R!f@@ I'd go with the larger one (300 oz) and you should never have to worry about it being underpowered.. Most DIY CNC kits typically include 200-300 oz steppers...

 

That is why having a good sturdy base and very good bearings for the axis's makes a lot of difference on how much load is on each motor.....

Having the right amount of bearings placed in the right places can aid in reducing the load on each axis, hence reducing the load the motors have to push or pull...

X axis below

Y axis

Both together

X,Y, & Z

With the added weight of the Y & Z axis on top of the X axis, the X Axis motor does not even draw any more current than the other 2 motors when running since all the weight is supported properly on the axis bearings...

B. Morse

 

Yes lots of good bearing are needed.......when your motors are whimpy
Nice design Bmorse

 

NEMA 23 Model 57BYGH408 ( 4 pcs )
General specifications:
Step Angle 1.8°±5%
Insulation Resistant 500V DC 100MΩ Min Insulation Strength 50Hz 1Minute 500V Min
Ambient Temperature 20℃~+50℃
Temperature Rise- 80℃ Max.
Radial Play -0.02mm Max.
End Play -0.1-0.3m

• • 
    
    [*]Step Agle ：1.8°±5%
    [*]2 Phase 4 Wires
    [*]Current ：3.0A
    [*]Voltage ：3.6V
    [*]Max.Static torque ：21kg.cm
    [*]resistance 1.2 Ω mH 4
    [*]Weight ：1.5KG

The Motors are on it's way.
So what's next BMorse. The Drivers ? I guess.
So now what do I have to find.
I am giving the spec of the steppers so that you guys can suggest suitable drivers for 'em.

PS. Sorry guys for being away for a brief time, I got too much to do, besides supervising the site construction. Still not enuf time to stay logged on for too long, just checking for updates on threads that concerns me.

 

check these stepper driver boards, it is open source so circuits can be used >> http://reprap.org/wiki/Stepper_Motor_Driver_2_3#Schematic

B. Morse

 

I checked them and they did not name the IC no.
and other thing is it says 1.5A/phase

My motors can handle 3A per phase at 3V.

What did you use BMorse?

 

the ones I used are the UDN2998W, which is a dual H-bridge...... and I believe it is obsolete...
and they do say what kind of IC, and also how to correctly adjust for a different current rated motor:

The A3982 is rated for 2A per coil, so if your stepper motor drives more than that, you should adjust the chopper so that it delivers less current than that.

Allegro does have some other replacement IC's that could work (example: A3977), check out their site and get samples...

The way I did mine is not a "Normal" stepper driver, since it uses a pic micro to do the stepping and sequencing using a dual h-bridge, so unless you want to go that route, I would just do a search for "Bi-Polar Stepper motor driver IC's", which will do all the sequencing and step controls and you wont have to write any code to control the motors, just provide a step and direction input...which is how almost all stepper motor driver circuits are configured so they work with "off the shelf" software like MACH3, etc....

B. Morse

 

OK then. I am ordering via digikey for the A3977.
Will this chip suffice ?

 

Rifaa,
Have a look at these:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=TB6560AHQO-ND
They will handle 3A with PROPER HEAT SINKING!
It's hard to emphasize the heat sinking thing enough. People will fry those IC's to a crisp in nothing flat if they don't have REALLY GOOD heat sinking on them.

Personally, I think they are pretty doggone spiffy. Read the datasheet a few times - it's on the page I linked to.

I'm attaching a "Usage Considerations" sheet for the IC. You MUST read it, and follow the directions, or you risk frying the things right off the bat.

I'm just trying to save you some frustration here.

 

Hey Thanks a bunch Sgt.
I think that chip is more powerful.

retched is helping me.
He is sending me the chips. I asked him to get the TB6560 and allegro one too.
So this way I won't run short on any.

One Q? though. Would the TB have the same inputs as the allegro chip, I mean the control pins that is connected to the PC?

 

Hey Thanks a bunch Sgt.
I think that chip is more powerful.

More powerful than what?

retched is helping me.

That's what you think.

He is sending me the chips. I asked him to get the TB6560 and allegro one too.

I hope you fully specified the part number, including the suffix. There are more than one version of the TB6560 IC; the other is rated at 1.5A and is SOIC (I think).

So this way I won't run short on any.

It depends on if your heat sink is large enough. If it isn't, it won't matter how many you have on hand.

One Q? though. Would the TB have the same inputs as the allegro chip, I mean the control pins that is connected to the PC?

Why don't YOU compare the datasheets? I don't know which Allegro IC you're getting.

I don't expect them to be identical, but they will have similar functions.

 

More powerful was meant by the 3A phase current, allegro is 2.5A.

The part no. was taken from Digi key site by selecting the IC no.

retched said he will get the IC's from Digikey and had them shipped to me.
Do u think otherwise?

 

I'm just yanking your chain.

I suggest you order some of these:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=IRLU8721PBF-ND
Vdss is only 30v, but they are in a very small package, can be used as either surface mount or thru-hole, are logic level, and have a very low gate charge (8.5nC) and a very low Rds(on); 0.0084 Ohms. If you decide to build your own stepper drivers using discrete components or experiment with switching regulators, these will be a good choice.

You should pick up some fast-recovery diodes, too - various ratings from 1A to 5A.

Schottky diodes will have a lower Vf than standard fast-recovery diodes.

 

The allegro par is out of stock.
reched had shipped the part u suggested.

I will get started once they arrived

Thank you all

 

Me got the motors .

Due to been it arriving late, a compliment was sent below

So guys. I have to check 'em. Do I have to wait for the IC's to arrive or is there a way to confirm these babies operation. I have to leave feed back u know.

 

I am so jealous of you right now.

These types of motors are just way above my budget, here on the bottom of Africa.

 

There is really no way to test the motors until you get some kind of driver setup.... unless you want to manually connect the proper phase to power to see it "pulse", thats about it..... The seller can wait for their feedback, you should always wait until they give you feedback, then leave one for them, most sellers on there won't leave any feedback if you give them one first....

That was nice of them to send you a Parallel port interface module.... that would definitely be one less circuit for you to build....

B. Morse

 

I am so jealous of you right now.

These types of motors are just way above my budget, here on the bottom of Africa.

Sorry abt tht...hey, if I make a lot of dough from this project I can give you a few steppers. Who now's?

BMorse
Ahh..So I'll wait for the Driver IC's from retched....
I am working on a driver for a small one. Let me see what I can do...
will keep u posted.

 

They just went in the mail to you rifaa.

 

I got it buddy. on 31st. So it took half a month.
I'd say it was in the post office much earlier, since they delivered it to my door step. I guess it will take longer to deliver on the road since we are literally next door.

So guys what's next. You want me to check the data and go about building a circuit or does any one have a better suggestion, if so shoot it my way, I'll be more than grateful.

and retched. Thanks buddy. I owe you twice. Things a beginning to get better, Every one will get what they deserve real soon.
God bless you all.