Myford ML7 Chucks – Which one?

[Dr_GMJNParticipant @dr_gmjn]

All,

I'm in the process of fettling my ML7, and it seems like the old 3-jaw chuck I got with it is a knackered as it looks:

There are different versions available from RDG, ARC, and Myford etc, but which would people recommend? Myford do a "precision" version, but I'm assuming for critical work I'd stick with the 4-jaw?

The Myford ones seem to need a backplate. Is this where you have to machine the backplate to match the chuck or something? I've never replaced a chuck before so don't know the ins and outs of it.

Also, is it possible to buy new jaws and screws for the 4-Jaw? It looks like the original Burnerd version – it says "Specially made for Myford lathe" on the face.

Please note that the condition of the chucks is how I got them – I didn't do the damage to them!

Thanks very much.

[Dr_GMJNParticipant @dr_gmjn]

[Andrew TinsleyParticipant @andrewtinsley63637]

Rotogrip do replacement "screws" for the Burnerd 4 jaw. They are not cheap, about £30 plus each,last time I looked. They have a hexagon adjustment hole instead of the traditional square hole. This means you really need to replace all 4 or you need two keys to adjust the chuck.

I would rather put the £120 to £130 towards a new chuck, unless you feel capable of making them yourself. Maybe you could use a large socket head bolt as the material source, that way you don't have to broach the hole.

Andrew.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Andrew Tinsley on 10/11/2020 10:22:48:

Rotogrip do replacement "screws" for the Burnerd 4 jaw. They are not cheap, about £30 plus each,last time I looked. They have a hexagon adjustment hole instead of the traditional square hole. This means you really need to replace all 4 or you need two keys to adjust the chuck.

I would rather put the £120 to £130 towards a new chuck, unless you feel capable of making them yourself. Maybe you could use a large socket head bolt as the material source, that way you don't have to broach the hole.

Andrew.

Thanks Andrew. Thinking about it, do the screws matter that much on a 4-jaw? Maybe the jaws are more relevant?

I can't find the price of new chuck like mine, but I found a good used one for £450. The cheaper ones seem to be less than £100.

Not sure – if you're adjusting the part to be true anyway, is wear as critical as for a 3-jaw?

[Andrew TinsleyParticipant @andrewtinsley63637]

One of the excellent things about a 4 jaw, is that you can get a much better grip on a work piece than you can with a 3 jaw scroll chuck. With a damaged "screw" you can't really tighten up the jaw without risk of further damaging the socket (for the chuck key). I have a 4" Burnerd 4 jaw with Myford fitting, this has been over strained at some point (not guilty!)Some of the jaws can be tilted in the radial direction to an alarming degree. Surprisingly enough, this does not seem to affect its working, provided there is sufficient material to span the jaws back to front. I.E. sufficient material to stop the jaw from tilting.

I shall probably be shot down in flames saying this, but it seems to work well in practice and I can use the little 4 jaw for most jobs, without worrying about its worn out status. Just don't even think of trying this for items like rings, which do not have sufficient depth to prevent the jaw from tilting.

I have purchased a Chinese 150 mm, slimline 4 jaw with Myford fitting from Rotogrip for a very reasonable price. I have had it for maybe 7 years and it is still performing as good as the Burnerd 6" That I used previously. Maybe I have been just lucky ?

Andrew.

[old martParticipant @oldmart]

I would get a new four jaw independent chuck first, the PB is not worth restoring. I made a set of screws for the museums 6" lightweight PB and then discovered other faults when it was stripped down. I was lucky to get hold of a NOS Toolmex which was better than the PB had ever been. To stop risking damage to the screws, never use a cheater on the key, and using a strap wrench to unscrew the chuck is better than using a hammer on any part of the chuck.

I bought a 100mm four jaw independent for my 7 x 12 home lathe, it is Chinese and not at all bad for the price. You would probably need a slightly bigger one for your Myford.

[Dave HalfordParticipant @davehalford22513]

Someone has indeed hammered the chuck off using the chuck key, however if the jaws are not bell mouthed save your cash for the 3 jaw.

