125mm HBM Chuck too heavy for Myford ML7???

[bodgeParticipant @bodge]

Ross, Hi & welcome

No apologies required, thats just the way it goes on here at times, and like your self, im not too sure just as to how the " bullshit baffles brains " got into it either ! seemed a simple enough question to ask, and as others have rightly pointed out a 6" four jaw is usually a stock item to go with a ML7 as far as that goes, if one wants to hold some thing lumpy and chunky ones probably going to need a bit bigger chuck, so as a general rule the 4 jaw is usually 2" bigger, the idea being the work piece most likely wont clear the cross slide anyway, plus if it"s lumpy ones going to have the revs down a bit, and then one gets to the face plate usually bigger again , 9" ,so i figured these two items were out side the scope of the original question. If you were to load the 5" up with as big a bit of bar as will clear the cross slide and 14" or so length then you would also be using a fixed steady or a rolling centre or both, so i dont think it"s going to matter to much.

bodge.

[Ian S CParticipant @iansc]

Do the "big bore" Myfords have roller or ball bearings rather than plain bearings, maybe that's the answer.

Ian S C

[ross748Participant @ross748]

Thank you Bodge, yes I completely agree with what you said – I'm not going to worry about it too much, although I will be interested to know what Myford have to say about it.

Regards,

Ross

 

 

 

Edited By ross748 on 10/10/2015 11:25:32

[AjohnwParticipant @ajohnw51620]

Posted by ross748 on 10/10/2015 11:24:58:

Thank you Bodge, yes I completely agree with what you said – I'm not going to worry about it too much, although I will be interested to know what Myford have to say about it.

Regards,

Ross

Edited By ross748 on 10/10/2015 11:25:32

Perhaps you should ask them how big a piece of depleted uranium you can machine on the lathe.

John

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[Martin KyteParticipant @martinkyte99762]

So I asked Myford at the Show. The essential facts are that there were a little concerned regarding bearing wear on the small bore lathe when running with the bigger 3 Jaw. They freely admit that you can do it, they recognize that you probably will do it but they suggest you should not do it all the time.

I think that's basically where we all go to on this thread too. I Use the 125mm when I need to but use my other chucks or collets when I don't.

regards Martin

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Martin Kyte on 19/10/2015 09:48:44:

So I asked Myford at the Show. …

.

Thanks, Martin … Nice to hear that they responded !

Perhaps they will now see fit to 'soften' the bright red upper-case 'shouting' on the web page.

I did try contacting them about this discussion, via the 'Myford' website form, but have received no response or acknowledgement.

MichaelG.

[AjohnwParticipant @ajohnw51620]

The weight of the chuck would help compensate for the upward pull of the belt drive which will and does cause bearing wear. Cutting forces push up and back too – hence the popularity of under drive and it's variants.

John

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[Michael GilliganParticipant @michaelgilligan61133]

UPDATE

I have received a reply from 'Myford'

[quote]

Hello,

 

Thankyou for your email.

 

We do not monitor the forums as we consider them to be purely for myford users to discuss their issues/ideas etc.

 

Regards, Angela
Myford Ltd,
2 Richmond House
Caldene Business Park
Mytholmroyd
HX7 5QJ
01422 885766

 

In a message dated 15/10/2015 02:01:00 GMT Daylight Time, writes:

Name:Michael Gilligan
Email Address:
Message:
Dear Sirs,

I don't know if you regularly monitor the ME/MEW forum, but; in case you do not, may I draw your attention to this thread … **LINK**

It would save a lot of idle speculation if you could post an authortitative answer to the question.

Thanks for your kind attention
MichaelG.
 

[/quote]

.

Quite frankly, I don't think I have the enthusiasm to pursue this any further.

MichaelG. 

Edited By Michael Gilligan on 21/10/2015 16:42:54

[ross748Participant @ross748]

Thank you to everyone who contributed to this thread.

I checked the spindle bearings on my lathe the other night and I can confirm that the large 125mm HBM chuck I've been using (and that's not a lot of use in reality) has significantly worn the front bearing shells on my lathe! I last checked the bearings when I bought the lathe a few years ago and the bearings were in fine condition. That was just before fitting the HBM chuck!!!!

In my opinion the 125mm HBM chuck is too heavy, too bulky and most importantly, it protrudes too far from the end of the spindle for use on the ML7, particularly when compared to the original Pratt Burnerd 4" chucks that were specially made for the ML7.

The 125mm HBM chuck and its backplate literally dwarfs the Pratt Burnerd chuck, and the difference in weight is massive. Further evidence comes form the fact that the specially made Pratt Burnerd chucks have a threaded body rather than a backplate to improve the rigidity on the ML7. So having a chuck that is much heavier and which has its business end much further away from the spindle bearings is not going to help with rigidity one bit!

Just to reiterate – my machine has the original white metal bearings, perhaps the later machines (or upgraded machines) fitted with bronze bearings and hardened spindle may cope better with the bigger chuck.

I've brought one of the Pratt Burnerd 4" chucks that were specially made for the ML7 now (a good second hand item), but part of me feels that RDG owe me a replacement spindle and bearings because they were selling these larger chucks as "take out if the box and screw directly onto the spindle of your ML7 or Super 7" without really considering its suitability for the older machines.

Oh well, you live and learn!

Cheers,

Ross

[Enough!Participant @enough]

Posted by ross748 on 26/11/2015 00:02:45:

In my opinion the 125mm HBM chuck is too heavy, too bulky and most importantly, it protrudes too far from the end of the spindle for use on the ML7, particularly when compared to the original Pratt Burnerd 4" chucks that were specially made for the ML7.

