Cheap stepper motor controller and driver

[webbyguy]

I'm trying to find a cheap 3 or 4 axis stepper motor controller and driver to experiment with making a milling/cnc machine. I was hoping to find one under $50 (even if it can only drive small motors). So far I've found:

Phidget controller - $75 - 4 axis, usb (which is nice), but it isn't really for cnc, as only one axis can move at a time, so it would be more for programming.

CNC Geeker's TA8345 - $59 - parallel port, 3 axis, Has option for a step current board that decrease the current upto 1/2, when motors are in idle for all axis so as to protect expensive step motor and driver board for long time running." Adding this board adds $29. If I need it, then it is more than I would like to pay.

CNC Geeker's TB6560 - $69 - Looks to be a better version of the TA8345, but again, do I need the step current board?

Ebay's TB6560 -$70 depending on the day - I guess this is the same board as above in componets, but not in layout?

Tachus42 - 3axis - This board looks like it would be below $50 to make, but I can't find anyone who actually sells it completely made. I also can find someone who simply sells the pcb so I could build it myself.

Tom McWire's controller - 3 axis - Again looks like it would be cheap, but I can't find a pre made board or a provider of the pcb, so I could make it.

I've also found some seperates designs like the linistepper, but these seem to be more expensive when all put together.

Is there anything out there that at least has a pcb that I can work from, and get me a total cost of less the $50 without major problems. Should I just get one of the TB6560 boards and call it a day?

Thanks already for your help.

[dilbert0815]

That 50$ limit seems to call for some frustration.
I have some serious doubts you can meet that without building the controller by yourself. That seems to include making your own PCB. The PCB is a big cost block even for DIY kits.

Those chinese made controller based on TA8435, TB6560 or A3977 seems to be as cheap as you might get. I remember to have seens them starting as low as ~50$, but transport and customs may have to be accounted for.

The Phidget controller seems to not supported by any controller software like Mach3 or EMC. It comes with C libraries to roll your own system, which seems outside your scope.

The CNC Geeker board is also in eBay for 50$:
http://stores.shop.ebay.de/Univelop-...fsubZ111991419
But it seems to have two big differences to the chinese ones.
It a) misses any optocouplers to protect your PC and
b) the current is fixed, the idle-current reduction costs extra.

So when you whant to buy a ready made board you will meet a hard limit at around 50$. Even 3 channel DIY kits including PCB might be above.

Staying below 50$ requires you to make the board on your own.
It might even being difficult to get decent components for 3 channels.

[webbyguy]

So is it the CNC Geeker board that doesn't have the opto couplers for the parallel port, or is the chinese made board that doesn't have optos?

It appears you are right that the $50 limit may have to be broken. The reason I was interested in a $50 limit was that I'm planning to just build a really simple milling machine like the Tom McWire instructables design. It looks like I can use $20 in materials. I was going to pull some motors out of printers that I have lying around, and probably use the power supply that went with them. Thus, I would end up with a milling machine that costs $20 for everything but the electronics, and it seemed silly to spend $70 or $80 on electronics. I was thinking/hoping there had to be a cheaper way on the electronics.

I totaled up the cost of the components on the Tachus42 board and it was about $33 in components, so it seems conceivable to find a board kit under $50.

[webbyguy]

I just ran into this, and it may be more my speed. It is a stepper motor driver based on the ULN2003. It will only supply 500mA, but this may be enough for the small milling machine I would like to make. Anyone know of pcb boards for sale for small motor driver/ controllers like this?

[dilbert0815]

Originally Posted by webbyguy I just ran into this, and it may be more my speed. It is a stepper motor driver based on the ULN2003. It will only supply 500mA, but this may be enough for the small milling machine I would like to make. Anyone know of pcb boards for sale for small motor driver/ controllers like this?

I belive it has the same difficulty as using the Phidget controller. No probem as long as you want to make your own controller software.
But practice proves that you need step and direction input to work with the generic CNC programs.

