Starting position of a CNC Mill Head

[Chris64]

Originally Posted by HuFlungDung We use a tool called an edge finder.

Thanks...that's exactly what I was wanting to know!

And as far as the Bandit goes...the saga continues. Someone cut the serial cable so now I have to figure out what the pin-outs actually are. I may be replacing that sooner than later.

[BobWarfield]

That bandit sounds really painful. If you have to debug it very much, you ought to consider going to Mach 3. You might need to purchase some Gecko drives and a breakout board, but the rest ought to be straightforward.

Best,

BW

[HuFlungDung]

Originally Posted by BobWarfield That bandit sounds really painful. If you have to debug it very much, you ought to consider going to Mach 3. ~snip~ Best, BW

Correct, Bob

[Chris64]

Originally Posted by BobWarfield That bandit sounds really painful. If you have to debug it very much, you ought to consider going to Mach 3. You might need to purchase some Gecko drives and a breakout board, but the rest ought to be straightforward. Best, BW

Well, the guy I bought it from dropped off a serial cable converter...it had the big round type plug and I expected it to be a converter from that to standard serial. Instead it was a little circuit board with a spot where I can clamp it onto the cut serial cable. It went on without any problems and now I have the pinout's with little screwdown connectors..."supposedly."

Between it's bad reputation and all the things getting shifted during the move...I'm really anxious to get this thing plugged in and see if anything even works anymore. Hopefully I'll get the phase converter this week.

But since you mentioned...who makes a cheap/good Servo driver? By driver I mean an interface between the servo and the PC. I'm not as concerned about the software as I have something I can use and modify/enhance as needed.

[HuFlungDung]

Chris,
The Bandit is primitive, but can still be useful if it runs. However, the way it is built, there is really no discrete 'PC end' connected to a 'servo driver'. All the functionality is integrated.

A jump to a Mach3 PC based cnc requires a major overhaul, and quite a bit of electrical know-how to reuse any of the power supplies and axis drives that exist in the Bandit. Even the old motors may need work (to add encoders).

When I re-retrofitted a Bandit to a Shadow, I started fresh with new motors and the new control. When I re-retrofitted another machine to Camsoft, I did the same thing. While a bit more expensive, it is nice to make your new-retrofit with relatively trouble free, drop in modules that you can buy anywhere, and that has documentation and tech support that you can get advice from, on how to hook it all up.

[Chris64]

Well, I'm just crossing my fingers that everything will work when I connect power. The servos look very good and still seem to be pretty common. I'm not quite sure how you would control a servo with a tach vs stepper motors.

I might look into making something to do this if it doesn't exist but it has to.
I was hoping someone would make a simple servo power supply with a PC connector for control. I know this would mean that ALL motion would need to be handled by the software but that's OK (I think).

Since the Bandit may be fine...my only problem with it is the size of all the damn boxes that go along with it. It is, afterall in my garage.

[BobWarfield]

If the servos are DC, you can use Gecko Drives to control them. You'll want to fit encoders instead of tachs/resolvers, which is another chore.

If your DC supply is good, and they are pretty simply, you can feed that pretty easily to the Gecko.

As far as generating step and direction info, Mach 3 does that, and sends it via a breakout board from the PC to the Gecko's (or other drivers). You can look at a lot of different breakout boards including Campbell Designs to get a feel for those.

If you just skim the docs for Mach 3, the Campbell Designs board, and the Gecko drives (G320 for servos, G2xxx for stepper motors), you will learn a lot.

Try my CNC Dictionary for terms that may be confusing:

http://www.thewarfields.com/MTCNCDictionary.htm

This is just to give you a quick overview of how to come up to speed on this sort of thing.

Best,

BW

[gbowne1]

I found this cool site when i was looking for more info on CNC & NC.

It's written by a professor in the Department of Technology at East Tennessee State University (ETSU).

http://faculty.etsu.edu/hemphill/ent...prog/index.htm

Hope this helps. Chapter 2 and 3 really helped me. :-)

Greg

[blksmith]

I have an older Bandit on a Wells index and your home position registers are set each time you power the machine up or each time you push the reset button in MDI mode. I know that on newer machines the G92 command sets your Absolute home but the older Bandits don't use a real "home" position. what they do have is a G98 command and this sets all axis registers to 0.000 What I usually do when I first set-up is find the edge of X then the edge of Y then move off a known distance from both useing MDI then push reset and this now becomes "home" and I can program from this point.

[gbowne1]

Here is some G92 / G98 reference links..

hope any of this helps.

It's in TEXT format.