Stepper motors

Out of all the parts to source the stepper motors have been the biggest head ache.

The beginning

First I looked over the forums for the best UK source and ZappAutomation seemed to have great reviews with the SY42STH47-1684A and SY42STH47-1684B.
For £11 each they looked like a bargin, however at the point of order the shipping cost was added on. £10.
This brought the total to £65, not as cheap as I was expecting.

As I was sourcing my hardware I noticed Thingfarm were selling stepper motors for £13 individaully or £58 for 5. Unlike ZappAutomation the shipping was only £5, perfect a total of £63.
A small saving of £2, but a saving none the less plus it cut down the number of suppliers.

First Issue

If you read my last post you'll know when I came to place my order with Thingfarm the set of 5 steppers where sold out.
Fine I'll spend the extra £2 any by them from ZappAutomation, nope they had sold out too.

I was left with 2 choices by them from Thingfarm for £13 each plus £5 delivery or find another source.

I picked the later option in the hope that Thingfarm would restock the 5 motor sets in the mean time. However every EU stepper motor source seemed to want either €20 (about £18) for each motor and/or a silly delivery cost.

Another Issue

Back to Thingfarm however just before I placed the order I did a quick google search and stumbled upon this blog by IndieFlows.
Who so happened to be the person who created the thread (link) which came to the conclusion of ZappAutomation being the best UK source of stepper motors.
Anyway the post in question which got me thing was this one. This discredits Thingfarm's stepper motors claiming nophead recommended ZappAutomation's steppers instead as Thingfarm's aren't ideal for the job.

Now I must have read the thread in question half a dozen times and I never noticed the conlusion Thingfarm's weren't ideal.
So I decided to pick through the thread one more time. For some reason I had over looked this paragraph from nophead
I was referring to the eBay ones but the Thingfarm ones do seem to be similar. It is almost impossible to get 2A from a Pololu / Stepstick, even with a heatsink. Since the current available is limited, the torque from these high current motors will be be limited to about 1.65/2.5 * 48 / 43 i.e. 74% of the torque you can get from the Zapp ones. I think that would limit the extruder max flow rate and for a given torque the drivers will run a lot hotter.

Now I read that paragraph before as just saying the eBay ones weren't ideal.
So I went back to Thingfarm's stepper motor page (link), which seemed to lack the specifics merely saying see download tab for datasheet.
At the time of writing this there is no download tab.
Not one to give up easy I decided to check there North America site.
On the stepper motor page (link) there is a download tab.

Finally I got the specs Thingfarm's stepper motors.
In short they are
Rated Voltage - 3.1
Rated Current - 2.5
Holding Torgue - 4800g/cm

Now I can see why nophead wouldn't recommend them as they need 0.5 more amps then the stepper drivers can give to achieve the torque rating.

What now?

So back to looking for another source.
In a last ditch attempt at finding a source I decided to post for help on the RepRap forums (link to thread).

Thankfully devijvers (you might notice I've posted his name before, he's becoming a real savour) recommended ruben-ikmaak on the #reprap IRC channel.

So off I went to the IRC channel.
Within a few minutes of sending him a message I got a reply and within a few more minutes he gave me a brillant price and quoted 2 seperate shipping costs.

It turned out the stepper motors he (I think it was a he) was selling where the ZappAutomation stepper motors I was looking at to start with...

Paid via Paypal, information sent and was told the latest it would be shipped would be tomorrow.

Success

I ended up paying a little more then I was expecting, but atleast all my parts should arrive at a similar time.

Cost of Stepper Motors (x5) - €82 = £74.26
Total Cost so far -  £372.55