EW Stringer Lathe Spindle Thread

[James AlfordParticipant @jamesalford67616]

I picked up an EW lathe today. Does anyone know what thread the headstock spindle is?

Regards,

James

[James AlfordParticipant @jamesalford67616]

Following on from my spindle thread question,  would anyone with a Myford ML8 mind measuring the register OD, please? I am wondering whether a ML8 faceplate will fit the EW lathe.

Thank you.

James.

 

[IanTParticipant @iant]

It’s 1″ x 12tpi James

Regards,

IanT

 

[Martin of WickParticipant @martinofwick]

You will need to consider more than simply the thread pitch, ie, depth of thread and depth of register may be significant. The commonly available 1” x 12 pitch backplates can be made to fit, but some reduction in overall thickness of the casting is required, otherwise it is hanging on by a couple of threads!

[Martin of WickParticipant @martinofwick]

And should have added need to sleeve down  the register area to 1″ from 1 1/8 (which may also be the case for ML8 faceplates) but someone may be able to confirm.

[James AlfordParticipant @jamesalford67616]

Thank you, Martin and Ian.

That is helpful. It sounds like there will be a fair amount of work to get a Myford faceplate to fit the EW, which is a shame, but not unexpected.

I think that it will have to be a job for another day as I have other jobs that are more pressing, currently.

James.

 

[Nigel Graham 2Participant @nigelgraham2]

Probably easiest to make a faceplate completely anew, from a blank. Do that, and you can also arrange and size the clamping slots or holes as you think best. The originals for both EW and Myford would be of cast-iron but I don’t see a problem with using mild-steel – except perhaps risking wearing the spindle as well as the plate – or even aluminium-alloy.

Turn raised rim on the rear to give a stiffening flange.

Thread 1″ X 12… but from measuring my lathe I could not decide if of Whitworth or Unified form! The BSW thread-gauge fitted much more comfortably than the UNF one, but of the standard threads, 1″ X 12tpi is UNF.

I have just investigated what Tony Griffiths can tell us, and the spindle thread is the one detail omitted. I did discover mine is the Model D – i.e. back-geared and screw-cutting.

 

[IanTParticipant @iant]

This may help James….

Courtesy of Alan @ Model Engineering Norge (which is a site any EW owner should check out)

 

Regards,

 

IanT

 

 

[Nigel Graham 2]

On Nigel Graham 2 Said:

 

Thread 1″ X 12… but from measuring my lathe I could not decide if of Whitworth or Unified form! The BSW thread-gauge fitted much more comfortably than the UNF one, but of the standard threads, 1″ X 12tpi is UNF.

 

 

Standard threads such as 1″ x 12tpi UNF etc are for fasteners (nuts and bolts). Special machine parts will commonly use “special” threads where the thread form (cross-section) is adhered to but the number of TPI is chosen to suit the maker’s needs, not to adhere to the standard fastener charts. So it is most likely a BSW thread form, being made in UK. (But not necessarily!)

[Howard LewisParticipant @howardlewis46836]

Use thread gauges to check that the thread angle and pitch conform to the drawing above.

Not knowing the lathe, guess that it is quite a few years old, and if of British manufacture, would expect the thread form to be Whitworth.

Assuming the aim is to produce a backplate , or catch plate to screw onto the sapindle, the most likely option will be to screwcut the thread. Thread depth will be 0.0534″

Tracy Tools do not show a 1 x 12 tpi Tap in their ncatalogue (It would take a lot of torque to drive one anyway.

You could rough it it out and then finish it with a thread chaser, or a single cutter from a Die Head, (In a  0.8932″ bore there may be enough room for a single single Die Head cutter).

You could make a plug gauge to check the internal thread, using the thread on an existing backplate as a gauge to check the thread on your plug gauge, as you make it.

The item will be located by the 1.000″ register, so the thread is to pull it into place, so ABSOLUTE precision of the thread is less vital.   Once in place, on the spindle, the final machining of the OD and the face and register for the chuck can then be done to maximise concentricity.

Howard

[Nigel Graham 2Participant @nigelgraham2]

You won’t find a 1″ X 12tpi tap of BSW or BSW form, but anyway at that size a tap is best used to finish a machine-cut thread to size and profile.

I have not tried it, but it is possible to cut an internal thread by using one “edge” of a tap in a suitable holder as a chaser, and here 12TPI Whitworth form are 3/4″ BSF, and 1/2″ and 9/16″ BSW.

Holding a 1/2″ BSW tap against my lathe’s spindle and in the back of a chuck suggested this could be feasible. Probably best to experiment first on a bit of spare material to ensure the settings etc. are all spot-on as rotating the tap in the holder will affect the cutting-edge height as well as the top rake and clearance.

[James AlfordParticipant @jamesalford67616]

Thank you for the drawing and for the advice and suggestions for checking and cutting the thread. The drawing is escpecialy helpful.

I think that this will have be something that I shall have to pay someone to do for me as I have no facility for screw cutting. My Flexispeed has no change wheels and neither does the EW.

Regards,

James.

 

[Martin of WickParticipant @martinofwick]

James,

not having a set of lathe change wheels is a major PITA, compounded by the fact that the EW deploys 16DP (absurdly OTT for a lathe of such small capacity). If Mr stringer had used something more sensible such as 20DP, you would be able to use the commonly available Myford Gears.

However, all is not lost…

if you dial in ….model engineering norge ew lathe.. or some-such into google, you should be able to find the v helpful site referred to above by ianT.

This site as well as having much useful info, also has a guide to an improved banjo design and optional extra conversion for DP20 gears which will significantly improve the utility of the lathe (I have implemented the revised banjo to give lower feed rates, but not made the full conversion to 20DP).

The other alternative is to make your own change gears. I have successfully used 3D  printed gears made from decent quality PLA (use traditional ‘rock hard’ PLA, not not the PLA modified for increased flexibility). Nylon would be better, but you will need a printer capable of running at 300c + and an a way of keeping the filament dry for optimal results.

Or cut your own, which will be a fabulously expensive and time consuming operation by the time you purchase/make the cutters and blanks!

As an extra thought, if considering a revised banjo, I don’t think it would be beyond the bounds of possibility to further adapt to use the commonly and cheaply available Chinese minilathe gearsets. You can get a set in metal for £ 60 to 70 on the Bay (ie less than a set of myford gears).  Clearly you will need to check what size can be adapted to fit on the spindle, then work out if the remaining selection will cover the pitches you are likely to use (including the feed pitches). They are module 1 gears, so easily available if you need to infill or a special (like a 21 or 63 for example).

BTW, Tracy Tools sell a 1″ x 12 whitform tap, but I would not advise attempting to hand tap at that size!

 

[Nigel Graham 2Participant @nigelgraham2]

Form a quick experiment with my own (I did not attempt a full train) you can use Myford change-wheels, with a new banjo stud to cope with them being slightly wider than the EW originals.

All you cannot do, is mix wheel sets!

I know many EW owners have modified their lathes but they were never intended to be used for self-acting feeds in original trim, with the standard change-wheels. This may be why they have permanently-engaged leadscrew nuts and a banjo giving only a two-step compound wheel trains.

[James AlfordParticipant @jamesalford67616]

Thank you, Nigel and Martin.

That is helpful. I shall have a look for the model engineering norge ew lathe that Ian also mentioned.

The advice is much appreciated.

Regards,

James.

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