OK since I toasted the stepper motor in my first scanner (replacement is not an option unless by chance I can find a direct replacement), I am going to move on to the second scanner I have in stock (I am trying to make a etchant agitator),

Sadly it appears that this one has a bipolar stepper (only 4 wires). I have read this article
and it looks like I am going to need a H-Bridge. Anything else I should know before I order parts?

I wanted to try and hack into the existing circuitry. With this old scanner it is likely that there will be less custom chips so easier to hack, but the circuitry is so buried it will be a major feat just to get to it. And I am afraid I would damage the scanner in doing so.

Good news is this old scanner is far more robust and rugged than these wimpy new ones.

 

The one advantage is the Bipolar is usually more powerful over uni-polar.
But the control is usually a little more involved.
Bipolar stepper motor circuits have the advantage of having just one winding and a low winding resistance. but they need more semiconductors than their unipolar counterparts.

A bipolar stepper motor produces the most torque, roughly forty percent more than a unipolar motor built on the same frame.
Max.

 

The one advantage is the Bipolar is usually more powerful over uni-polar.
But the control is usually a little more involved.
Max.

Will I actually need to heat sink the ground pins of the HBridge chip as called for in the datasheet? I would really rather put it in a socket if I can.

Could I use something like this?

https://www.ebay.com/itm/5PCS-8-8x8...152994?hash=item3af5df43e2:g:WAUAAOSwRbtZ9qGo

 

I just read the article here. Nice and welly written. Glad to get the info.

 

I just read the article here. Nice and welly written. Glad to get the info.

Wow amazing. Simply amazing.

 

I just read the article here. Nice and welly written. Glad to get the info.

Now stop mucking up my thread and please don't post to my threads again unless you have something of value to add.

 

Will I actually need to heat sink the ground pins of the HBridge chip as called for in the datasheet? I would really rather put it in a socket if I can.

I primarily use servo's, but the odd time I have used bi-polar steppers, they were fairly high current and I have used descrete devices mounted to 1/8" aluminum.
Max.

 

Will I actually need to heat sink the ground pins of the HBridge chip as called for in the datasheet? I would really rather put it in a socket if I can.

Could I use something like this?

https://www.ebay.com/itm/5PCS-8-8x8...152994?hash=item3af5df43e2:g:WAUAAOSwRbtZ9qGo

OK since I toasted the stepper motor in my first scanner (replacement is not an option unless by chance I can find a direct replacement), I am going to move on to the second scanner I have in stock (I am trying to make a etchant agitator),

Sadly it appears that this one has a bipolar stepper (only 4 wires). I have read this article
and it looks like I am going to need a H-Bridge. Anything else I should know before I order parts?

I wanted to try and hack into the existing circuitry. With this old scanner it is likely that there will be less custom chips so easier to hack, but the circuitry is so buried it will be a major feat just to get to it. And I am afraid I would damage the scanner in doing so.

Good news is this old scanner is far more robust and rugged than these wimpy new ones.

Is there a current draw listed on your new stepper motor? Or, what is the dc resistance of each coil?

 

I know you don't see my input as helpful, but as someone who tried and failed at running steppers(bipolar) myself with homemade circuits, do your self a favor and just get one of these - https://www.ebay.com/sch/i.html?_sacat=0&_nkw=tb6600&_frs=1 I don't think you can even buy the individual parts, let alone make a board that will work as cheap as one of these. And they have all the bells and whistles that are needed to run most bipolar steppers just by selecting the correct dip switches.

 

Don't waste your time with home made solutions that don't have current limiting. Standard practice is to drive steppers at well above their spec'd voltage but limiting the current. A scanner's stepper motor will be pretty low powered so they are pretty easy to toast as you found out. Those TB6600 drivers are way overkill. I would look at getting a pololu style step stick or rep-rap. It's what's used in most DIY 3D printers. Super cheap and will handle up to about 2A. It has current limiting which is what you need when you over-volt the steppers.

And ebay search gets you lots of choices for not much money. Search for rep-rap drivers. pololu.com has lots of choices, too

 

do your self a favor and just get one of these - I don't think you can even buy the individual parts, let alone make a board that will work as cheap as one of these.

Unfortunately back when I was considering steppers for projects, deals like this were unavailable and the only option was to build.
Max.

 

Unfortunately back when I was considering steppers for projects, deals like this were unavailable and the only option was to build.
Max.

I know what you mean. I have an assortment of controllers from Anaheim Automation and Superior Electric that were bought used for way more money and aren't as good as these new ones. We can thank the DIY CNC community for it.

 

I know you don't see my input as helpful, but as someone who tried and failed at running steppers(bipolar) myself with homemade circuits, do your self a favor and just get one of these - https://www.ebay.com/sch/i.html?_sacat=0&_nkw=tb6600&_frs=1 I don't think you can even buy the individual parts, let alone make a board that will work as cheap as one of these. And they have all the bells and whistles that are needed to run most bipolar steppers just by selecting the correct dip switches.

Why would I not find it helpful? You are the CNC guy right? What I don't find helpful is people telling me they have read an article that I posted a link to and that it is "welly" written.

But this might be a better deal. Does it look like it will work?
https://www.ebay.com/itm/5X-Dual-H-...752336?hash=item33cbc0f410:g:bwIAAOSw7U5Y-XC3

Heatsink and everything too.

 

Why would I not find it helpful? You are the CNC guy right? What I don't find helpful is people telling me they have read an article that I posted a link to and that it is "welly" written.

But this might be a better deal. Does it look like it will work?
https://www.ebay.com/itm/5X-Dual-H-...752336?hash=item33cbc0f410:g:bwIAAOSw7U5Y-XC3

Heatsink and everything too.

I don't know why I did not consider these before. I have a few on an Ardunio for a CNC project. Another project I need to finish.

 

Why would I not find it helpful? You are the CNC guy right? What I don't find helpful is people telling me they have read an article that I posted a link to and that it is "welly" written.

But this might be a better deal. Does it look like it will work?
https://www.ebay.com/itm/5X-Dual-H-...752336?hash=item33cbc0f410:g:bwIAAOSw7U5Y-XC3

Heatsink and everything too.

That's an ancient design (L298), no current limiting. Get the reprap/pololu step stick.

 

That's an ancient design (L298), no current limiting. Get the reprap/pololu step stick.

These?
https://www.ebay.com/itm/2pcs-A4988...059816?hash=item1a3d07a0e8:g:oo0AAOSwPcVVi83W

They are what I got with my Arduino. Dummy me, I already have these in stock!

 

Yes. exactly! (not the dummy part)

 

Is there a current draw listed on your new stepper motor? Or, what is the dc resistance of each coil?

I am reluctant to uninstall it to see. It is really buried.

How would I determine voltage requirements on that motor?

 

If you run at fairly low RPM, you do not need current limit, in this case the rated voltage is used in order for the current to be limited to the motor rated current.
The torque only drops off as rpm is increased past a certain point.
One problem with salvaged motors, they often do not have a rating plate attached.
Max.

 

Yes. exactly! (not the dummy part)

Thanks for the vote of confidence.


And you really saved me. Now I will be able to continue with this project this weekend. Ruining the other motor really had me upset.

Will these also work with unipolar steppers or do they have a version that does?