Early Myford Super-7B gear change wheels??

[flatlineParticipant @flatline]

I purchased a 1955 Super-7B a while ago. The lathe came with several alternate gears to fit between the spindle & gearbox input.

Can you tell me what the standard set of gears would be between the spindle & gearbox, i.e. the gears (tooth numbers) that run between the tumbler reverse gears and the gearbox input gear… see photos of the actual lathe.

Unfortunately, the previous owner is deceased, so I cannot ask him. I would like to ascertain that I have the standard gear-train between the spindle & gearbox input.
<p style=”text-align: right;”>
My apologies if my description sounds a little disjointed!!</p>

[Nigel Graham 2Participant @nigelgraham2]

It does look very much like it – very like the set-up on my Myford 7.

It would be easy to test, by putting the central gear-pair in its screw-cutting way round (it’s in fine feed mode there), cutting a few threads of widely differing pitch on an oddment of bar, and using thread-gauges or known screws to compare them with the gear-box settings.

If you’ve more change-wheels than in the photo, you may have an Imperial / Metric conversion set for it, but you’d really need the manual to verify that.

[peak4Participant @peak4]

Double check with the gear layout tables, normally behind the gear cover door, which should effectively list any other gears originally supplied or needed.
Also, is that a Mk1 gearbox, as the smaller of the gears below the tufnol pair might be different twixt Mk1 &2

Do enjoy the new toy, and remember those nipples are oil, not grease nipples.

Bill

[noel shelleyParticipant @noelshelley55608]

They look right, they all mesh, you have the quick change box and you can change ratios by reversing the last gear before the wide one, swing the link over remove wheel reverse and refit.  Working back from the wide wheel which is 72T, 19/57t reversible cluster, 19/57 fixed cluster, the tumbler sleeve gear, tumblers and the spindle gear. If you have spare gears it is posible you have the metric conversion set. Instructions for the lathe and the gear box will tell you what you need to know. For lube use ISO 32 (sae 10 ) Hydraulic oil, and ISO 68 ( sae 30 ) engine oil.  Noel

[Nigel Graham 2Participant @nigelgraham2]

 

you can change ratios by reversing the last gear before the wide one

That needs exapanding. Yes, it does change the ratios of the entire gearbox but the change is that between either fine feeds or screw-cutting.

[bernard towersParticipant @bernardtowers37738]

Surely the set up is extra fine feed?

[noel shelleyParticipant @noelshelley55608]

Looking at the very small gear it does look like an extra fine feed cluster, possibly a 12/25T. The standard cluster gear is I THINK 20/25T. NOTE it is 2 gears as a cluster not 2 separate gears. Noel.

[noel shelley]

On noel shelley Said:

Looking at the very small gear it does look like an extra fine feed cluster, possibly a 12/25T. The standard cluster gear is I THINK 20/25T. NOTE it is 2 gears as a cluster not 2 separate gears. Noel.

I can’t speak for this particular gearbox setup, but just chucking in the comment again about the difference between Mk1 & 2 boxes; something I was unaware of until a couple of years ago myself.
On a changewheel lathe, without gearbox, that pair of gears below the tufnol tumbers, is actually a two piece setup.
One gear has the stub for the other machined onto the face of it; mine has needle rollers.
There is also a fine feed gear cluster, which is made from one piece of metal and is plain bore.

The photo however shows the gearbox model; I understand that the difference between Mk1 & 2 is that one runs twice the speed of the other.
My genuine S7 is a changeweel model, so used the two gear clusters, but my Warco 720 S7B clone seems to duplicate a Mk2 gearbox.
The photo here seems to show a gear cluster with about 12 teeth, whereas mine on the Warco is 24, which is why I wondered if the lathe in the photo had a different box, or the wrong gear cluster for the box which has been fitted.
A photo of the right hand side of the box should provide clarification.

In normal use, it probably makes little difference, unless the owner needs a different setup for DP, BA, or metric threads.
The 33/34 tooth gear trick to approximate metric works with the Mk2, but I believe other solutions are needed for the Mk1.
The photos in some of Myford’s own literature don’t help, as they seem to mix and match a bit.

Bill

[Peter SansomParticipant @petersansom44767]

There is are major differences between the Mk1 and Mk2 gearboxes.  You can get a copy of the gearbox manual from lathes.co.uk and this has both gearboxes.

Output from the Mk1 is on the Right Hand side of the gearbox and there is a bulge on the casting with the gears behind from memory of the photos I have seen.

The Mk2 has the output on the Left hand side with the lead screw passing through the gearbox.

