Stepper Motors


The motors I used was harvested from some old printers. They are size Nema23 and have got 6 wires. This means some checking to see which 4 wires to use. It also means that I can’t use them with any of the “normal” RepRap printers without some major modifications to the motor mountings due to the size.

For X,Y and Z – axis I used these motors:

The steppers I used for x,y and z axis

They are labelled:

  • Step-Syn,Stepping Motor
  • Type 103G771-0611
  • DC 2.46V
  • Amp 1.82A
  • Deg 1.8 deg/step
  • Made By: SANYO DENKI CO. LTD.

I collected them from old printers over the years and found that I had plenty for a printer or two in my shed. Sometimes it pays not to throw away things. (Just need a bigger shed). 🙂

I do not use the black and the white wire.

Red and red/white is used and so is Blue and blue/white

On my printer, the way I have mounted the motors (see photos), this is how the wires are connected on the ramps board.

1A = Blue

1B = Blue/White

2A = Red

2B = Red/White

Just insulate the ends of the black and the white wire.

For the extruder (E) I used this motor:

(Same motor as above can also be used)

STH-53D101

1.8deg/step, 5.0V and 0.8A

No: 01930

SHINANO KENSHI CO. LTD. Japan

6 wires, do not use the yellow and the white wire. Cut these and insulate.

1A = Blue

1B = Green

2A = Red

2B = Black

The reason I used this motor for the Extruder is because it has a toothed gear/pulley on the shaft (like a G2) and I kept the belt and the pulley it used to drive as well. The pulley has been modified to fit on a 8mm shaft (hobbed bolt) with a flat end and locking screw. The pulley is approx 50mm dia.The belt is perfect size for an extruder setup.

This motor does run quite hot. The pot on the driver is at 11 o’clock where 7 o’clock is min and 5 o’clock is max. This motor is rated at 0.8A so I guess it may be running a bit close to the limitations of what it can handle. But it works fine.

If you have not seen it yet, here is a very good page from the reprap site: Click Here

Torque Converter

It is quite important to have good strong stepper motors. If they are week you get missed steps and all sorts of problems. The not so strong stepper motors will not be able to cope with the forces that they are fighting when they change speed directions.

I am not the expert on the motors but if you are going to buy the motors get proper ones. The price is much the same so get it right first time. Do not get 6 wire or 8 wire motors, 5 wire is a big no no. 4 wire is the only way to go (as I said before the price is much the same). They are stronger and will perform better. There are lots of steppers for sale on ebay but many of them are not really suited for reprap, be careful when choosing. I make this assumption from the information I have found on the reprap site and by looking at the specs for the motors.

Here are some good strong motors from an Australian seller

What I look for in a stepper motor is: 4 wires, around 1.5 to 1.8 amp, around 3V and high torque such as 60+ oz/in or 0.40+ Nm. In a nutshell the stepper motor reaches its full torque when it is drawing the rated current. If you have a motor that is rated 60 oz/in and 2.5amps then the torque is much less if all the amp you can give it is let say 1.8amps. Remember that the pololu drivers are rated at 2amps max, so if you get some 2.5amp or higher rated motors you will not be able to get the full torque from them unless you change drivers.

1.6amp motors will be perfect as you can run them at max but still have some headroom on your drivers. In other words you are not running your drivers at max and they should not shut down due to over current or over heating as long as you use heatsinks and a fan. But you have all the torque the motors can give you if you need it.

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Why are high voltage low amps vs low voltage high amps so different….the wattage is the same…..

Imagine it like this:
You have 2 different cars. Both have a 100Hp engine. One is a sports car and the other is a 4WD diesel.
The sports car gets up into speed fast and can rev the motor quickly into the 10-15000revs range. The 4WD is much slower and may only go to 3500revs.
Now, imagine you hook up a caravan to both of these cars. A 2ton van…(this is your table) Who is going to win now?
The sports car will not cope but the 4WD will not really be much hindered by the extra weight.
Ok, the sports car is a stepper with high voltage but low amps and the 4WD has low voltage but high amps, the 4WD has got torque at low revs which is what the sports car only have at very high revs. When the stepper changes direction (low speed), the high voltage and low amps motor don’t stand a chance.

No point being a fast runner trying to catch a plane if you can’t carry your luggage.. 🙂

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Cheers

Jan (IceMan)

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