G code standard practice (DIY routers)

[flash319]

So I got my machine running and am very excited to get working with it. Just need to get a router for it. Anyway, I am setting up my homeing switches and stuff and it has me thinking about writing code.

Is it standard practice in the DIY router world to use the machine coordinate system (home zero) for running parts or set up a part coordinate system off of the home (world) system? I am a robot/PLC controls person and do not know much about G code practices.

I read some people do not have home switches so I assume they just zero on the stock part somewhere?

[revwarguy]

Don't think there is a standard - different folks do it different ways. A lot of it has to do with the machine's limits. Some have limit switches that prevent errors of over-running an axis, some use home switches and specify to the software the max travel on an axis. In any event, there comes a time when you want to specify the origin of a carving or engraving other than where the home position is. Just depends on the kind of work you will be doing, and personal preference, really. Some limiting mechanism needs to be in place, though. Test it and make3 sure it works!

[ger21]

My day job is programming big commercial ($100K) routers, so I set up my home machine similarly. First, I don't have home switches, but I home to the hard stops, so I have a pretty repeatably home position. Then I have X and Y fences, or stops a fixed distance from the home position, which is my 0,0 position. 99% of my parts are programmed from this 0,0 position. I also have threaded inserts in the table for bolting parts down. I have the table drawn in AutoCAD and use that as a template for drawing my parts, in reference to the origin.

[jsheerin]

I do my parts in two ways. One is for cutting 4'x4' sheets of material. I have a spoilboard that has an edge cut it in it so that I can line up the corner of the sheet to be cut at 0,0. The offsets to produce this 0,0 point are stored in an offset in mach3. I do have home switches and I home my machine when I turn it on. This also square my gantry.

The other way I do things is for more custom parts that are tougher to hold. I just zero on the part wherever I've placed zero when I programmed the part. However, if your stepper motor stalls after you do this, you are SOL unless you have home switches, have homed your machine and then zeroed on your part. If you've done that, you can re-home the machine and then have your zero point back. This just happened to me last night.

[ImanCarrot]

As rev said, it's a personal choice really.

On my Mill I'll do the drawing in AutoCAD , drag the centre of the part to the UCS X,Y Zero, export it to my CAM system then centre the tool on the mill at the part blank X,Y Zero.

On my lathe, the ABS X, Y Zero I'll set at the Stop Limit, the CAR X, Y I'll set at the spindle centre and part touch on.

All depends what you fancy, whatever works best for you and the beast oops, I mean machine