Attaching Leads to Micro Stepper Motor Pins

[Mark W]

I found and bought 20 of these micro stepper motor linear actuators for a bunch of different projects I have in mind.  But during initial experiments it's clear they will be useless unless I can find a better way to wire them up.





The issue I'm having is, once you touch the pin with any kind of heat, they fall right out of that little plastic thing. Even with a a lucky solder, without securing the wires in the exact position they were soldered the smallest twist/pull will un-seat the pin.  So, anyone have any creative suggestions?


I only have two ideas so far.

1. Once soldered, epoxy the wire to the length of the bracket, including over the pins. 

2. Make a custom PC Board to lay over the pins and route the pins out to larger contact pads.  Then secure the board to the bracket by taping a screw hole or two along the bracket below the shaft.   


For idea 2, I'd have to get thin PC Board, but I think it has the most merit vs using epoxy.    Anyone have any thoughts or suggestions?

[RBrodzinsky]

Mark - I think option 2 is your best bet.  You might also want to try a very low-wattage soldering iron

[peteski]

A flexible PC Board is a good idea but it would have to be very precisely made for the holes to line up with the pins.  I would first try soldering some thin magnet wire (maybe about 36 AWG)  to the pins, then epoxy them.

For this type precision soldering you need a soldering iron with a very fine conical tip (something like 1/64" or 1/32").  Wattage is not really important - it is vital that the iron is temperature controlled. You would dial it up to a temperature just high enough to melt solder, then solder the (pre-tinned) leads very quickly (using flux to make sure the solder flows well).  A simple hobby-type soldering iron is not quite up to the task.

BTW, where did you pick up those tiny gems?

[Mark W]

Thanks guys.

I'm gonna try both methods and report back.


For reference, here are the 3 types of stepper linear actuators I ordered.

20 of these (the ones in question)
http://www.ebay.com/itm/391515440046
Hoping they'll work great for moving crossing arms.  Being steppers, should allow me extra fine control and easy calibration with a few pots to tune "Up" and "Down" positions, rather than trying to tune that mechanically.

4 of these guys
http://www.ebay.com/itm/252380331698
Backup for crossing arms should above be too weak.

40 of these super micro's too.
http://www.ebay.com/itm/172274059804
Should be perfect for animating doors and gates.

[Mark W]

Super micro's just arrived!  Dayum.  So small I could almost animate some N Scale windshield wipers!!


 

[C855B]

What are you driving them with?

[Mark W]

What are you driving them with?

Arduino

[peteski]

Those are so cool!

[Scottl]

Very cool.  Would they be suitable for turnouts?

[woodone]

Try using Silver Epoxy.  This stuff works.
       a link for you  http://www.all-spec.com/Catalog/Adhesives-Sealants-Tapes/Adhesives/Epoxy-Adhesives/8331-14G-33018?utm_source=bing&utm_medium=cpc&utm_campaign=Product%20Listing%20Ads%20-%20Shopping&utm_term=1100404856921&utm_content=PLA

[Mark W]

Very cool.  Would they be suitable for turnouts?

The larger ones possibly.  I doubt the smaller ones have enough torque for a turnout.  I'm worried if they'll even have enough for a crossing arm. 
I may test their strength at some point. 

[Mark W]

Got the first test with epoxy complete.  Used 32 gauge strand.  I roughed up the bracket to help the epoxy stick. 




With the ribbon, the super micro was cake compared to above!


Decided to sacrifice one to check out internals.  Crazy that this tiny thing is a 20 step motor!  That's the tip of a jewelers file for scale btw!


Salvaged from my sacrificial super micro, the ribbon kinda sorta fit on the other size. 


Will hook up the Arduino now and play around with stepping. 

[peteski]

Cool!  Stepper motors are really simple - just a magnetic rotor and electromagnets with multiple poles. So each electromagnet has 5 poles, each electromagnet is staggered that results in 10 poles and I guess half-stepping results in 20 steps/revolution.

I have to get me some of these and start messing around with Arduinos.

I think they will be plenty strong to activate things like NJ International crossing gates using the linear-motion feature.

[Mark W]

Took a while to get things working smoothly.  Had to deconstruct the Arduino stepper library and modify the coil sequence.   But, I now have working stepper linear actuators and code to drive them!!



It comes out to just over 300 steps to travel the  4.5mm shaft, making each step a minuscule .015mm! This super micro gif is running full speed at just over 1mm/sec, so about one half a scale mile per hour.


I think at this point I have the original question solved, so all that's left is... what ideas would you use these for? 
My top idea is a backyard barbecue with a guy periodically opening the grill hood to check on those bacon wrapped steaks!  Gonna have to 3D print a nice Weber Grill.   

[peteski]

That's awesome Mark!
How much delay did you put in after each step?  How loud is the motor and what kind of noise does it make?

I'm all fired up to try my hands on those steppers and Arduino, but have too many projects on my plate already. Someday I might be asking your advice though.  I'm thinking of using these to animate crossing gates on friend's layout and the Arduino will also be used for train detection and for flashing the RR crossing LEDs (using PWM outputs to softly turn them on and off like the real signals).