Myford Quadrant

Does anyone know if the standard ML7 quadrant is the same as the one in the metric conversion set for the quick change gearbox? I can't afford the full metric set, so looking at getting just the gears I need.

Cheers, Stu G

Reply to
stooby-doo
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I think they are different, however.... If you want to try and cut some metric threads, you might want to have a look at my ML7 gear calculation software which works it out for you:

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Many metric threads cut with the imperial wheels are so close that errors elsewhere such as the leadscrew become more important. e.g.

1.00mm pitch thread can be done with the standard wheels to 1.000125 mm/rev which would be an error of 6.25um (quarter of a thou) over a 50mm length thread.

Anyway, the software is free so nothing to lose by giving it a whirl. It also takes stock of what gears you have so if some are missing or you have bought some extra, it will take account of that. A 63t is useful, a 127t is very useful as it allows true imperial to metric ratios, but I've never found the need to buy either for any of the threads I've had to cut.

Reply to
Duncan Munro

Sent some pics to the email, on the premise that it might work.

Cheers Trevor Jones

Reply to
Trevor Jones

Stu

Hi, the banjo is different and has a longer slot at I believe a slightly different angle to allow for larger gears to mesh. Have a look in your inbox for a copy of a drawing that was included with a ME/ MEW article. Hope this helps. If not I will measure my S7 metric conversion quadrant if it helps any, I'm not sure however what the ML7 one looks like as a starting point but I guess it is the same.

Keith

Reply to
jontom_1uk

The metric conversion set is for those poor benighted sods with imperial gearboxes to cut metric threads with, since the quadrant that comes with the gearbox isn't much good with change wheels (all say ahh :-)

The quadrant on the metric conversion set clamps around the boss on the Norton gearbox. If you haven't got a gearbox, then you don't need the extra quadrant, just the appropriate gears as per Duncan's program or Myford's manual.

HTH

Mark Rand RTFM

Reply to
Mark Rand

Correct as always Mark but I nearly took exception to "poor........sods" but then I remembered how much the gearboxes cost these days so correct on all points :-))

Reminds me of a guy who went to watch a polo match in his posh new Audi to show off, as they paid to get in his wife asked where they could get a cup of tea. The girl on the gate shouted with the biggest plum you could imagine, "Giles where can the ORDINARY people get tea"

- straight down to earth with a BUMP.

So do ORDINARY people have a gearbox or not??? :-)))

I'll get my coat, or maybe finish that bottle

Regards

Keith

Reply to
jontom_1uk

I bought a Myford new in 1968, just a bog standard ML7 with normal chucks etc, no expensive add ones. Over the years I lusted for a screwcutting gearbox, all my mates had pin ups of Marianne Faithfull and Bridget Bardot, sad bastard that I was I had an exploded view of a screw cutting box.

On the plus side none of my mates got to screw Marianne or Bridget and Myfords never got to screw me either

Many years later I found a lathe with a box fitted, bought it and fitted the box and cover to the ML7, got the metric conversion set and 30 years on I was set, or so i thought.

As a lot of my stuff are specials and need weird setups. It was a pain on the ML7 keep swapping gears but on a gearbox equipped machine it's worse as you don't have the range of adjustments on the gearbox model.

In hindsight unless you get all the gears in the same box then it's a toss up whether it's an advantage.

-- Regards,

John Stevenson Nottingham, England.

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Reply to
John Stevenson

box and cover

the range of

whether it's

at:-

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Hide quoted text -

John, "sad bastard", "pictures of screw cutting gearboxes", "toss ups". Gert needs to sort you out! :-))

It was always Twiggy with me and the years seem to have been much kinder to her than to me. Ah well, where is that drawing of a Merlin? looks rather good through the bottom of this bottle!

Regards

Keith

Reply to
jontom_1uk

box and cover

the range of

whether it's

as well as a S7 with a gearbox in my shop.

I found that I very much missed the capability that the ML7 had to set up for various non-standard threads.

I have since gathered up a collection (as yet incomplete) of change gears and a quadrant for the gearbox equipped S7, and am gradually gaining back most of the abilities that were lost, but it has taken some time.

Cheers Trevor Jones

Reply to
Trevor Jones

Have you seen 220075936955 on ebay yours in the workshop John

Reply to
hinkela2

of Marianne

Myfords never got

box and cover

have the range of

up whether it's

What about the hemingway box seems to have the best of both worlds, the quickchange box and the original quadrant

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Yours in the workshop John

Reply to
hinkela2

The Myford gearbox is a complete waste of time unless all you are interested in is Imperial threads and convenient switching between threads and fine feeds - which is basically what the box was designed for. As soon as you fit the Metric quadrant to a box-equipped Myford you might as well not have the box at all.

Regards, Tony

Reply to
Tony Jeffree

Pity they don't hire the jigs out for building the box. Fifty odd quid extra to make a set of jigs that are no use afterwards.

