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Myford tailstock ML7 / Super 7

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Dave Whipp05/02/2019 23:58:31
15 forum posts

Hi - Looking for a little advice from the more experienced Myford users.

I bought a 1950's Super 7 on ebay a few months ago and after many hours of work I have now got it into pretty good shape (Many new parts, bed scraped flat, 3 phase motor, repainted etc etc.)

However after looking at a lot of photos and old Myford literature it appears that my Super 7 has a ML7 tailstock instead of the correct Super 7 one.

The ML7 tailstock seems to be in reasonable shape although obviously it has some wear and I have put it to some light use without any obvious problems (but I am fairly new to the machining game)

I'm just wondering, is it worth me searching out a used Super 7 tailstock ? The ones I've seen online are not particularly cheap, However if the Super 7 tailstock design is much improved over the ML7 one then I may make the upgrade but if there's not much in it from a practical point of view then I'm not going to change it simply for the fact of having "all original" parts.

Any advice gratefully received.

Thanks - Dave.

 

Edited By Dave Whipp on 06/02/2019 00:00:24

Chris Trice06/02/2019 01:31:26
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1269 forum posts
5 photos

IMHO, the Super 7 tailstock is much better for three reasons. It has greater rigidity, it self ejects morse tapered tooling and thirdly, it does away with the annoyance of getting oil/grease on your hand from the barrel everytime you reach for the hand wheel.

Kiwi Bloke 106/02/2019 07:47:50
122 forum posts
1 photos

Just remember to check the centre height of a replacement tailstock. I don't think Myford held to specified dimensions too rigorously - it was easier to fit individual parts to each other.

jwb06/02/2019 09:18:19
15 forum posts

The ML7 tailstock has the major advantage that it will take a drawbar. Also, one turn of the handle moves the quill 1/8 inch; on the Super 7 version this is not the case. The self-ejecting feature of the Super 7 is little better than a gimmick and more of an irritation than an advantage - I've lost count of the number of times I've turned the wheel too many times and the drill chuck has fallen out.

For me, the ML7 tailstock wins hands down. Unless you're concerned about authenticity, or there are alignment problems, I'd say stick with it.

Brian Wood06/02/2019 09:21:53
1799 forum posts
36 photos

Dave,

It may not look as elegant and the correct unit has a longer support for the barrel

But setting those features aside, and if the centre height is close enough to that of the headstock and you are happy to knock out the tooling rather than have a self ejecting feature for that, in my opinion it will do a perfectly adequate job

Regards

Brian

Lambton06/02/2019 10:28:05
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662 forum posts
2 photos

I agree with JWB that the self ejecting feature of the Super 7 tailstock can be a confounded nuisance. The S7 tailstock cannot be fitted with a draw bar so it is quite easy for a drill chuck or an MT drill to slip free within the Morse taper socket when drilling large holes to the detriment of the tailstock barrel.

Eric

Mike Crossfield06/02/2019 10:45:06
158 forum posts
9 photos

I think it all comes down to condition. If the existing ML7 tailstock is in good order, with minimal barrel lift when applying the lock, minimal slop in the handwheel, and a good height match to the headstock spindle, stick with it. A secondhand Super 7 tailstock is an unknown quantity, and you could end up paying a high price for a worn out item.

ega06/02/2019 10:57:50
1072 forum posts
89 photos

A new base will rectify the height if necessary.

I long ago replaced the standard S7 hand wheel with the Myford lever attachment and regularly use a drawbar.

Chris Trice06/02/2019 12:12:24
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1269 forum posts
5 photos

I confess I too have the lever attachment fitted most of the time but don't use a draw bar. The taper is well cared for and seems to hold OK. I like the fact you can feel the cut when drilling with the lever arm, although you lose a bit of travel. I've also got the rack attachment but prefer the lever. It only very rarely gets swapped out if I need the longer movement.

ega06/02/2019 17:01:03
1072 forum posts
89 photos
Posted by Chris Trice on 06/02/2019 12:12:24:

I confess I too have the lever attachment fitted most of the time but don't use a draw bar. The taper is well cared for and seems to hold OK. I like the fact you can feel the cut when drilling with the lever arm, although you lose a bit of travel. I've also got the rack attachment but prefer the lever. It only very rarely gets swapped out if I need the longer movement.

I like the security of the drawbar which also functions as a tap-out bar for tooling. Incidentally, I discovered that the 9/16" dia lever can dop1030645.jpgthe same job; mine is fitted with a brass pad at one end and a custom-turned handle at the other which I prefer to the standard ball.

p1030646.jpg

Edited By ega on 06/02/2019 17:01:54

Edited By ega on 06/02/2019 17:02:33

Dave Whipp06/02/2019 20:57:16
15 forum posts

Thanks for all the info and opinions. Lever attachment looks mighty fine (But I probably couldn't justify the cost of one, plus a S7 tailstock as well, unless the forum opinion is that my current one is shot.......)

So as to the state of my existing ML7 tailstock - I've taken some measurements tonight.

It is less than 1 thou higher than the headstock (0.02mm) and the bar lifts by 0.025mm when the clamp is applied, so I don't think I have too much to worry about there (or do I ? - I don't have anything to compare it to)

However the handwheel is pretty loose and wobbly, and there is 1/2 a turn of slack in it over most of the travel range. I'm guessing that this is quite a bit more than it should be ?

The only things I have done to the tailstock since I bought the lathe is to fit a new oil nipple, slap on some grey paint and oil it up.

My current ML7 tailstock

Regarding drawbars - none of my taper tools or attachments have an attachment for one - I assume this would normally be a threaded hole in the end of the taper ?

Opinions gratefully received....

Dave.

