stepper motor bulk purchase

Hi Zach

Sorry i looked at the Web Page and the mounting hole dimensions are different to the datasheet which as you state is Nema 23 next time I'll pay more attention.

Ian

Zach,

That sounds like a plan! Do the pre-order thing.

Demented

I'm willing to lend Zach (the USA foundation) $1000.00 to get 50 motors until February 1, 2008 at 0.0% interest rate. This is based on the USD$20.99 price x 50 units. And I'll take the risk if he doesn't fully pay it back, as he has more than earned respect with his hard work to date. Nothing real formal, no risk to Zach except his internet reputation if he runs off to Tahiti with the money I think that getting the motor price down is a worthwhile investment.

I can send the money right away, as long as I get some kind of simple receipt. Does this look like the best motor deal / best prospect? Please chime in, best to get it right the first time.

Edited 4 time(s). Last edit at 11/20/2007 01:24AM by RoundSparrow.

I'm in the US, and would defiantly order some of those!

Mike

Just be sure on the Torque they are much less than the currently spec'd motors 0.35Nm as opposed to 1.06Nm I'm sure this will not be a problem, I will be able to confirm this very soon when I test my moulded RepRap as I'll take current readings.

This will also give the advantage of less heat generated in the electronics

Ian

RoundSparrow Wrote:
-------------------------------------------------------
> I'm willing to lend Zach (the USA foundation)
> $1000.00 to get 50 motors until February 1, 2008
> at 0.0% interest rate. This is based on the
> USD$20.99 price x 50 units. And I'll take the
> risk if he doesn't fully pay it back, as he has
> more than earned respect with his hard work to
> date. Nothing real formal, no risk to Zach except
> his internet reputation if he runs off to Tahiti
> with the money I think that getting the motor
> price down is a worthwhile investment.
>
> I can send the money right away, as long as I get
> some kind of simple receipt. Does this look like
> the best motor deal / best prospect? Please chime
> in, best to get it right the first time.

wow! that is very generous of you! i will certainly take you up on your offer. i'll send you details in a PM and a receipt as well. also, you have quite a few witnesses here on the forums. (open source legal?)

anyway, we should closely examine any technical stuff and then if we can't find any better motors than these, we should go for it.

i've tested these motors in my own RepStrap, as well as in my Darwin machine. i have had 0 problems in my repstrap (no missed steps, etc) i did have a couple problems with the Z motor in my darwin, but that was mainly because my Z axis is horribly mis-aligned (and the motor mounted backwards)

one of the major design changes we need to make to darwin is to change how the motor is mounted, so that shouldn't be a problem (ie... it will get or be easily changed by the time we're printing out parts)

so yeah, if everyone wants to scour the internet for stepper motor deals, please do so! feel free to submit quote requests, etc. because thats probably how we'll find the best deals. post back any sort of info you find here on the forums so we can keep coordinated. if you find a stepper deal with a URL to link to, you get bonus points.

technical things to keep in mind:

* we need NEMA 23 size motors
* more torque is better if it is <= $25, but has higher torque we should consider it as well
* dual shaft output would be a huge bonus, but not required.

thanks guys!

ok, we will work out the funding transfer via PM. given the holday week and all, I suggest goal is everyone have the motors picked out and place the bulk order on Monday November 26. I'll have they money to you by then.

For the record: the loan will be from my small business to the reprap foundation you setup. 0.0% for first 70 days then 0.1% APY for the next 60 days. Hopefully that will give you plenty of time to do one or two order cycles.

If for some reason you can't sell all the motors within the 4 months, either give me the unsold motors or we work something equivalent.

It seems to me you have been putting up the cash for the foundation PCB's and other products and have done a good job managing it. I know that stuff isn't as fun as doing the RepRap, but I really appreciate it. Glad I can help out.