[Dr_GMJNParticipant @dr_gmjn]

I remove the chucks by engaging back gear and putting a large adjustable spanner on the sides of one of the jaws. A bit of pressure releases them.

[Dr_GMJNParticipant @dr_gmjn]

So does anyone have any recommendations for a specific make of 3-jaw chuck?

Do you just fit them, or does a backplate need to be machined somehow?

Thanks.

[old martParticipant @oldmart]

Arc have a Chinese 125mm three jaw self centring chuck with both sets of jaws and backplates with the 1 1/8 Myford thread. The backplates have to be machined on their fronts to match the rear of the chuck, and the screw holes drilled.

[Andrew TinsleyParticipant @andrewtinsley63637]

I have recently purchased a 4 jaw chuck from ARC. It is engraved ARC but seems to be a Sanou chuck. Very reasonable price and the quality is first class. You can't go far wrong with such a chuck, although you will have to machine up a backplate. Buy one of ARC's backplates, this already has the register and thread done for you. You only need to machine the front face to fit the chuck and drill the mounting holes.

Andrew.

[Dr_GMJNParticipant @dr_gmjn]

Looks like the 100mm diameter ones are out of stock – According to Myford, their 125mm chuck is too heavy for the ML7.

[Rod RenshawParticipant @rodrenshaw28584]

I use a piece of hardwood about 300mm long and 35 X 25mm section to remove and replace the chucks on my Myford.

I just open the chuck jaws about halfway and the wood fits between the jaws and is used as a lever.

Seems to work well enough and the wood does not mark the chuck.

Rod

[Andrew TinsleyParticipant @andrewtinsley63637]

A 5" chuck too heavy for an ML7 ?! Well my lathe bearings must be well and truly trashed as that is the standard chuck on my ML7 and has been for getting on for 40 years.

Andrew.

[Pete RimmerParticipant @peterimmer30576]

Posted by Dr_GMJN on 10/11/2020 14:57:44:

I remove the chucks by engaging back gear and putting a large adjustable spanner on the sides of one of the jaws. A bit of pressure releases them.

You risk shearing teeth off the back gear. Many have been wrecked doing this.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Andrew Tinsley on 10/11/2020 18:43:50:

A 5" chuck too heavy for an ML7 ?! Well my lathe bearings must be well and truly trashed as that is the standard chuck on my ML7 and has been for getting on for 40 years.

Andrew.

Here's the quote from the Myford website:

THIS 125mm CHUCK IS TOO HEAVY TO MOUNT ON ANY MYFORD WITHOUT THE M42.5 x 2mm 4MT SPINDLE

[Dr_GMJNParticipant @dr_gmjn]

Posted by Pete Rimmer on 10/11/2020 18:48:46:

Posted by Dr_GMJN on 10/11/2020 14:57:44:

I remove the chucks by engaging back gear and putting a large adjustable spanner on the sides of one of the jaws. A bit of pressure releases them.

You risk shearing teeth off the back gear. Many have been wrecked doing this.

So what's the best way of locking the spindle?

[David George 1Participant @davidgeorge1]

On my M Type I have a notch and use a C spanner to unscrew the chucks. Just put on C spanner put a hand on the pulley and give the C spanner a tap with a No 0 copper hide mallet don't lock the back gear and don't disturbed the chuck alignment. As supplied by Myford.

David

[Rod RenshawParticipant @rodrenshaw28584]

My Super 7 has a spindle lock at the rear end of the spindle, came with the lathe.

I thought the standard 3 jaw chuck for Myford 7s was a 4"/ 100mm.

Rod

Edited By Rod Renshaw on 10/11/2020 21:12:46

[Dr_GMJNParticipant @dr_gmjn]

My ML7 also has a 100mm chuck, and appears to be standard from what I can tell from the manual.

I have no way of using a c-spanner to lock the spindle. As far as I can see the only practical method is to engage a gear. I don’t need to apply a shock load, slight pressure on the long adjustable spanner always breaks it loose with not much effort. I never felt I was applying enough load to strip a gear.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Dr_GMJN on 10/11/2020 20:36:41:

Here's the quote from the Myford website:

THIS 125mm CHUCK IS TOO HEAVY TO MOUNT ON ANY MYFORD WITHOUT THE M42.5 x 2mm 4MT SPINDLE

.

