Ok, I give up. 7 start thread

Well the 5.3 has the ijnjector wiring cut, no engine harness, no ecm. A guy that does wiring said I nee the throttle pedal and throttle body for it or good luck getting it running. The injecrtor harness unplugs at the back of the intake, and they cut it at the injectors.
such a waste. I just turned down a 65 camino for $3500. I have 3 projects now, it's tempting though.
65caminjo.jpg

I ran another part and same outcome. I've not been able to figure out how to identify which thread it is. Still thinking on that one.
 
alloy said:
I ran another part and same outcome. I've not been able to figure out how to identify which thread it is. Still thinking on that one.
Click to expand...

Put a M1 after the finish pass of each thread and turn on optional stop on the controller
 
It seems like it is the last start that is infringing on the first and causing the issue. Which still makes me feel that the parameters for each of the starts are not aligned to the final outside diameter.
 
Papa Charlie said:
It seems like it is the last start that is infringing on the first and causing the issue. Which still makes me feel that the parameters for each of the starts are not aligned to the final outside diameter.
Click to expand...

I don't understand how the exact diameter of the workpiece can cause the problem.
After all, I can cut a .250-20 thread or a .500-20 thread without changing the QCGB.
Both threads have the same Z motion per spindle rev.
The same pricipals apply cutting multiple lead threads.
 
I suspect the tool is a touch too wide or the pitch is off just a bit. Just my best guess. :dunno:
 
More input from the Non-NC guy. :grin:

Assuming that the code doesn't have a "typo" in it, I'm thinking there is some (significant) non-linear (unexpected) behavior of the machine.
As I understand it, the machine is cutting air at the start of each pass. Is it possible that the machine takes more time for the Z motion and spindle rotation to "sync" than we expect? In other words, is it possible that the start closest to the part is too close for the Z motion and spindle rotation to "sync"?

If the problem was caused by a "sync" delay, wouldn't the controler throw an error code?

If my comments are causing more heat than light, just send me a PM telling me to shut-up. Will do.
 
extropic said:
I don't understand how the exact diameter of the workpiece can cause the problem.
After all, I can cut a .250-20 thread or a .500-20 thread without changing the QCGB.
Both threads have the same Z motion per spindle rev.
The same pricipals apply cutting multiple lead threads.
Click to expand...

When you cut a single start thread it doesn't matter. When you cut multiple, then they are basically independent threads. You only have so much surface area that is being occupied by the threads, If the parameters are such that the pitch is too great then there won't be sufficient surface and the last thread will infringe on the first.

At least that is my thinking. No expert by any means.
 
I am so *LOST*... I should have stayed with CNC instead of branching off...
Did programming on machining centers, very little on turning centers, never any threading.
Well it's 5:20 here, I'm headed to fridge to grab an adult beverage and to await further details - on this. :grin:
 
Papa Charlie said:
When you cut a single start thread it doesn't matter. When you cut multiple, then they are basically independent threads. You only have so much surface area that is being occupied by the threads, If the parameters are such that the pitch is too great then there won't be sufficient surface and the last thread will infringe on the first.

At least that is my thinking. No expert by any means.
Click to expand...


If you're cutting a 7 start thread and each start is 52° 360°/7 away from the next, the diameter will not cause one (and only one) to impinge on another.
All the starts can impinge on the adjacent starts as you feed in Y, but they will all be uniform, IF the starts are 52° 360°/7 apart.

I don't know NC, but I'm OK with geometry (I think :grin:).

Edited: Because 360°/7 = 51.4285714....°. Not 52°. :bang head:
 
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