I belive going the DIY way has some charme but also limits.
You might have to be looking at designs with L297/298.
There are also a number of designs using cheap controllers like PIC or AVR with a power driver, e.g. http://mech.vub.ac.be/teaching/info/...Electronic.htm.
Very important to use generic CNC control software is having STEP and DIRECTION, not individual bridge inputs like the one posted.
ULN2003 might be usable in conjunction with PIC/AVR designs.

As for PCB you need to make your own for price reasons.
Buying a finished PCB might account for 50% of the price of a DIY kit. Very hard chance to stay below 50$ with a finished (semi)professional PCB.
The etching of a PCB is not that hard and needs no special tools except the etching chemicals. You need no transfer foil and photochemical process. Simply drawing the board pattern with a permanent marker pen. It must have a dense ink to work but is pretty cheap to achieve and requires only drawing skills. You can also use a brush and solvent based color.

Using generic grid PCB and wire wrap might also give some price benefits.

Originally Posted by webbyguy So is it the CNC Geeker board that doesn't have the opto couplers for the parallel port, or is the chinese made board that doesn't have optos?

It's the chinese boards thats offering more here.
But as a side note the optocouplers on the linked TB6560 board are not doing galvanic isolation. Ground is connected between power and LPT. I have a TA8435 board from the same manufacturer with the same "flaw". Easily recognisable by the cheap three pin regulators on heat sinks.
The better boards use a DC/DC block to power the input side isolated.
It's the black relay-like block on the upper left edge at the 5th-axis extenton connector : http://cgi.ebay.com/4-Axis-CNC-Route...item19b94d7dd0

At least the signal lines are isolated, no chance to get runaway voltage on the LPT pins.

But the Geeker bord has not even some buffers between LPT and PC. In case a driver breaks it's not unknown to kill the PC side by getting the driver supply connected to the LPT pins.

EDIT
Another good link for (almost) DIY boards: http://pminmo.com/driver-comparison
But be warned, 3 axis + interface is ~30$ just for the PCB.
That tells you how serious to take the remark about producing yor own PCBs to go the cheap way.

EDIT2

Originally Posted by webbyguy The reason I was interested in a $50 limit was that I'm planning to just build a really simple milling machine like the Tom McWire instructables design. It looks like I can use $20 in materials. I was going to pull some motors out of printers that I have lying around, and probably use the power supply that went with them. Thus, I would end up with a milling machine that costs $20 for everything but the electronics, and it seemed silly to spend $70 or $80 on electronics.

Thrust me, that's the biggest misconception of all ;-)
The $20 are only for first visit in the hardware store.
That's only until you realise that you need some more of this & that and go again.
You will spend a lot more even on these "cheap" designs.
The driver electronics may serve you a lot longer than just for the first mill design. But that's only if you spend a little more on it initially.

It's like the frog in the hot water.
You don't count all those little single dollar bills for nitbits, even if the sum might be tremendous. But the single 100$ brick counts as it's more visible.

[webbyguy]

dilbert0815,
Thank you very much for all of the good insight.

I thought you may be interested...I looked a little more into controlling cnc setup with only direct drive of the parallel port instead of driving with the "step" and "direction" controls. It seems it can be done with EMC2, but only in 2 dimensions. It looks like it was for an etch-a-sketch controller. The basic problem is that each motor needs 4 inputs, and the parallel port has only 8 output bits. Therefore, only two motors can be controlled with this method. Net result, I can't go that route, as you said for 3 axis.

I'm going to look a little more into designs that use ULN2003 or ULN2803 for the output, but with multiplexing (through "step", "enable", and "direction" inputs) before I buy a premade one. I'll also look at designs based on L297 and L298.

[dilbert0815]

Originally Posted by webbyguy I thought you may be interested...I looked a little more into controlling cnc setup with only direct drive of the parallel port instead of driving with the "step" and "direction" controls. It seems it can be done with EMC2, but only in 2 dimensions. It looks like it was for an etch-a-sketch controller.

