PIREP: quality drill bits matter!

[wjb]

Hi Guys,

I'd often buy my drill bits from Avery or Brown, but I had had to make a Aircraft Spruce order, so I'll pick up some drill bit stock too.

Fast forward to a few weekend ago. Working on drilling the firewall to start the mounting of FF components and I had a heck of a time drilling the firewall, especially when it was backed up by a structural component. I'm using my best SS techniques; lube, low speed, consistent pressure, sharp drills. What am I missing? The drill bits were poor quality.

I picked up a dozen #40 135 deg split points from Pan American tool (I think Avery used to stock their stuff) ... and, somehow, the impenetrable SS turned into butter. wow!

I don't know whose product ACS is stocking, but for SS, quality sure does count.

[snopercod]

I have a need (not aircraft related) to drill a bunch of holes in 1/4" thick 304 stainless steel bars. My friend who owns a CNC machine shop recommend Guhring Series 659 stubby screw machine bits. They are 3D (flutes are 3 diameters long), cobalt material and TiN coated. I ordered a couple from MSC ($12 each in 13/64 dia.) to try. I'd never heard of MSC - apparently they're the Grainger of machine tools- and just their drill bit catalog is 516 pages long! Warning: 17 MB download: MSC Industrial Direct Drill Bit Catalog