[Sanghera]

Hi,
I was wondering if anybody has had any expierience with the FET3 package from stepper world, and if it would be a good choice for a hobby router.
Thank you.

[Urgundiz]

Pros: It's Quick and Clean. Perfect if you do not know much about electronics.
Cons: Maybe not so cheap IMHO if you are able to scavenge some laserjets for steppers .

The board itself looks pretty interesting.

Hope it helps
/U

[balsaman]

Don't get the cruiser nema 34 motors. Very slow. The FET3 board is ok for a unipolar board. Buy some nema 23 motors from him or from ebay or whatever if you go with his board. Don't get the sp-ht.

Eric

[Sanghera]

Are the Nema 34 motors still accurate and good. Also, why is the board only ok. And, do the nema 23 motors come in 150 oz in size, and is this enough for a CNC Router.
Thanks for the replies.

[Sanghera]

Also, do you know of anybody that sells A Kit without the board. If I decide to get a Xylotex board I need all of the motors and doo dads. Do you know where I can purchase these motors and software stuff.
Thank you very much.

[ger21]

If you get the Xylotex, all you need is the motors and power supply. A lot of guys with the Xylotex get motors from Ebay, from a seller named deepgroove1. Very reasonably priced. And for a power supply, a lot of Xylotex users use this: http://www.mpja.com/productview.asp?product=12424+PS . But, you can probably find a cheaper one on Ebay if you're not in a hurry. search for 24V power supply. Get one at least 5-6 amps.
From what I've read, typically you'll get better performance with the Xylotex than the FET. But thats just what I've read, as I've never used one.

[Sanghera]

Where have you gotten some of this information about Xlyotex being better than FET. Also, do you know what software Xlyotex works on, or is it any software?
Thank you for your reply.

[Sanghera]

Are the mpja people pretty reliable?
Thanks.

[Sanghera]

Also, how big, as in torque can the motors get with the FET3 and the Xylotex?
Thanks.

[Sanghera]

Sorry for the tons of questions, but what about buying motors from somewhere other than Ebay.
Does anybody know any good sources.
Thanks.

[balsaman]

Xylotex used to sell motors, you just need to ask him.

Stepperworld has lots of motors, they just are not on his web page. I used the FET with some 100 oz nema 23 motors from him and it was a good combo. For PS you can use a 12 vPC PS for now.

The FET is probably more robust than the Xylotex but the latter uses newer technology and it's easier/cheaper to make the motors go faster with it.

100 oz motors are plenty for a home made machine.

Eric

[Sanghera]

What do you mean by more robust? So just to clarify you are saying that the Xlyotex is better?
Thanks you so much.

[ger21]

The Xylotex can only handle motors up to 2.5a/phase,and ~30V max, which limits your motor size to around 250 oz-in. I believe (not entirely sure) that the FET can handle more amps and volts. Plus, I believe the FET board has provisions for relays and limit switches right on the board. With the Xylotex, you'll have to make your own connector to plug into the board for limit switches. This is probably what Eric is talking about. One thing about the FET, you need to use current limiting resistors to maintain the proper current to the steppers. These waste a lot of energy and create a lot of heat. So you may need a bigger power supply with the FET. The Xylotex, on the other hand, is a chopper drive and regulates the current itself, so no extra power is wasted. They are much more efficient.

The motors Xylotex sells (used to sell?) are the same ones from Ebay I posted above.

Both the Xylotex and FET can be run with Mach2, TurboCNC, and many others.

You can buy Vexta motors direct form oriental motor. http://www.orientalmotor.com/products/index.htm
But Ebay, or surplus stores will be a lot cheaper. What size motors are you looking for. It seems like the bigger the motors, the harder they are to find for good prices.

[Sanghera]

Could you buy the board with limit switches already in it? The Xylotex I mean, also, what leads you to believe that the FET puts out more voltage and amperes? It says only 1.25 amps or so, but with mofset I'm not sure? So, the FET can handle bigger motors than the Xylotex. I thought that because the FET is unipolar it cannot put out as much power or amps as the Xlyotex. Which one would you guys choose for torque and performance? Thank you guys so much for all of the information that you have given me.

[Sanghera]

I am also not too worried about speed as long as it is not tooo slow, and as long as it doesn't affect accuracy. How slow are we talking about the FET or Xylotex.
Thanks.
P.S. Sorry for the tons of questions.

[Sanghera]

I read the SPEC sheet after I e-mailed, and the FET3 has 8 Amps at 40 watts per phase. The FET has Half step and the Xylotex has microstepping. Which driver is smoother? And more accurate? Also, stepper world says that the FET3 can handle 500 oz-in motors.

[Sanghera]

Thanks

[radio-op]

Hi Sanghera,
First off, I'm no expert on driver boards and I'm sure there are many on these boards that have much more experience with stepper drivers. That said, I was (still am) looking at the same issues you are.
After many hours reading threads, web sites, data sheets here are the points you may consider:
1. Motor selection will dictate the driver board selection. Most steppers are rated with Toque in oz/in for max Voltage Amps. As a rule of thumb, the higher the toque, the higher the current rating of the motor. The voltage applied will determine the time it takes the field to build in the coil, so a higher voltage will allow a shorter time interval between steps I.E. higher RPM. The resistance of the motor winding (the gage of the wire used in the windings) limits the current allowed, at some point the wire will heat to a point that it will begin to melt. So, to generate the max toque and speed for a given motor the drive and power supply must be matched to the motor.
2. A Unipolar driver design will only enegerize one winding at a time. This will lower the delivered toque. A Bipolar drive energizes two windings at a time allowing the most toque, but requiring the power supply to deliver more current (two windings).
3. Chopper boards control the current to the motor winding by turning the circuit on and off at a high rate (2 to 20kHz), the average on time determines the amount of current flowing. To lower the current applied the off time is increased. The Fet type board is an older design, enegerizing the coil circuit at full on and requires a bias resistor to control the current flow. Excess current is dissipated as heat (wasted) and requires a bias R that can handle the power load, the watt rating. This can add quite a few $s to the cost of the driver for a high current motor. Both designs allow you to use a higher then rated voltage to the winding (allowing the motor to achieve higher RPMs). The winding's DC resistance will not change, so as you raise the voltage applied, the current to the motor will rise also and must be controlled. If you run the motor at say x20 the rated voltage the current flow will raise x20 also so you will need to keep the current within the design limit of the motor.
4. Full, Half and Micro stepping are related to the way the coils are energized, the waveform. Full stepping energizes the coils at full current for each step taken. Half stepping adds half current steps to the wave and micro stepping divides the current levels between the full step points even further. A motor’s holding torque will be lower at a half or micro step point and at max at a full step point. Micro stepping allows for fine control of the transitions of movements.
5. To realize the highest speed, toque and smother rotation, run the motor bipolar at full rated amperage, up to x20 times the rated voltage wile micro stepping. Running at less then rated amperage will lower the delivered toque; the lower the voltage the longer it will take the motor’s windings to build up their fields and effect the RPMs; the steps per rotation will influence the quality of movement.
Sorry for the long-winded posting, but I hope it sheds some light on the selection of the drives.
Bill

[Sanghera]

So, are you saying run the motor at 20x what the rated voltage is on the box. Isn't that a lot of power?
Thank you very much for clarifying a lot of things.

[balsaman]

20 times the rated voltage but all stepper drives use some sort of current limiting, so the motor doesn't see that voltage all the time. Because a stepper has impedence, the higher voltage allows the motor to reach it's rated current faster, allowing higher speeds.

Tell you what. Tell us what your wanting to do, and we will help as best we can. It's hard to make a recommendation if we don't know the application.

In the mean time, read this tutorial on steppers here: http://www.cs.uiowa.edu/%7Ejones/step/

Eric