I'm surprised you could even open the jaws far enough (without them hitting the bed) to make the use of this chuck advantageous.

[Flying FiferParticipant @flyingfifer]

One of my "tooling" luxuries is to have 2 four jaw chucks for my ML7. One is permanently fitted with internal jaws & the other with external jaws. Both of these chucks are Pratt Burnerd.

One is marked "Specially made for the ML7" & is "Badged" as a Model 34M it weighs 4447gms or 9Lbs 12.9ozs in old money.

The other has Pratt Burnerd Int Stamped on the edge and no other markings. It weighs 4383gms or 9Lbs 10.6 ozs.

Don`t know how old my lathe is but there is no wear in the white metal bearings & it is in pretty regular use and well kept. Personally speaking if I had been in the market for a 4 jaw & seen the warning label as originally stated I wouldn`t have touched it with a bargepole ! You pays your money & takes what you get. At the risk of being hounded off the forum I would say only buy British, U.S. or German tools but they are getting scarcer than hens teeth.

Alan

[Ian S CParticipant @iansc]

I think one of the main problems is in a chuck that requires a back plate, this adds the weight of the back plate, and pushes the weight further out from the bearings, ideally the chuck (on any lathe) should be as close as possible to the bearing.

Ian S C

[Flying FiferParticipant @flyingfifer]

Definitely agree with you Ian. The Pratt chucks mentioned couldn`t get any nearer the bearings.

Alan

[egaParticipant @ega]

Ian S C:

I agree also. However, it is worth pointing out that, on my own machine, with the Myford pattern PB 4" SC chuck I cannot machine right up to the jaws without the saddle oversailing the gap or winding out the topslide.

Some years ago I bought a used 4.5" Taylor 3J with a view to making a backplate and using the chuck with my S7. These excellent chucks are very heavily-built and an instinctive feeling that it would be wagging the dog has kept me from doing so.

I assume that the Myford pattern chucks are no longer available new but, depending on the construction of any given chuck, it is sometimes possible to reduce overhang by positioning the backplate thread within the chuck body.

[Ian S CParticipant @iansc]

It's only now that I realize that the Myford does not have a filler piece for the gap, this seems a silly omission when it comes to face plate work, I suppose all Myford 7 lathes are like that.

Ian S C

[AjohnwParticipant @ajohnw51620]

From memory Ian some of the face plates make use of the gap.

Personally I am not convinced that Myford have always supplied chucks that don't need a back plate. I have the impression that it's a more recent thing even on 7's.

John

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[LambtonParticipant @lambton]

Ian,

You are correct in thinking that no Myford 7 lathes have loose gap pieces. The reason for this is actually allow for oversize work attached to the face plate e.g. flywheels and similar. Myford also offer a 9" diameter faceplate that certainly needs the gap.

In general loose gap pieces are a mixed blessing as they are often difficult to set up properly especially when the front on the bed is a bit worn and the gap piece is still in pristine condition so creating a very shallow step. Loose gap pieces are normally only found on larger lathes such as Colchesters.

I do not think it is quite fair to criticise the original Myford gap bed design as this makes a small machine very versatile without more expense and complication.

[V8EngParticipant @v8eng]

I have Myford (Nottingham) document from 2009 which lists a few chucks on back plates for 1 1/8" spindle noses.

I am not at home until late today, will see what I can tell from it when I get time.

[AjohnwParticipant @ajohnw51620]

Loose gap pieces spend most of their time in the gap. If lathes for a job are sized correctly they are only intended for occasional jobs. In fact it can be a right pain getting them back in exactly where they need to be.

Myford's problem with the 7's if that is the correct word is that they are budget machines and that explains many things about them. They are still budget machines now.

Some one mentioned bearing wear on an ML7. That's what the shims under the bearing caps are for. Periodically when the bearings are too loose to do what's being asked of the lathe they caps should be removed, a very thin layer off the shim removed and the top 1/2 of the bearing scraped back in. At the same time this is done all of the bearings should be blued because at some point both of the lower bearing halves will need scraping to level and align the spindle and get good contact all over them. A new spindle will probably be required at some point especially with the later phos bronze bearings they supplied. Myford have always had a good stock of ML7 spindles. When I requested one of a super 7 they reckoned they had never supplied one but did make a few for spares. The same sort of problems crop up with these too but the bearings can always be made to fit the spindle.

Loose bearings on a ML7? At some point, crap finish, carbide tooling chipping more often than they should and even relatively easy materials to machine throwing bits of swarf all over the place. A fix some use that doesn't really help all that much is to set the belt to the headstock very tight. That increases the bearing wear even further.

John

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[V8EngParticipant @v8eng]

Adding to my previous post:-

The document I mentioned is titled: Accessories and Ancillary Equipment for Series 10, Series 7 and 254 Plus Screwcutting Metal Turning Lathes.

At some 35 pages it seems very comprehensive and was handed to me at a Myford Exhibition Stand, not sure exactly where though.

In the list of Chucks for Small Bore Spindles – Bored 5/8" Threaded 1.1/8" x 12 TPI Whitworth Form, there is part No 40/120. Which appears to be a 125mm (5")  3 Jaw TOS Svitavy Geared Scroll (self centring) Chuck, complete with 2 sets of jaws (inside and outside) and key. Fitted to an A3091 Backplate.

This particular listing covers Series 7 Machines.

I do not have the knowledge or experience to comment on this matter, but did think this might be of interest to those posting comments in this thread.

 

 

Edited By V8Eng on 29/11/2015 20:17:15

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