Myford ML7 Gearbox

I am looking to add a gearbox to my 1948 ML7 and would appreciate some advice.

Will a gearbox from an S7 fit?, I understand that the leadscrew on my ML7 would need to be shortened and sleeved up to 3/4" to fit an S7 gearbox and there is a packer between the gearbox and the lathe for alignment purposes, but is there anything else that I need to look out for?

The same basic gearbox is used on both machines.

If you look here **LINK** and look for a file "s7gbox2.pdf" this is the fitting and operating instructions which may help you.

It's about 35 down in the list, with a red Adobe badge.

Edited By Robbo on 06/04/2014 19:17:09

Hi there, SteamGeek,

As Robbo says, it's the same gear-box for both ML7 and Super 7.

I'll check for certain tomorrow but I'm fairly sure that the end section of the lead-screw that passes right through the gear-box to pick up the gear-box output on its left-hand side is 5/8" diameter for both ML7 and Super 7 lathes. So you won't need to sleeve for an ML7 fit.

The threaded part of the lead-screw is 5/8" diameter on the ML7 and 3/4" diameter on the Super 7 machines.

What you do need to do is check whether when you remove the gear quadrant and left-hand lead-screw bearing from your ML7, your lead-screw is revealed to have TWO positions for the Woodruff key, early versions only had one. The 'outer' key-slot will be removed when you shorten the lead-screw and the drive gear that picks up the gear-box output uses the 'inner' key-slot. You say that your ML7 dates from 1948 - I'd expect that a lead-screw that old will only have the one key-slot. So you will either need to machine a new key-slot or procure a more recent lead-screw.

The packing strip is not used on the ML7 fit - I think it is required on the Super 7 fit because the effect of the 3/4" diameter lead-screw is to displace the lead-screw axis further from the machine bed than it is on the ML7.

If you look on the web-site of the new proprietors of Myford, you will find the Illustrated Parts Lists (aka 'exploded diagrams' ) for the ML7, including the Quick Change Gear-Box.  Go into 'ML7 spares', select the assembly of the lathe you're interested in, scroll right to the bottom of the page and click on 'larger diagram'.  I haven't looked but I expect the parts lists for the Super 7 are there too.

The Beeston Myford fitting instructions for the gear-box require the lead-screw guard to be shortened to 3⅛". If the lead-screw you eventually fit is of the two-piece type with a collar at the left hand end of the threaded portion, I reckon 3⅛" is still too long by somewhere between ⅛" and ¼". At 3⅛" the end of the lead-screw guard fouls the collar before the carriage reaches the left-hand end of the lathe bed. When you refit the lead-screw guard after shortening, you may need to adjust the half-nut gib-strip - the adjustment studs double as the fixings for the guard! If you're careful, you might be able to remove the 2BA nuts to release the guard without moving the studs. The Beeston Myford fitting instructions don't warn you about that one!

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 06/04/2014 22:02:58

Edited By Swarf, Mostly! on 06/04/2014 22:03:43

Edited By Swarf, Mostly! on 06/04/2014 22:06:12

Hi there, again, SteamGeek,

I forgot to mention that the gear covers for the ML7 and the Super 7 are not the same. The gear back-plate, however, IS the same.

Best regards,

Swarf, Mostly!

Hello SteamGeek,

Another little tip for you to plan ahead on. When the gearbox is fitted it covers the access to one of the headstock alignment screws. It would pay you to drill a suitable access hole in the box before fitting.

Mine was fitted when I acquired the lathe and I hope I don't need to go there as it means taking off the box to do so.

For the benefit of others would you measure the displacement of the two holes please, I for one will make an access hole taking suitable precautions of course.

Regards

Brian

Hi there, SteamGeek,

I have measured the off-cut from my shortened ML7 lead-screw - it is 5/8" diameter.

If your ML7 dates from 1948, does it have the mounting holes for the gear-box in the front shear of the bed?

Brian, in response to your post:

Here is a picture of the Beeston Myford drilling jig for the gear-box mounting holes:

I measured the hole-to-hole centre spacings (by putting suitable drill-shanks in the holes and averaging the external and internal caliper readings to eliminate the drill diameters).  My results are as follows (from left to right):

1.188", 2.560" and 2.624" . (They look fairly close to fractional spacings.)

I am a bit puzzled by Brian's post. The Myford fitting instructions call for the push-screws to be temporarily removed from the lathe bed and their tapped holes to be used to secure the drilling jig. The head-stock casting is held to the bed by the four securing bolts that go in from the top, beneath the mandrel and back-gear cluster. My understanding is that the function of the push-screws is to position the head-stock casting against the rear shear of the bed until those 'in from the top' bolts are inserted and tightened. Once that is done, surely the push-screws have done their job? The gear-box fitting instructions do call for the push-screws to be re-inserted once the gear-box mounting holes have been drilled and tapped - but they do not call for any re-alignment checks on the head-stock & mandrel.

The push-screws may, however, need to be shortened if they protrude from the bed and prevent the gear-box from fully contacting the front shear of the bed.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 07/04/2014 10:32:07

Edited By Swarf, Mostly! on 07/04/2014 10:34:39

Hi there, again, SteamGeek,

To illustrate the point I made about lead-screw key-slots, here is a photo I found:

The upper lead-screw is the early type and the lower one is the later type. You can see from that picture how shortening an early lead-screw loses the key slot.

Best regards,

Swarf, Mostly!

Thanks Swarf, Mostly!

The headstock does have some holes bored where the gearbox would fit, some careful measurement this evening and compare to your numbers before I go much further.

Need to have a look at the leadscrew and see how many woodruf keys it has.

The guy I bought it off told me it was a late 50's machine, some parts probably are some parts a little older!

Fingers crossed for a later leadscrew

Thanks

Steamgeek

Hello Swarf,

Thank you for the information, not having fitted the gearbox myself I was in ignorance of those details. Yes then, I agree with you, the push screws are redundant after the headstock is bolted down, but I am still grateful for the information. If things ever need to be reset, access would be available again.

Kind regards

Brian

Hi there, SteamGeek and Brian,

Just to be clear, both the lead-screws in the photo are full length, un-shortened, as supplied with non-gearbox ML7 lathes. Their tail-stock ends are level with each other.

Best regards,

Swarf, Mostly!

SteamGeek,

Have just had a look at a 1948 ML7 leadscrew, and that has only one slot, which would be removed if it was shortened.

Also have a leadscrew which came from a gearbox equipped ML7, so is already shortened, and still has the slot.

Sold the gearbox and the buyer didn't need the leadscrew as he was fitting it to a Super 7.

I would be happy to send this to you in the UK for the price of postage and a pint, should you need it.

You don't have a member profile so I don't know where you are.

Phil (in Lancs UK)

Hi there, Robbo,

Did your buyer also leave you with the Gear Cover? SteamGeek will need one.

Best regards,

Swarf, Mostly!

Hi Swarf,

Sadly, no. The cover had been damaged (how they break when you drop a big chuck on them). The repairs to it had left it as a dual-purpose which would also fit the Super 7. Just a few little gaps here and there!

Phil