Holder/drill combo for tight tolerance drilling in aluminum

[Milland]

Yah know, rather than all this faffing about, a plastic shield that slips over the dome and drill, drill, drill seems like it's ultimately easier...

 

[crossthread82]

It has to stick out of the holder 2" which is why I wanted to try a larger/stiffer tool; we have to baby our 1/4" tool since its hanging way out there. I have both 1/4" and 5/16" extended reach w/stubby LoC tools coming to test.

Hopefully I get parts back from anodizing in a few days and it turns out we can just drill the holes but I'd rather try some more tools out while I wait.

Reason I say smaller tool is neither the gws or swiftcarb tools are center cutting. They need a certain amount of radius on the helix to clear the non cutting center.

 

[Mtndew]

what is the best style holder and tool for "tight tolerance" holes?
.3165 dia, +/-0.0008, .315-.355 deep, through the part, 6061.

If you're doing thousands of these holes, I'd definitely get hydraulic holders. A good carbide drill and a carbide reamer or boring head.