G41/G42 with diffrent D value on same tool

Hi.

Is it possible to use diffrent D values on same tool? if i use diffrent values? ex D20 D22 etc?

I want to rought the surface first and then leave 0.5mm left for a finishing cut? or do i need to move out from the part? Or do you have any better tips?


#D20 = 20MM
#D22 = 20.5MM
G0 X0 Y0
G41 G1 X57 Y0 D22 F123
G3 X-57 Y0 R57
G3 X57 Y0 R57
G3 X-57 Y0 R57 D20
G3 X57 Y0 R57 ...
ETC..

best regards

You can also just use no comp on the rougher, and comp on the finisher.

Every pass doesn't have to have cutter comp. I only use it when I
ACTUALLY need it. There is really no point.. More programming,
more offsets to worry about, lead ins.. lead outs.. screw that,
takes time, use it ONLY when I NEED it.

plus or minus 5 or 10 or 30.. Or a print I had the other day, ±1/16"
Not going to waste my time. Straight up centerline. Let her rip.

YES, on 99% of controls you can use multiple offsets. I do it, when I
NEED to. But I suggest if you are using T20, make your second offset something
that also ends with a zero.. T3, I will use D3 and D23.. Just makes it easier in
my head. Less likely to make an error. And the longer you do this, the more you
will realize that you really need to eliminate as many error points as possible..

Old Fanuc I had for only a short time, thankfully. Offsets weren't D or H.. They just
had a number. So I had height offset 1 for tool 1.. I couldn't use offset "1" for my D,
it already had a height in it. So it was 21.. But that's old school.

Set yourself a system NOW.. That makes sense(at least to you), because as you get older, and this gets less fun,
you need to be able to rely on those habits to keep you out of trouble.

Sure you can use multiple offsets, not just diameter but height as well.

I do it every time I feel absolutely lazy with finger-camming something.
Or, when some fucking bitch of a feature doesn't want to come out correctly like all the others, I just hand-poke a different D-word
into the code ( even if it's CAM generated ) to coerce it.

Remember, the D-word is modal and does not need to be on the line with the comp-on move.
All you gotta do is enter it on any block, and it will take over from the previous one.

Are your programs run by operators who have always used the same comp # as T? If yes, things can go bad very quickly. If you run them yourself, go ahead.

You might want to take note that the new offset change amount will be applied over the full trip around the bore/boss. So during your "2nd" finish pass, the cutter will be presented with a continuously thinning finish stock allowance. All the way to zero in fact. Whether and how much this will effect the circularity of the final bore will depend on a lot of things. Just something to keep in mind. Leaving the roughing comp and returning again to a newly comped finish pass will eliminate this variable. And like others have said... it is also easy enough to create a basic offset pass without comp, and then comping for finishing.

Using two comp numbers for the same tool is yet another tool in the arsenal. I think it can be used as both a creative tool and a corrective one. I've used the gradual onset of mid stream comp changes to create or correct a shallow angle in an otherwise straight wall. (Don't remember the details, just the process that solved my problem.)

Also as has been mentioned, perhaps you have a tool that is being used for finish cuts on two different runs of the same part, but the finish stock to remove or part feature difference is too great for one compensation amount to handle. Simply set one for each and control them separately. Has mad my life easier many-a-time.

Of course having a 30 tool carousel and 48 offsets makes this easier. Fanuc folk have to concern ourselves with these things. If limited by your control, don't forget that you can use an unused D offset that say a twist drill is using the corresponding H address. Meaning say T4 is a drill. That D address in it's row is available. This idea of borrowing D addresses from other tools is best left for one man shops or where changes at the control are tightly controlled.