Aaah … Fond memories

It’s almost exactly five years since we looked at that ^^^
**LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=111162

MichaelG.

[peak4Participant @peak4]

Posted by Dr_GMJN on 10/11/2020 21:30:36:

My ML7 also has a 100mm chuck, and appears to be standard from what I can tell from the manual.

I have no way of using a c-spanner to lock the spindle. As far as I can see the only practical method is to engage a gear. I don’t need to apply a shock load, slight pressure on the long adjustable spanner always breaks it loose with not much effort. I never felt I was applying enough load to strip a gear.

Mine came with a 4" Griptru, which is worth seeking out if you can find a good used one at the right price.

Re locking the spindle, I've not used this method as I have a S7 with spindle lock, but Mr Jordan's method looks nice and easy.
Previous mention of a C spanner was to turn the chuck, rather than lock the spindle wasn't it?

Bill

[Andrew TinsleyParticipant @andrewtinsley63637]

I have a 4" chuck, but in the main I prefer the PB 5" chuck for general work. I consider the statement that a 5" chuck is too heavy for an ML7, to be utter tosh. My bearings are still in great condition, although I must admit to scraping them in about 30 years ago

Andrew.

[Ramon WilsonParticipant @ramonwilson3]

Posted by Dr_GMJN on 10/11/2020 14:57:44:

I remove the chucks by engaging back gear and putting a large adjustable spanner on the sides of one of the jaws. A bit of pressure releases them.

It's much better to hold a stub of large hex in the chuck then use the spanner – over time, constantly doing it your way will stress the jaws/guides eventually, however slight the torque required. Personally though, I always use the chuck key to provide leverage

Engaging back gear and or inserting a piece of hardwood between the mesh is about the only way of locking the spindle on an ML7 if I recall correctly. As said the S7 has that very convenient locking pin.

 

Something you may want to consider – a few years back I bought a TOS self centering 4 jaw chuck the aim being to use it primarly for square section (obviously) but without the need to clock an independent in. Prior to this my main chuck of use was a Myford/Pratt Burnerd precision scroll 3 jaw bought with an ML7 around 1974. I kept this chuck when selling the lathe on and still use it today however it now takes second place, virtually permanently set up with soft jaws, in favour of the TOS four jaw. Constantly in use now it's a brilliant chuck – accurate (enough) and will do all the other one will. Wouldn't be without it now for sure and would uy another in favour of a sc 3jaw without hesitation – just a shame you can't get one with a Myford internal thread.

With regards to the 5inch – bought one of those about four or five years ago. Concerned about the overhang/weight with a conventional backplate I took it apart and found that I could machine the backplate in reverse and fit it to give a mounting same as a Myford chuck. I use only when neccesary – it doesn't 'appear' to stress anything but it does 'look' like it is.

Regards – Ramon

Edited By Ramon Wilson on 10/11/2020 22:28:18

[Dr_GMJNParticipant @dr_gmjn]

Thanks all.

I refer to L. H. Sparrey’s book quite a lot, and he suggests locking the spindle by engaging backgear, then putting some brass bar between the chuck jaws and levering it undone. Using a spanner isn’t that different – probably less damaging than a bar if I’ve assumed the contact points and load paths correctly. So I use a combination of Sparrey’s method and the one in Peak4’s video). Can’t see any harm in it tbh.

The 5” chuck being too heavy may well be “tosh”, but it’s not my statement. I read through the thread that M.G. linked too, and the only certain thing is that nobody really seems to know if it overloads ML7 bearings or not. I have no particular desire or need for a 125mm chuck over a 100mm one, so there seems little point in going against the supplier’s recommendation. I’ll just have to wait until they’re in stock, or get an alternative such as Ramon’s suggestion.

Ramon – you said the self-centering 4 jaw chuck was in constant use; what do you use for non symmetrical parts? Does it work independently as well somehow, or did you mean you’ve got another independent chuck?

Thanks all.

 

Edited By Dr_GMJN on 10/11/2020 23:10:38

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