NOT an auspicious beginning...

[moto633]

NOthing like jumping into CNC and then directly into making a clock!!! May the force be with you.

Keep posting pics.

Nick

[tamathumper]

Yeah, probably crazy, but if it wasn't something like making a clock, I'd be making it by hand/power-tools anyway!

[metalworkz]

Maybe the machine did not get returned to the X0Y0 home position after hitting the limits? Then if zeroed at a different point all the toolpaths would not coincide with the first ran toolpaths? Before you begin the program and usually at the same time I zero my Z axis I will set my X and Y axis at the point I want to be the HOME(X0Y0) for the program. Simply use the TAB key to bring up the MPG Mode panel in Mach3 and you can use this to jog your X axis to the location desired for X0 and then hit the 'zero X' axis button near the readout display for each axis position. Do the same for the Y axis and hit the 'zero Y' axis button. If you have zeroed your axis like this and you run into a problem during machining that causes you to stop, you can go to the MDI mode tab(along top toolbar) and click the INPUT text box which will allow you to key in commands:(You may have to hit the RESET button to clear the stopped state in Mach3)
to be sure the toolbit will clear everything first raise the Z> key in: G0Z2.0 and hit ENTER(will raise Z axis to 2.0")
bring X & Y HOME> key in: G0X0Y0 and hit ENTER(X and Y axis go HOME)
Be sure to hit the 'Rewind' button on the 'Program Run' window before starting the program again so that it starts from the beginning.
This way you can restart the program and at least know that the toolpaths should be in the same postion. I have not had any luck restarting the program from the stopped postion, but at least I know when I return home I can restart and finish a job with some confidence that the finished part will be good. I hope this helps some and pardon me if you already are using these ideas. I'm anxious to see some more parts you have made!

[tamathumper]

Maybe the machine did not get returned to the X0Y0 home position after hitting the limits? ...

After hitting the limit switch I hit Reset and jogged the Z axis up to clear the part, then I typed G0X0Y0 and during its traverse the X axis bound and lost some steps. That coupled with my newbie-ness was the real problem.

Mach3 was now out of sync with the machine, and I had to reposition it manually to X0 and hit the "Zero X" button. X, Y and Z were all zeroed appropriately before I restarted the program, but I set "Next Line" where the program had stopped so as not to go through a half-hour of machining in air.

It didn't simply cut all the spokes at the wrong X,Y position, it cut them overlapping and some of them it tried to cut in three different places, so something was *really* whacked, like absolute vs. relative positioning or ... ?

Beats me, but it cut them successfully on the second attempt, so my real challenge is learning how to reset the machine successfully after a limit switch gets hit, and maybe I need better limit switches or I need to not get so close to them during regular machining, or, or, or... For now I'll separate my toolpaths and play it safer on the expensive wood.

I think what I might do later is add a toolpath to plunge a hole in the scrap portion of the material at a known coordinate, then if there is a problem later in the cut, I can manually jog the tool back into that hole and I will know my X,Y even if steps are lost. That wouldn't do for machining metals I know, but this is woodworking and if I'm within a 64th I consider that pretty good for most of my projects.

[Thkoutsidthebox]

Those teeth look NICE!

[tamathumper]

Thanks! They're a bit furry, but it is MDF after all and I didn't touch them up much before I snapped a photo.

I'm curious about using the Exact Stop function in Mach3 just for that one toolpath to make them sharper still.

So many things to try, so little time.

[metalworkz]

In Mach3 you can set up SOFT LIMITS for the axis. I use the soft limits for my SX3 mill because I don't have limit switches on each axis. I only have a home switch on each axis. You could set the soft limits a bit short of the actual limit switch for each axis and then if a job is going to reach the soft limits Mach3 will give you a warning when the file is loaded. You can sometimes simply reposition the work so that all the toolpaths are within the soft limits.

[tamathumper]

Good point, I'd forgotten about the soft limits!