Just got in a PK266-02A stepper from MPJA to replace my Z axis easy-cnc stepper.

The PK266-02A is a 166oz/in stepper which is actually about 1/8" or so shorter than the easy-cnc 90 oz/in stepper so it fits perfectly as a direct replacement.

I went from 13 IPM to 42 IPM by swapping steppers and did not even have to touch my vref settings which was set to 1.2 volts for the easy cnc stepper. I could bump up the vref and probably get a little better performance yet.

These are brand new steppers, not refurbished and you can hardly complain about the price.

 

Here is the link....

http://www.mpja.com/prodinfo.asp?number=17748+MS

 

Call me crazy I just ordered 1 z is driving me crazy at only 8 ipm

 

Hmmm - the weblink doesn't seem to work.
I think they shut the website down while they're ratcheting the price up. "Why are there suddenly 50 people looking at our $12.99 steppers? Maybe we goofed on the price."

http://tinyurl.com/dhkgm3

 

Site is up.....pretty good deal but I'm not too sure.....

I was looking at out PS we got with the kit. It can supply about 2.5 Amps.....if we get larger drives that consume more power. These are rated at 1.4A per phase in bipolar (166 Oz/In) or 2A unipolar (and only 127 Oz/In).

 

Note: I swapped my Z axis stepper and did not touch my VRef. It is still set for the 90 oz/in stepper and I got a three fold increase in speed.

I have not bumped up the current to achieve the rated 1.4A per phase mostly because I have the aluminum enclosure installed over my controller now and cannot easily get to the adjustment pots without removing it, but I am running two 282 oz/in steppers at 3.6 volt VRef and the 166 oz/in stepper at 1.2 volt VRef using the standard supply and have not run into any problems so far.

MPJA also sells a beefed up power supply for about $25 if you really want to soup up your machine.

 

Thanks guys....electronics/electrical is not my area.....gee can you tell.....

If the PS is rated at 24 volts at 2.5 amps it can supply 60 Watts....right?

So if our motor is say 2 volts and 1.5 amps we are only pulling 3 watts right....or does the 3 axis controller always see 24 volts at 2.5 amps? If this is the case we would have to have 3 motors drawing more than 20 watts each...right? :?

 

No math whiz myself... Unless all three axis are moving at the same time at full speed, you are not going to fully tax the power supply. Most of the time it is only one maybe two axis moving and then probably not drawing the full amount of current that the motor can demand.

So long as you are not missing steps, you can pretty much forget about the math behind it. If I can run two 282 oz/in steppers and one 166 oz/in at 1200 ipm (which I am doing) and not miss steps due to the power supply not being able to run the steppers and the controller, I am sure you should have no problem.

My VRef settings for each stepper are 1.2v; 3.6v; and 3.6v respectively. If I remember right the Vref is 2 * desired current so my current requirements should be 4.2 Amps for the steppers which means I should be having problems if the power supply only supplies 2.5 amps, but knock on wood, I don't seem to have any issues with the power supply that I know of at least.

 

Y'know, if you order 10 of them the price drops to $9.95 each. I could use 4 of them for the CNC hotwire I'd like to build - - - - Is there anyone else interested? I don't know what the shipping costs would be to your neck-of-the-woods, (their site says $12 for 4 of them, and $19 for 10 of them, UPS ground to Calif) but there are a bunch of us here who could save a few bucks with a group-buy.

 

Sounds like a plan Dennis....I may be in need of 4 as well.

 

Thewz, I may have been talking too soon.
Seriously, at $9.95 each for 10 and $19 for shipping, the averaged cost equals $11.85 per servo. Then, since I don't get corporate rates for shipping, I'll guess it will cost me $14 to ship 4 of them, or $3.50 each. That totals $15.35 each, re-shipped and delivered to your door, so it will total ($15.35 X 4) $60.70 to you, for example, if my cost estimate is correct, and if I don't have to go buy boxes to re-ship them.
If you ordered 4 of them directly from them, that's $12.99 X 4 + $12 = $63.96, so if others buy them 4 at a time, they'll save about $3 to do a group buy, and their total shipping time would be at least doubled.

Well, it was an idea. It wasn't a good one, but it was an idea.

 

this link is working.. motors are still 12.99

http://www.mpja.com/prodinfo.asp?number=17748+MS

 

Yah....that's true Dennis....the shipping costs will add up.

I'm going big.....

I'm going up to Anaheimautomation to pickup 3 24Y504S-LW8 432oz/in monsters....for $88 bucks each....no shipping.

Matthew

 

Hmmm - Did you see these? http://www.mpja.com/prodinfo.asp?number=17456+MS
I think they're actually 82 millimeters = 3.22834646 in long, like the PDF data sheet says.
21 (Kg / cm) = 1 881.51313 (oz / in)

 

Wow!...that might be over kill and I don't think my Easy-CNC board will drive it....it's 3A....what a great deal though!

 

That looks 5X too large. Should be ~ 291 oz-in. You probably multplied by 2.54 instead of divide.

 

Kwok, 2.54 is the multiplier of inch to centimeter, not torque. The multiplier of torque is an other one. Metric torque is Kg/cm imperial torque is oz/in. Don't feel like calculating it right now, though.

Yoram

 

TigerPilot,

I didn't say 2.54 was the conversion factor for torque. The error in Dorsal's calculation was in the units. Torque is a product, so (1/cm) is not the right length unit. I originally asummed the result was 2 * 2.54 = 5.08 times too big. But that is wrong. It's 2.54 * 2.54 = 6.45 times too big.

The conversion factor for torque would be: 2.2 * 16 / 2.54 = 13.86 oz-in/kg-cm.
So 13.86 x 21 kg-cm = 291 oz-in

-Kwok

 

good lord....