Higher resolution is better up until the point where you exceed KFLOP's max count rate of 1 million quadrature counts/second at your maximum speed.  So for the example of 4000 counts/rev the max Spindle RPM would be:

1000000 / 4000 x 60 = 15,000 RPM

HTH

Regards

TK

 

I found information in another thread here that kflop can do threading on a lathe if there is an encoder mounted on the spindle to allow for synchronization.

What kind of resolution should this encoder have? 400 counts per rotation? 4000 ?

Thanks for taking the time to read this.

I suspect it would depend on many factors such as how much and quickly your Spindle Speed will vary, how low of an RPM you would be operating, your accuracy requirements, etc...  The main benefit of higher resolution is more instantaneous velocity measurement.  But some machines (not KFLOP) operate using 1 ppr and claim to work well.   So I would expect 400ppr to be more than adequate in most cases.

 

I anticipated that more is better up to a point, but can you give me any guidance on what results are to be expected with common encoder sizes. Say 100/400 LPR/PPR and 1000/4000 LPR/PPR in terms of if steps are visible in the formed thread and whether it affects functionality?


Thanks!

KFLOP is able to synchronize Z position to Spindle Position as shown there.  I was thinking more in general terms as with servo control where higher resolution helps with speed and damping control where the first difference in position indicates speed.

So now I see if you really want to operate at near zero speed like that then higher resolution would help.  In the video it looks like ~ 10 threads per inch.  So with a 400 count/rev encoder and super slow speed there would be a Z step approximately every 1 degree of spindle rotation of:

0.1 inch / 400 = 0.25 mil

Regards

TK

 

Oh, you synchronize to spindle speed and not the encoder counts? I know of Mach3 doing that, using the index pulse, but what I want to be able to do is this:

EMC2 Threading

			EMC2 Threading This feature is not available right now. Please try again later.
			View on www.youtube.com	Preview by Yahoo

 

I can't do that with my kflop?

Thanks for taking the time,

 

Ok, X and Y axis and spindle are working. I have put an encoder on the spindle motor and KMotion counts accurately when I turn it by hand.

Now, how do I set it up so that I can do a threading routine that follows the spindle encoder?

Thanks for taking the time,

Jan

Sometimes we get lucky :)

 

Thanks! That was shockingly easy :)

DSC07342-14724.JPG

Nice!  Thanks for documenting.

(FYI your site doesn't show images on my iPhone but all shows perfect on the PC/Firefox)

TK

 

Ok, after getting timing pulleys to replace the vbelt, I get excellent results threading. I put a video up here:
https://youtu.be/OIOkBdL5hGw
As you can tell, it successfully replicates the LinuxCNC behavior I wanted from here:
https://www.youtube.com/watch?v=pxXGN2SVrhU

Full details for posterity:
https://sites.google.com/site/janbeck/optical-table-cnc-lathe---spindle-encoder-for-threading

Thanks for the help again!