Myford ML7 Chucks – Which one?

[HopperParticipant @hopper]

RDG sell a 100mm 3-jaw to screw straight on to the Myford spindle without a backplate. I dont know of any others.

As Stevie says, a good used Grip-Tru would be very nice to have for a fellow who likes things to be just so. But we all know how buying used without inspection etc can go. Safer bet to get started with the RDG. Maybe a Grip-Tru will pop up at a bargain price in the future and be worth a punt. But even then, I have had mixed quality items purchased from RDG in the past, ranging from very ordinary to good. Based on that, I'd rate them as a mid-range quality supplier.

 

Edited By Hopper on 22/01/2021 02:31:24

Edited By Hopper on 22/01/2021 02:32:07

[Tony Pratt 1Participant @tonypratt1]

I'm not sure why but all the import chucks seem to be 'long', i,e, more overhang from the spindle bearings.

Tony

[Dr_GMJNParticipant @dr_gmjn]

Thanks both.

Steve – I'd want a new chuck, I wouldn't risk second had unless of course it was new and unused. The chucks for sale from the usuals, or a Google search don't really need much further investigation – they are what they are.

It's just that I can't find a new chuck with similar dimensions to my existing one. Not sure if I'm searching for the wrong thing, but mine has a backplate, but no spigot – the spindle register and thread are inset into the back face of the chuck. It's overall length is 50mm. All the new ones I can find look to be getting on for double that.

Hopper – I think the RDG chuck you refer to is pretty much the same as the others I've seen in terms of length, it's just that the backplate is already fitted by the supplier. I will give them a call and see what's what.

I'm not bothered about a small increase in overhang, indeed with the current chuck, sometimes when working close to the jaws with a short tool length, the saddle felt is off the end of the slides.

I had a look at some old books (Sparey etc), and they show their chuck jaws overhanging the slides slightly. I noticed that this enables a packing piece to be put between the front slide and a jaw, as a rough indexing method. This is impossible with my chuck because the jaws are nowhere near the end of the slides. So I really don't know what a "standard" chuck is for the ML7.

[Dr_GMJNParticipant @dr_gmjn]

I just spoke to RGD.

All their chucks are backplate types with an external spigot.

They did say that they've sold hundreds and never had a question or issues related to the length of the chuck.

So it seems like all currently available chucks for the ML7 are effectively similar lengths.

Unless someone can point me in the direction of a new chuck with an internal register rather than an external spigot?

Thanks.

[HopperParticipant @hopper]

Never seen them advertised anywhere. Even Myford these days does not. Youre only alternative might be to take a standard modern chuck, flip it round and clamp it to the face plate and turn your own thread and register recess in the inner diameter of it. Would necessitate ensuring there was enough meat in the right places to take the thread and recess.

Would be a lot easier to fit the modern type chuck and backplate. They seem to work ok.

One reason the modern chucks might be a bit wider is the chuck key pinion/barrel appear to be larger diameter and so take up more room.

[Dave HalfordParticipant @davehalford22513]

Rotagrip still sell them, but it will make your eyes water

[Dr_GMJNParticipant @dr_gmjn]

Hopper – agreed, I think I'll go for the Arc one and machine the backplate myself. I can then at least thin the backplate a bit at the same time as machining the spigot.

I suppose I should re-check the front bearing play, since I assume the longer working distance from the bearing will exacerbate any looseness here. Any advice on tolerances, checking and adjusting would be great.

Dave – yes, I should have said that as per previous suggestions on the thread, I looked at Rotagrip chucks, but they are well out of my price range.

Thanks all.

[Dave HalfordParticipant @davehalford22513]

Don't thin that backplate very much and the spigot is the only register for the spindle/backplate joint + the spindle can't stick out of the backplate.

Just cut the chuck register.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Dave Halford on 22/01/2021 12:40:44:

Don't thin that backplate very much and the spigot is the only register for the spindle/backplate joint + the spindle can't stick out of the backplate.

Just cut the chuck register.

As I understand it, so long as the register boss is left untouched at the bearing end, and the spindle thread doesn't protrude beyond the face of the register boss (ie into the chuck), everything should be OK?

For example, If I turn the register, and the end of the spindle is, say, 5mm from the register face, I could machine 5mm off the backplate with no issue? Assuming of course that leaves about 5 mm -10 mm of backplate thickness. I'm not suggesting thinning the backplate itself to a couple of mm or anything like that.

