Intercon C axis turning

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suntravel
Posts: 1967
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Re: Intercon C axis turning

Post by suntravel »

tblough wrote: Fri Dec 02, 2022 5:53 pm
Scary wrote: Fri Dec 02, 2022 5:26 pm ...was inspired by your recent milled knurl only I used a threading insert..
You are going to have a huge problem with a threading insert trying to do knurling. Threading inserts do not have enough flank clearance to prevent rubbing. You'd actually have to tilt the tool to match the helix angle of the knurl.
You are right.

Can be done with G32 and changing Z start for the passes, but looks like shit



With a tilted insert it would be better, but needs one right and one left pass with two tools for a diamond pattern

90° tilted tool for broaching:



this way with a form tool, you can make gears also

Uwe
Last edited by suntravel on Sat Dec 03, 2022 2:08 am, edited 1 time in total.
Scary
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Re: Intercon C axis turning

Post by Scary »

Thats cool! Silly question time..... why do you have a seperate index on the spindle, couldnt you use the index pulse that is already on the encoder? Is it just so you can index C zero to one of the chuck jaws?
suntravel
Posts: 1967
Joined: Thu Sep 23, 2021 3:49 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
CNC Control System Serial Number: 6433DB0446C1-08115074
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
Location: Germany

Re: Intercon C axis turning

Post by suntravel »

Scary wrote: Sat Dec 03, 2022 1:53 am Thats cool! Silly question time..... why do you have a seperate index on the spindle, couldnt you use the index pulse that is already on the encoder? Is it just so you can index C zero to one of the chuck jaws?
sorry wrong video above, changed it to the one with broaching.

This one was the one with homing C



You need an input to use M92/C L1 and I found no way to trigger an Input with Index from encoder, so I use a proximity to set C0 next to the index pulse, and then find the encoders index with a loop, that is slow but precise:

N400
#109=#5043+0.1
G1 C[#109] F3600 ;exact HomePosition from encoder
IF #23408==1 THEN GOTO 500 ELSE GOTO 400
N500
M26/C ;Set exact C Zero Position

I do not want to run this loop for 359° in the worst case, takes to long, so I position the prox 2-5° before the index to speed it up.

If you drive C-axis with a 1:1 geared spindle servo, you can trigger ThirdAxisHome from the servo driver it it features an output for Z signal from the servos encoder.

But that would need a lathe without gearbox and for the size of my lathe at least a 5.5kw servo to get some low speed torque.

For example a Traub TNC30 (production lathe for max 30mm stock) drives C-axis with the spindle 7.5kw Servo and uses a 1024 encoder for turning and a second 90000 encoder for C-axis.

But this is out of my DIY hobby range :lol:

Uwe
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