Stringer EW lathe

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Alan ,

' Martin Cleeve''s articles on the EW lathe are not very helpful really but the many more that he wrote about the ML7 are much better . In this connection he described a mechanical fine feed drive which was simply OR coupled to the standard ML7 gearing . The feed box was just a couple of plates holding gears and a simple lift and lock engagement device . The feed box could be belt driven from main motor or independently driven .

Since there is no essential difference between EW and ML7 apart from size an adaption of his design may provide you with a simple way forward .

Regards ,

Michael Williams .

[jason udallParticipant @jasonudall57142]

"There is a posting from Jason Udall that seems to confirm that my ideas for the operation of the digital slow feed can be acheived, but again no hard details."

Ok My thoughts.

With a suffienctly powerful stepper motor coupled to the ( extended towards the headstock) leadscrew no gear train would be needed and no clutch required since steppers are relativly free moving .

A gear train would allow smaller stepper but more complex coupling arrangement.

An encoder wheel of some type attached to the spindle, maybe even using an existing gear wheel ( pardon my ignorance of the EW ), would provide pulses syncronised with the spindle..

( simplest.. "index wheel I holes per rev..)

these pulses ( produced by either OPTO interuptor or inductive pick up of say gearwheel)

are feed to stepper interface "board"..one pulse (from spindle encoder ) steps lead screw one step ( depending on gearing of stepper/leadscrew) wich coresponds to a fixed movement of leadscrew..( N steps per rev of stepper G reves of stepper to lead screw S inches/mm per rev of leadscrew..thus N*G*S per inch etc.)

Thus leadscrew advances for one rev. spindle I /(N*G*S) inches etc. thus I needs to be large and G not excessive if resonsonble feeds are to be achived.

so far so good.

Varible feed.to produce varible feed you need to " divide" down the pulses so D pulses now produce 1 step of leadscrew (your Knob might be really a multipostion switch)

Varible values of D can be done "on the fly" , in my guess for low volumes( number of units) best handled with A MICROCONTROLLER….

which would also handle foward neutyral reverse from a (as simple as desired) switch(1-0-1) or even pushbutton select.. style at users choice..

once the above is done you can clearly see screwcutting is possible..(to a finite accuracy)..think of metric and imperial encoder "disks" and away you go…

These are all thoughts cosidered for my own SL lathe even more petite .but simple mechanical ( pullies and belts) soulutions would have seemed too bulky..

No I haven't got anyway to wards this myself but the method outlined above is the route I would take when I do. ..

BTW yes "wiper motors" can be reversed but the would need the field coil windings lead out first.(did it with startermotors once)

unless you have a PM type.

[alan smith 6Participant @alansmith6]

Hi MichaelW,

Thank you for the posting. Yes the Cleeve EW articles were based on the ones that he did for the Myford and I believe other lathes. If you look at the photo of the front cover of the ME that was posted a few days ago you will see the Cleeve modified EW lathe. This has the gearbox at the headstock end of the lathe. I call it the "grandfather clock" because that`s what it resembles. This gearbox will work satisfactorily but in my opinion the place for the gearbox is between the headstock and the countershaft.

I would fit a cover for the headstock gears instead. At the moment I`m designing a countershaft come geabox to create the slow speed that is needed. However this will probably take a few weeks to finish.

Alan

[alan smith 6Participant @alansmith6]

Suspended for 7 days

Edited By David Clark 1 on 30/08/2012 16:08:48

[VersabossParticipant @versaboss]

7 days is far too less by a wide margin, David! Make it 70 at least!!!

Greetings, Hansrudplf

[Ian S CParticipant @iansc]

Alan, the motor I use is an old Lucas, with a wound field, and to reverse I use a 2 pole, three possition switch,on, off, on, to reverse the polarity. Speed control could be electronic, but I just made some resistors from the nichrome wire from an old heater element, and made a rotary switch, and fitted it in a metal box. The drive is from an extension to the wormwheel shaft on the motor via a 10 tooth sprocket, to a 20T sprocket on the mill lead screw. To operate manually, the chain is loose enough to lift off with out needing any adjustment. All you need to do with this system is adjust the resistors to give the speed you want, and match the drive ratio to suit. I run my feed on 17v as that is my low voltage supply around the workshop. IAN S C

[IanTParticipant @iant]

If anyone is interested in owning an EW lathe – one has appeared on eBay.

**LINK**

Usual caveats – It's not mine – nor do i know anything about it BTW – Just for info.

Regards,

IanT

[IanTParticipant @iant]

Just looked at the lathe above again – there doesn't appear to be any slides present – so it's incomplete as shown.

