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Any home built CNC'ers - Mach3 E-stop

I've got a lashed together 3 axis mill/router.

I replaced the Dremel tool with a 12V DC spindle. Now the limit switches (wired to the E-stop input) false triggers when the spindle is loaded rapidly.

I've bonded the spindle supply gnd the motor/controller ground. I've placed a 0.1uF cap across the E-stop loop at the controller. I've placed a fly-back Schotky diode across the spindle motor terminals.

By configuring the E-stop for an active low input and shorting out the switch loop I've proved its the spindle causing the false E-stop signals.

I currently run the E-stop loop open circuit with the switches closing when the axes travel too far.

Can I simply swap the E-stop pin configuration to active low and run the axis limit switches normally closed (opening when they are hit?

Any gotchas?

Thanks

Reply to
snafu
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Guessing from a distance: seperate the 12v supply from the logic/estop supply. As a check, use a completely different supply - a 12v wall plug type with adequate power if possible; or a stray computer supply. Out of curiosity, what is the 12v spindle?

Hul

snafu wrote:

Reply to
Hul Tytus

Yep, they are already separate and as it happens I'm using a wall plug unit for the e-stop etc.

The 12V spindle is a home brew thing.

I think the motor may have originally been off a large centrifugal fan, maybe automotive.The motor is about 4" diameter x 5" long with a 1/4' shaft. Its coupled via a small tooth belt to a shaft. The shaft is mounted in a couple of bearings with a rotary tool collet fitted to the bottom.

I'm only routing plastic with a 2 flute engraving bit so I don't need too much HP. The Dremel was too fast and was melting the ABS plastic so I changed to the 12V motor to drop the speed.

Reply to
snafu

I figure a follow up post is in order..........

I tried lots of different things, filter caps, changing pull up resistor values etc.

I could not get Mach3 to work with the switches set in a normally closed manner & gave up on that route.

What did work was using s shielded 2 wire cable. I kept the shield separate from the grounded switch wire, commoning them only at the interface pcb. Now its all good (for now!).

Thanks for the motivating suggestions gents.

Reply to
snafu

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