Edited By Dave Whipp on 06/02/2019 20:59:27

Edited By Dave Whipp on 06/02/2019 21:17:27

Chris Trice07/02/2019 01:22:24
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1269 forum posts
5 photos

What you have there Dave is a very early Super 7 and a late ML7 tailstock. It's possible that it is the original tailstock even though officially it isn't.

Hopper07/02/2019 06:44:22
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3161 forum posts
53 photos

Posted by Dave Whipp on 06/02/2019 20:57:16:...

...

However the handwheel is pretty loose and wobbly, and there is 1/2 a turn of slack in it over most of the travel range. I'm guessing that this is quite a bit more than it should be ?

...

They all have a bit of slack there if they have done some work. You might be able to get rid of some of the slack by making a new "C" plate that fits in the slot and holds the handwheel in place. They seem to get worn where the edge of the groove in the handwheel rubs against the flat C plate. (Or making a lever attachment would do away with the problem too!)

Tailstock sitting one thou higher than the headstock spindle is perfect. Lot of lathes are made like that to accommodate wear in the tailstock base as they age.

Edited By Hopper on 07/02/2019 06:45:29

Dave Whipp07/02/2019 21:52:22
15 forum posts

Thanks Chris & Hopper.

Lathe is approx 1958 vintage going from the serial number, though it's got a later clutch, a later wide bed saddle and roller bearing races, so it won't win any originality prizes.

So it looks like my ML7 tailstock is in fairly decent shape, apart from the loose handwheel. I won't bother sorting out the C plate, I'll go straight for making a lever arm setup instead, I've found some photos of the ML7 version of the lever arm and it doesn't look that difficult to replicate. The hardest part will be turning the internal Acme thread (I'm a first timer doing screwcutting, though I've watched plenty of youtube videos on it) I assume that it is an Acme thread and not a special Myford one-off thread ?

Regarding drawbars on MT tooling, is it permissible or advisable to mod MT tools by either drilling & tapping them (assuming they're soft enough) - or welding on a nut if not ? None of my MT drills or centres have tapped holes in the back.

Is there a standard thread for MT2 drawbars & tools ?

 

Dave.

Edited By Dave Whipp on 07/02/2019 21:55:09

Phil P07/02/2019 23:20:51
443 forum posts
116 photos

I use both types of tailstock on my S7.

The normal one is used for general work and stays on the lathe most of the time, but the ML7 one is fitted with a Cowells capstan rack attachment, and I use that for threading with a Coventry die head.

Phil

Hopper08/02/2019 00:54:38
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3161 forum posts
53 photos

Would you really need to screwcut the internal surface of the lever attachmment? I'm sure I've seen designs over the years that just clamp onto the quill. A nice piece of aluminium would have enough "give" in it to clamp nicely on to the threads without causing damage.

Otherwise, yes its a standard Acme thread AFAIK that could be turned into a piece of aluminium eaasily enough with a home-ground tool bit in a boring bar. But probably not the best project for a first time at screwcutting. I'd seriously be looking at clamping options.

As for drawbar on tailstock, I have never used one in 50 odd years of messing with lathes at home and at work. I wouldn't worry about it. If the internal taper is in good shape it should hold whatever you need to do without problems with no draw bar.

Just one example, I have used the tiny MT1 taper on my ancient Drummond Flagellator to hold a drill chuck that in turn held a 1" diameter drill bit with reduced shank to fit the chuck. Drilled a 1" hole in steel with no slipping of the taper. So when I use the ML7 with the big MT2 taper, I'm pretty confident it's never going to let go. Ever.

Pic: MT1 tailstock taper on "The Flagellator" Drummond M-type holding a 1" diameter drill bit drilling steel. No draw bar. What more do you want?

picture 7. chuck arbour.   taper does not budge under load when drilling a one-inch hole with heavy feed..jpg

The secret is to make sure that both tapers are scrupulously clean and free of burrs. A rag pushed up through the tailstock with a screwdriver will clean it out usually. Then slide the chuck or whatever into the tailstock with a good "bang" so the impact seats the taper. I think I might have cheated on the 1" drill and tapped the tip of it once or twice with a piece of brass bar to make sure the taper was seated good and solid.

 

Edited By Hopper on 08/02/2019 01:03:08

Edited By Hopper on 08/02/2019 01:06:43

Hopper08/02/2019 07:53:24
avatar
3161 forum posts
53 photos

PS I just had a look at the drawings for ML7 lever tailstock in MEW issue 16 and no screwcutting required. It uses a ring of steel or aluminium (suitable alloy such as 6061 of course) that clamps around the right hand end of the threaded quill using a split and a pinch bolt. Very simple.

Chris Trice08/02/2019 10:22:11
avatar
1269 forum posts
5 photos

Both the official Myford Super 7 and ML7 versions just clamp on the barrel without screw threading.

Dave Whipp08/02/2019 22:38:05
15 forum posts

Thanks once again. A simpler job than I thought. (though to be honest I was relishing the challenge of the acme threadcutting) If you don't try , you don't learn....

Thinking about it, if it was to screw onto the thread of the quill it would make fitting and removal a hassle because you'd have to dismantle the assembly each time instead of fitting it all as one unit.

I have ordered some 20mm aluminium to make it from. Will post up some photos when I've finished it, but before that I have some ebay DRO's to fit.

And also thanks for clarification on the need (or not) for drawbars. In my short time working with the morse tapers I haven't had one slip yet. I take it that they are not supposed to be oiled ?

Dave.

Mike Poole08/02/2019 23:05:37
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1695 forum posts
44 photos

As one of the main tasks of the tailstock is going to be drilling I feel it would be useful if rotation was limited like a drilling machine quill, I feel this would protect the taper from a spinning tool if it releases due to grabbing in the job while drilling or tapping.

Mike

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