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Going to withhold any further comment/judgment until seeing it work.
Why won't my linear stepper motor work?
- Thread starter Ben Varvil
- Start date
Lol! ... as I've gotten to know you, Shortbus, through these last few years, I can easily picture you impatiently biting your tongue at this moment ...
And as this goes through to it's conclusion. There are many "stepper motor" "solenoid" inaccuracies being floated about in this thread. Inaccuracies that I had until doing some deep research. And it doesn't come from the first few internet search pages, that are mostly glorified advertisement for a companies product.
Like many things on this and other sites someone that wants attention gets it, even if it's not the real answer. It will be hard to keep quiet when the rabbit hole slowly comes to a dead end. So I'll say it now, "told you so".
Like many things on this and other sites someone that wants attention gets it, even if it's not the real answer. It will be hard to keep quiet when the rabbit hole slowly comes to a dead end. So I'll say it now, "told you so".
This is funny but this moves both ways it's only one coil now if there was more how much could it move .
Then let's make it better it's rubbing the shaft so there is lots of friction let's make that less.
Then let's see if it can hit a pool ball with needed. Force
Then let's make it better it's rubbing the shaft so there is lots of friction let's make that less.
Then let's see if it can hit a pool ball with needed. Force
This is a very interesting page, Ben, that might help you grasp the basic concepts regarding solenoids. It's got a calculator that you can play with too!
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Shots fired. Ouch. So much for "withholding comment/judgement". LOL
More motivated than ever.
Two things I'll throw out for good measure:
1) Use a brass threaded rod, to avoid magnetic effects in your support structure for the cores.
2) Avoid using metallic components in your coil bobbins- even if they are non-magnetic.
They end up looking like "shorted turns" in your coil, which will absorb energy (eddy currents) during switching- in a way you do not want.
You can use these materials if you "gap" the metal so current cannot flow around in a loop.
1) Use a brass threaded rod, to avoid magnetic effects in your support structure for the cores.
2) Avoid using metallic components in your coil bobbins- even if they are non-magnetic.
They end up looking like "shorted turns" in your coil, which will absorb energy (eddy currents) during switching- in a way you do not want.
You can use these materials if you "gap" the metal so current cannot flow around in a loop.
This can be made Ben you just started with wrong coil ideal but if you made 4 of those with one coil each you be ahead of the game.
You'd get 4 inches of push pull then make the sick have 15 to 20 inches of rotor let's call it that spaced to match the coil.
And make the stick to ride on some kind of bearing. So it can slide without binding.
Test the movement with one coil that way you can see how it moves.
Then you make it push the stick by firing the coils with the arduino.
You'd get 4 inches of push pull then make the sick have 15 to 20 inches of rotor let's call it that spaced to match the coil.
And make the stick to ride on some kind of bearing. So it can slide without binding.
Test the movement with one coil that way you can see how it moves.
Then you make it push the stick by firing the coils with the arduino.
For maximum efficiency and control, you will want to bake a closed-loop feedback system around it.
Then you would not need to expend tons of power to hold it in position, as you would in variable-reluctance stepper mode.
I would make a linear incremental encoder using a strip of photo-etched stainless steel, with the grating etched into it.
You can buy optical readers with 2 quadrature outputs than can read it.
Or - if you want to go analog, a big, long LVDT* would be great, providing absolute position feedback. (no need to HOME it)
*Linear-variable-differential-transformer.
Then you would not need to expend tons of power to hold it in position, as you would in variable-reluctance stepper mode.
I would make a linear incremental encoder using a strip of photo-etched stainless steel, with the grating etched into it.
You can buy optical readers with 2 quadrature outputs than can read it.
Or - if you want to go analog, a big, long LVDT* would be great, providing absolute position feedback. (no need to HOME it)
*Linear-variable-differential-transformer.
I like this plan.
I learned a lot from today's build.
thinner, longer cores. More of them. (as you say also)
You are right about friction. I'm going to need to figure out a bearing solution.
Ditch all metal other than windings and cores. (Thanks Sensacell)
I'm going to wind some coils for these fat cores anyway, to test/better understand what to expect. A center-tapped one and a normal one.
I'd like to get a non-inverting driver chip ordered ASAP.
Any help selecting a part would be much appreciated.
For bearings, I suggest you consider Igus line of derlin plastic bushings, they're inexpensive, durable, and low friction. Just google it up.
DNA Robotics
- Joined Jun 13, 2014
- 670
2 Pcs 12x21x30mm Lm12uu Linear Ball Bearing for 3d Printer Tool CNC Machine
$4.86 Free Shipping
https://www.ebay.com/p/2-Pcs-12x21x...m=352066277063&_trksid=p2047675.c100005.m1851
$4.86 Free Shipping
https://www.ebay.com/p/2-Pcs-12x21x...m=352066277063&_trksid=p2047675.c100005.m1851
Even better, but a little more expensive to implement, considering the cost of the pillow blocks. Www.Vxb.com also has a pretty good selection of these bearings at affordable prices.
Having used those type (originally called Thompson bushings) they don't work so well with anything that isn't slightly hardened steel, the harder the better.
An even better source of those bushing, actually the real manufacturer for many of the "big name" companies -
http://www.asbbearings.com/plastic_bushings.html
http://www.asbbearings.com/ They are very nice people to work with, have bought from them many times.
Not really shots fired just truthful statement. Post #264 is just the first installment. To think you're going to get complete movement of anything through a solenoid is defying known science.
And I know I'm not keeping my promise of keeping quite, but it is hard when you see so many misleading things.
Now them, I didn't know about ... that link you've posted is gonna come in handy for me in the near future, Shortbus. Thanks!
DNA Robotics
- Joined Jun 13, 2014
- 670
Just that solenoid, mounted correctly in a cue stick would be good enough for breaking.
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