good source for non-captive linear steppers?

Hello I am looking for a good source for affordable non captive linear stepper motors, something in the nema17 range. I need at about 150mm usable stroke for driving the plunger down in a syringe, finest pitch so the most possible power is generated.

Preferably in the US, as I am based there for some more months but anywhere else is helpful too!

Thanks!

"NEMA 17" is the name of a standard for stepper motor mounts. It doesn't even describe what's behind the mounting plate. A "NEMA 17 linear stepper" can't exist, because a mounting plate for a circular stepper doesn't fit a linear one.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

I don't get your point Traumflug, a Nema 17 sized non-captive linear stepper fits a Nema 17 mount just fine, thats why they are Nema 17 right? They have the exact same face plate dimensions, hole spacing flanges etc as a rotational Nema 17, the fixed axis is just replaced with a threaded rod and internal nut:

[www.haydonkerk.com]


There are round tin-can linear steppers that definitely don't fit on Nema 17 mounts (although there exist optional flanges) but I'm less interested in those although happy to find a source for those too:

[www.haydonkerk.com]

... check here - NEMA-8 to NEMA-23: [us.nanotec.com]

But the pricing is heavier than with common RepRap-motors

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Thanks a lot Viktor, hand't found that one yet. Thats actually reasonable in price for one from a non-chinese vendor, I can easily find 150$ ones. Thanks a lot, knew you would have a good source

I also found this one, which is cheap at 24$, but it is 12V: [www.tdvdesign.com]
I understand that 12V steppers should work but don't perform to their full capacities? What issues can I run into at 12V?

Viktor, I'm having a hard time figuring out what a good one would be. I am not good at understanding all the electronic specs
From the RepRap wiki I understand that anything in the 3-5 V and 1-1.5 A ranges should work fine. But I don't see any voltage ratings...
I am looking at this one: [us.nanotec.com]
Maybe model L4118S1404-T6X1, with a 1mm pitch since I need force > speed.

btw I see now that they don't include leadscrews so that makes them a bit less affordable. but ok..

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unfold
I don't get your point Traumflug

What you show isn't a linear motor. It's a rotatry stepper with a threaded nut integrated. Undoubtly a useful arrangement in some situations, but linear motors work without any spindle.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

... this 'linear motor' naming stuff is a bit fuzzy ... call it better linear drive or actuator

'Good' steppers for the RepRap-electronics are normally rated with currents of around 2 Amps and corresponding voltages below 5 Volts ... but I have steppers with 325 Volts too, that have realy good dynamic properties ... so this could be different ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

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Traumflug
What you show isn't a linear motor. It's a rotatry stepper with a threaded nut integrated. Undoubtly a useful arrangement in some situations, but linear motors work without any spindle.

Now I get it. That makes sense, I was confused by you talking about how it could not be Nema 17...

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VDX
... this 'linear motor' naming stuff is a bit fuzzy ... call it better linear drive or actuator winking smiley

Thanks for clarifying, I found the linear actuator naming confusing when looking for one that is stepper based since a linear actuator can be so many things, pneumatic, hydraulic. Since I have no engineering education whatsoever I go by Google and a google image search for Linear stepper shows far more images for what I need than a search for linear actuator.

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VDX
'Good' steppers for the RepRap-electronics are normally rated with currents of around 2 Amps and corresponding voltages below 5 Volts ... but I have steppers with 325 Volts too, that have realy good dynamic properties ... so this could be different ...

Do I understand well that voltage isn't that relevant?
At Nanotec I can find that the ones I was looking at are specced as 1,4 A/winding, 2 Ohm/winding. Now that leads to 2,8 V/winding right? But what are the correct numbers for the total of the stepper? I am lost here. Help appreciated.

... the essential number is the amperage - with the common bipolar drivers you define the max. current through the coil, then the driver switches the voltage on the coil with a high voltage peak and controls the current to the set value.

The higher the voltage, the faster is the switching/loading of the power, what's defining the dynamic properties.

I'm driving 2V@2A-steppers with drivers, that can output until 70Volts@6Amps without burning the coils by setting the max. current to 2Amps

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

OK, so got the cheap TDV one with 250mm leads crew TDV linear actuator and installed it on a print head that I made. Adjusted the voltage on the pcb and worked. That was until I actually had it push 60cc of clay through a 1mm nozzle... On and off it skipped steps. So clearly I need a more powerful stepper, combined with maybe the finest pitch screw. I had no idea how to calculate how much pressure I actually needed but today figured something out. Please let me know if this sounds correct:

-I need around 4 bar of air pressure to extrude clay from a 60cc syringe, 6 bar max.
-1 bar = 10 N/cm² so 6 bar = 60N/cm²
-diameter syringe is 28 mm so surface area syringe is ±6,2cm²
-6,2cm² * 60N/cm² = 372N force needed correct?

So, quest open again....

Edited 1 time(s). Last edit at 04/08/2014 12:37AM by unfold.

Just ran across this stepper motor site today, might have what you're looking for:

http://www.omc-stepperonline.com/linear-stepper-motors-c-3.html

Did you find your stepper and solve your problem!? I'm currently where you were when you posted this.

I'm looking at nema23's because I feel like the 17's aren't going to cut it for me - my syringe capacity is going to be more like 250-500mL.

I'm totally unsure how to calculate the required force.. did you calculate yours theoretically or not?

Any information you could pass on would be so great