slaving a motor?/cooling electrics

[country kid]

hey forum... all the electric havent made a thread for it, its a school project. im using a TB6560 4 axis board, i need to slave one motor as im using two to drive the gantry... how do you set this up in mach3..? and where is the best place to connect a second cooling fan.. the PSU is over 12V and the board already has one, i dont want to double up the board and over load it were could i connect the fan to cool the whole case (its a 12v brush less fan out of a mac computer). i gotta have this thing going for school open day so quick response please other wise im going to crash and burn..
cheers

[doorknob]

For slaving two motors to drive a single axis, see Help with Drivers & Stepper selection please.

For a quick and dirty way to generate 12 volts to drive another fan, you could put together a simple 7812 voltage regulator circuit (there is already one 7812 on the driver board to put out the voltage for the fan on the heatsink - it is possible that you could draw additional current from that regulator, however depending on the motor voltage that you are using, the onboard regulator is already dissipating a lot of watts, so it might be better to use a second regulator):

http://www.national.com/ds/LM/LM340.pdf

You should be able to get a 7812 or equivalent from any electronics hobby supplier. You will want to have a good heat sink on it. Take the input power from the motor power supply.

[ger21]

how do you set this up in mach3..?

Config > Slaving

Just make sure both motors have the exact same steps/unit, velocity, and acceleration in motor tuning.

[country kid]

thanks guys... i got it in theory know i just gotta get it working... with the cooling issue i was thinking, since the TB6560 board has a small fan on a heat sink, could i disconnect this fan and use the boards power supply to drive the main cooling fan, since all of its going to be mounted on aluminum it will cool everything to an average, not just a specific component...? thoughts please.
to give an idea of size:

the one on the board.

the one im going to add... both 12V i believe... sorry for the crummy Mobil photos.

[doorknob]

with the cooling issue i was thinking, since the TB6560 board has a small fan on a heat sink, could i disconnect this fan and use the boards power supply to drive the main cooling fan, since all of its going to be mounted on aluminum it will cool everything to an average, not just a specific component...? thoughts please.

It depends... My guess is that you may not be able to get by with that, but to know for sure you would have to do some electrical measurements.

How much current does the small fan draw? How much current will the larger fan draw instead? You could measure each of those values with a multimeter while powering each fan individually with a 12-volt DC power supply (although it might be tricky to do that with the small fan since it uses a tiny connector).

The problem to beware of is drawing too much current through the onboard 12-volt regulator, which could lead to overheating of the regulator (or, shutdown of the regulator if too much current is drawn).

With the design of that board, the onboard 12-volt regulator feeds both the small fan and also the nearby 5-volt regulator, so if you wanted to use a fan that draws more current than the small fan, you would have to know how much current is also being drawn by the 5-volt regulator in order to avoid exceeding the 1 amp rating of the 12-volt regulator.

The other factor to be aware of is that the onboard 7812 gets its power from the motor power supply - so if you have a 24-volt motor supply (for example), in order to drop the voltage to 12 volts, the 7812 ends up dissipating a significant amount of power (because it is a "linear" voltage regulator) - if the load on the 7812 approaches 1 amp, then you could be dissipating as much as 12 watts of power in the 7812, which is a huge amount of heat for such a small component. I haven't looked closely at the device ratings, but my guess is that the only way you're going to get by doing that is if you put a humongous heat sink on the 7812. As it is, the 7812 gets very hot during normal operation, so I don't think you have much headroom for drawing extra current, if at all.

Those are the electrical issues involved. I have not even addressed the TB6560 heat sink cooling issues that may be involved, but my guess is that if you can handle the electrical issues and if you can provide a decent airflow across the heat sink by using the larger fan, then you will be OK.

[country kid]

that all sounds to hard mate... might just wait on and get a 7182 regulator and run it of the spare termianls on the PSU unit... simple and effective... no chance of frying the board.

[country kid]

hey guys... i have got the motors running together but they are turning in oposite direction... the motors have their backs to each other... what must you change in mach3 to alter this..?

[4R8]

http://www.cnczone.com/forums/plasma...tml#post963680

Screen shots and all.

[doorknob]

hey guys... i have got the motors running together but they are turning in oposite direction... the motors have their backs to each other... what must you change in mach3 to alter this..?

It's early in the morning and I'm just having my first cup of coffee, so I'm a bit foggy still, but it occurs to me that if you swap the wires to one winding of one of the motors it should address that.

(be sure that the power is off before you disconnect any motor winding wires)

[country kid]

will that not fuse the windings doornob? ie:
A- swapped with b-...?

[4R8]

will that not fuse the windings doornob? ie:
A- swapped with b-...?

Simply see the correct way above the post you refer to. check the "reverse" box in mach3
The link i gave (to winegars build) has screen shots and all needed to do it correctly, it was found by a quick use of the search feature (a little memory of the thread helped though!)

[doorknob]

will that not fuse the windings doornob? ie:
A- swapped with b-...?

I did not suggest swapping A- with B-.

Rather, I suggested swapping A- with A+.

(or B- with B+)