A few electronics questions!

[cxixer]

I am a long time reader of this forum and you are all very knowledgeable! I appreciate the valuable information on this forum but can't seem to find exactly what I'm looking for.

My background: I am a college student already running a business (www.able-audio.com). This CNC will be used to help out with that business. I have paid for this entire venture out of pocket and do not plan to change that any time soon. I understand the mechanics of building a machine, I have been working with MDF, plastics, composites, and metals for quite some time in this business and think I can build the machine nicely. I also consider myself very good with computers, I have much experience with graphics programs, and can figure out CAD/CAM. My problem is with the electronics side of the machines (subs and amps don't exactly compare to the workings of a CNC)

I am wanting to build either a 26x26" or a little smaller, 26x15 CNC (fully 3D cappable) for my first machine for mainly cutting MDF, Acrylic, and maybe small engraving in soft metal (aluminum?). I will also be using this CNC to cut parts for a larger CNC down the road when I have more room to work. I plan to fit the CNC with a small Porter Cable router. I'd like to keep this as cheap as possible, if I wanted to spend thousands, I would buy a pre-made CNC!

I really like the design and cost of this machine: mvaughn's CNC machine worklog
I realize I am looking to spend a little more because I will be purchasing the motors, and other things are different, but lets start there.

My electronics concerns:

I understand the difference between steppers and servos, and plan on using steppers. I am not sure how powerful I need, or if it needs to be unipolar or bipolar - could someone explain this? Also, does one have to spend a mint on steppers? Someone mentioned this website:
http://www.homeshopcnc.com/page5.html
Which has affordable motors. I have a few printers laying around, but the motors on them are relatively small unlike the ones I've seen used on some inexpensive machines on this forum.

I am almost completely lost when it comes to the "drivers" except to know that I need them. Each motor need it's own, correct? Are there any resources available on them that I could learn more about them? Some people have their own designed, is there a benefit to this vs. buying off the shelf?

How do I match all this up with a power supply?

I'm not sure where to source the electronics, or how to piece them all together. It would be great if someone would point me to a kit with everything I need (a cheap one). I have seen parts kits to build the machine, but never the electronics kits to move it.

The computer I would like to use is this laptop I am on. It is fast enough to run anything, but is running Vista with only usb ports. Vista has a problem with Rhino3D, and I have never seen anyone running a cnc off a usb, only parallel ports. Does anyone know of software that would work for me, or how to deal with the usb issue? I could make the drawings on my other computer and transfer them to here to hook to the CNC. If all else fails, I could set up a computer (I have tons of extra parts and cases) in the shop to be hooked to the CNC full time, but this is not my first choice.

Also, my only question about the building of the machine itself is the rollers. Many of the CNCs that I have seen have sliders cut from some plastic, but I have also seen people use rollers in several designs. Which is the best to use? Is there any reason for one design or another?


Thanks for any help on this subject, I hope to join the ranks of all of the awesome CNC DIYers on this forum pretty soon!

[cxixer]

I have answered some of my questions. Pretty much every second I’m not working, I’m reading about CNC.

To anyone who has similar questions, I’ll answer them to the best of my ability using information from this forum and other sources.


First, not that I was looking, I have found that I made the right decision going with steppers instead of servos. I was just seeing everyone else use them and they seemed easier, but I guess it is better for a smaller machine and a beginner like me anyway. Post #6 on this link tells more: What stepper motor should I use thread


Bipolar vs. Unipolar

Still couldn’t find any information after loads of searches on this forum, but I looked elsewhere to find this. http://www.linengineering.com/site/r...nipolarBipolar Simple enough.

[shashank ayyar]

i was gonna try using the guides on windows and ball bearings for the rollers.thanks for the links.useful

[bones]

Bla Bla Bla. You can argue over steppers and servo's until your face is blue.
Basicly servos are better. If they weren't you would have steppers in the large industrial machines.
But Stepper are cheap easy to tune and just work. Great for hobby stuff.

www.xylotex.com sell a 3 axis kit for $475 USD
Thats driver board, power supply and 3 stepper motors.
My friends and I use this combination on 3 routers, 2 milling machines and a 9X20 lathe. No problems at all.
There you go thats the whole electronics side done.
Plug it straight in the parallel port and the power point and your done.

Build a pc specifically to be used as a controller, otherwise if it takes and hour to cut your job then thats an hour you can't use your laptop to start designing something else.

Get linear rails from ebay and ballscrews from www.homeshopcnc.com
Preloaded nuts or double up on the nuts so you can adjust out the backlash.

The base is best made from steel as it's really riget. Angline is good for this.

The gantry can be made from alloy. 10mm or bigger is good.
Then a nice router mounted on it. The tiny little ones don't cut it.
Ha I made a funny.....hmmmmm sorry. lol.

Have a look there are a lot of guys that have done it this way and the machine will be really nice and strong. Then you will not have to worry about it wearing and you will have lots of hours out of the machine.
The best part is accurate. It will cost a bit more but truthfully it's the absolute basics I would recommend on building a machine.

If you go to lead screws, delron nuts, stepper motors out of printers, draw rails etc. They will last for a little then they will have to be replaced, not accurate and will cost you more in the end.

It's a learning curve and I've been there.

Hope it helps.

Cheers
Bones