Single point threading (lathe) with EMC

[chafik]

I have just finished a CNC conversion with steppers for a mini lathe (on going thread at the mini lathe forum).

I was able to get the steppers and limit switch working using the EMC2
steconfig utility, it was a lot easier than I originally thought.

I've tried both Mach3 and EMC2 and I prefer EMC2 a lot more than Mach3,
I think I have pretty much settled on my choice now. But I have been banging my head for a week now trying to get single point threading working.

I am using a slotted opto switch with a one notch disc on the spindle,
that part is working, I can see the pulses at the right frequency on the output, the EMC pin is working fine as well. I checked with a regular scope and mutlimeter and also with the EMC2 built-in HAL scope.

I have a piece of gcode with several sections (facing, grooving...etc)
and it runs fine (dry run, no tool in the QCTP), the problem is when it gets to the canned G76 line, the tool goes to the right location (on screen and on the lathe), and it just sits there on that line. The spindle is running, so the pulses are going to EMC2, but I am not sure what is wrong.

The major reason for this CNC conversion was to be able to do single point
threading without all the headaches of the gear changes, manual stuff, and now I feel like I am not getting anywhere (I google'd the @#$% out of it, with no luck).

I exchanged some e-mails with a very helpful fellow on cnczone (acondit, thanks!), and he suggested that EMC might be looking for a quadrature encoder with index style output from the spindle.

Anyone have this already working, or has information on how to get single
point threading working with EMC. Is a spindle index signal enough, or a quadrature one is required? Any online definitive answers?

Thanks,

Chafik

[samco]

for emc (at the moment) you need alteast a 100 ppr + index. Most people just put an encoder that has an a,b,z(index) signals. you can get by with a,z though.

someone asked similar question
http://www.cnczone.com/forums/showth...hlight=encoder

sam

[chafik]

Sam,

Thanks for the quick reply, which with the link you provided clears up everything.

Chafik