By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Evaluating & Correcting Wear in an ML7

All Topics | Latest Posts

Search for:  in Thread Title in  
mgnbuk30/10/2020 12:07:12
843 forum posts
61 photos

The usual way to remove small amounts from a face would be to scrape it - at the rate I scrape (with a sharp carbide scraper), that is around 1/4 of a thou per pass.

A known good flat reference that is longer than the face to be scraped & some marking blue (NOT layout blue) will show the high areas on the bed face, but a shorter flat piece to apply the blue used with your surface gauge & indicator arrangement to look at the bigger picture would also work. Less chance of taking too much off , rounding or tapering the face that way than with a file.

I did the "wide guide" conversion on my mid-60's Super 7 with a piece of 1/16" x 1/2" gauge plate Loctited to the rear of the saddle. It hasn't come loose in the several years since I did it & no machining of the old "fast side" on the saddle was required. There was so much wear to that short face that it was well clear when the gauge plate was inserted. There was also sufficient clearance in the apron securing screw holes in the saddle for the apron to be replaced without modification.

Good luck,

Nigel B.

Dr_GMJN30/10/2020 12:11:28
610 forum posts
Posted by mgnbuk on 30/10/2020 12:07:12:

The usual way to remove small amounts from a face would be to scrape it - at the rate I scrape (with a sharp carbide scraper), that is around 1/4 of a thou per pass.

A known good flat reference that is longer than the face to be scraped & some marking blue (NOT layout blue) will show the high areas on the bed face, but a shorter flat piece to apply the blue used with your surface gauge & indicator arrangement to look at the bigger picture would also work. Less chance of taking too much off , rounding or tapering the face that way than with a file.

I did the "wide guide" conversion on my mid-60's Super 7 with a piece of 1/16" x 1/2" gauge plate Loctited to the rear of the saddle. It hasn't come loose in the several years since I did it & no machining of the old "fast side" on the saddle was required. There was so much wear to that short face that it was well clear when the gauge plate was inserted. There was also sufficient clearance in the apron securing screw holes in the saddle for the apron to be replaced without modification.

Good luck,

Nigel B.

Thanks Nigel,

Yes, the 0.75mm shim steel has the same effect on mine - makes the short bearing clear its bed face - no machining required. Intention is to bond it with retainer.

I just need to flatten that front face slightly.

I've never done scraping before so I'll try the file method - carefully!

There is a region of the front bed (far right side) which still has has its machining marks, and never gets used, so I'll practice on that area first, and see how much gets removed per stroke.

peak430/10/2020 14:30:03
avatar
1243 forum posts
144 photos

If you want to practice scraping, rather than doing it on the back of the bed, perhaps try on a length of spare continuous cast iron bar.
That was the first thing I made on the way to re-scraping my grinder, and used it both on the flats and the dovetails.
In my case I didn't use continuous cast, but took a slice of a cast iron bus bar fishplate clamp.

Strikes me that there are two advantages there,
one you aren't changing the lathe,
and two, when you are happy enough with your technique, you will then have a straight and flat straight edge to use on other jobs.

I wonder if your front shear is more worn than usual is it was because a previous owner primarily used the lathe for boring work, where the forces were in the opposite direction to external turning.

Re. bed grinding, I gather you followed by link to Garside's machinery moving web site, but were you able to access the Facebook link.
The latter has a photo of them grinding Myford beds, and a discussion of pricing for larger work.

Bill

Dr_GMJN30/10/2020 15:34:47
610 forum posts
Posted by peak4 on 30/10/2020 14:30:03:

If you want to practice scraping, rather than doing it on the back of the bed, perhaps try on a length of spare continuous cast iron bar.
That was the first thing I made on the way to re-scraping my grinder, and used it both on the flats and the dovetails.
In my case I didn't use continuous cast, but took a slice of a cast iron bus bar fishplate clamp.

Strikes me that there are two advantages there,
one you aren't changing the lathe,
and two, when you are happy enough with your technique, you will then have a straight and flat straight edge to use on other jobs.

I wonder if your front shear is more worn than usual is it was because a previous owner primarily used the lathe for boring work, where the forces were in the opposite direction to external turning.

Re. bed grinding, I gather you followed by link to Garside's machinery moving web site, but were you able to access the Facebook link.
The latter has a photo of them grinding Myford beds, and a discussion of pricing for larger work.

Bill

Bill,

That's an interesting theory about the boring operations. The thing is, the lathe always seemed in pretty good overall condition for its age (0.002" wear on one slide isn't huge I don't think for a 54 year old machine), and the person who owned it immediately before me used it for making steam engines and narrow gauge locomotive models, so a range of turning jobs. It's history before that is unknown of course.

I couldn't get any information from the Garside website or Facebook page, but gave them a call. I am sending some photographs and my measurement data by email, and they said they'd get a price for me.

I have to say though, I spent about 5 minutes with a fine file earlier on this morning, used very gingerly flat-on to the face, and already I can get the saddle to more than 3/4 of full travel with no significant tight spots or play. This amount of work didn't even bottom out the machining marks on the right side of the bed, yet it seemed to make a huge difference. I could feel (but not see) a very slight roughness along the top corner of the vertical slide, which I smoothed off. I wonder if that was contributing to the issue somehow?

