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engineering challenge
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Fdmorrison
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(Carlos Valor)
with regard to drilling an axial hole in a bolt end
the best idea i can think of is to bolt the 5/8" bolt on to the drill
press table and hope the press table is perpendicular to the chuck
axis. got no clue how to find the bolt center so i can punch it.
You can find the bolt center with a combination square's center head. File the
bolt end flat, then mark it with magic marker before using a scribe and center
head to make crossed lines to pinpoint the center. Punch (the bolt held
vertically in a bench vise), with a prick punch, then punch again with a center
punch.
If you don't have a center head, go to a place that sells them with the marked
bolt and scribe in hand, and do it there.
At the drill press: get a piece of hardwood (2by2by8--or such, whatever's right
for the length of your bolt) that you clamp to the table, in the center so that
the drill will clear the hole in the middle of the table. Drill the wood with a
5/8 drill (or just under if you have it--19/32). From underneath the table,
insert (screw) the bolt up into the hole in the hardwood, and (from the top)
run a nut on the bolt down to the top of the wood. Washers on both ends would
help. Use spacers if there's not enough thread on the bolt (or thicker wood).
Crank the nut down firmly onto the wood.
Change the 5/8 drill bit (without moving a thing in your setup) to first a
center drill, or something small enough to be able to find the center-punched
60 deg indent you made in the bolt end. Then change that drill out for a 5/16
drill (again, without moving a thing in the setup).
Go slow; use cutting oil on the bit.
Frank Morrison
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