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WHERE ARE THE SHAPER USERS ?

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Bazyle12/02/2019 18:22:55
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4344 forum posts
184 photos

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.

Mike Crossfield12/02/2019 18:56:46
158 forum posts
9 photos

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

Mike Crossfield13/02/2019 10:45:27
158 forum posts
9 photos

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

5521f5a9-c85a-44db-836d-93df4d5ed411.jpeg

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Michael Gilligan13/02/2019 15:26:10
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12544 forum posts
544 photos

Thanks Mike yes

MichaelG.

ega13/02/2019 15:53:09
1067 forum posts
89 photos

Mike Crossfield:

A fascinating blend of old and new!

ChrisH13/02/2019 17:30:21
798 forum posts
12 photos

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

Mike Crossfield13/02/2019 18:48:41
158 forum posts
9 photos

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

ChrisH13/02/2019 21:12:22
798 forum posts
12 photos

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

Chris

not done it yet14/02/2019 07:49:19
2573 forum posts
11 photos

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 strokesmiley).

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.smiley 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.

Mike Crossfield14/02/2019 09:00:41
158 forum posts
9 photos

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

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