There is a difference in the gearing between which means the output gear on the Tumbler sleeve gear pair is half the size.

Peter

 

[Simon Williams 3Participant @simonwilliams3]

+1 from me for the comments above – the photo shows the gear train for the Mk1 QCGB of the same vintage as the lathe.  The 30T gear on the tail of the spindle drives the tumbler reverse gears.  These are idlers so they don’t affect the gear ratio of the overall train. There is then a 30/12T cluster gear driven from the tumbler reverse which is a 30 T gear (driven) and a 12T gear (driving).  This cluster gear is where the difference between the Mk1 and Mk2 gearboxes exhibits itself, as the Mk1 QCGB runs at half the speed of the Mk2 g/b.

The comments above that the reversible 57/19 gear (last gear before the big 72 T gear input to the g/b is presently in the fine feed position are correct.

Proof of the pudding is in the cutting of the specified number to TPI as per the g/b top label for a given sector combination.  Try it and see, but reverse the 19/57 gear first.

The OP’s original question remains, i.e. what ‘are the remnant changewheels he got with the lathe for.  If they are a metric conversion set there should be a dedicated banjo to carry them.  What gears have you got.?  The contents of the metric conversion kit (of which there are two editions) is in the user manual, also in the archive here but before the Great Change.  There were pictures of the user label showing the gear set up for both in my album of pictures.

Finally (for the time being) here is a link to a thread where we discussed all this stuff.  If the OP wants to cut metric thread – and has confirmed empirically that it is a Mk 1 g/b – then I can supply the two sets of compound mandrel gears as per this thread:

https://www.model-engineer.co.uk/forums/topic/myford-super-7-screw-cutting-gears-metric/

I don’t have them in stock as I sold the last ones only a few months ago, but it’s no big deal.

Hope this helps best rgds Simon

[Simon Williams 3Participant @simonwilliams3]

If it helps at all here’s a (poor) picture  of the label mounted in the gear cover on my Mk1 QCGB.  I assume that the selector choices accommodate the hal speed feature of the Mk 1 g/b but I haven’t checked.

 

 

xxx

And here is a picture of the label accompanying the later Mk2 QCGB.

Beware of assuming that gear kit 1 will fit on banjo 2 and vice versa.  I’ve never fathomed out the details, I don’t cut metric threads this way.

Rgds Simon

xxx

[flatlineParticipant @flatline]

Hello again Simon,

you may recall that I visited you last year (blue & silver Suzuki m/cycle) to collect the relevant gears to enable a ‘conversion” for my early S7 so that I might cut metric threads. I have only just got around to using the gears that you supplied, and as my first post in this thread indicated I wasn’t sure exactly ‘where I was starting from’….

Many thanks to everyone who has answered, you have helped clarify the situation.

A question was asked about the appearance of the early gearbox where the leadscrew emerges, which I have attached to this post.

[Simon Williams 3Participant @simonwilliams3]

Hi again, it’s good to know you got home safely.  Always pleased to hear from you, good luck and any questions do please ask away.

Best rgds Simon

[flatlineParticipant @flatline]

Many thanks Simon, I probably have a raft of questions – but will endeavour to solve before admitting my defeat here!!

Regards, Rich Dolby

[noel shelleyParticipant @noelshelley55608]

I seem to remember that early QC gearboxes had unhardened gears but later ones were hardened ? I think I have somewhere Myford instructions for fitting a QC box and I believe the gearboxes were serial numbered. The QC box was offered as a kit so a machine could be converted, this may account for the OP having spare gears, should also have the change wheel quadrant Etc. Noel.

[flatlineParticipant @flatline]

Here are the additional gears that came with the early (1955) Super-7B when I bought it last year (2024).

In the original photograph above is the lathe as it arrived; in a zip-tie bag was a label, ‘Myford 12/30 Fine-Feed Tumbler Gear’ – which is what was fitted at the time.

In the same zip-tie bag was what I took to be the standard tumbler cluster (my label), which is a 24/30….

The additional gears that could be fitted to this ‘standard cluster’ are a 24, 30 & 32…..

The gears with the yellow cable-tie loop are the metric conversion gears supplied by Simon, specifically in my case for the early QCGB… Although I do have copy of Brian Wood’s excellent book ‘Gearing of Lathes for Screwcutting’ I have yet to even begin to fathom out the reasoning behind the optional (24) 30 & 32 tooth gear options for the tumbler cluster… Simon??

 

[Brian WoodParticipant @brianwood45127]

Flatline,

If I might add some comment here. My book was written based on  the later gearbox,—I was at that stage unaware of the earlier gearbox.

