WHERE ARE THE SHAPER USERS ?

I hazard a guess that the switch is at the back end of the ram - just gets a quick trigger at the end of the stroke.

A stepper is low torque and needs a psu and a bit of electronics but a simpler system would be that little 12v geared motor at the back of your 'useful bits' box that was either a windscreen wiper or window opener. Use a few cams to lift a microswitch after a part turn or a full turn each time it is set going, bit like the way a windscreen wiper does intermittent wipes.

The micro switch arrangement was a quick lash up to test everything out, but it worked so well that it became permanent and has been in place for 5 years now. It’s one of those micro switches with an actuator which is a length of springy wire. The operating lever for the shaper simply butts up against it on the back stroke, and the spring absorbs any overtravel

I’ll try to take some photos tomorrow.

Mike

GOk, here are a couple of photos of my Adept 2 with stepper motor feed. The micro switch which triggers the feed can be seen behind the control box. There are another couple of photos in my album.

Regards

Mike

Thanks Mike

MichaelG.

Mike Crossfield:

A fascinating blend of old and new!

Just seen this - been travelling most of the day - many thanks Mike for posting the pictures, very nice set up. Why I don't know, but I had assumed the set up would have been on the other side to the table; I guess on reflection because I was thinking it would just replace the handle. I was also expecting a toothed belt drive rather than a direct drive, shows how wrong one can be!

Did you just have the motor and controller lying about or did you have to go out and buy them? If so, do you still have details of what they were, or a circuit diagram if you made the controller yourself, that you could share please? I know nothing about stepper motors and controllers but have started trying to get info off the internet, but enlightenment from you would save having to reinvent the wheel.

You shaper looks in lovely condition by the way, love the downfeed handle and dial, that really looks the business - must copy that too!

Chris

Chris

The stepper motor is a Nema23 5v 1A unit that I had in the spares box. It’s just about man enough for the job, though if your slide is stiff you might want to go up to a beefier version - you can get higher current Nema23 motors in longer lengths with correspondingly increased torque. The controller is my own design, using a couple of digital cmos chips and a few discretes. Quite simple, just responds to triggers from the micro switch to give a selectable number of pulses to the stepper motor driver. The direct gearing worked out quite nicely with a 400 step/rev stepper motor, so it was easy to arrange for step sizes of 2, 4, 8 or 16 thou. Regretably I don’t seem to have kept details of the circuit, The stepper driver is a standard design based on discrete components which I had to hand.. If I was doing it again I would use one of the widely advertised eBay Chinese drivers which are more efficient and cost just a few pounds. It’s a good idea to allow for disconnection of the stepper motor when you want to use manual feed. If you don’t disconnect the motor from the driver there is significant “cogging” when you turn the handle, even with the power off, due to back emf in the motor. The effect is much less with the motor disconnected.

Regards

Mike

Thanks for the heads up Mike, I'll explore along the lines you suggest.

Chris

Thanks Mike. I had got it in my head, I suppose, that the feed should be advanced while on the actual back stroke, not as one changes direction - but I suppose the advancement will be fast enough to complete before the next forward stroke begins (when you have a rhythm going, you don’t want to hesitate at the start of each stroke).

I think I will incorporate a robust adjustable stop for the back stroke so the switch is protected from the momentum of the handle and my arm. A hardish rubber stop (door stop?) seems to be a good starting point, plus a timing circuit to delay the next trip - to avoid any double feed advancements.

Ndiy

I used a clock rate in the control unit such that the feed advance takes just a fraction of second. Since the trigger occurs just before the reverse of the feed stroke there is little risk in normal operation of the advance occurring during cutting.

A backstop buffer would be no bad thing, but If you are able to find a microswitch like the one I used you will find that the flexibility of the operating wire is such that it will absorb considerable overswing of the handle without any damage(so far!). Not clear in the photos, but I mounted my microswitch with a single screw, so I can easily tilt it to make some adjustment if I want to vary the length of the stroke.

I seem to remember adding an RC combination on the microswitch input to prevent double triggering.

Regards

Mike

My Drummond manual shaper's been busy lately!

I've just fitted a 3-ph motor set to my Harrison L5 lathe, and made the pair of tensioning arms holding the motor frame above the headstock* , from bits of old miniature-railway rail that our Mam would have said "looked as if they'd been dragged though a hedge backwards". They almost had been, left stacked among shrubs and dead leaves.

That shaper gave a pretty decent finish on the two shorter parts of the arms, more importantly with no rocking when tested on the table of my Meddings bench-drill. It did take a long time to cut below the worst of the rust pits, and I ended up with a sore shoulder, but it was otherwise rather relaxing and satisfying.

I chickened out and milled the mating faces on the longer arms, and the slots in the shorter ones!

As a point of model-building integrity, it occurred to me that a really good shaper finish would not only be functional but also right in looks for surfaces whose prototypes would indeed have been shaped or planed.

It's worth searching out older reference-books on shapers and shaper-tooling, and noting that the cutting edge should be under the clapper-box fulcrum to minimise digging-in. It was also common to use spring-tools, but this is less essential.

This means borrowing your lathe's tools may not be right. I recall seeing one poor shaper holding a lathe tool not only too deep itself, but packed out to push the edge even further forwards. I was too polite to query this with its operators, in a demonstration workshop at A Major Model-Engineering Exhibition!

