can G71 work a 20-TA control

[firekoe]

have been told to use a G71 instead of G90 but can't find it in the operator's manual and was wondering how it works and if i can use it on a 20-TA control on a Kingston lathe

[stevo1]

Hmmm..Where did you get that from? G90 is for absolute mode and the opposite of that is G91 for incremental mode. They don’t have anything to do with the G71 canned cycle mode. Well they will affect the outcome of the code but relate nothing to a canned cycle. Well let me rephrase that. I have seen them on G-code system "A" under cutting cycle A but IIRC this was for threading and I don’t recall seeing this for the 20 series control. I could be wrong.

Anyway G71 should be a valid code on your control but only when using G-code system A or B, not C. Attached is an example of a G71 cycle from the programming manual.

Stevo

[stevo1]

My apologize guys I stand corrected. Sorry for posting misleading info. I should have done a bit more DD before posting. Here is the G90 that says outer/inner diameter turning in G-code system “A”. I have never used it before and would be curious to see an example of it.

Stevo

[dcoupar]

G90 is a simple box turning cycle. The following takes 2 roughing passes and a finish pass:

G00 X2.1 Z0.1
G90 X1.9 Z-2. F0.012
X1.8
X1.75 F0.008
G00 G28 U0 W0
M01

[firekoe]

i am looking for a Ex. of G71 and what it is used for

[CNCRim]

Originally Posted by firekoe i am looking for a Ex. of G71 and what it is used for

G0X2.2Z.1
G71U.2R.05
G71P1Q2U.005W.005F.008
N1G0X-.0312
G1G41Z0F.002
X0
G3X2Z-1R1
N2G1G40X2.1

It for rough out complex part... all you need is program finish path, G71 will do the rough cycle. Alot less program that way, and less programming mean less mistake equal to less crash.

[stevo1]

Thanks for the examples guys.

Stevo

[sinha_nsit]

See the attachment for more details about G71 Type I cycle.

G71 does not use radius compensation, so there is no point in commanding G41/G42 between P/Q blocks. G70 does use it. But a better way would be to command G41/G42 just before calling G70.