Regards,

IanT

[alan smith 6Participant @alansmith6]

Hi Ewers and others,

I’ve done my time, licked my wounds and now I’m back but things will not be as before.

I did provide some valuable information such as the original EW catalogue and price list of accessories but then went on to take over the thread. This is time consuming and has not been very successful in creating progress with our EW projects, which is not what we wanted.

The concept of “Open Source Design Projects” simply does not work! I know this from my own experience of design during my career in design engineering. Every team needs clear leadership otherwise the results can turn out looking like a dog’s breakfast and take forever to complete.

The Forum is a very popular system of getting help or advice from folk that have already trodden the path that one is following.

To further the EW project I propose that there be a kind of competition. There will be no prizes only the satisfaction of having participated. As you all know we want to get a design for the slow feed.

EW SLOW FEED COMPETITION

The rules are simple:

This is for a mechanical solution not a digital one unless it’s the digits on your hands.

We are looking for the simplest way of doing this at the least cost

The original lathe castings are not to be changed in any way and any other changes made will have to be reinstateable. The exception being the leadscrew, which will have to be cut in two, although this can be reinstated by the use of a pinned sleeve or some other suitable method.

Sketches should preferably be drawn full size on A4 sized paper, scanned and then transferred into the dialogue box so that we can review them.

Where the device has already been created then photos can be submitted.

Obviously EW owners will have the lathe to use as the design basis, others who do not have access to the EW may find the task difficult as the design parameters will not be clear.

If anybody is able to provide us with a complete design for the digital case, then I’m sure that we would all be very interested.

GOOD LUCK.

v

[alan smith 6Participant @alansmith6]

[alan smith 6Participant @alansmith6]

Hi EWers butterflies and others,

Just a word of explanation about the rather chaotic, back of a fag packet, sketch that I posted:

This sketch is based on Martin’s ideas. What I have done is to bring the design of the lathe leadscrew clutch down to the absolute bare minimum.

Under commercial design projects, because of the cost and time restraints it’s often the case that a safe over designed path is followed.

In our humble little lathe project, no such constraints are in place, so that design safety can be partially ignored which increases the fun for the designer.

When I say designer I mean anybody that can hold a pencil, as in my experience, lay people are capable of creating radical ideas although in all probability, not able to bring these ideas to completion, that’s where the proff’s come in.

The design of the clutch presented several problems. Those of you that have read my previous postings will remember that I was critical of Martin’s proposal to drill a hole in the lathe bed and not only that; he wanted to profile the intermediate leadscrew bearing that was being attached to the lathe bed to sit on a curved rough crackle enamelled casting, instead of a machined surface.

The other criticism was that in order to eliminate any need for splines keyways etc. He proposed that the driving end of the leadscrew and clutch be in one piece, which meant that the whole part would be moving in and out of the rear leadscrew support and thus move the leadscrew gear in and out of the intermediate gear, not desirable in my opinion.

 

OK that’s the preamble, now to my design thoughts:

I thought through several ideas such as creating a support for the leadscrew by mounting a bracket on the face of the screwcutting quadrant mounting plate, this would also serve to mount the operating lever as well. It’s all very well having brilliant ideas but quite often these ideas are not found to be suitable when drawn out on paper or other medium. The killer of this idea was the need to have access to the quadrant locking screw, which made the bracket too fiddly to be practical.

I deemed it sensible to keep the leadscrew nut whole and not split it as proposed by “Exactus”, as a split nut would require the use of a screwcutting dial if cutting threads not devisable by 8, the tpi of the leadscrew.

Instead of making the dog clutch using a pin as Martin did, I opted for a stepped face clutch which is much simpler to make as it doesn’t require that level of accuracy that the pin type does and engagement is easier.

I would eliminate the leadscrew intermediate bearing and replace this with a long sleeve to support the two ends of the cut leadcrew. There is a risk in this as any radial play in the two leadscrew ends relative to each other could cause problems and the probability of the sliding sleeve sticking and not moving smoothly into engagement with the driven clutch. In mitigation we have to remember that at a feed rate of .006” per rev of the spindle, the leadscrew only turns at about 5 rpm and also, that the leadscrew nut would tend to steady the leadscrew.

To take the torque of the leadscrew whilst allowing the sleeve, which is part of the driving clutch, to slide forward on the leadscrew to engage with the driven part of the dog clutch, I cut a slot in the sleeve and drilled and tapped the leadscrew so that a caps crew with the head machined down to accurately engage in the slot could be fitted.

As you can see the workings are very simple and can be made from parts lying in your scrap box. The probable cost will be nothing!

Only a working prototype can prove this design.

