Newbie from NZ

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Originally Posted by rjsutton

Doddy
i think you may mean don't "underestimate" Chinese motor-gearbox as you seem quiet happy with there performance. !

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No, I meant don't overestimate. These are very small devices, very small motors. They are reasonably rugged (the first that I stripped down was a mostly metal gearbox). I think these are particularly under specced for the numbers that Andy provided - but I'm trying to understand my gut-feel (rather than science) that they might just be worth a look at if the $30 cost is not prohibitive to you. But understand that you'd be in the realm of practical experimentation.

Quote:

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Originally Posted by rjsutton

Doddy
I had a look on Arduino website and im more confused than ever..H-bridge driver ! STK500 Protocol ! ICSP Header.! loT Bundle......
i will have to join their forum to get answers on how i get the motor to stop at one end and reverse and stop and go forward and stop and reverse.......... I love your comment "That's the easy part " mmmmmmm.
I thought by buying a motor with a built in-on encoder then i would just pick up a controller with a few buttons to press when the limits were where i wanted. Not be be it seems ,
I was going to use 2 micro switches to limit travel but i still cant work out how they must be wired to stop travel and reverse the next time the controller button is pushed. My Bob the builder brain doesnt work very well in these situations
Richard

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If you wanted I could provide the suitable software(or at least the basic framework that could be adapted by yourself) and help advise on the wiring. I'm not promoting Arduino as the only solution here - and at the end of the day these are simply based around COTS microcontrollers, but they do promote an accessible set of capable programmable hardware.

Doddy
Thanks for that
The $ cost of the motors etc is not a problem. But if these won’t work then I will be in another place [emoji30]
Appreciate any help in program and wiring diagrams. Any of your guys knowledge I can glean then that is a 100% more than I started with
Thanks
Richard

B


Sent from my iPhone using Tapatalk

Quote:

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Originally Posted by rjsutton

Doddy
Thanks for that
The $ cost of the motors etc is not a problem. But if these won’t work then I will be in another place [emoji30]

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For clarity, I’m not convinced that these motors are big enough. I think they will be operating at their max power rating to get close to what you want, but then you’re only looking to run for 20 seconds at a time under load. This is why I say you’re in the land of practical experimentation

Doddy and All
Mate the next thing ive found is
https://www.aliexpress.com/item/3290...chweb201603_55

they reckon ( i think ) that @ 220rpm then torque is 24.25 kg.cm is this 2.4NM ?
alot more expensive but will see if i can source a cheaper supplier $NZ -$US not very good exchange ( thanks Trump)

I hope i could put an encoder somewhere ( can it go on the end of the ballscrew?)
Richard

I’m not going to comment on the motor choice other than to say it looks much closer to the numbers that Andy suggested. I’m guessing the rating is more appropriate for continuous rating than peak (a good thing)

To answer your question: you essentially want to add an encoder to the gearbox output, either directly or on either end of the ball screw.

You will always want a “home” microswitch close to the home position for the mechanism to reset/calibrate the closed position... that allows you to include soft stops on the traverses by predicting position.

Thanks
Can You "suggest " an encoder and controller setup that would do what you mention. Im not sure where (or How) a Home microswitch would be wired into the circuit to reset-recalibrate.
If not too much bother could you please give me a diag (or lead me to where i would find one) with the encoder wire and microswitch.
I do think those chinese motors would not work as they just too small. I don't want to WASTE time and money . I will have to shorten the ballscrew slightly to fit the wider gearbox in as well

Andy if your still around do you think the new motor link above will be better choice of power for the ballscrew ?

Quote:

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Originally Posted by rjsutton

Thanks
Can You "suggest " an encoder and controller setup that would do what you mention. Im not sure where (or How) a Home microswitch would be wired into the circuit to reset-recalibrate.
If not too much bother could you please give me a diag (or lead me to where i would find one) with the encoder wire and microswitch.
I do think those chinese motors would not work as they just too small. I don't want to WASTE time and money . I will have to shorten the ballscrew slightly to fit the wider gearbox in as well

Andy if your still around do you think the new motor link above will be better choice of power for the ballscrew ?

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I'm "thinking" that you're looking for an off-the-shelf solution, and there are such things readily available. For example.

https://www.amazon.com/uniquegoods-W...gateway&sr=8-1

All you need are two limit switches. The instruction manual (linked at the bottom of the page on Amazon) shows how to attach two NPN proximity switches (https://www.amazon.com/Twidec-Induct...s%2C204&sr=8-7 and from the photo that you provided in post 12, I'd simply drill two holes in the side-wall an inch or so above the moving sled, one at each end of travel, and fit the proximity sensors there; Add a short piece of angle steel attached to the bolts on the linear blocks (you show 8 bolts in the image) to project up to provide a moving vane to actuate the proximity sensors when the sled is in the two end positions.

Job done.

cool
so i wouldnt need an encoder to check the revs moved if i just use the gear you show above?
bloody marvelous if thats the case ( can you please confirm my reasoning )
ive just ordered

https://www.ebay.com/itm/120W-High-T...97.m4902.l9144

with a ratio of 1:7.5 which should give me 3.21 NM as far as i can see
its a 120w motor so will be heaps better than the little ones
I hope im reading everything as i should be.
appreciate all your help.
Richard

The purpose of the encoder is to allow the control system to determine where the sled physically is (actually, where it thinks it is, based on the number of [partial] revolutions and a knowledge of the screw pitch). That's one way of skinning the cat. The other is to simply think of what your actual use-case is - which is to understand when the sled is fully opened, and when it's fully closed - which the two proximity sensors will allow you to determine.

This simpler solution offers fewer bells and whistles (e.g. stall detection and acceleration/deceleration around limits), but also fewer things to go wrong - potentially higher reliability. You could introduce stall detection with a suitably rated circuit breaker. You'll have to tune the system with the actual position of the sense vane but it should be robust enough for your simple use-case.

I'm not a motors man - a bigger number looks better than a smaller number to me.

...and one other thing - with heavy duty motors (or rather, heavy current draw on a low voltage supply) - remember Ohm's law. I'd personally slave a lead-acid battery close-by and trickle-charge it from the vehicle battery. Then use the shortest, beefiest cable runs to the controller and to the motor, maybe even bi/tri wiring it to reduce the power loss in the cable.