.

-- Regards,

John Stevenson Nottingham, England.

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Reply to
John Stevenson

In article , Tony Jeffree writes

Tony,

While I take your point, I think you are perhaps overstating it. I bought a Super 7 sans gearbox in the 80s, and found screwcutting a real pain. Even changing feed rate for normal turning was a chore.

Since fitting a (Myford) gearbox a few years later, I found I was screwcutting most screw threads, and changing feed rate at the flick of a lever. Agreed, metric threads can be a chore, and I ended up buying a conversion kit a few years ago to make some microscope accessories, but I have used it (IIRC) twice. For most metric threads I have done, they are short enough to use a close imperial equivalent. or small enough to cut with a die. I had to make a replacement bezel for the control box on the lathe stand I bought a few weeks ago - 25mm x 1.5mm - and I found that for the 3-4 threads engaged on a plastic switch barrel, a 16 tpi thread worked perfectly, and took a fraction of the time changing to the metric kit would take.

Another benefit is in turning up to a shoulder under power; I can now disengage the gearbox a few tens of thou short of the shoulder, and finish off with hand power using the leadscrew handwheel. No crashes, no need to disengage the leadscrew.

I know I would never again want to buy or use a lathe without a gearbox; if I were starting now, I would probably use the Hemingway kit, but it was not available then, and I certainly have no regrets over fitting the Myford one.

David

Reply to
David Littlewood

David, Can you explain that last bit again please? How do you disengage the gearbox ? Am I missing something if I were to drop the half nuts out and feed up to the shoulder with the apron handwheel, because surely once you are at the shoulder you have to drop the half nuts to wind the carriage back.

I know it's late but I must be missing something, you did say turning and not screwcutting ?

-- Regards,

John Stevenson Nottingham, England.

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Reply to
John Stevenson

to drop the

screwcutting

If you are using a fine feed it can be hard work turning the leadscrew hand wheel against the resistance of the gears if you have just disengaged the reversing lever. What you can do is either lift the gearbox 8-way lever or (as I do) turn the 3-way lever till it's between ratios. That puts the gearbox out of gear and you can turn the leadscrew hand wheel easily.

I think that's what David means!

Mark Rand (just got up at 04:00 to reboot a server at work) RTFM

Reply to
Mark Rand

In article , John Stevenson writes

John,

Sorry if I was not a model of clarity!

I was indeed (on this point) talking about straight turning, not screwcutting.

The Myford gearbox can easily be disengaged by moving the little black lever on the top of the box to one of the two positions between the three ranges (high, medium and low). You have to be a little careful not to push or pull too far and drop into one of the other engaged positions, but a little familiarity soon gives you the knack.

Dropping the half nuts and feeding the last bit to the shoulder using the apron handwheel is, for me, a totally inadequate method. As one needs to get the tool, at each pass, to within a thou or so of the shoulder, the apron wheel is just not precise enough, and is not calibrated. I always use the leadscrew handwheel for work requiring any precision (which is almost always).

The cautious way of doing this would be: (1) disengage half nut a few tens of thou before the shoulder; (2) disengage gear box using lever on the box; (3) re-engage feedscrew by turning feedscrew handwheel while pushing down gently on half-nut lever; (4) proceed to shoulder using leadscrew handwheel. My method simply combines (1) to (3), and is much quicker, a great benefit if you are turning down a large diameter bar in a lot of stages. I know the Myford is capable of taking fairly heavy cuts, but I generally limit myself to 20-30 thou at a time.

BTW, I generally aim to do all the stages of reducing the turned part to about 3-5 thou short of the shoulder; then, on what I judge to be the penultimate pass, I take the leadscrew handwheel on to the final position of the shoulder, and withdraw the turning tool back across the face of the shoulder to clean it up.

Hope this clarifies what I was trying to say. I appreciate others may have completely different ways of doing things - and for sure, my slow and steady ways would not suffice for anyone doing this for money! - but that's the beauty of our hobby, there is no fixed rule about how we do operations in our workshops.

David

Reply to
David Littlewood

In article , Mark Rand writes

Yep; see more detailed response to John.

David

Reply to
David Littlewood

Note that when turning up to a shoulder, you can power feed to within ten thou or so of the shoulder until you are down to the desired diameter. Then, with the same tool, face off the shoulder down to that diameter. Then move the tool away from the shoulder, to clean up the ridge left by the clearance angle of the tool.

Mark Rand RTFM

Reply to
Mark Rand

Thanks for the replies everyone. To clarify, I already have the gearbox, it came with the lathe, I wanted a long bed and this was the first nice one I saw. I now have the dimensions for the quadrant (got the attachments, thanks guys), so I can go to the auto-jumble at the weekend and have a rummage, failing that I might get the one from RDG, they also sell loose gears if I don't find any at the jumble.

Cheers Stu G.

Reply to
stooby-doo

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