Any risky design moves should come with a way out and this would be to provide provision for an intermediate leadscrew support if required.

TO BE CONTINUED.

Edited By alan smith 6 on 28/09/2012 16:30:58

Edited By alan smith 6 on 28/09/2012 16:32:20

Edited By alan smith 6 on 28/09/2012 16:34:00

Edited By alan smith 6 on 28/09/2012 16:36:18

[alan smith 6Participant @alansmith6]

Hi EWers and others,

Don't forget to click on the sketch that I posted which will increase the size.

I encose a photo of the materials that I've collected from the scrap heap in the garage. The Aluminium is for creating a pair of 1.25" square packing blocks for placing under the lathe feet. I highly recommend this addition and they are also useful for hanging brackets from.

The bronze bush is from spring hanger bracket from a large vintage car and will do for the sliding sleeve.

The mild steel bar is a 30mm dia offcut and will serve to machine the clutch ends from. The flat bar is for the clutch operating lever.

Alan

[alan smith 6Participant @alansmith6]

The parts are starting to be created.

[alan smith 6Participant @alansmith6]

Hi EWers,

I'm sure that you are all gagging to see the progress on the EW leadscrew clutch, well I won't dissappoint you.

Here are some shots of the leadscrew clutch in situ on the EW latheTo be continued

Edited By alan smith 6 on 09/10/2012 20:07:02

[alan smith 6Participant @alansmith6]

Some more photos and explanations:

Photo of the parts laid out

The leadscrew has been cut and a brass thrust bearing has been inserted into the driven shaft. I have made this .25 long to lengthen the shaft. In the centre we can see that the bronze sliding tube has been soft soldered into the mild steel clutch driver and the finish maching carried out. On the left we can see the new thrust bearing now necessary because the leadscrew is split.

Photo of the sleeve being machined.

Just to prove that I did all this work on my Boxford. You can tell it was previously a school machine.

Detail of the shear pin arrangement.

Here you can see a close up of the shear pin arrangement. This is what holds the driven part of the clutch onto the leadscrew. I drilled the clutch and leadscrew 2.5 mm diameter ( .100" ), then opened out the hole in the clutch part to the 1/4 BSF tapping size, making sure that I had left about 30 thou of the 2.5 mm dia at the end. Then it's down to tapping the hole and machining the 2.5 mm dia on the end of the 1/4 BSF screw, make this long enough to engage with the hole in the leadscrew before the threads engage in the clutch thread. This will make this fiddly assembly easy, don't forget to drill the hole in the leadscrew all the way through so that a sheared pin can be knocked out.

Alan

[IanTParticipant @iant]

That's looking really neat Alan – thank you for sharing.

I've not got quite the same progress to report but I did use a great idea from Martin Cleeve to machine two EW dovetail slides last week on the Myford. It worked a treat – just like he said. They will enable my milling attachment to clamp directly to the bed (tailstock end) of the EW. I will then use my EW boring table to provide me with what will be (in effect) a small vertical mill.

It should be even easier to use the same major components on my Super 7, either using the slotted cross-slide as a milling table (as per the EW) – or mounting the milling head on the Myford cross-slide itself for milling operations directly on work held in the chuck – but I wanted to do the more complicated EW dovetailed mounting first.

Winter is Coming!

Regards,

Ian T

[alan smith 6Participant @alansmith6]

Ian, EWers and bookmarkers.

Thank you for your support Ian, we need some more stimulation, so maybe its time for you to start your series on the EW milling attachment. Are you going to use that lovely little EW vertical slide.

I was going to finish the prototype clutch today but caught some bug which has put me Hors de Combat, maybe tomorrow.

I'm well on the way to a solution to the drive which will explode onto the thread shortly, it's not the one that I briefly touched on in a previous contribution but it is obliquely Martin inspired.

I checked the hits that we had on this thread in the last 28 hours, it came to more than 250, so there are quite a few bookmarks on this thread, no doubt hoping for a little drama to occur to put a little excitement into the day.

A bit of worldly advice Ian: Don't fall into the modellers trap of going into hibernation whilst working in that damp cold garage, best prepare a large box of straw!

Alan

[IanTParticipant @iant]

Fortunately Alan it's not that cold here yet – so I'll be off down the Shed later (after I've done various small jobs for my Manager). I'm afraid it's not just the machines that feel the cold these days – it gets into my fingers etc. And before anyone chips in – I do have a fan heater but it doesn't always help. I think it's also harder to get out of the armchair and go do something productive "down the garden" if it doesn't look too inviting outside.

