ML7 Leadscrews/nuts Still Available?

As my cross slide nut has some play in it, i've been following this thread. Unfortunately nobody seems to be selling these to suit an ML7 with imperial thread. (except Myford listing nut & screw sets at fairy tale prices).

So the brass nut listed on ebay mentioned above (143946170355) seemed my only option, though I also noted the lack of feedback on it etc. Reckoning that if its an obviously bad fit, I can send it back, and if it wears prematurely, well it will have been nicer to work with for a while, than the present set up.

So I ordered one and it arrived today and it fits and seems Ok. The scew action is a little stiff but I'm hoping this will be as i, running in a stiff engine. I will post again if it wears too quicly, though I'm not using the lathe every day, it may take a while.

(except Myford listing nut & screw sets at fairy tale prices).

Myford's "fairy tale prices" are Ebay placeholders for items that they don't currently have in stock - apparently it is preferable to keep a listing showing when you don't have stock but place a price on the item that disuades orders being placed than remove the listing. When the item becomes available agin, the price is changed to suit.

I sent a message to Myford asking when the ML7 screws & nuts would be available again & got the following reply :

"Unfortunately we have no confirmed date at the moment. I'd suggest trying us in 6-8 weeks time if you still want one."

So it would appear that replacement stock of these items is in hand, just have to be patient.

Nigel B.

Leadscrew you can buy from McMaster Carr (LH, 5/8 inch).

You can buy 3 feet section.

Feedscrews you can turn yourself. Do it from 40-45 HRc rod and they can work with phosphor bronze.

ACME taps Chinese are selling cheap so nut is not a problem.

ACME nuts together with section of screw they also sell. They are cheaper than p&p alone from most of Western dealers.

You may adapt Chinese ACME screw by turning and threading ends and brazing thrust collar.

Leadscrew half nuts are best poured out of white metal.. Use secttion of leadsrcew as a form.

You will need to process ends though albeit it gives you good opportunity o install shear pins as gearbox protection.

Martin

Probably 20 years or so. Most original half and feed nuts were brass or even the softer Mazak zinc-aluminium alloy for a reason. So they don't wear the non-hardened feed screw.

This gives greater accuracy as the parts wear. A worn nut will still track accurately, just with a bit more slop which is not particularly important. As long as it engages with the screw, it will follow the screw thread faithfully.

But a worn feed screw or lead screw has a slightly varying pitch between the worn section and the unworn section. So turning the cross slide dial say 100 thou on the graduations could result in only 90-something thou of movement of the cross slide.

So better to use brass nuts and preserve that feedscrew thread for best accuracy.

Thanks that is encouraging.

I’ve got a pair of ‘brass’ nuts ordered, £25 delivered. So we will see what happens. I believe the person who is making them for me is experienced and will do a good job, based on their comments and images of their work. Feedback from other people who have used them is positive.

One thing you might need to do is set the alignment between the new feed nut and the cross slide end bracket (the bracket that holds the end of the feed screw, the dial and the handle etc.

Slacken off the two Allen screws that hold the cross slide end bracket in place. Wind the cross slide all the way in until the cross slide bracket comes up against the feedscrew nut. Then turn the handle back a 1/8 of a turn or so. Then tighten up those two Allen screws so the cross slide bracket is held in position. This locks the bracket in the correct position with the outer feedscrew support bearing in line with the feed nut.

So, theoretically, the feed screw is held in line with the thread in the nut and all screws in and out nice and freely without binding.

A bit of graphite or moly grease or similar on the feedscrew helps too. ON the Myford the screw is hidden away from swarf so it wont stick to the grease.

Bit O/T but what’s the recommended lubricant for the gears? I’ve been using hydraulic oil or slideway oil (whichever I happen to have in my hand at the time I remember to oil them). I’ve been reluctant to use grease because it forms a horrible mess.

The absolute best lube I've found for the back gears and change gears is spray-can motorcycle chain lube. Use the colourless roadbike formula, not the nasty black graphite dirt bike formula. Spray it on when you finish using the lathe and let it sit there and go tacky and dry until next time you use the machine. Stuff sticks like the proverbial to a blanket and is made for extreme pressure applications so perfectly suited. And it is designed to not stick road grit to the chain so likewise does a good job of not sticking swarf particles to the gears.