[Nigel McBurney 1Participant @nigelmcburney1]

The comment on a the cost of a Myford 3 jaw 100 mm chuck sold by Rotagrip is classed as eye watering,for a start if decent work is expected from your lathe then it should be fitted with a good condition r new chuck,the Myford Burnerd 3 jaw with threaded body set the body of the chuck closer to the spindle to reduce overhang, the cost is £321 is this really expensive for a good 3 jaw,back in 1967 when I was looking to buy a ML7 the cost of the direct mounted chuck was £14 and 2 shillings now in those days a skilled engineering worker was earning around or or a couple of pounds above this figure per week Nowadays according to my info a skilled man now earns around twice the amount so could possibly buy two 3 jaw chucks for a weeks wage instead of one in 1967, Its not really eye watering prices its just that we have got used to with cheap fsuspect quality far eastern imports.

[KWILParticipant @kwil]

I have found that TOS brand (Czech) chucks have been reasonable in price and within their stated specifications.

[Dr_GMJNParticipant @dr_gmjn]

Posted by Nigel McBurney 1 on 22/01/2021 13:52:19:

The comment on a the cost of a Myford 3 jaw 100 mm chuck sold by Rotagrip is classed as eye watering,for a start if decent work is expected from your lathe then it should be fitted with a good condition r new chuck,the Myford Burnerd 3 jaw with threaded body set the body of the chuck closer to the spindle to reduce overhang, the cost is £321 is this really expensive for a good 3 jaw,back in 1967 when I was looking to buy a ML7 the cost of the direct mounted chuck was £14 and 2 shillings now in those days a skilled engineering worker was earning around or or a couple of pounds above this figure per week Nowadays according to my info a skilled man now earns around twice the amount so could possibly buy two 3 jaw chucks for a weeks wage instead of one in 1967, Its not really eye watering prices its just that we have got used to with cheap fsuspect quality far eastern imports.

I think the £321 is for a "super precision" chuck, there is another standard looking item for much less. However, they both still require a back plate – I just spoke to Rotagrip.

So in terms of geometry they would still appear to be the same as the rest of the backplate type chucks.

From what I can gather, the last internal thread/register Myford chucks were made 25 years ago, and have never been made since.

Apparently there is a method of modding a certain make of chuck to have more of an internal register and thread, but I am waiting for some more info on that.

[noel shelleyParticipant @noelshelley55608]

Cheap chucks ! As has been said, we loose sight of quality and what it costs. Me, £17 a week, a nearly new Myford S7, well equipped £202 in 1970. Still have it ! Noel.

[Dave HalfordParticipant @davehalford22513]

Posted by noel shelley on 22/01/2021 14:27:34:

Cheap chucks ! As has been said, we loose sight of quality and what it costs. Me, £17 a week, a nearly new Myford S7, well equipped £202 in 1970. Still have it ! Noel.

Me,

£30 for a 100mm Solidarnosk era 80's polish chuck, came with a leaflet bearing a little bison on it.

[Dr_GMJNParticipant @dr_gmjn]

Thanks very much all – I know this thread has gone round the houses a bit, but having re-visited my lathe checks last week, my existing chuck is indeed knackered – I can see daylight between the jaws and the workpiece at the ends (the jaws are indeed bell-mouthed). This is what caused the issues with surface finish when machining the unsupported test bar (I re-did the test in my 4-jaw chuck and it was sorted).

Accepting that the 'slim body' chucks are unavailable, it pretty much boils down to:

Pratt Burnerd plus a backplate from RDG, total cost £179.12

HBM including backplate (pre-fitted) from RDG, £124.50

Arc "Chinese Origin" plus a backplate, total cost £68.64

Is it better to go for a separate backplate and machine in-situ, or is the pre-assembled HBM version OK?

Which should I get? The price differences are a bit concerning.

 

Edited By Dr_GMJN on 26/01/2021 17:27:57

Edited By Dr_GMJN on 26/01/2021 17:28:08

[Andrew TinsleyParticipant @andrewtinsley63637]

I purchased a 4 jaw independent, slim, Myford threaded chuck from Rotagrip, maybe 5 years ago, so they may not yet be extinct.

I don't know of any current 3 jaw chuck with a Myford thread. I have an Arc 3 jaw Chinese chuck. I believe they are made by Sanou but marked Arc. My Arc /  Sanou chuck was quite a revelation. The quality and finish were far better than anyone could expect from its modest price. Maybe not up to Burnerd  standards, but not far off.

Andrew.

Edited By Andrew Tinsley on 26/01/2021 18:47:24

[Dr_GMJNParticipant @dr_gmjn]

Posted by Andrew Tinsley on 26/01/2021 18:39:05:

I purchased a 4 jaw independent, slim, Myford threaded chuck from Rotagrip, maybe 5 years ago, so they may not yet be extinct.

I don't know of any current 3 jaw chuck with a Myford thread. I have an Arc 3 jaw Chinese chuck. I believe they are made by Sanou but marked Arc. My Arc / Sanou chuck was quite a revelation. The quality and finish were far better than anyone could expect from its modest price. Maybe not up to Burnerd standards, but not far off.

