Need Help!- Starting position

[billiards]

Does anybody know.........

I am machining a 125mm square block of Aluminium. I am using a 50mm diameter slab mill (45 deg inserts) to rough cut a 122mm diameter boss. I will be using the "Mill circle" option in Conversational.

.....What defines the starting point for the cutter? The reason I ask is, I will be using 3 vices and the billets will be quite close, and I didn't want the cutter to hit the 2nd billet as it rapids down to the starting 'Safe' position.

[bloke]

If you are using cutter comp, the start will be around the three o'clock position but with the blend offset and blend overlap (found in the program parameters page) taken into account. With an offset of 1.000mm and an overlap of 0.000mm, the start point will be X= your centrepoint+your radius+1.000mm, Y= your centrepoint.

[billiards]

Thanks for that bloke.

I did the set-up today and it worked fine. After the boss I then had to put an o-ring groove in. Interestingly, I looked at the blend offset = 3mm and the blend overlap also = 3mm. The diameter of the boss is 122.96 and the o-ring groove 117.5. I would assume then that the tool clearance for the groove tool would be just a meagre .27mm?

Is the blend offset the distance the tool carries on past the start/finish point? Or does this only come into play if I am using a blend/arc?

[bloke]

The blend overlap works in circles, frames and ellipses. The best way to see how it works is to set it to a big value and watch how it behaves. Don't forget to set it back to a sensible value though!!

[SKICARB]

If you wish to have full control of where the cutter enters, even with close billet spacing, just rotate the circle -90 degrees and it will start at the 6:00 positon, or whatever degree works for your setup. Then you can increase the blend in and the offset back to large value Just remember to rotate all of the circle locations. not just one.

[jetski]

You might even try using a pattern rotate to hit it at 90 degrees and stay out of the left to right problem. I didn't read all of the posts here just some hope this helps.