Myford ML7 Chucks - Which one?

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.

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?

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.

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.

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.

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.

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.

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.

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.

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

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

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.

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

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

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

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

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

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.

.

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.