So that's why I purchased the little EW and set it up inside the house (with management agreement I hasten to add). I was able to make various boiler fittings and small tools over last Winter in complete comfort. Over time I hope to increase the EWs capabilities and to be able to machine a wider range of things in comfort whenever the whim takes me – the whole lot fits on an old printer table.

With regards the Milling attachment – Once I've got the device assembled (getting closer now) I will post a photo or two. The EW vertical slide was a bit too small – so I used my much larger (chinese) slide that I originally purchased for use on the Super7 (had to make a new mounting plate to fit the cross slide when I got it home however). The spindle is a Taig ER16 head so it has been fairly quick to build. So far it's cost just over £100 for the Taig spindle, pulleys, belts etc (already had the vert slide) and the other bits came from my scrap bin (mainly ali lumps flycut to size in the lathe). The motor is from an old 'power' shower – so it may not have enough oomph for this use but one step at a time…

Regards,

Ian T

[alan smith 6Participant @alansmith6]

Hi EWers and bookmarkers,

Herewith a little treat for you, a composite view looking in the direction of the Headstock towards the tailstock.

Also an explanation to follow:

Please remember that this is just an Idea, It's not a finished design

Edited By alan smith 6 on 19/10/2012 12:37:35

[alan smith 6Participant @alansmith6]

We’ve covered the simple part of the EW leadscrew clutch with a 90 percent probability of success but are now are faced with the daunting task of the leadscrew drive.

Martin Cleeve proposed that the drive take the form of an additional gearbox which would be placed at the headstock end of the lathe and drive the leadscrew via a limited torque coiled wire belt due to his dire warnings about possible clashes that would damage the lathe.

You can see the articles part 1 in ME 2952 and part 2 in ME 2955 and I would urge you to read them as it will bring sense to the following monologue.

Those of you that have faithfully followed the thread will be aware that I’m not enthusiastic about this gearbox, it may have been very useful for the MY***D lathe but on inspection does not suit the EW lathe!

The only good thing that one could say about the “grandfather clock” as I call it is that Martin did not fit Westminster chimes to it. I’m tempted to make a giant winding key to fix to the box. Does anybody know whether any of these gearboxes were made for the EW? I doubt it somehow.

Joking aside, I’m not sure why Martin chose to add his already successful gearbox design downsized to suit the EW. I’m surmising but there could be several reasons for this.

It could be editorial pressure from the ME which caused Martin to take the easy and quick way to solve the slow feed problem by simply reducing his classic gearbox design to EW proportions.

Martin ignored an easy way to solve the problem which would have taken two pages to present via the ME. The ensuing Five plus pages of copy for the reduced design gearbox would have been a better earner for him. More of this in the design notes.

The other possibility is that Martin became embroiled in a “design fog” which can happen and prevents clear lateral thought once following a design direction.

DESIGN THOUGHTS.

In one of my postings I proposed a sort of gearbox which used timing wheels and belts between shafts on the new countershaft that I intended to build for my lathe which lacked one. The idea had me fired up for a while; I just loved the thought of those belts whirring around. This idea would have worked and was capable of flexibility in the choice of speeds. The idea was to take a drive from the rear of the headstock to a loose wheel on the lower fixed bar of the proposed new countershaft and then drive to a compound wheel free to revolve on the countershaft shaft which itself is revolving. After three compound passes between the shafts, the drive would go to a wheel attached to the 25T gear on the quadrant and then an idler and then to a 60T gear on the leadscrew.

I still love the idea and I might build it for myself but after all this activity I suddenly realised that all you EWers had already built your countershafts or had an original one so that this idea became yet another stillborn one destined for the rubbish bin.

In part one of Martin’s independent feed articles he discusses how he tried to create a slow feed by using the gears provided with the EW lathe. There is a question that needs to be asked, why did Mr Stringer choose 16 DP gears for such a small lathe when MY***D, Boxford and other manufacturers had embraced 20 DP gears.

One answer to this problem is the method that Mr Stringer used to drive the gears, he used 1/8 dia. Pins and driving collars. Perhaps he thought that the 20 DP (the 20t one) gears were too small in diameter to use this system. I will check this out; duly checked the 20T gear has enough meat on it to take the 1/8 pin

Another marketing reason why he used the 16 DP system could be that it would prevent purchasers of his lathe from using cheap second hand 20 DP gears.

The problem with the EW lathe was that due to the small size, Mr Stringer only designed for a three gear set up, meaning that the drive from the spindle gear went via an idler gear to the leadscrew gear which would allow one compound gear set only. I understand his design philosophy; this set up gives a good range of modeller’s threads but no possibility of a slow feed. There have to be financial limits otherwise he would have ended up making a Boxford when he intended to manufacture a small, cheap but good lathe with its own niche in the marketplace, which I believe he did.

