On Aug 28, 1:30 pm, Fortunat1 wrote:
Charles Vincent wrote . net:


...


Couple of things I'm still uncertain of, though. The steel parts have
quite a tight fit on the bolts. Obviously any paint on the inside of
these holes is simply going to be forced out when I push a bolt through.
this is normal?

Others may have a better answer, like they did about the drill bits,
but I would mask off the inside of the holes so as to not get paint
on them and use never seize on the bolt shaft. A little dab will do
ya.

There are some places where never seize should not be used. A
fellow I know used it on his spark plugs on his Stinson. Normally
that's OK (I think) but his heads had been rethreaded with helicoils
and the helicoils backed out when the engine was running.

Also, there's a small ridge formed on the edge of each hole.

I think that's called a burr--sometimes called a wire-edge.
It is metal that has been cold-rolled around the corner
on the edge during drilling. Usually it is much bigger on the
exit side than on the entrance side. If drilling down a pilot hole,
that effect can be minimized by drilling part-way through from
each sides. Without a pilot hole alignment is too difficult.


I figure
it's OK to leave the excess material there for a couple of reasons, one,
it provides more material for the bolt to rest against, and two it
won'ts interfere with tightening the bolts down since there will only be
a washer up against the hole anyway.

I don't follow you here. Doesn't the burr stick up above the flat
surface?
Won't that interfere with proper seating of the washer?

If it is poor practice to leave the ridge on the edge, what's the best
method for getting rid of it? Aside from a special machien, I thought of
carefully cutting it down with a large dril bit, but I'd be afraid of
doing some damage to the part.
Any suggestions?

Draw filing is a technique wherein the file is held with both hands,
one
on the handle and one on the tip and drawn across a flat surface as
if slicing with a drawknife, to remove high spots. I've never gotten
the hang of it myself. The parts could also be lapped on wet/dry
sandpaper on a very flat surface like a one-foot square marble
tile, or a good quality table-saw or jointer table. Of you could
use a fine rat-tail, cylindrical or half-round file, through the
hole.
A hand grinder,even a dremel, used very carefully would do the
trick too. A conical stone would do a nice job.

Using a very large countersink bit would do it too, a very large
drill bit would do the same but is more likely to grab and tear.

I don't think that slightly chamfering the holes would hurt at
all. The sharp edge or wire is a stress riser that is relieved by
chamfering, though in this case I don't think it is a serious
issue.

If you practice on scrap, you won't have to practice on your
project!

--

FF