// Stephen Gutknecht
// Canyon Lake, TX
// Stephen @ Hill Tx .com

awesome.

yeah, i put in some money to start it, as did Adrian Bowyer. from there, its mostly been self-sufficient. we do mark up prices a little bit to cover overhead. other than buying parts, the only expenses the RRRF has are rent on its mailbox and the art studio i rent to store stuff and do research.

unfortunately we've only been breaking even lately, so its been hard to expand into things like stepper motors and such.

this is going to be awesome!

i scoured the jameco website and found a couple of motors that could make decent substitutes:

1. this one is similar to the one i currently use, except it appears have higher torque, lower resistance per coil, and its wired as unipolar. its also actually *cheaper* at 50 units.

[www.jameco.com]

2. this one is by Lin Engineering, and it appears to be too small. its really che ap though and would make a great motor if we could find one the right size:

[www.jameco.com]

the only problem with finding a new motor is that the one we have picked out right now i have (and am) actually using successfully. switching to a different one means ordering it and testing it. it would be crazy to spend $1000 without knowing that it *will* work with both our two current stepper driver boards.

Can someone who understand these more than me study this list:
[www.kelinginc.net]
Note lines 11A, 14, 15.

they have a few NEMA-23 for under $30 in single quantity, not sure how much price break they give for bulk.

Edited 1 time(s). Last edit at 11/20/2007 02:10PM by RoundSparrow.

I am running these motors from kelinginc.net and they are running very well. just a little on the high current side and they are causing some heat on my large heat sinks ( to warm to hold on to for 20 Sec. ) but other then that they are very smooth running. I did my home work and they seemed to be very close.

here is the model and spec. [www.kelinginc.net]
I do not know about a bulk buy but i think he might since he has a lot of ebay auctions

Bruce Wattendorf

Hi RoundSparrow,

... the 11A-Bipolar is stronger (~6 Volts, 1,7Amps in serial-arrangement), dual-shafted and cheaper, so it's my favorite ...

Viktor

kelinginc.net wrote me back, they only want to do a 10% discount on a quantity of 50. So that puts the KL23H251-24-8B (#11A) at over $23.

Zach seems to have the best deal so far at quantity 50:
[www.jameco.com]
Under $20.58 each (have not yet confirmed shipping cost)

Zach!! Look here, I found that motor you mentioned (that you had not tried) for $19.60! [www.kysanelectronics.com]
1125003; 57BYG009; MOTOR,STEP,2.4VDC/2.4A,1.8deg.,6.0kg-cm; 19.60

It doesn't show that price in their normal catalog, only on the "Specials" page.
So I'm guessing worth a phone call to find out if they will do that. As that $19.60 price is below their 100+ quantity price ($23.43) by a substantial amount.

Let's all study this one guys, does it look good? Someone with the skill (Zach?) should order a couple and try them.

Edited 3 time(s). Last edit at 11/20/2007 03:53PM by RoundSparrow.

Hi RoundSparrow,

... the 57BYG009-motor isn't as worthy, as the 11A in the [www.kelinginc.net]

- Look at the higher current - 2,4Amps against 1,7Amps
- only half the holding-torque - 6 kg.cm against 110 N.cm
- and it's only single-shafted

As for the price, the 11A seems to be a better deal for me ...

Viktor

hmm. 11A looks like a good motor. it had dual output shaft and should be very similar to the 'orthodox' stepper, except its 200 step vs 400.

i'll order one and test it. that way we'll know for sure!

it seems Bruce is using the #11 successfully. that is good news! its little brother the #11A is still quite powerful. i have a good feeling about this guy. having an extra output shaft is definitely good news in that we dont have to modify the darwin design to accept single shaft z-steppers.

~Zach

How much do they charge for shipping on 3 vs 50? With only a 10% discount on quantity 50, a bulk purchase may not be worth the trouble? I'll cool lending the money, just want to consider all the angles.

He is selling quantity 3 on ebay for $88 shipped. [cgi.ebay.com]

Edited 3 time(s). Last edit at 11/20/2007 05:07PM by RoundSparrow.

yeah, thats something to find out. i'll get a shipping quote from jameco too.

also, if its not leaps and bounds better than our current ones, it would still make sense to get the $20 one. its significantly cheaper and it definitely gets the job done.

bad news: the jameco motors i'm using they only have 12 in stock. the other motor (57BYG009) has 50 in stock: [www.jameco.com]

i think i'll order one of these too as a test order as well. never hurts to have too many data points.

www.kelinginc.net
I think his shipping is the same for one as it is for 50 I might be wrong...

