Choosing a stepper or servo for a small positioner, low vibration

[Reddinr]

Ok! I think I'm launched. I'll post pictures when I get the rig together, hopefully in a few weeks. I think I will start simple with a direct drive stepper and use my parker servo indexer driven by a laptop. That way I have a chance of getting something working sooner vs. later. Then I can debug / improve it from there. I'm 90% there with move-stop-shoot-repeat mode. If continuous is needed I'll go back to the drawing board.

Thank you for all of the advice so far!

 

[Reddinr]

You can also get nice performance from steppers, especially nice quality ones

Where does a person get a "nice" stepper? In an internet search, the nema 17 ones that come up don't seem to have much of a pedigree. My junk box is full of scavenged steppers but I don't know what quality they are. Most are unipolar and I need a bipolar type.

 

[macardoso]

Where does a person get a "nice" stepper? In an internet search, the nema 17 ones that come up don't seem to have much of a pedigree. My junk box is full of scavenged steppers but I don't know what quality they are. Most are unipolar and I need a bipolar type.

First off, try what you have. It might work perfectly with no added cost.

I'm unsure what the specific requirements are for macro photography but from your comments it seems like the precision of the motion control was very demanding.

Stepper motors can be made cheaply (import) or higher end industrial ones are available. They look the same, however the winding uniformity, magnet strength, etc. is better in the industrial models available. This leads to better torque uniformity, less torque ripple, smoother motion, more accurate step division, etc. Here is a series for Kollmorgan, a well known industrial controls company which acquired Pacific Scientific, known for very high end steppers in the 80's and 90's.

KM Series Stepper Motors | Kollmorgen | High Torque Stepper Motors Stepping Step Microstepping Motors Brushless DC

www.kollmorgen.com

For most of us, even the CNC guys, any stepper will do. However, I have worked on industrial projects with work where the motion control requirements were demanding and higher end steppers were selected.

Again, just start with what you have. Good chance it will work well enough.

Can you share any of your photography? I'm curious about it!

 

[Reddinr]

Actually, we're just getting started. Lots of reading and picking equipment but little buying or doing yet. We're both retiring this year and macro photography has been a some-day interest for both of us. We're planners so it takes a while to get going. For some eye candy for the extreme stuff, have a look here: http://extreme-macro.co.uk/ These guys actually clean the dust off the bugs before shooting... I have tiny Pacific tree frogs and maybe ice flowers in mind for subjects.

 

[Reddinr]

OK. So I've got this stepper motor in front of me. I think I bought it surplus long ago. It seems to be a hybrid stepper, which is good I think. Unbelieveably I found a data sheet for something close to it. Is this my lucky day or what? I measured 0.6 Ohms for the coils. Searching a bit I saw a description of current type "AC". What does that mean? I saw another description that it was rated 2.4A. It is 103mm long. Most search results are in other languages though. I measured 2.5mH on an inductance bridge. So, probably most like the 0290 AX08 below, series connected. Sound right?

MAE HY200 2240 0240 AC04​

0240=2.4A, 2240 I think is roughly the size 2.2" x 4.0" The ACO4 part is the remaining mystery.​

 

[macardoso]

Unsure about the AC current part, but it looks like you're on the right track.

Hunt down a stepper drive with 3A output and preferably serial command input with S curve interpolation and you're golden. Otherwise a standard stepper drive and an arduino to drive it.

 

[Reddinr]

I have about a dozen or so Parker OEM750X drives that fit the bill. It uses simple serial commands. I just need to find a darned 25 pin dsub for it. I know I have one of those somewhere! I also just found a Parker OS series stepper that I forgot I had. OS22B-SNFLY. I'll need to look that one up too.

 

[Cadillac STS]

It is interesting how you look closer and closer into God's creations it gets more detailed and interesting. Look closer and closer into man made things and you get down to the flaws and imperfect creations.

 

[spumco]

That Parker 750 is a proper stepper drive. Stall detection, vibration reduction, etc. It can even take single-ended inputs from an encoder. I think you'll be very happy with it and just about any stepper motor. If you pair it with that Parker OS stepper you should a sweet stage.

Edit- i think the "B" model OS22 is for the higher voltage Zeta drives, but it will probably still work.

 

[Reddinr]

So I got my Nema 23 spinning today. I'm starting to think that a lower mass stepper might have less vibration. Maybe a Nema 17 would be a better physical fit anyway. I see a number of Nema 17's (Amazon, Ebay) aimed at the 3D Printer market. There are 1.8 Deg/step ones and 0.9 Deg/step ones. What are the trade-offs on that? I imagine those are not the best motors out there, just guessing.