Programming rads without cutter comp

[sandrewb]

Is there a formula that can be used to program a rad toolpath for a lathe without using cutter comp? Or do you just have to play with numbers and keep the good old fingers crossed?

Need a .380 O/D rad using a .8 rad grooving insert in G3 format.
Yes thats in metric.

Thanks.

[mark3209]

basically if it is an outside radius such as a shoulder you add the tool radius to the .380 in your case making it 1.18mm or if it is an inside radius such as in a corner you subtract it. This would not work in your case because the insert radius is bigger than the .38mm radius.

[Delw]

add the radius of your tool to the rad of the part for od rads and subtract the rad. of your tool from the rad. of your part for i.d.

if the rad blends into an angle then there is a calculation that needs to be used, there should be a chart online somewhere.

[sandrewb]

I was on the right track then with the adding and subtracting. I didn't make this program. The guy who made it put in chamfers sent it into quality. They obviously rejected the first off since it was suppose to be programmed with rads. Now he is gone since its the weekend. First thing I tried was adding the insert rad and using 1.18 but no luck. I called him and he assured me i can get the rad with the larger insert but id have to "make up " numbers. Not a big fan of tossing pop at the wall and hoping it sticks so was hoping somewhere out there there was a formula.

Thanks for you responses and reassuring me I wasn't just brain farting on an easy fix.