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Non standard feedrate while threading

CommanderKeen

Plastic
Joined
May 10, 2022
I'm newish to machining, but I'm learning.

Here's the question: I'm tapping a bunch of 5/8-11 holes and having issues breaking tap teeth. Material is 1045 steel, using a 4 flute tap, lead drill is 35/64 with an 11/16 counter bore. They are blind holes. I blow the chips out thoroughly before tapping. And we hand apply cutting fluid before each hole, cleaning chips off the tap each time as well.
(We have the same issue with other sized holes as well)

Here's the question part: So on the first op,
G99 S100 F.0909 while threading

Second op (other side mirrored holes)
G98 S110 F10 while threading

Both run G84 for the cycle.

The second op cut way better than the first. Id like to know why? Of course I'm running an established program someone wrote a while ago.

Thank you for the help,
Keen
 

sinha

Stainless
Joined
Sep 25, 2010
Location
india
The second command ix exact.
The first one is approximate because 1/11 = 0.09090909
Try F = 0.090909
Feed can be specified up to four decimal digits in mm mode and six decimal digits in inch mode, in G99 mode.
 

706jim

Stainless
Joined
Jun 14, 2006
Location
Thunder Bay Canada
The second command ix exact.
The first one is approximate because 1/11 = 0.09090909
Try F = 0.090909
Feed can be specified up to four decimal digits in mm mode and six decimal digits in inch mode, in G99 mode.

Or just run 110 rpm. Feed rate is now 10.00000000000000000in/min
 








 
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