Spar Riveting with Harbor Frieght Press
by Rich Klee
Using a 12 Ton Press to Squeeze Your Spar Rivets.
If you have a shop press (the Harbor Freight $99 12 ton variety
is just fine) you can, with minor modifications, squeeze your
rivets very consistently and relatively quickly.
Modifications to the press - both dies must be held rigidly.
The bottom die ( 3/16" factory head rivet set) is held in a steel
plate with a 3/16'" hole drilled in it. This is in turn clamped
to the cross-member and finally the cross-member to the press
structure itself. These presses are made pretty cheaply, so the
clamps will remove any rocking out of the "base".
The ram (arbor) must also be steadied a bit - there is too much
lateral motion - I used a 4x4 drilled with the appropriate hole
for the ram and wedged it into the frame. The ram is just a mild
steel rod about .75'' dia which is jammed into the existing tube
of the press (see photo). It could just be free floating in the
4x4 hole with a return spring and a collar which would be pushed
by the original press arbor. The only trick here is to make the
hole in the 4x4 a snug fit on this .75" rod. Drill a 3/16" hole
in the end of the rod for the flat rivet set.
It will help to have a pair tables (or rollers) to act as the
infeed and out tables for the spar. Make sure that all the holes
where the bolts will go are marked (I put the bolts in those locations
to hold the flange strips rigidly together). The shop head of
the rivet should be held tightly against the base rivet set (make
the infeed and outfeed) tables tiny bit lower than the press base).
Now you only have to put together enough feeler gauges to get
.094" (1/2 of 3/16") and start pressing away leave the feeler
gauge right by the rivet (where the shop head will form) until
it starts getting tight. Check you shop head for the proper diameter
just to be sure. Gripping the jacks release knob in a pair of
vise-grips will speed up the job because you don't have to remove
the handle all the time to release the jack. The whole operation
took me about 3 hours for each spar and everyone of the rivets
came out perfect.
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