Oval holes

[abcdef]

Hi guys,

I am making holes of dia .261 ....on 1" aluminum pipe (.087 " thickness) ..
these are one wall holes ..so they want them neat and clean...

i used 1/4" E -MILL ...which is giving me oval holes... then someone told me to try this ...
divide the circle (hole ) into 2 and then made 2 different toolpaths for 2 half circles....

didn't get time to try it... but i wanna ask your inputs ?

thanks

[sdopp]

sounds like your spindle or gibbs are alittle loose

try a small ramp in and out

Skip

[mhtom]

Sounds like something is not tight. Work holding must be ridget and your spindle can't have any play in it.

[dertsap]

predrill with a 1/4" drill then drill the rest with a letter g drill

[HuFlungDung]

Which direction is the short axis of the oval?

Measure the hole ( in several directions) while the part is clamped. Then, measure it when it is released.

Consider that clamping the part in a vise may spring the part enough to cause a dimensional change after clamping distortion is removed.

[tobyaxis]

Try using a 5C Collet Fixture to drill then Bore/Ream the I.D.'s The part will remain concentric and the finishes will benefit as well. Make sure you leave at least .015 for Reaming.