My intention is to now do a much more detailled filing, measuring and flatting session, remove the saddle steps (not that I can actually see or feel anything significant), fit the new gib strip and re-evaluate.

I'm currently a lot more optimistic about being able to sort this out myself than before. I was always surprised that less than 0.002" would cause the degree of binding I was experiencing.

mgnbuk30/10/2020 15:54:25
843 forum posts
61 photos

I was always surprised that less than 0.002" would cause the degree of binding I was experiencing.

Wait until you get to play with dovetails - doesn't take half that to get them stiff.

Nigel B.

Dr_GMJN30/10/2020 16:47:06
610 forum posts
Posted by mgnbuk on 30/10/2020 15:54:25:

I was always surprised that less than 0.002" would cause the degree of binding I was experiencing.

Wait until you get to play with dovetails - doesn't take half that to get them stiff.

Nigel B.

Next job after the saddle is re-fitted is to put re-settable dials and needle thrust bearing conversions on the top and cross-slides. I got a new cross slide gib strip to fit too. I don't think they're bad to start with though - never had any issue with them apart from the crappy feeling and backlash in the wheels/cranks.

peak430/10/2020 17:59:15
avatar
1243 forum posts
144 photos
Posted by Dr_GMJN on 30/10/2020 15:34:47:

Bill,

...........................

I couldn't get any information from the Garside website or Facebook page, but gave them a call. I am sending some photographs and my measurement data by email, and they said they'd get a price for me.

..............................

Not Garside's Facebook page, the link I posted in the last post on P2 of this thread, which was to the Myford Facebook Group. It was a general posting, but didn't include a Myford price.
You need to join the group to be able to read posts on there.

Bill

 

Edited By peak4 on 30/10/2020 18:01:33

Hopper30/10/2020 21:25:24
avatar
4868 forum posts
105 photos
Posted by Dr_GMJN on 30/10/2020 15:34:47:
Posted by peak4 on 30/10/2020 14:30:03:...

...I have to say though, I spent about 5 minutes with a fine file earlier on this morning, used very gingerly flat-on to the face, and already I can get the saddle to more than 3/4 of full travel with no significant tight spots or play. This amount of work didn't even bottom out the machining marks on the right side of the bed, yet it seemed to make a huge difference. I could feel (but not see) a very slight roughness along the top corner of the vertical slide, which I smoothed off. I wonder if that was contributing to the issue somehow?

That sounds pretty good. You don't usually need to move the saddle that last quarter of the travel to the right so I would leave it at that. The less metal removed the safer. But it could be binding in that top corner. You can safely file a small chamfer along there for clearance without it affecting the bed dimensions negatively. It may be binding some on those corners on the unworn part of the saddle.

Dont get too carried away with trying to eliminate absolutely all play. Many a lathe with more than your 2 thou wear has the saddle set to the tight spots and allowed to run a bit loose on the worn spots and it generally works ok. Under cutting loads, the saddle is pushed into contact with the guiding surface.

Scraping is good but not practical for an inexperienced beginner in an instance where a few file strokes will carefully do the job.

Dr_GMJN31/10/2020 00:11:21
610 forum posts

I think this might have worked. I used the Excel graphs as a reference for filing, and set up the DTI again on the rear vertical as a checking method. I just used the fine file and a 6” gauge block wrapped in #800 paper lubricated with 3-in-1 oil:



The feeler gauge material happens to be 1/2” wide, so a perfect fit for the rear bearing surface. Mine has shims inserted under the retainer strip, so that’s guaranteed some clearance. I Had to saw it to length and polish up the cut end. It’s secured with retainer. I also filed off the old wear edges from the horizontal faces. I might clean those up a bit more:



After cleaning everything with degreaser I test assembled it, and I can now easily move it all the way to the right, with some very slight binding towards the very end of travel at the chuck. This tallies with the graph, but not the DTI. I think this therefore might be a bind on the old short bearing. I measured 0.003” clearance at the tailstock end with the new bearing shin fitted. I’ll double check it at the chuck end tomorrow.

According to the DTI I’m less than 0.001” of flat at present. I’m not going to pretend it’s consistent handwheel resistance all the way, but it’s very close. A massive improvement. Hopefully I can get it even better with some further work at the chuck end, the new gib, and some proper slideway oil.

Not bad for 30 minutes’ work. The real test will be the faceplate, perpendicularity and taper turning checks...

Thanks for sticking with me all!

Hopper31/10/2020 01:18:25
avatar
4868 forum posts
105 photos

That sounds good. Well done.

Yes I would machine at least 30 thou off that old narrow guide surface. Otherwise, you will surely get swarf in that 3 thou gap and cause binding or skewing of the carriage.

Gib should be set loose enough that you can slide the saddle freely without resistance along the bed by pushing gently by hand on the saddle without the apron and handwheel in place. Binding between the handwheel, its pinion gear and the rack can give a false "feel".

When you have the apron back on, you can loosen the rack screws and position the carriage first at one end with a slip of paper between pinion gear and rack and tighten up rack screw at that end.then repeat at the other end of the bed. This ensures clearance between rack and pinion gear along the full length of the travel.

