[AT] Drill bits for drilling our old tractor steel and iron.

[Stephen Offiler]

I've done some work in this area, Dean.  Here's the long version:   my
company (Central Tools Inc) makes a variety of dial indicator sets.  We
have some dial indicator mounts based on Vice-Grips.  Here's a link:

https://www.centraltools.com/6450-brake-rotor-ball-joint-gage.html

Note in the image a black block pinned to the Vice-Grip.  That is where the
dial indicator support (our "Flex-Arm" is shown) attaches to the
Vice-Grip.  We have to drill holes in the Vice-Grip to pin the blocks on.
And we have drilled a LOT of holes in a LOT of Vice-Grips.  We've offered
this set for many years.  It was an old established product when I joined
the company 23 years ago.

Getting to the drill bits:  we use cobalt.  They don't last terribly long;
we get somewhere around 50 holes per bit.  Purchased in quantity, the bits
are only about $1.75 each so about 3.5 cents per hole.  We have a guy who
likes to resharpen them in his spare time, but it's actually more
economical for us to toss them.  Resharpened bits only go 15-30 holes and
his labor costs as much or more than a brand new bit anyway.

Not long ago we conducted a big experiment to see if we could find better
drill bits.  Understand that we use a fixture on a drill press; this is not
a rigid CNC setup; therefore we cannot use carbide.  The best modern
non-carbide drill bits use powder metallurgy to create alloys with
properties you can't get with traditional metallurgy.  Vanadium is one of
the critical factors.  If you Google "powder metal drill bit" you'll find
them readily available.  The cost is definitely at the "Snap-on" level.
The ones I experimented with were ballpark 10X the cost of my cobalt
drills, so I'd need to make 10X the holes to break even.  Results of that
experiment:  the powder metal drills lasted, at best, only modestly longer
than the cobalt.

Steve O.



On Fri, Oct 25, 2019 at 3:12 AM <deanvp at att.net> wrote:

> The closest drill bits I have that I would call decent are a set of
> reverse direction drill bits made by Irwin that are Cobalt.  I’ve used them
> for removing broken off bolts, etc. but even those are not worth writing
> home about.  On grade 5 bolts they are ok but on really hard stuff they
> don’t cut the mustard. Cobalt drill bits do have a negative and that is
> they are very brittle. But…  what brand and version of drill bits have you
> guys found that are better than the average bear and work good on our old
> iron which seems harder than the current stuff. I’m fed up with my multiple
> indexes of drill bits that might work in wood if I was patient. On steel a
> nail might work better. :-) I know its going to cost and I’m prepared for
> that. What is the “Snap-On” of drill bits?  What have you had a long and
> successful relationship with.  However, I am convinced that no matter how
> good they are I will break anything less than 1/8”  So a set from 1/8 to ½”
> in 1/64th “  increments is about my style. Or as an alternative. What
> drill bit sharpener do you recommend? I do have a lot of drill bits that
> could be sharpened. Not sure some of them are worth it though.
>
>
>
> Dean VP
>
> Snohomish, WA 98290
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