DIYbanter - View Single Post

In article s.com,
(DoN. Nichols) wrote:

Hmm ... I would check to see whether a step drill (UniBit is one

Steps are nowhere near deep enough. The frame rails are at least 3/8
of an inch thick, and I got stuck with a doubled frame. I also haven't
seen a step bit that tops out at 5/8, but for what I suspect it costs I
could get my own reamer anyway.

One thing to consider is that you will probably want to reduce
the RPM as the drill moves up to larger steps, or you risk running too
fast and overheating the drill -- step drill or normal style.

Yeah, I took that into account. Started off at about 300ish RPM and
steadily went down as I got into larger sizes. Air drill, so I went
mostly by sound.

HSS drill bit. The reamer (also HSS) handled that stubborn hole just
fine.

Different angle of cut (as was mentioned by another), and you
are running it at a much slower speed (manual power, instead of air or
electric drill).

No, it was also chucked in the drill. But I did make sure to run it
much more slowly.

So, what the hell? Did it harden on me?

I suspect so.

I wasn't building up
much heat at all.

Work hardening does not need much heat.

Do you happen to know the physics involved in work hardening? I've
never understood how it's even possible. I figure if I know how the
process works I can avoid it next time.

I could pull the drill out of the hole and grab the
bit and while hot, it didn't burn me.
BTW, my "cutting fluid" was 50wt transmission oil because that's all
I had, and was recommended by the guy who loaned me the reamer. It
worked, but probably isn't optimal. For next time, what (obtainable)
fluid is suggested?

Not sure for the bridge reamer, but I would probably use
Molly-Dee (Molybdenum Disulfide in oil) with the step drill.

What's a product name I can search for? "Molly-dee" just got me some
stupid song's lyrics. Adding "oil" got me articles mentioning cutting
fluid, but nothing about where to get the stuff.
Next time I do this I'll try rigging up some sort of leverage so that
I can mash down on the drill more efficiently. If I can get some access
to machine tools I can build a setup based on the auxiliary handle my
drill already comes with. I'm thinking a clamp-on collar with an air
cylinder and three chain hooks. Chain it to the frame, use a regulator
to set the pressure I want, and pull the trigger. But I'll probably get
get a pipe and wedge it against the handle. (:

--
B.B. --I am not a goat! thegoat4 at airmail dot net