The result is that the tables I published will be incorrect by a factor of two; the difference between a 12 tooth driver following the reversing cluster and the later driver of 24 teeth.

Simon is the man to help you, he made conversion gears to correct that.

Regards   Brian

[Simon Williams 3Participant @simonwilliams3]

Well, thank you all for that vote of confidence, very much indeed.  I guess I’ve now got to live up to it.

I think the answer is actually quite simple.  If you take the QCGB out of the equation you’ve now got just another lathe with an 8 TPI leadscrew.  Back in the day before I bought a gearbox I used change wheels as did everyone else, and thereby needed a range of wheels and a bit of arithmetic to make the gear train do what was needed.

My recollection is that a set of standard change wheels for the non gearbox application consisted  of one each of the sizes 20, 25, 30 etc by 5’s up to 65T.  Here’s a copy of the reason why:

xxxx

 

That’s taken from the back cover of this document:

 

I had an ML1 at this time – still got it – which I bought off a scrap man for £37 in 1979.

And you’ll note that this duplicates the information Brian has shown in his book.  Table 67 refers though there is a 2:1 factor to accommodate because the Seig lathe imperial leadscrew is 16 TPI.

I dare say the same information is in the ML7/S7 handbook with the brown cover.  I couldn’t lay my hands on that though I’m sure I’ve got one somewhere.  Note that the metric trains only need the same set of gears, though two 20’s are needed to get something pretty close to 1.00 mm pitch.  I seem to remember buying a 21 T gear for something to do with the metric set-up, but the why is lost in the mists.

Hidden in this is the need to fit a 20, or a 40 or a 30 t wheel to the mandrel, which is why that keyed 30/x gismo labelled “Standard Idler Cluster” was included with the kit of parts above.

The 30/12 cluster was sold as a fine feed gear, it’s incidental that this same is needed to feed power down the gear train to the Mk1 gearbox.

Which doesn’t explain what the 24T (nor the 32) gear was about, but maybe we’ll come back to that.

[Brian WoodParticipant @brianwood45127]

Simon,

When my father bought a new ML4 in 1945, that very same handbook you displayed was then standard supply. The lathe spindle was fitted with a fixed 25T drive gear. Looking at the gearing tables it lists shows it is severely restricted in what the lathe was actually capable of. When he died in 1963 the lathe became mine and I used it to good effect in machining most of the work needed to make my Dore Westbury Mk II milling machine. It is still in use, much modified now.

The ML7 that replaced my Dad’s old lathe came with a 30/12 cluster gear for very fine feed. That lathe too is now in new hands.

I find it interesting that Myford resurrected the concept of a fixed 25T change wheel on the spindle of their ML10s.

However, the resemblance stops there. The ML4 had tumbler reverse, the workings of which fascinated me as a 7 year old; the ML10 and its variants dispensed with that refinement.

As for your capabilities, you are being too modest!!

Best wishes   Brian

[Simon Williams 3Participant @simonwilliams3]

That 21T gear has been twitching my curiosity ever since.  So a restorative cup of tea kicked the little brain into remembering that the gear cover of the old pre-gearbox change wheel banjo had a label inside it.  Here’s the view of the metric part of said label:

xxx

And for the sake of completeness here’s the imperial section of the same label:

 

 

Apart from the obvious anomaly for 19TPI (3/8 BSP) the whole shebang needs only that 21 gear, plus 70 and 75 if those TPI’s are of interest.  Apart from that 2 thou per rev fine feed using our old friend the fine feed cluster of course.

Now, going back to the 24 and the 32 T the OP has inherited….

Nope, I’m none the wiser!

[bernard towersParticipant @bernardtowers37738]

Yes I used to use 21t wheels on my old ML7 for metric threads

[Brian WoodParticipant @brianwood45127]

Simon,

I too have been checking on those two wheels. The 24 may have been included in a purchase for the modern gearbox, along with the 32 which can provide imperial threading, in the modern gearbox for 6 tpi [gearbox set for 8 tpi]; 15 tpi [gearbox to 20 tpi]; 21 tpi [gearbox to 28 tpi]; 27 tpi [gearbox to 36 tpi]; 30, 33, 39, and 42 tpi [ gearbox to 36, 40, 44, 52 and 56 tpi respectively] Table 4

It can also provide gearing for two Holtzapfell pitches Table 7 and two others in the Enfield Small Arms Table 9. These tables from my book. How useful they might be is uncertain and whether Flatline wants to bother with them is debateable

 

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