Also make sure the half nuts are not rubbing on the lead screw causing binding. They are adjustable with a small grub screw uin the lower half nut to set clearance. Make sure the operating handle pivot spindle nut is tight enough to hold the handle in the disengaged position.

It would be good to double check your across the full width of the bed measurements with a mike too. The sled and DTI method can be subject to some error if the top surface of the bed way is not perfectly flat, kicking the arm that holds the DTI at an angle and affecting the reading by a small amount.

peak431/10/2020 01:47:37
avatar
1243 forum posts
144 photos

Nice one, it's looking quite good at that.
I'll get around to doing mine at some point, but obviously using the tape, as I have it in stock.
Currently making a batch of arbors for the grinder at the moment.

Re your comment on oils.
Don't know if you're aware, but Pennine Lubricants are reasonably priced for slideway, and hydraulic oils, (and also for cutting oils in their Metalwork section).
I'm using their neat synthetic cutting oil in my larger Warco GH1330 as well as their slideway oil on all my lathes.
The Nuto equivalent hydraulic oil on the other Myford bits, and a soluble oil in an old hand sprayer for the power hacksaws and grinder.
They are at the top end of the old Batchelors pea factory off Claywheels Lane.

Bill

Dr_GMJN31/10/2020 15:22:20
610 forum posts

So the new gib strip arrived from Myford. It’s not like the original, which had recesses neatly machined in it to suit the rounded-end gib screws. This one just has two rather ragged looking holes in it which don’t appear to line up with anything:



If I line it up with the closest screw, it sticks out the front and the felt retainer doesn’t fit:



If it’s not aligned with any bolts it just slides out the end when moving the saddle? Any ideas on this, apart from the saying about a fool and his money?

Anyway, the short guide is machined back 0.0030” and so there’s no going back now:



Also drilled the saddle for the new wide-guide felt retainer.

Thanks all.

Michael Gilligan31/10/2020 17:36:15
avatar
16616 forum posts
723 photos
Posted by Dr_GMJN on 31/10/2020 15:22:20:

[…]

Myford. It’s not like the original

[…]

.

So it would appear sad

MichaelG.

.

Apologies for quoting just those few words ... but I think you will see my point

Dr_GMJN31/10/2020 18:27:12
610 forum posts
Posted by Michael Gilligan on 31/10/2020 17:36:15:
Posted by Dr_GMJN on 31/10/2020 15:22:20:

[…]

Myford. It’s not like the original

[…]

.

So it would appear sad

MichaelG.

.

Apologies for quoting just those few words ... but I think you will see my point

So I bought it off EBay (From Myford) as a Standard Length (four T slot) Saddle Gib Strip for ML7, ML7-R etc.

After consulting my parts list in the old Manual it seems like there might be one digit difference in the part number prefix.

No note as far as I can see on the listing that warns that there might be two types.

So now I’ve got to measure the existing dimple centres, and drill it myself. And I’ve paid £14.40 for a piece of steel that would have probably cost me less than £1 from my materials supplier.

Thanks Myford.

Dr_GMJN01/11/2020 20:13:39
610 forum posts

 

Got the saddle rebuilt and fitted today. I thought I'd document it just in case anyone was going to try it.

I spotted a potential issue with the locking mechanism - my feeler strip was pretty much size for size in terms of depth, and I wanted to make sure that when the locking block was pulled up it didn't crimp and distort the strip, so I dremelled and polished a slight recess in its top edge:



This is everything fitted:





As per my other "gib strip" thread, I drilled the new Myford item using a transfer punch through the saddle holes to get things aligned, then de-burred and polished. I also used the locking method proposed on the other thread - cross drilling the screws and inserting Nylon strimmer fillament to form a self-locking pin, obviating the need for lock nuts. I also polished the hemispherical ends of the gib pins:





And fitted the new wide guide felt and retainer. The front vertical retainer needed a layer of shim peeling off each side to eliminate some slight play there.



All seems to work very nicely now. I also did the faceplate test, a video of which I'll post here in a bit.

Edited By Dr_GMJN on 01/11/2020 20:14:57

Dr_GMJN01/11/2020 20:28:31
610 forum posts

I did the faceplate test using Hopper’s article method. I’ve got two Myford faceplates. Measuring face runout, one isn’t too bad, the other’s like a farmer’s welly. I took the good one, and got 0.002” runout on the face. I put this at 12 o’clock and ran the DTI over it with the cross-slide. Click on the image a couple of times and it should play the video:



So a bit of movement, but didn’t seem too bad? I tried it with the faceplate rotated to a couple of other positions and got similar results.

Full disclosure - I also tried it with a parallel in a 4-jaw, and got 0.001” o/d to centre. The plunger was going towards the chuck winding from o/d to centre. I think this means I’d be machining convex, which is bad. Not sure which to believe. Then again it never occurred to me to ever check this before, and the 10V turned out fine, so perhaps ignorance is bliss? Cheers!

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
ChesterUK
Eccentric July 5 2018
EngineDIY
cowells
Warco
emcomachinetools
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest