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. :D

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

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

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.

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.

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.

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.

Are the mpja people pretty reliable?
Thanks.

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

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

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

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

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.

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.

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.

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.

Thanks

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

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.

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

Anybody else had any expieriences with the two drivers? Which one is smoother, and which one would you suggest and why? My dillema here is that:
The FET has higher amperage at 8 Amps per phase and up to 500oz/in, it is unipolar and up to half step.
The Xylotec has 2.5 amps per phase bipolar and microstepping. The 2.5 amps can use almost all 2.5 amps, while the 8 amps because it is unipolar cannot give 8 amps of torque, is this right?
Anyway, each has their advantages, what I want is a smooth, accurate, driver with enough power for at least a 3' by 4' home built CNC Router, or 4' by 8'.
What do you guys think.
Thanks.

So because I have heard that microstepping actually loses torque and accuacy, should I just go for the FET because either way I would maybe run them both at half step because of an article I just read (although I might be mistaken and have not understood it fully). The article is posted in another thread in the DIY Router Section.
Another point about the FET is that it has relay already built in, although I probably won't use them anyway. The Xylotex can have one but you have to add it on.
Thank you guys so much.
Could you clarify if I am wrong about any of this?
Thanks.

So Confused.

What the heck is resonance, I have heard it everywhere?
Thanks BalsaMan

Maybe for wood or for some metal.
Thanks.

Hi Sanghera,
I may have confused you more then helped. But from my point of view, I would choose a microstep bipolar chopper drive. The microstep will give a higher degree of control and smooth rotation over the full or half step. A Bipolar drive will develop more torque and a chopper design will be more efficent. You will have to pay a bit more but the value is there.
The current rating on the motor is the max regaurdless of the applied voltage. In other words, if your motor is rated 5V at 1.5A, but you wish to run the motor at 25V you still need to limit the current to 1.5A. Running the higher voltage will speed the motor up but the torque delivered will remain the same. Think of two cars, a VW and a Corvett, both can go 60mph but one will get to that speed alot quicker.
Bill

Ok Thank you, but doesn't the 8 Amps make up for the torque lost with Bipolar? And Won't the torque be really low with the Xylotex driver because of the microstep?
Thank you very much

Also, what is the maximum router size that you would use with each of these. Also I meant to say "...but doesn't the 8 Amps make up for the torque lost with UNIPOLAR ON IT....."
Thanks.

Also, what is the maximum router size that you would use with each of these. Also I meant to say "...but doesn't the 8 Amps make up for the torque lost with UNIPOLAR ON IT....."
Thanks.

For example, I have a 80 oz/in stepper labeled 5.1V 1.0A 5.1ohms. If I apply 20V to the 5.1Ohms load the motor would draw 3.92A, or die trying. So to use a linear drive, such as the Fet drive, I will need to add a bias resistor to bring the total coil resistance to about 20ohms, I.E. 1A of current flow. This resistor will convert the excess current to heat and needs to be able to handle 20Watts of power.
On the other hand, to run a 214 oz/in motor rated at 5V 2.3A 2ohms with a 20V linear drive, 10 ohms total R is needed to mantain 2.3A. The power through the bias R will be at 46Watts.
So for smaller motors, the trade offs between the chopper and linear drives are not that big of a deal, but for a 500 oz/in motor you could end up spending alot of money on high power resistors and a large power supply that is wasting alot of power by using a linear drive.
The chopper drives control the current by switching on and off at a high rate, so limiting the current through the motor is a matter of balancing the on and off periods to average the desired current. Like a dimmer switch on a lamp, you can't see the off periods because the light bulb can't react that quick. The total effect is less light.
Bill

Originally posted by Sanghera
Also, what is the maximum router size that you would use with each of these. Also I meant to say "...but doesn't the 8 Amps make up for the torque lost with UNIPOLAR ON IT....."
Thanks.
Second part first: the current rating of your motor should stay the same reguardless of the applied voltage. If your motor is rated at 1.5A you must maintain 1.5A at what ever voltage you apply. The 8A rating of the driver board will allow you to use a larger motor with a higher rating, but you will still have to stay within that motor's max rating. The trade off is the power rating of the bias resistor for a linear drive.
First part: the size or weight of the router and gantry and force from the cutting bit will effect the size of the steppers you will need to move this total weight/force. If I am cutting balsa wood with a Dremel the total weight is less and the force to move the bit will be less then using a 2.5 Hp router cutting alum. This is where the oz/in rating of the stepper motors will come in to play.
Bill

Both driver boards you are looking at will drive steppers in the 100-200 oz/in range fairly well. With this size motor you should be able to build a table that can cut most woods and some light alum. The quailty of your table construction will play a roll here also.
Bill

So, can you clarify why the 8 amp FET can only do 100oz to 200 oz fairly well, and not the 500oz fairly well. Is there a catch to the FET other than you have to buy big resistors and big power supply and lots of energy waste? The resistors come with it anyway don't they, but I guess for a bigger motor you need a bigger resistor. I know you just explained it, but I think it might be over my head right now anyway. Also, what table size router would you suggest could be used at the biggest size? 4' by 8' possibly?
Thank you so much for all of this information.
I really appreciate it.

1) 100 or 200 oz is not 'only'. Those torques are perfect if you move the adequate masses.
2) you do *not* need big torque. Only if the mass you try to move demands that torque to move, then you need it.
3) the correct size to start is the *smallest* you can understand how to build or to put at work yourself. If you wanna go biggest, also go to good drivers like te gecko's, go to good steppers like vextas 600 oz, go to HSK linear slides.. and go to big $$$ too, specially if you make any mistake.

There is a very very very useful rule of thumb in this forum, intimately related to the word 'DIY': the rule is KISS and means 'keep it simply, stupid' (sorry, not triying to offend, that is the word :)). Lot of ppl has spent lot of (too much) money and hours and hair triying to DIY the titanic when really only needs a zodiac. Start asking yourself what do you want, go fishing with a zodiac or cruise the atlantic sea?

just my 2 cents.

Fer

On the one hand, yes you could run large 500oz/in motors with the linears but the most limiting factor will be the bias resistors. With a 500Oz/in motor you would need a resistor in the +200W range, or a string of resistors, to handel the power load. This will run you quite a few $s, $30 to $50 per motor unless you have a very deep junk box. By the time you sink that much money into the drives, you could have spent a little more and gotten Geckos that can handel the load and give you better proformance without all the waste. The table I'm working on will use 214 oz/in motors, the drivers I settled on are bare boards from Embeddedtronics.com. These are just the boards so I had to order the parts needed from Digi-key and build them. For me this isn't a big deal but I wouldn't requmend it for everyone.
Now these boards are a compromise, the motors can be wired as bipolar or unipolar. The best configuration would be parallel bipolar, but the current draw would be over 4 amps per phase. I priced the bias resistors and could not see spending more on them then the driver boards. So I found chopper drivers that would handel up to 2.5Amps. I would have just got the Zylox drivers but I like to build. So with these boards I will run the motors as series bipolar @ 30V, this will draw 2.3Amps and deliver a good amount of toqure. If I need to upgrade in the future I will sink the money into Gecko drives.
And no the resistors do not come with most the boards I have looked at. For a smaller sized motor, either design will work well, but as you start demanding more from the drives I feel it's better to invest in better drives then try to push a circuit to it's limit.
As far as the router, I am planning to use a 1 3/4HP Porter-Cable. My table will be 30 x 44.
Bill

Thank you so much,
I think I will be going with the Xylotex. I see what you mean on the megabucks for resistors. By the time you buy enough resistors for 500oz in, you will have spent enough money to buy a Gecko system possibly. I thought that you need more torque for the thicker wood and aluminum, is this still true? Or is it that wood is wood and you can cut it at any torque, doesn't matter the thickness.
Also, can this Xylotex get to 4' by 8' table. If it can do 30 x 44 or whatever shouldn't it be almost the same except for the extra weight which shouldn't be that much?
Thank you so much for all of the info.
You have helped me tremendously.

I think is not only a problem of the driver and matched steppers torque being able to move the weight. The size of a machine it's not only related to the weight but the mechanics and dynamics of the machine too: to rigidity, linearity and parallelism among others. I'm sure a Xilotex and a matched steppers can move a big mass if the mass moves with low friction. If there is too friction, probably will stall with much less mass.

4'X8' is a big machine. You will need bigger pieces, and if exist any misalignment it will manifest more severely at that ranges. Also the rigidity will be compromised if you use too little sections for the pieces. This will be more important if you plan cutting Alu, that need bigger router spindles and have a lot more resistance against the routing process.

Just plan careful. The usual way is doing a simple/little machine first and use it to cut the pieces for a second, bigger machine.

Fer

Does the quality of the movement diminish if you run a motor at a lower amperage than it's max level.
What about the lower voltage, will this just cause the motor to run slower. Would a lot of torque be lost.
Thank you very much for all of the information.

Also, what does it mean when a motor has a higher degree of movement per step to your quality and accuracy torque and whatever?
Thank you.

Newbie Question Probably. :)

Well the toqure you will need depends on alot of terms, the quality of the table and linear bearnings and the mass you are trying to move in addition to the force from the cutting bit. There can be a big difference between a dull bit and a fresh sharp bit. The thicker the wood will be an issue if you try to cut the full depth of the bit but if you take of a little at a time it won't be that big of an issue. Alot has to do with the feed rate and depth of cut, this is where experiance comes into play. If you have used a bandsaw or table router you get a feel for the amount of force and feed to make a clean cut.
As far as the size of the table and the drive, the only difference between a 12" x 12" and a 4' x 8' is the time it will take to move across the table. This is a little over simiplified but the bottom line is as long as the driver runs the stepper correctly its just a matter of distance. Now this is assuming that the bearnings are top rate. A larger table will require more attention to detail with the alignment of the guides and rails and an overall better grade of construction. That is why more often then not you will hear many tell you to start small and build on your experiance. I can't argue with that but I will say, you need to judge your skills and if you feel sure you can go for a large table by all means dream big and pay big! It is far easier to build a working table if the design is a smaller, the materials are stronger in shorter lengths and useable linear motion bearings are far cheaper.
Anyways, its all good, I've seen some guys build a router with plywood and drawer guides. Hey it works. And there are plans on the net for 4' x 8' tables, if you have the time and money I'm sure the plans would make building much easier and take the guess work out. For me it's a hobby, I don't mind making a few mistakes along the way.
Bill

Sanghera,

Do NOT build a 3x4 or 4x8 machine. Too big and by your questions it is clear that you are not ready for such a machine. I am not trying to offend you. I am saying crawl, walk, THEN run. I can almost guarantee that you will not be successful.

If you want to build a machine:

1, start no larger that 12"x24", preferably less.
2, Build a simple, wood router. Use a dremel or small laminate trimmer, or a rotozip.
3, Build first, buy a drive last.
4, read, read, read
5, for a small machine, either drive will be fine. For a large machine, niether is adequate.

Now to try and answer your question. FORGET about the amps for now. Figure out what motors you will need. If they are 1.5 amps, the ANY driver will make them produce the same torque. They just go about it a little differently. A 100 oz motor will produce 100 oz on a xylotex, or on the FET3. The xylotex is a little easier to make the motors go fast, but ultimately the same motors on the same voltage will make the same speed and torque (ignoring microstepping for now) on either of the controllers. The FET3 says 8 amps because the outputs are rated for 8 amps, but without heatsinks on the outputs (and there are none and no room for any), 3 would be pushing them hard IMO. Also, there is more to a circuit board than the rating of the components. I cant see more than a couple amps flowing thru the traces on the board without frying them.

I used the FET3. It worked perfecty. If I did it agian, I would probably go with the xylotex. BUT, the xylotex is unforgiving. if you hook up something wrong, you will be sending it back. The FET3 is more immune to newbies mistakes. This is why I said the FET3 is more robust.

Now go back up and reread this post. Take heed to the first part. Trust me on this one.

Eric

Eric, well said.
Trent

The only thing I would change about Eric's post is to make "read, read, read" #1 instead of 4. There is a ton of information out there. The more you read the more you will learn. And the less likely you'll be to make costly mistakes.

Thank you all very much for all of the support. :)
I really appreciate it.

Originally posted by Sanghera
Does the quality of the movement diminish if you run a motor at a lower amperage than it's max level.
What about the lower voltage, will this just cause the motor to run slower. Would a lot of torque be lost.
Thank you very much for all of the information.
Sanghera, there is some very good advice above; learning the dynamics of a multi-axis machine is not to be taken lightly. The learning process starts when we get the idea to build a CNC table and continues to the point we shut off the tool for the night. I like to call a failed attempt a 'learning opportunity'.
On to your questions. As you may know, motors are composed of coils and magnets. The magnetic field developed around the coils works with or against the fields from the permanent magnets to produce rotational force. In a stepper motor the permanent magnets are arranged with alternating poles, much like teeth on a gear, the number of poles will determine the step angle for the motor. The strength of the magnet fields determines the holding toque of the motor. The pattern that you energize the coils will determine the direction the motor moves. You could think of the motor as two gears where the teeth are the magnet fields working with each other, one set stationary and the other pushing and pulling against the first. Very simple model and the way that a particular motor is built will determine the cost and quality.
Your question on the Amperage: when the motor is running at lower amps the developed toque will be lower, the quality of the movement will degrade when the friction of the system, bearings, is greater then the toque. The motor will stall and lose steps. A minor reduction in amps may not even be noticed, but there will be a point at some level where the delivered toque cannot overcome the friction. This point will depend on all the loads on the motor, the static mass and the dynamic forces.
As far as the voltage, the ‘rule’ is the higher the voltage the higher the RPM. The motor windings are an inductive load; the nature of this term is they will resist a change in the current. This is referred to as a ‘lag’. As you apply a voltage to an inductor the current flow will not be instantaneously, also when you remove the voltage the current will continue to flow for a period of time (called ‘fly back’ sometimes). Chopper drives take avenge of this, by switching the voltage on and off at a high rate the coil maintains a lower average current flow. The point of using a higher voltage is to reduce this time lag; you are charging the coils up quicker, and the motor will develop the toque quicker. Same amount of toque for the amperage, just faster.
To keep thing clear I haven’t included the effects of momentum or inertial forces from the mass, these too will influence the reaction of the motor.
Hope that helped, keep at it. Half the fun with these machines is the learning.
Bill
;)

Thank you very much for your informative reply.
I understand most of what you are saying. So the step angle is determined by the number of poles. And the strength of the magnetic fields gives the holding torque. So, would the only difference between a 2.0 degree and 1.8 degree stepper motor be that the 1.8 degree has more poles than the 2.0 degree? Does this in turn affect anything else, as far as performance of the motor? Does the accuracy lower? Because there are more poles, does the magnetic field's strength increase, so it increases torque?
Thanks. I think I might be getting some of this stuff now.

Yes, the more poles the smaller the angular step. This is the resolution of the motor and to micro step you are energizing the coils in such a way that the coil’s field is balanced between the poles. In effect, creating more poles. So with a higher number of poles the accuracy is higher then a motor with fewer poles. If you ever get hold of an old VCR, tear apart the main drive motor. It is a flat configuration with a circle of fixed coils on the inside. Over these is a shell, like a lid from a jar. Inside the lip of this shell is a layer of rare earth material that has magnetic stripes. These motors are designed to allow very precise control of the speed. They don’t develop a great deal of torque, but it’s a good illustration of a high-resolution motor. Brushless fan motors are simular also, but these also have the control electronics inside it.
The torque is a function of the field strength of the permanent magnets and the coils, keep in mind that at any given time the coil is interacting with only one or two of the poles. More poles will not in itself increase the torque of a motor. On the contrary, to pack more magnets into the same size frame, smaller magnets and coils are required. So the physical size of the motor’s frame will limit the size of the magnets for a given resolution. With improvements in materials, stronger magnets can be made allowing either greater torque for a given resolution or higher resolution in the same frame size.
So you see that there are many trade offs.
Bill

Thank you very much for the info.
I really appreciate it.

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.

Hi, Balsaman
If I want to get nema23 motor for my FET3, what spec should I look for(V.,A.)?