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help with G71 roughing cycle

I have the starting point at 1.9158 so that I can rough out a 30 degree chamfer at the opening of the bore. I'M drilling the hole with 1.75" drill, then rough boring the chamfer and the smaller bore and finishing the large bore with a fillet and a chamfer on the back side. I'm then finishing the smaller bore with another tool since the 1.8917" bore has to have a finish of 32ra. The larger 2.2835" bore has an F finish so I'm not to concerned with that one. thanks for the advice i will try the corrections you suggested.

G71 just doesn't work that way. When using the G71 Cycle to rough a bore, you have to start at a diameter less than the existing hole in the part, period; its clearly set out in the Fanuc Operators Manual. Similarly, when roughing an OD Profile, you have to start from an X Start Point larger than the OD of the Work-piece.

All of the various surface finishes in the various bores can be accommodated by specifying different Feed Rates in the appropriate Blocks in the G71 Cycle Profile Description. In the G71 Cycle, these Feed Rates will be ignored and the Feed Rate specified in the G71 Block will be overriding. But when the G70 Block is executed to take a finish cut, all the Feed Rates specified in the Profile Description will be used.

Post a copy of the program that you have made modifications to and is still not working.

Regards,

Bill
 
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The very first cnc lathe I learned on was a new 1989 Mori SL35 with a Yasnac control on it.
We had the guy come in for some troubleshooting from Yamazen-Chicago and his name was Saito. Supposedly he wrote the software for that control.

Anyway long story short he showed us that if we put an R1 in the G71 line, it would do a relief cut.
Now will this work on Fanuc? I think I tried but it didn't work, I can't remember.

Hello Mtndew,
I've never heard of that before. Yasnac and Fanuc use the same syntax for the Multi Repetitive Cycles and to have the cycle cut a profile having concave features, what wmpy is referreing to as reliefe, is accomplished by specifying both X and Z in the "P" referenced block of the G71 Profile Description. It's common when using the G71 Cycle, that the tool not move in Z when the DOC is being performed and therefore, the Z coordinate in the "P" referenced block will be the same as the Z Start Position before the G71 Cyle is executed. A simpler method, so that when applying Finger Cam, is to specify the Incremental address for the Z axis and use W0.0 in the "P" referenced Block. The OP's case, the following Block would work:

N3 G00 X1.9158 W0.0

Regards,

Bill
 
New programmers often get confused while using G71.
My suggestion are as follows:
Try to visualize how roughing can be done on a manual lathe. That will decide the start X/Z of G71.
After roughing is complete, step-removal operation begins. The profile for G71 must be defined in the direction of the step-removal pass.
 
New programmers often get confused while using G71.
My suggestion are as follows:
Try to visualize how roughing can be done on a manual lathe. That will decide the start X/Z of G71.
After roughing is complete, step-removal operation begins. The profile for G71 must be defined in the direction of the step-removal pass.

Hello sinha,
I think the OP has left the building. As per his Post #16, I don't think he has taken much of the advice given.

Best regards,

Bill
 
Hello Mtndew,
I've never heard of that before. Yasnac and Fanuc use the same syntax for the Multi Repetitive Cycles and to have the cycle cut a profile having concave features

I believe the control was a Yasnac LX-3 and the "R" usage was extremely limited in how you could use it,but it worked. At the time I just did what he said because I was still brand new to cnc's at the time.

I miss that machine, they don't make them like that anymore.
 
Well, since it's just us now. Anybody use a optional block Skip other than at the beginning of the block?

I'm not and won't be in the position to test it for a while is why I'm asking.

Brent
 
I don't remember the specific Yasnac control but one of the few differences from the fanuc 6T sitting right next to it was the use of G41, G42, G43, G44 when using TNRC depending on the tool tip selected. This was mid to late 80's.

8 station turret, 12" chuck, 2" boring bars, piss poor coolant pressure, I liked it.

Brent
 
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I believe the control was a Yasnac LX-3 and the "R" usage was extremely limited in how you could use it,but it worked. At the time I just did what he said because I was still brand new to cnc's at the time.

I miss that machine, they don't make them like that anymore.

Hello Mtndew,
With the LX3 control, address "R1" was used to enable the execution of a Part Profile that had concave features. There was no other address, just R1. If omitted, what Fanuc call G71 Type 1 (monotonous direction of X increase or decrease (OD, ID roughing respectively), was enabled.

Regards,

Bill
 








 
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