I also file a small chamfer on the entry edge of the work-piece, slightly reducing the shock as the tool starts cutting.

For internal key-ways and splines, it is normal to draw-cut with the clapper-box locked. Some books show a locking bar screwed across the box. If you don't want to risk modifying the machine in a way that weakens the clapper-box holder, you can use a tool-holder with a jacking-screw in a top end that projects above the clapper-box.

For those who like making tools (to make more tools?) there exists an old design principle for a secondary table that allows a shaper to cut large-radii concavities such as smoke-box and motor saddles. This alternative to rather alarming fly-cutting, uses the geometry of rigid guides constraining the sub-table to move horizontally and vertically, simultaneously, so at each increment it forms a new tangent to a constant arc.

Most people motor-driving a manual shaper probably use these machines' usual crank and swinging-arm, but given that higher return-stroke speed is less important in amateur than production work, I have wondered if a self-reversing screw-drive would work here. It would be a challenge to thread-mill a full L+RH reversing-screw, but its main disadvantage is the fixed travel. I think my dear little Drummond will remain driven by an H.Sapiensis powered by tea!

*Lathe motor. The original Harrison L5 motor-mount was a massive steel box welded to the back of the cabinet, forcing the machine a long way out from the wall. To regain this lost space in a cramped workshop, I have cut the box off, and placed the new motor on a wall-frame over the headstock. It also raises the motor away from the dark and dusty depths.

Nigel

Any chance of a reference to this guided secondary table principle? I think I may have an applications for such a device in the near future.

Clive

Clive,

I suggest you have a look at "Contour Work with a Metal Shaper" - Popular Mechanics October 1958

It's available on Google books - and hopefully this link will take you there...

https://books.google.co.uk/books?id=iNsDAAAAMBAJ&pg=PA218&source=gbs_toc_r&cad=2#v=onepage&q&f=false

Regards,

IanT

That's an excellent article, Ian

Thanks for the reference.

MichaelG.

IanT

A most excellent article. Thank you very much. Especially as one picture shows exactly how to make a part that I'll need sometime in the near future for a repair job. Although I'd sort of worked out how to do it seeing the proper way to do the job and reading the article ha saved me from running into trouble from a couple of devilish details.

Clive

There is another technique for doing large radius arcs of a circle on a shaper. It uses a supplementary table, pivoted at one side of the main table, and constrained to tilt by an angled guide bar. I built one, based on a special vice for a planer described in an old book, and used it to make expansion links for my steam launch engine. I wrote an article for Model Engineer some years back, it can be found at:

The curve cut is not actually a precise arc of a circle, but it is close enough for all practical purposes. The radius can be anything up to infinity, but there is a limit to how small it can be depending on the size of the supplementary table and the machine. Smaller radii would be better done on a lathe. The ones I did for my expansion links would be about 6 inches or so radius, somewhat larger than I could do on the Myford.

The shaping between centres technique, as shown in the Popular Mechanics article, is a very useful one when you need something to have a partly round shape. I have used this to produce eccentric straps, where they have a half round shape but the ears for the screws stick out so they can't be turned on the lathe. Ammco used to make an attachment for their six inch shaper to do this sort of work. Not being able to get hold of an original one, I've made a copy for my Ammco. I also have a ground flat bar about 2 inches by 4 inches by a couple of feet long that lets me mount my Vertex dividing head on the 18 inch Alba shaper The tailstock goes nearest the shaper and the dividing head is over the edge of the table, allowing the use of most of the stroke for the actual job.

John Olsen

Clive -

Sorry, I could not cite it, but as I had rather hoped, at least I have inspired others to supply such information; for which thank-you!

John Olsen -

Yes, that seems to be the arrangement I meant, but I could not recall the details of where I'd read of it . It was most likely your ME article!

I take it the shaping between centres is by putting the cross-feed in neutral and notching the dividing-head round a few degrees at a time? It may be feasible to make an attachment driven by the table-feed, that drives the dividing-head (or a rotary-table) instead.

Essentially yes Nigel - somewhat like a indexing head for a mill - index centres for shapers often have a baseplate which allows the head to extend a bit further back from the normal shaper table. Atlas used to sell one for their 7" shaper - I'll attach a scan of their catalogue from many years ago,,,

You can use a 'normal' dividing head but would probably need to make a table extension to mount it. A variation of the full indexing centre is the gear cutting set-up proposed by Base Circle, where the rotation of the 'head' is tied to the table movement and is used to generate involute gear shapes using a simple cutter.

Clive - in terms of cutting concave shapes, there was also an article by Eric Hughes in Model Engineer ( 7th May 1993) - called (strangely enough) "Shaping Concave Shapes" which has a diagram of the device he used to cut a loco saddle.

Regards,

IanT

Edited By IanT on 24/03/2019 22:31:33

John & IanT

Thank you very much for those Model Engineer references. Definitely sound like the sort of thing I'm looking for.

Time to hit the back numbers. My collection goes back to 1974, all in binders, so shouldn't take too long to find.

Clive

Edited By Clive Foster on 24/03/2019 22:35:41

Edited By Clive Foster on 24/03/2019 22:36:24

Clive,

The Base Circle article was published in 1950 - so you probably won't have access to it but if you have ME copies going back to 1974 then have a look at "Shaper Cut Gears" in ME 20th January 1989 - by C Bamford. It shows the arrangement Base Circle proposed.

Regards,

IanT