On Sat, 7 Jul 2018 13:35:35 -0500, Doug Cimperman
wrote:

On 7/7/2018 9:27 AM, Emanuel Berg wrote:
Are there any secrets to drilling holes in
steel bike frames? I have a couple of discarded
ones I can test on but I thought I'd
ask anyway.

Do you use normal power hand tools like
a drill-screwdriver and/or a drill press (if
possible with the desired bolt position)?

Do the normal rules apply, e.g. to get
a threaded hole for an M6, you first drill with
a 5.0mm drill?

And you can use chainsaw oil, right?


From playing with the metalworking machines I have...

1) A drill press w/vise will work far better than a hand drill. If you
use a hand drill in thicker (1mm) metal, the bits will go dull really
fast and tend to break as they come out the back side of the hole.

2) there are tap/drill charts online that tell you what hole size is
needed for which tap size.

3) for cutting fluid--real fluid is best but any lubricating oil you
have is way better than nothing.

4) cheap taps tend to be really ****ty--there's no other word for it.
The metal is weak, the thread fit is loose and even with lube they are
hard to turn in (being ground poorly),,, which makes breaking them even
more likely. They aren't worth stealing.

But good taps,,, cost money (just like drill bits). The $50 set at Sears
would cost you $400+ from a real machinist supply place. I would suggest
you buy a single spiral-point tap online, as you need them.

For am M6x1mm, this is what I'd get at McMaster: part # 2703A74, $10.72
https://www.mcmaster.com/#2703a74/=1dm1s97

5) and you didn't ask, but just FYI: stainless steel is a royal bitch.
It is way, way, way tougher than carbon steel. Other than an angle
grinder, cheap tools simply won't cut it. You pretty much need a BIG
drill press or mill and good cobalt/carbide drill bits w/real cutting
fluid.

I have seen posts online where people wanted to drill a hole in a cheap
stainless-steel mixing bowl, and they couldn't figure out why the drill
bit would just spin around and not go through.

Stainless is a far more complex subject. For example, we used to drill
holes in the SR-71 fuselage by hand using a simple air drill and high
speed drill bit. I've also seen (as you say) people that couldn't
drill a hole in a cooking bowl :-) The basic problem is usually that
"stainless" frequently "work hardens" very rapidly, sometimes in one
drill rotation and changes from a rather benine material to something
nearly as hard as glass.
--

Cheers,

John B.