Why havn't I tought about that.
I'm using EMC2 and have frankly seen the stepgen component seen wired to outputs in my own HAL files.

I just warn you that EMC2's HAL is quite flexible but also quite demanding in configuration.
I have no idea if Mach3 is as flexible for discrete quadratur outputs

Originally Posted by webbyguy The basic problem is that each motor needs 4 inputs, and the parallel port has only 8 output bits. Therefore, only two motors can be controlled with this method. Net result, I can't go that route, as you said for 3 axis.

You may have to look at that configuration again.
You might be positivly surprised that they speak about not less than 3 axis control.
A standart LPT has actually 4 additional control lines that used to be used for handshake. That makes a total of 12 usable output.

Seems like this indeed a rather cheap usable solution, regardless of what's being told before.

That solution doesn't need to be restricted to ULN2x03.
There are a lot of other usable dual H-bridge drivers.
L293 being a rather cheap one, should be good for 1A (http://www.st.com/stonline/books/pdf/docs/1680.pdf ; there is even discrete a chopper circuit described).
Another one: http://cgi.ebay.de/4x-SN754410NE-QUA...item335ae907ab
You might even use a L298 as driver and control it this way from a LPT port using EMC2. Benefits is a lot more potential for supply voltage and load current. Disadvantage is that it might need a few changes in the HAL configuration.

Anoter disadvantage of these "stupid" driver design is that they don't use constant (chopper) current for the stepper control. This makes the reachable speed rather limited.
A L297/298 combination has the constant current control and whould be in the class of a TB6560, but without micro stepping.

[Doug Schwochert]

Hi All

I am looking for a stepper motor driver that does not use step direction commands from a PC. It uses a pulsed input one pulse one step
Three input terminals +CCW negative +CW Can anyone steer in the right direction where to look.

Doug

[webbyguy]

You may have to look at that configuration again. You might be positivly surprised that they speak about not less than 3 axis control. A standart LPT has actually 4 additional control lines that used to be used for handshake. That makes a total of 12 usable output.

Good catch, I can't believe I read that wrong.

I'm going to look at those inexpensive H-bridge drivers soon, but for now I wanted to add the link to the EMC2 documentation that says it can control 3 axises discretely, so I don't forget where it is. Hopefully someone already has a simple board that I can buy.

[dilbert0815]

Originally Posted by Doug Schwochert I am looking for a stepper motor driver that does not use step direction commands from a PC. It uses a pulsed input one pulse one step Three input terminals +CCW negative +CW Can anyone steer in the right direction where to look.

Hi Doug, No idea, sorry.

You might better open a new thread.
Hidden inside here the visibility or your question is rather limited.

[RomanLini]

I'll translate for him.

He needs a stepper driver with 3 inputs;
CW -> a pulse here makes a clockwise step
negative -> common ground pin for the inputs
CCW -> a pulse here makes a counterclockwise step

I have a feeling this was a standard back in the dark ages of stepper motors, 1960's or so, but I don't know any modern drivers with this interface standard.

[webbyguy]

Ok, I found some cheaper things. Here we go:

Robokits 2A driver based on L298 - $7.03 per axis. Doesn't have opto isolation, but seems like it would work for this. Also, doesn't have parallel port already. (Update: This is a fully built kit)

Robokits 5A driver board - $9.38 per axis, but still doesn't have opto isolation or a nice parallel port included. (Don't know if this is a kit or built)

Chromasystems 3axis CNC controller kit - $44.99 - This one is also featured in an instructables build. It does feature opto isolation, and includes the parallel port, but it is a kit, so I would have to build it.

It seems the ebay controller from china is still looking good at $70. It is probably worth $25 to save the time of building this guy up. I still kinda wonder if there is some design I'm missing that would be cheaper, as I keep finding things. Maybe I'll keep looking a little more.