Emco Compact 5 interface with linuxcnc (painless)

5/8 11 threads in plastic



sam

last video - I swear!


and on a more serious note..

So - as far as I can tell - the original control did 1/2 stepping up to about 19ipm - then full stepping from there to 30ipm. Now the lathe runs fine on full stepping from 0 to 40 (maybe 45)ipm. Half stepping only works well up to 20ipm-ish. (stalls above that)

But why stop there..

I started thinking about if linuxcnc could do that.... (without coding anything)

A couple advantages of halfstepping..
1 higher resolution 0.000273403/step vs 0.000546806 per step
2 reduced resonance.. (I have not run into this with full stepping on the lathe)

Then at normal cutting speeds - < 16ipm you get a higher resolution.

So why not have 2 stepgens running. One that half steps (type 9) with input scale of 3657.6073152 and the other full stepping (type 6) with a scale of 1828.8036576 (lathe calculation - metric screws)
Then switch between the two stepgens at a specific feed (I picked 16ipm with a hysteresis of 1ipm)
All I can say is - HAL IS AWESOME
I setup a Lut5 with Jeff E's help (thanks jeff!) that switches the printer port between the 2 stepgens.
A offset componant was used between the 2 stepgens to better align the phasing. (not tweeked 100% yet) but we jogged it around - could not tell that it was switching between the 2 stepgens and it always came back to 0.
there is a bit more than that.. (ddt for calculating the axis velocity, abs of that, comp w/hystorisis, and stuff I have forgotten already.)


And here is a halscope capture. Left side is halfstepping - right side is full stepping. The trigger is the velocity threshold.
www.electronicsam.com/images/emco/Screenshot.png

I think the offset could be tweaked more scientifically to maybe get rid of the blip. But as it is running the 4 phases directly - it didn't seem to effect the motion.

here is the initial configs.

www.electronicsam.com/images/emco/linuxc...full-half_step_test/

again - jmk and everyone that has worked on hal - Very very awesome work!

sam

The last part is sweet when you screw the nut on. Was that your first attempt at 5/8-11 threads on the Emco?

JT

heh - I don't know - that was dad playing with the lathe. I think he went in a bit too deep... but it worked

sam

Forgot to post this

So

After some slight tweaking... (it hasn't lost steps - but I wanted to get the
alignment as close to perfect as I could.) it ended up being 1/2 step
(0.000273403). Obvious I guess with the way the patterns line up...

accelerating (halfstep left side - full step right - xswitch is the velocity
trigger point)



de-accelerating (full step left - half step right xswitch is the velocity
trigger point)



sam

Sorry for double posting