How straight is a drill blank?
How straight is a drill blank?
(OP)
Morning / Afternoon*
I need to know the straigtness tolerance for a HSS drill blank to DIN338, anyone able to point me in the right direction?
My copy of DIN338 is conveniently in German (which I can't read) and I can't make out anything to do with straigtness as it's more to do with the geometry of twist drills.
I'm looking at using a blank to form the basis of some locating pins for the reason that they are straight, hard and have the surface finish I require thus negating the faff of making some.
*Delete as applicable
I need to know the straigtness tolerance for a HSS drill blank to DIN338, anyone able to point me in the right direction?
My copy of DIN338 is conveniently in German (which I can't read) and I can't make out anything to do with straigtness as it's more to do with the geometry of twist drills.
I'm looking at using a blank to form the basis of some locating pins for the reason that they are straight, hard and have the surface finish I require thus negating the faff of making some.
*Delete as applicable
Designer of machine tools - user of modified screws





RE: How straight is a drill blank?
RE: How straight is a drill blank?
h
RE: How straight is a drill blank?
I might take a handful to the metrologists and get a tolerance that way. Will give them something to do other than stick slip blocks together.
Designer of machine tools - user of modified screws
RE: How straight is a drill blank?
I need around 70mm plus a bit to sink into the tool. I also need a snug fit with the mating part (a stack of disks with holes in). I can get drill blanks in 6.9mm diameter which gives me 0.085mm calculated clearance (assuming a very straight pin).
Designer of machine tools - user of modified screws
RE: How straight is a drill blank?
RE: How straight is a drill blank?
RE: How straight is a drill blank?
For long, straight, and hard, I use ejector pins where possible.
Mike Halloran
Pembroke Pines, FL, USA
RE: How straight is a drill blank?
I assume it's possible to get them in annealed but ours are certainly hard. I use them to make rivet punches and quite often grind them into locating pins.
Juergen,
My DIN1414 is in German as well (I suppose it's to be expected working for a German company). I managed to make out Figure 1 as a graph of tolerances against length and diameter. It looks like they are tight enough for what I need.
Designer of machine tools - user of modified screws