RE: CNC lathe threading?

["Tim Goldstein" <timg-at-ktmarketing.com>]

I am also a Shoptask 3 in 1 owner.


TurboCNC ( www.DAKEng.com ) has treading capability built in. I have not
tried that function, but reports I have read seem to indicate it works.

Tim
[Denver, CO]
Sherline products at Deep Discount
Mach1 & DeskCNC with credit card ordering
www.KTMarketing.com/Sherline
Now selling Visual Mill


> -----Original Message-----
> Funny, I have a shoptask 3 in 1 as well.  Back to threading...
> 
> 
> I tried writing a g code program that would just cut the 
> threads with multiple passes assuming a particular machine 
> RPM.  The problem that I ran into is that EMC doesn't seem to 
> have a constant time between task starts, even if I set 
> bridgeport CYCLE_TIME to 0 and others to 0.001 and no machine load.
> 
> I've now "discovered" emcsh.  I've modified the code to cut 
> the threads based on an assumption of constant spindle RPM.  
> It cuts a pass by sending MDI commands out.  After the pass, 
> it just does a
> (while(ewait() != the_right_time +- some_small_number)) then 
> sends the MDI code for the next pass.
> 
> I'll use it like this :
>      start up tkemc
>      get the machine running
>      at a command prompt, type "thread -r machinerpm -d 
> thread_depth -t tpi..."
>      Then watch the tkemc gui follow the thread cutter's commands
> 
> I'm going to see how that works today with very low spindle 
> RPM's (120).  I've already ordered a hall effect sensor in 
> case that doesn't work.  I figure I'll modify the above code 
> to watch a parallel port input pin for transitions, calculate 
> the feed rate based on it, then start the MDI code threading 
> passes by clocking on the magnet.
> 
> RT-linux is what's giving me the most trouble.  It's not 
> nearly as simple as some other RTlinuxes.  Could anyone out 
> there give me an example that will run emcsh at a real-time 
> priority so I can translate it to my thread cutter?
> 
>    On a positive note, it's really awesome how emctask, 
> bridgeportio, etc are all separated and communicate.  It 
> makes it really nice for someone like me who wants to get in 
> the middle and play with things.
>