This may seem obvious to some of you, but it's not to me.

I now (basically) understand the construction of a router table, and all 3 axes. I have a clue about bearings, mounts, etc. I understand how the controller software drives the stepper driver card. However, there is one little detail that is nagging at me.

How does the router know where to start cutting? Basically, how does it "zero" itself?

On most printers, if the cartridge is replaced, the printer head does a little dance and resets itself to the top left corner of the paper -- everything is keyed off of this spot.

Similarly, on my old plotters, the paper would dance a little, as would the plotter head, and it would establish a starting point off of which all plotter commands were keyed.

How is this done on a homebrew router? I've heard mention of limit switches, but have no idea what that means...or if that's what does it.

Thanks for any insight you can provide.

-- Chuck Knight

To start, all the axis are sent home by a home command. Each axis eventually hits a switch when the axis is at home and the software sets the axis to zero (or some other number as chosen by the operator).

I home my machine, the axis get set to x=0, y=12, z=3 (cutter to the far left, back, and up). This allows for easiest access to the table for placement/clamping of stock.

The machine just goes from there.

Another option is to forget home switches and just move (jog) the machine to the corner of the stock and manually set the axis' to zero.

Eric

So, in other words it's keyed off whatever is the starting position. If you don't make accomodations to identify the starting position (i.e. limit switches) it just starts at whatever the "current" position is...

You mention jogging the machine -- that's basically setting it by hand?

Just want to make sure I got it right.

THANKS!

-- Chuck Knight

P.S. I really don't intend to offend with these nagging little questions -- they're just questions I have not found answers for, and this forum seems the proper place to ask them.

Yes jogging is set manually by yourself. meaning you move the machine by the software to where you want to start it. Or by crank handles on the machine. Then you zero it out in the software.