Mr Stringer could have quite easily created a four gear system which would allow for two compound gear sets and enable a decent slow feed. Exactly as in the MY***D lathes but he didn’t.

The EW lathe having the three gear system has a problem in that it has a right hand threaded leadscrew and to keep this right hand thread system entails that we create not a four but a five gear system. Of course we could always change the leadscrew to a left hand one and revert to a four gear system and make the gear quadrant more compact.

I don’t think that modellers like to spend money and would probably prefer to go for the five gear system which would be much cheaper. This also has the advantage that we can have up to three compound gear sets which can potentially give us a very fine feed indeed.

Martin discussed how he had tried all possibilities to create a slow feed for theEW, even going to the extent of using MY***D DP 20 gears, the 20 and 100 gears in the intermediate position which gave 129 tpi. My Boxford has a slow feed of 160 tpi which is good for me but might be too fast for others.

This is the moment that I have to ask, why in the light of what he was doing in the gear quadrant area, did Martin not look further and create a five gear system which would give as what we want but instead, pushed his gearbox system onto us with all its limitations. What do you think?<

[Ruaidhri MurphyParticipant @ruaidhrimurphy46564]

Wow! What did I start?

Due to a succession of illnesses my own is still unfinished, but most definitely not forgotten.

Unfortunately my friend who gave me this little gem passed away last month, but is fondly remembered by all who knew him.

Regards,

Ruaidhrí

[IanTParticipant @iant]

Hallo Ruaidhri, I hope you are well down the road to recovery. I'm sure your EW will appreciate some of your spare time (and getting some use) once you're feeling better.

Alan, very interesting discussion on EW gearing. I've not tried to use the EW for thread cutting – most of my stuff is quite small and therefore die-cut. I do have a slow feed routinely (default) set-up on the Myford though and it does help to give a very good finish.

So a leadscrew dog-clutch and larger quadrant would certainly be useful. I'd like the dimensions of the various components if you have them – and would certainly be interested in any versions you build – and reports on their utility.

My milling attachment has reached the stage where I've "erected" it on the back of the EW – and it seems to be rigid enough. Lots of details still to sort out (and I'm still not sure the motor is up to it) but will have to de-bug in stages as things progress.

Regards to all.

IanT

[alan smith 6Participant @alansmith6]

Ruaidhri' IanT and EWers,

You started a snowball rolling down a long hill!

I will continue with the gearing idea in a couple of days, you will be surprised at how easy it all is, if you have the gears the quadrant will cost about £25 and your lathe will be a proper lathe consistent with its date of manufacture and not have all that control gear, wires, transformers, steppers littering your bench.

The ideas that I'm fleshing up for you are just ideas until the first prototype is made and then just a prototype until all the tweaking and testing has been done during the development phase. Only then can it be called a finished design if succsessful.

If the designs turn out to be useable I intend to make drawings.

Alan

[alan smith 6Participant @alansmith6]

EW Gear Train continued.

The quadrant is made up from three pieces of ¼” plate which I personally will have laser cut to size by a specialist rather than hack them out from plate and it saves having to machine out the slots as well.

I had begun the design of the gear system with Martin’s words ringing in my ears where he tried using 20 DP gears combined with the 16 DP gears supplied with the lathe to create a slow feed.

Of course the three gear system defeated this attempt but then I wondered why Martin had not opted for a five gear system? Was a five gear system possible with the space available?

I started to sketch out a five gear system but the limitations of a drawing board soon became tiresome as at every attempt to draw out a viable system involved a lot of rubbing out of the last. This is an instance where CAD is very useful as changes can be quickly made.

Then came the inspiration, why not have the quadrant made from two separate arms?

EW Lathe screw cutting arm and spacer.

The clue was that the EW single arm has a spacer between it and the lathe end plate; this spacer could be replaced by another arm so that the quadrant would be variable. Of course the faces of both arms will be flush, which you can see if you look at the drawing.

Martin did not have to draw out his gear system he had the gears and the arm, so that by creating the variable quadrant all the possible gear combinations could be tried out by using the available gears with no need for drawings.

I have to admit that I’ve used Martin’s excellent book “Screw cutting in the Lathe” to recap the principles of gearing and chose one of the ratios that he proposed for slow speed feed.

Design wise, I can see that the single arms of the quadrant could be twisted by the forces on the cantilevered gears and the one bolt securing the quadrant may not be enough but there are simple solutions to this, so no worries.

So that’s it, too simple to be true.

Edited By alan smith 6 on 23/10/2012 19:00:28

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

**LINK**

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