3 axis board

[extreme]

http://pminmo.com/3axis/3axis.htm

What do you think about this one ? It looks like it's low cost. I'm a bit confused, is this a full driver system, or does it need a3977 board also ?
Anyone tried this one ?

Thanks,
Robert

[TigerPilot]

Originally Posted by extreme http://pminmo.com/3axis/3axis.htm What do you think about this one ? It looks like it's low cost. I'm a bit confused, is this a full driver system, or does it need a3977 board also ? Anyone tried this one ?

It is a low cost driver but so is the a3977 driver. If I understood it corectly the three axis drivers are not microstepping where as the a3977 is. And, no, you don't use the a3977 in the three axis driver, you use the 4030n and the 4013n which I think are only full and half steppable.

Yoram

[H500]

If you're building a serious machine, microstepping is almost a necessity. Otherwise, resonance might spoil things for you.

[extreme]

I understand that... I own one board and my cnc is going bit crazy so want to try something else (not expensive). Since i allready got transistors for it than it would cost me some 10 $. I'd say thats cheap. Another 10-15$ for the chopper. We'll see how it works. How so I know if it has halfstep ? It should run much smoother. I think it's only a full step driver.
Besides, I cant get that allegro chip anywhere near (in my country).

Thanks,
Robert

[pminmo]

It doesn't do halfstep.

Phil

[extreme]

It works fine. I have some questions about the chopper. Too bad i has no ducumentation. I dont understand the whole thing with current limiting resistors. I thought it was designed to effective. Now, there are some 5 or six resistors per motors, should they be the same ? I dont get it. What wattage.
Then there are 6 resistors that i need to suit for my voltage. It says r= (source-10)/0.05. My source now will be 5 volts (Steppers are 2.4 v), so I get -100 Ohm resistors.
It would be awesome to get instructions.
Thanks.

[pminmo]

On current limiting resistors, when you use a power supply higher than the rated motor voltage you must limit the current to not damage the motor. Resistors are a passive current limiting device. They are simple, but not efficient. Rasing the power supply voltage allows the user to increase the step speed. A "chopper" is an active current limiting device. It senses the maximim current then opens an electronic switch for a set time interrupting current flow. Then closes the switch until the maximum current again is sensed. This all happens typically in microseconds, thousand of times a second.

Phil

[extreme]

I understand that. I'm asking about curent chopper (http://pminmo.com/3axis/3chprschematic.pdf). Pminmo, i guess you can help me. On current setting resistors, lets say I want to get 2.5 amps to my motor, so I get 5 0.47 ohm resitors (r20..16..15...3..2) and connect them like in the schematic right ? How do I choose timing ? How much voltege can I give for a 2.4 V motor (supply voltage)? Is jp1 for wires from controller ?
Like I said, there should by a manual...

Thanks,
Robert

[pminmo]

Robert,
If you want a current limit of 2.5A, I believe you need three .47 ohm resistors. The resistor bank r2, r3, r15, r16, r28 is to be treated as one value. i.e. if you can buy one .47 ohm resistor of suitable wattage you can use it instead of the bank of r2,r3,r15,r16,r28. The other two channels the same. Timing isn't critical, and really would be tweeked for optimum performance based on your power supply voltage, motor, and step rate.

I didn't design the circuit, tachus42 here at the zone did. You might email him. As for a manual, while I can't disagree, it's not been high on my priority list.

Thanks,

Phil

[extreme]

Thanks, when I finish this project maybe I will write some tips. I would have to correct it because I'm not that good on english.

[pminmo]

I can correct it, no problem. THanks, Phil

[extreme]

How do I calculate the wattage of current setting resistors on the chopper board ?