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CNC Circuit Boards for My CNC Router Table Mad Mod

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Bernd:
As I mentioned in my thread, CNC Router Table Mad Mod that I might make my own circuit boards for this project or at least make a prototype to try out the motors on the different axis's as I get them done. I may still decide to buy a whole package. It all depends on the out come of this trial.

I figure since I had the IC driver chips and the motor that somewere in a pile of papers I'd find some info on the boards. I found where I had orginally got the info. But as usall the site had disappeared. So I did some searching and finaly found it again. It's Aaron Bowser's site. He has downloadable circuit diagrams that can be used by the "toner transfer method". What I also found was several other ideas from different sites on using this particular chip. After looking at all the info I had I decided that I could come up with a board that incorporated all this info.

Now one word of warning. The UCN5804B is no longer made. I did find a place that you can purchase a simalar chip. Here's a place that you can buy the whole works from, StepGenie. The StepGenie is a 14 pin package, the UCN8504B is a 16 pin package.

Now, I did say I have programs to do the schematic layout and board design. That still left the making of the board. Since I had done this a while back, making my own boards, it's a rather messy project, plus you are working with a very highly corrosive liquid, sulfuric acid. Then I remember a freind of mine saying how he found a place on the interweb that you could down load software, the program contains both a schematic design and a circuit board design program. When your done with your design all you need to do is upload it to their site and for a fee you get your circuit boards in 2 to 3 days. So off I went on another surfing expedition and came across the ExpressPCB site. If your interested in this take a look and read how it's done. The software is free. I've already downloaded it and am playing with the software.

So as soon as I get something that's of interest electrically I'll post it in this thread.

Bernd

Gadget:
Very interesting Bernd, I went the easy way and bought a driver and motor kit but I didn't know what I was doing so a kit was the easiest. Be sure to let us know how it turns out.
Dan

Bernd:
I spent quite a few hours Sunday night surfing the interweb and reading about stepper motor driver chips. The one I have are no longer made, the Allegro UCN5804B. The closest chip is the “StepGenie” I mention in my original post. It’s not an exact duplicate. One of the differences between the two chips is that 8504 can only output 1.5 amps max at start up and has a continuous current rating of 1.25amps. This could be one reason why it’s no longer made. The “StepGenie’s” output can be connected to hexfets for higher amperage output, as high as 200amps. Also the 8504 is a 16 pin dip, were as the "StepGenie" is a 14 pin dip.

After all that research I’ve decided that it’s pointless to make my own boards for this project. I’m either going to buy a kit, since I like soldering my own boards, or buy a complete package. For now I’m going to hardwire a board so I can run the axis’ to just try them out.

I also studied the break out boards that are used to interface the computer and motor driver boards. I came across a web site in the UK that has some very interesting info. They added an opto-isolator chip. IIRC I haven’t come across any mention of opto-isolated break out boards that are available to the CNC router table hobbyist.

Here’s the web site: opto isolated break out board. Go down to the “schematic.gif” and click on that. You’ll get a schematic showing how to connect the parallel printer port to the break out board. So it looks like I’m going to go that route to make my break out board. I think this is a great idea since it isolates the computer mother board from the rest of the system.

What’s next? Well, I’m going to try and get all this info in one area so it’ll be easier to follow. In the mean time I need to work on designing the parts to hold the motors I have. I need to first figure out what NEMA size they are.

That’s it for now.

Bernd

Bernd:
I've done more surfing and found that "some" of the commerical boards have opto isolated conections to the parallel printer port. So I stand corrected in my previous statement of saying that they weren't.

Bernd

Gadget:
I bought a kit from Hobbycnc.com, it's optoisolated.

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