Bruce

Zack, in reference to your most recent post: the 57BYG009 is the one that you can get for even Cheaper ($19.60) off the "specials page" at [www.kysanelectronics.com]

My guess is this is a phone-in only special, I haven't contacted them. But it is the exact same mfg part number.

UPDATE: I wrote them to ask what it takes to get the $19.60 prices on their specials page, here is response I just got:

------------
info .AT. kysanelectronics com

Please just send me a PO or returning this email with quantity you want.
Nothing is required. We have 80 in stock now.

Thank you,

Sam Wang

Kysan Electronics
www.kysanelectronics.com
650-396-0184
-------------

So they have 80 in stock, and no minimum to get the $19.60 price!

Edited 2 time(s). Last edit at 11/20/2007 11:49PM by RoundSparrow.

wow, thats a fantastic deal. i'm going to contact them and order a test motor. i'd also like to try that other one as it definitely is superior. to be honest, i dont think we really need all that powerful of a motor since we're doing additive stuff, but it never hurts.

update: i got the Kelig motor yesterday and tested it.

this one is a 2 shaft, unipolar stepper motor. i wired it up in series configuration just to test it... it worked like a dream. good power, smooth running, etc.

unless the other one really blows things out of the water, i think i'm probably going to go with the kelig one. it allows us to use the darwin design as-is, and is just generally a solid motor.

Hi Zach,

... an unipolar motor isn't so easy used for microstepping, as most discrete drivers are designed for bipolar ones.

So if you want to rise the accuracy in future designs, a bipolar motor should be better - look, if you can get the kelig motor in bipolar too ...

Viktor

i'm sorry, i wasnt being clear.

as you may or may not know, you can wire a unipolar motor as bipolar. our stepper motor drivers are currently bipolar drivers. to test this motor, i wired it in a bipolar-series setup. you can also wire it as a bipolar-parallel with the two coils in parallel instead of series. i think this makes it have less impedance and less resistance.

from what i gather, a unipolar motor is nice because it can become a bipolar with no real difference, whereas a bipolar can only be used as a bipolar period.

is there something i'm missing?

also, i have a video of it in motion when i remember to bring my camera to work.

VDX Wrote:
-------------------------------------------------------
> Hi Zach,
>
> ... an unipolar motor isn't so easy used for
> microstepping, as most discrete drivers are
> designed for bipolar ones.
>
> So if you want to rise the accuracy in future
> designs, a bipolar motor should be better - look,
> if you can get the kelig motor in bipolar too ...
>
> Viktor

Hi Zach,

... there are two types of unipolar motors: the simpler ones have only 5-wires, where the coils are in the middle connected - here you can't wire as bipolar.

The better ones have 6 wires (coil-middles separated) or even 8 wires (every coil separate) - here you can wire as uni- or bipolar.

So when you have 6 wires, its OK; with 5 wires it shouldn't work really as bipolar setup, or you would have to drive every of the four coils in bipolar mode, not only 2 coils (without the middles) as in 'normal' bipolars ...

Viktor

these are 8-wire unipolar motors, the ones a few posts earlier you said were the best ones!!

Edited 1 time(s). Last edit at 11/30/2007 10:53AM by Zach Hoeken.

Hi Zach,

... then it's a good one

With 8 wires it's your deal to drive it as uni- or bipolar, so the 'unipolar' was a bit misleading ...

Viktor

cool, got it... so its essentially a 'universal' stepper motor, since you can drive it any which way you like?

okay, here is a video of it in motion: [www.vimeo.com]

i know you cant see it, but this is being driven by the new Stepper Motor Driver!

i should have the other stepper motor on Monday or Tues, but I have a feeling that this one is going to win out. Its strong, dual shafted, 8-wire which makes it easy to configure, etc.

the loan check from RoundSparrow should be in the mail, so as soon as I get that, i'll be making that bulk purchase of stepper motors. yay!