[modulus]

Hi all,
Does anyone know the parameter and bit number to make G71 perform a semi-finishing (smoothing cut?) cut after performing the roughing cycle on
a Fanuc 16T control?

Thanks

Andy

[fizzissist]

Why not just use the 1st G71 pass with an offset pair with the desired difference between the "pre-finish" pass and the finish pass, and the 2nd G71 pass
with the actual offset pair?

[modulus]

I've written a kind of macro, but using VB that outputs a full G Code program when supplied with certain parameters. I want to make the process
fully automatic so that all the operator has to do is set the tool offsets. I need to use G71___U0.5W0.5__ to leave a grinding allowance (Actually a hard turning allowance) and would prefer a smoothing cut leaving this allowance on. I suppose I could run G71 twice. second time with a huge depth of cut and slightly smaller finishing allowance, but if I can just set a parameter I'd rather do that.

[fizzissist]

If you are compelled to use a macro approach, why not just add in some lines to write the real tool's offset pair into a virtual offset pair, plus or minus the values you want to use for grinding material?

My history on Fanuc macros goes back to the 6T-B, not familiar with yours, but from what I understand, you should have those addresses and variables available. Have the macro read the offsets, add or subtract the desired extra stock, then write the result to the table.. that is, if T1010 is your actual, use T1020 for the alternate, where offset pair 20 is your macro result.
My general approach is to leave as little discretionary choice to the operator, but include sufficient explanation in the comments to explain what's going on.. so you can see what you did 4 years from now too!!
Hope this helps a little.

[modulus]

Hi, I confused the issue by saying macro.
What I have actually done is write a visual basic program to calculate intersection points, stock diameter, TNR compensation (G71 does not use automatic comp, alas) etc
Then using these parameters it writes a text file for loading into the cnc
I have literally hundreds of rollers to make whose profiles are basically the same shape just with different diameters, lengths, radii, angles etc
The prog works fine, I just want the cycle to run over the profile again with the finishing allowance still on. One machine does this already (10T) the 16 T does not.
Using different offset pairs wouldn't alter anything as I just want to get rid of the witness marks where the roughing cuts were

[angelw]

Hi, I confused the issue by saying macro.
What I have actually done is write a visual basic program to calculate intersection points, stock diameter, TNR compensation (G71 does not use automatic comp, alas) etc
Then using these parameters it writes a text file for loading into the cnc
I have literally hundreds of rollers to make whose profiles are basically the same shape just with different diameters, lengths, radii, angles etc
The prog works fine, I just want the cycle to run over the profile again with the finishing allowance still on. One machine does this already (10T) the 16 T does not.
Using different offset pairs wouldn't alter anything as I just want to get rid of the witness marks where the roughing cuts were

Hi Andy,
The FS16 control can be set to use either a two block G71 or single block G71 format. What format is being used with your machine?

Regards,

Bill

[modulus]

Hi Bill,
It's running single block format at the moment for compatability.

Best regards

Andy

[modulus]

What determines when a thread gets closed? Can't see anything in the faqs