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xairflyer
11-14-2003, 09:19 PM
Just done a search on this board on the forum and dos'nt seem to be much here on it.

Just wondering what it is like in general as it is easy made up and I can put it on stripboard no problem or i'll make a pcb if I take the urge.

(Don't say but one form Crankorgan cause he won't sell one outside the US ).

My motors are 2A unipolar x 2 and 1.4A unipolar x 1

cbcnc
11-15-2003, 02:16 AM
Xairflyer,

I have one of John's Piker boards on my CNC Router. It has operated flawlessly. I am running my machine at 24v and am using 3- 1.2a Vexta steppers. It is basic, but durable, in design in that it uses 5v, 7400 logic and TIP 120 transistors. I think that that will handle up to about 2.5a per motor with proper cooling. Some people have installed TIP 122 transistors for higher ratings, but, you are on your own about that one. I also made a daughterboard that contains the diodes and wiring connectors. You do need to use power resistors to limit the current to the motors depending on how many amps the can handle.
For the price of the board and parts from a electronics supply house I think I paid about $70.
If you need more help let me know.

Chris

xairflyer
11-15-2003, 07:51 AM
Thanks for the reply,

Yes I am fairly happy with it for my first machine which will be used mainly for cutting balsa and marking out pcb's etc.

Unfortunatly I am not allowed to buy anything from crankorgan being in europe but I have came across the circuit on the web.

Can you please check something for me.
On the pinouts for the parrallel socket, the z step pulse output is on pin 9, where as it should be on pin 8 going by the tracks.

Also is their any recomendation for the 470pf caps - polyester ceramic etc, don't think it's a problem as they are only for decoupling.

Thanks

cbcnc
11-16-2003, 02:46 AM
Hi Xairflyer,

Where on the web did you find the circuit?
I ask because that doesn't agree with the documentation and setup I have.
Going by his papers and my setup that works; the Z step pulse output is on pin #6, the Z direction output is pin #7. Pin #8 is the W step pulse output and pin #9 is the W direction control.
I used ceramic caps on all except the input which is an electrolytic cap.
Hope that helps.

Chris

xairflyer
11-16-2003, 08:13 AM
Hi,

Not sure now where I got it, it was not called the piker but it is the same circuit I'm led to believe.

I have uploaded the circuit dia and I believe the old version of the crude pcb.
Please have a look and tell me if it is the same as you have.

http://www.esatclear.ie/~xair/cncstuff.htm

MrBean
11-16-2003, 08:36 AM
Parralell port pin-outs are:

1----
2----X Step Pulse
3---Y Step Pulse
4---Z Step Pulse
5---
6---X Direction
7---Y Direction
8---z Direction
9---
10---Limit & Pause
11---X Home
12---Y Home
13---Z Home
14---
15---
16---
17---
18 to 25 Ground


Pretty sure this is how it is...

xairflyer
11-16-2003, 10:03 AM
Thanks that seems to match up with other driver boards.

Is the circuit the same as yours ?

MrBean
11-16-2003, 12:20 PM
I am still in the building stage of my CNC, about 80% done. Construction has been slower lately as I'm working on building my own driver board for Unipolar motors utilising 5804b ic's, also with variable PWM current limiting. It's all on breadboard at the minute, to facilitate easy changes. So the board will not be the same as the one you mention.

The pinouts mentioned above are what I'm using.

I've not really got into the software aspect just yet, but I think you can alter the parallel port pin configuration from some CAM programs. (correct me if I am wrong). Not too sure on this though.

Nearly all of my machine has been built from scrapped machine parts from work. So far I've paid for 3 110oz/in steppers, surplus. And the 5084b ic's. I love playing with electronics, although I'm not that good at it, but it's all learning. The free software DS Oscilloscopes have been a big help on this project, and saved me buying a real CR-Oscilloscope.

I don't suppose this helps you much, but I thought I'd share a bit of what I'm doing.

Regards to all.....

cbcnc
11-16-2003, 02:24 PM
Xairflyer,

Yes, that seems to be a copy of John K.'s plans but it is an older version as things are different in my documents that I purchased about 6 mos. ago.
What isn't on there are the diodes in series with the motor. They aren't absolutely necessary but they do help to decrease the back EMF from the windings. They would go between the windings and the TIP 120's and be pointed towards ground. I used 1N5408 diodes.
Also what you have shown is 1/4 of the circuit and is also just the circuit diagram. The circuitboard can be made how you want and you would specify the pinouts in your software.
You might have a look at this site:
http://www.buildyouridea.com/hardware/4_axis_controller/4_axis.html

Chris