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ML10 apron issue with half nuts

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Ignatz02/08/2020 18:08:52
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119 forum posts
72 photos

Took the time today to disassemble and clean the apron on my Myford ML10. It sorely needed the attention, being rather filthy, filled with old grease and tiny metal chips. I reassembled and reattached the apron as before. As expected the action of the hand wheel and half nuts is far better than before the cleaning.

However, I’ve noticed that when I engage the half nuts the leadscrew is pulled slightly upwards. I believe that this was already the case before the disassembly and cleaning except that I hadn’t noticed it. When the half nuts are engaged the pull on the leadscrew bends it very slightly upwards, something between 0.20 and 0.30 millimeter. Of course, I don’t think this is as it should be.

The apron and half nut engagement arrangement of the ML10 is an amazingly simple affair, almost toy-like. But I don’t see any obvious adjustments that would allow me to compensate for that upwards pull that I am seeing. In fact the only sort of adjustment on the half nuts at all is an extremely tiny set screw in one of them that serves (I assume) to adjust the maximum tightness of the half nuts on the leadscrew when engaged.

The half nuts do not show any great signs of wear. I don’t think the previous owner(s) did any great amount of threading, especially since the lathe when purchased hadn’t any gears (full set since purchased). The leadscrew also appears to be in good nick.

My questions:

A) Is there any sort of adjustment (of which I am not aware) that would allow me to change the clasp height of the half nuts?

B) If that is not possible, is inserting something like a 0.20 millimeter shim between the apron and the carriage a reasonable solution? Would something like this put undue downwards pressure on the hand wheel gearing at the other end of the apron?

C) I’m assuming that this downwards pull is not good for the action of the carriage (probably worse as it approaches the headstock), but is leaving it in this condition really so terrible?


Thanks to all for any input on this.

Graham Meek03/08/2020 11:31:09
253 forum posts
184 photos

You do not say if you re-assembled the Apron onto the carriage at the Tailstock end of the bed, or not.

Your leadscrew displacement might be due to the Half Nuts in the Apron not being aligned correctly on the Vertical axis of the leadscrew. This would have the effect of lifting the leadscrew, and moving it laterally. Assembling the Apron to the carriage in the middle of the Bed, or near the Headstock will allow some movement on the true centreline of the Leadscrew, especially if there is some distortion in the Leadscrew. This situation will also be not helped if you have the Myford Leadscrew Clutch fitted.

Hope this helps

Regards

Gray,

Mick B103/08/2020 12:01:35
1656 forum posts
88 photos

Do the pins on the halfnut that engage with the lever rotate eccentrically? Is it 'cos you've got the halfnut with the little standoff adjustment grubscrew on the wrong up/down side of the lever?

I sorted an issue like this on my Speed 10 (which is just a renamed ML10) about 8 years ago - but I sold it in 2015, so I haven't got the thing in front of me.

I *think* there was a solution, but ARRRGH!! I can't soddin' remember!

Edited By Mick B1 on 03/08/2020 12:02:42

Ignatz03/08/2020 12:27:15
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119 forum posts
72 photos

Thank you both for the comments.

@Graham - The leadscrew is (to my eye) straight and without distortion. Regarding the alignment, yes, I did notice that the apron has no strict alignment method (pins, grooves, etc.), there being a bit of play to allow for subtle alignment between apron and leadscrew. The first time I tightened it down that alignment was a bit incorrect. What I did to correct the situation was to loosen the retaining bolts and then engage the clasp nuts. With the apron now free to move a bit that engagement of the half nuts pulled the apron into proper alignment with the leadscrew at which point I re-tightened the retaining bolts.

@Mick - I didn't notice if those engagement pins can rotate eccentrically. The pins didn't seem to be made that way, but I'll examine them again. When I disassembled the apron the half nut with the little standoff grubscrew was on the top of the apron. I returned it to that same position when I reassembled everything. I'll try reversing the positions of the two half nuts top-to-bottom and see if that makes any difference.

Ignatz03/08/2020 13:33:17
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119 forum posts
72 photos

@Mick - You are prince, sir. wink

I switched the position of the two clasp nuts , now with that half nut with the adjustment grubscrew on the bottom of the apron instead of the top. There is no more leadscrew deflection. On top of that the engagement of the half nuts seems just a wee bit easier... although my perceptions might be affected by my sense of joy.

Last thing I'll have to do is go and find some heavier grease with which to lube the half nuts. When I cleaned off the dirty, grotty old grease the only thing I had at hand to re-lubricate the half nuts with was some graphited grease. It works well enough, but is perhaps a bit too thin... might tend to run and color things blackish.

Mick B103/08/2020 15:09:56
1656 forum posts
88 photos
Posted by Ignatz on 03/08/2020 13:33:17:

@Mick - You are prince, sir. wink

...

Thank you, but I'll be a frog again by teatime.... laugh

Howard Lewis03/08/2020 15:39:44
3536 forum posts
2 photos

Good to know that you got it sorted O K.

Typical of the help that is always available on the Forum.

Howard

Clive Hartland03/08/2020 19:21:58
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2593 forum posts
40 photos

Grapghite grease has been used on my ML10 since It was bought 25 years plus. The half nut with the small grub screw shoul;d go at he bottom position.

sadly the lead screw is exposed when cutting and catches all the swarf. I am at the moment working on a cover that will fit on the front of the carriage with a tube with a slot so it can be removed for close work.

Ignatz03/08/2020 21:52:40
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119 forum posts
72 photos

@Clive - Thanks for the comment on the graphite grease. I'll keep my eye on it. Of course, I've had so much experience (recently) removing and replacing the apron that should the need arise to clean and re-grease the half nuts it will be done very quickly.

As I think about it... this lathe being as old as it is, but the half nuts showing so little wear AND having been mounted in reverse position would lead me to believe that they were replaced at some point. Either that or else, like me, the then owner also decided to take apart and clean the apron but for whatever reason wasn't aware of the requirement to (re)place the half nut with the small grub screw on the bottom when he reassembled it.

I, too, was not aware of the positional requirement for the half nuts, but was simply putting things back the way they had been when I took it apart.

Glad you forum guys are so knowledgeable and... helpful. thumbs up wink

Graham Meek04/08/2020 10:47:13
253 forum posts
184 photos
Posted by Clive Hartland on 03/08/2020 19:21:58:

sadly the lead screw is exposed when cutting and catches all the swarf. I am at the moment working on a cover that will fit on the front of the carriage with a tube with a slot so it can be removed for close work.

Hi Clive,

There was a Swarf Guard designed, (I think), by Ian Bradley. It either appeared in the Model Engineer as an article, or in a Book on the ML 10. He also fitted the Super 7 Cross-slide to the ML 10 lathe, something I think was later fitted by Myford's to one variant of the ML 10 as standard. I remember the 3D drawings but not a lot more.

Regards

Gray,

Jim Guthrie04/08/2020 11:39:38
94 forum posts
5 photos
Posted by Graham Meek on 04/08/2020 10:47:13:He also fitted the Super 7 Cross-slide to the ML 10 lathe,
something I think was later fitted by Myford's to one variant of the ML 10 as standard.

It was actually an official upgrade kit. I remember trying to order the indiviual bits from Myford and the nice lady taking orders advised me of the kit, and it was significanlty cheaper than the sum of the prices of the individual parts. The longer crosslide is an absolute necessity on the ML10 if you use a rear toolpost.

Jim.

Edited By Jim Guthrie on 04/08/2020 11:40:15

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