Andrew.

Edited By Andrew Tinsley on 26/01/2021 18:47:24

Yes, the Arc chuck does look nice. I have no idea whether inexpensive = less accuracy or less durability. If it was clear-cut then I'd go for the P-B chuck.

The RDG HBM chuck under their Myford page comes with a fitted Myford register/threaded backplate – it's not integral with the chuck.

[Dr_GMJNParticipant @dr_gmjn]

I got this one in the end:

The old one was dead. Should be much nicer to use now:

Once I've turned the backplate spigot, does anyone have any tips for marking and drilling the three threaded holes?

Would a transfer punch be ok, then drill and tap in the mill, or does it need to be more accurate? I'm assuming the spigot will fully locate it, and the screws will be in clearance holes to give some wiggle room, and are there just stop it from falling off.

Thanks.

[DiogenesIIParticipant @diogenesii]

Transfer one, once that's drilled & threaded you can bolt it up and do the others using the clearance holes as a guide. Mill accuracy will be perfectly adequate, as you say location is provided by the register.

Once mounted, use a known-good object (shank of a fat, unused end mill?) and DTI to check run-out at the jaws. I have one of those chucks, the original 'set-up' pinion wasn't marked, you will probably find that you get wildly differing results depending which pinion you use to tighten down the work. Mark the one that gives best results.

Once you have done that, rotate the chuck about the mounting holes on the backplate, you may find a particular position will give an improved result.

I think it's a good choice, I wasn't that impressed with the 'feel' when I first had mine, but a bit of 'a wire-brush' deburr & some use, and it's improved markedly, repeatable run-out in the less-than-half-thou to one thou range depending on how fussy one wants to be setting the work.

Occasionally EK10 soft jaws turn up on sale at decent prices – well worth getting a set.

Edited By DiogenesII on 05/02/2021 15:41:57

[Dr_GMJNParticipant @dr_gmjn]

OK great – some good advice.

I was surprised the jaws weren’t stamped 1, 2 & 3; I understood it was good practice to replace in the same position if they’re ever removed?

So when you say check which pinion you turn for tightening – do you mean the one you use for initial tightening? I usually nip all three up one after the other. So mark the one that gives the best initial clamp?

Thanks.

[Peter SpinkParticipant @peterspink21088]

That looks nice!

I was in a similar position a few years ago – inside jaws very worn and belmouthed but outside jaws as new, so now have the luxury of a new (TOS) 3 jaw and an old dedicated chuck with just the outside jaws – saves a lot of faff changing the jaws over!

[Dr_GMJNParticipant @dr_gmjn]

Posted by Peter Spink on 05/02/2021 16:23:21:

That looks nice!

I was in a similar position a few years ago – inside jaws very worn and belmouthed but outside jaws as new, so now have the luxury of a new (TOS) 3 jaw and an old dedicated chuck with just the outside jaws – saves a lot of faff changing the jaws over!

Must admit I'm quite chuffed with it – at least how it looks and how nice the movement of the jaws feels with the key. Shame its going to be more of an overhang than the old one, but there appears to be no way around this these days. Overall it should be way better than the old one though.

[Mike PooleParticipant @mikepoole82104]

Posted by Dr_GMJN on 05/02/2021 16:00:31:

OK great – some good advice.

I was surprised the jaws weren’t stamped 1, 2 & 3; I understood it was good practice to replace in the same position if they’re ever removed?

So when you say check which pinion you turn for tightening – do you mean the one you use for initial tightening? I usually nip all three up one after the other. So mark the one that gives the best initial clamp?

Thanks.

The jaws are all different so they must be in the correct order when loaded into the slots. It is common to label the slots and jaws so they are in their own slots. The order of assembly is important but if you get it wrong it is very obvious. If the jaws are definitely not labelled then it would be useful to mark them. They are likely to be very hard and will ruin a number punch or centre punch if dot marking. A discreet grind mark or electric etch pencil mark will identify them. I would suspect that the jaws are given a final grind of the reference faces after the chuck is assembled so they are matched to the slots.

Mike

Edited By Mike Poole on 05/02/2021 17:03:27

[Dr_GMJNParticipant @dr_gmjn]

Thanks all.

[Ex contributorParticipant @mgnbuk]

I was surprised the jaws weren’t stamped 1, 2 & 3;

In your top photo of the new chuck showing the outside jaws, I can see 1,2 & 3 stamped in the bottom of the darker grey un-ground slot at the LH end of the jaws.

Nice looking chuck, but probably beyond the depth on my pocket. I have a £38 (delivered) Sanou K11 100mm 3 jaw sat waiting for the lathe to get a replacement inverter fitted & I thought that was pushing the boat out !

Nigel B.

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