How does a drill drift in x,y, with drill depth?
I would like to drill four 5/16 holes through a series of 1/4" alum plates (actually wide 6061 or 6063 bar), where the holes must line up later (within .001-.005), and wonder how deep I can stack these plates and stay out of trouble. The hole is a clearance hole for 5/16 threads, but a semi-tight clearance hole.
I am hoping 8 plates would be OK, with a "regular" drill, either 118 or 135 deg. If not 8 plates, about how many?
How does drift vary with speed, feed, pecks, drill point geometry, etc? Best drill? I will of course spot the hole. On a fadal, altho I have considered a P-pushing fixture on a drill press or BP to do this, as well.
On the fadal, I suppose I could come back with a long 5/16 em, which would increase the clearance a bit, but would improve alignment. But I'm hoping to not have to do this.