. If there is a need just make or buy new ones. They have never really caught on as back play has to be accounted for when working anyway. If some one makes any changes the most sensible one would be to make them longer.

Wear on the screw cutting lead screw is a bit more difficult but lathes were never intended to cut calibrated micrometer threads. For fixing type work and better there would have to be an awful lot of wear before it became a problem. If some one wants a very precisely pitched thread they are probably going to be better of finishing it with a die or a hand chaser.

John

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Edited By Ajohnw on 26/08/2016 13:38:25

The two half nuts on the ML10 get filled with swarf, To clear undo the hex head screws and the whole front plate will come away, firstly undo the nut on the engagement lever and lift away and then undo the two screws with slots in them. it will be easy to juggle free.

The two half nuts have a screw that can be abutted to the other to limit the engagement of the half nuts. Clean out the half nuts and re-adjust to just clamp lightly.

I am in the process of making a metal shroud to try and keep swarf out of that area.

Re the grease/oil gun, make sure which bearings you have as the ball bearing type needs grease not oil.

It is worthwhile doing the bearing mod to the cross slide spindle, (See Arc Euro's page that shows detail and you can get bearing from them) I used the vertical slide bearing housing to modify first and then when complete swopped with the one on the lathe.

Clive

If your leadscrew is worn and you need to make a more precise long thread just use it in reverse. The reverse side is probably far less worn.

Don't limit the half nut engagement unless some idiot has done that before and worn a ridge on the half nut thread and possibly the leadscrew too. You want maximum engagement to minimise the wear. It is not a way to compensate for being too lazy to clean off the swarf.

Thanks very much indeed for your considered replies. A great deal of information there and I will take heed of what you say.

Thanks also for the information on oil guns and oilers!

I have just realised my ML10 is a ballraced headstock version. Now I seem to remember that these should be grease lubricated. If my memory is correct is there any particular grease? I assume that the carriage leadscrews should be oil lubricated, as the lathe came with an almost full container of Myford slideway oil.

Having got the lathe mounted and cleaned down, I am happy to report that wear appears non existent, except for a few bed dinges caused by a dropped chuck. At least I always put a wooden "shock absorber" under said chuck when I am putting on or taking off!

Thanks everyone for their help,

Andrew.

Drip feed oilers, and spring loaded ball oilers are available from Arc EuroTrade, (Just a satisfied customer).

My genuine Myford oil gun left almost everything, including me, covered in oil. Not sure how much actually went where I wanted it to go.

Bought a Reilang, and years on am still MOST impressed. It was a good buy!

Howard

It's a good job your ML10 is the one with taper roller bearings in the headstcok. The earlier ones need some care in buying as they can't simply be replaced when worn.

I have always used moly grease on bearings. Initially Castrol and more recently the high speed one from ArcEuro.

It's never caused me any problems on anything I have used it on. I also noted that it's what Ford got out of the cupboard when some items were not making it through warantee. A car scrap dealer pointed this out to me years ago when I wanted a cheap used starter motor for something.

John

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