At 01:32 PM 1/22/05 -0800, MICHAEL JONES wrote:
>Help.....has anyone installed weld nuts on the frame for the wooden
>floorboards? I have obviously misunderstood how this would be done. I
>suppose I could still do it the way I thought (tack welded), but as I
>removed them because of stuck screws, I found they were neatly welded to
>the floorboard support angles. Too neatly to be simply tack welded. Looked
>like a jig was used with a special welder. Any help will be greatly
>appreciated.
I don't know what this has to do with "Antifreeze Mixtures", but probably
deserves a new subject line.
These are weld nuts, originally resistance welded in place. The nut has a
male pilot diameter with a shoulder and fits in a punched hole in the frame
for location. Around the edges of the nut on the shoulder side there are
at least three small protrusions (sometimes more). Squeeze the parts
firmly together and pass a high current through it, and the nut is
effectively spot welded to the frame rail at these points. The weld is
almost invisible, even when new. This is called piloted projection welding.
For a catalog listing and picture, start with McMaster Carr here:
http://www.mcmaster.com/
In the search box type "weld nut" and click on "Find".
Then click on "Nuts".
Then click on "Weld Nuts".
Then click on "With pilot projection"
Original parts were 1/4-28 fine thread hex pattern, which unfortunately are
not listed here. If you check around you might find the proper fine
threaded part. If you have a spot welder you can probably rig a pressure
head to install these same as original, and much quicker than tack welding
each one by hand.
You may have already figured out that this weld is also not terribly
strong. Wrenching on a severely rusted bolt may break the weld nut loose
from the frame before the thread turns or before there is sufficient torque
to twist off the bolt. The weld joint should provide more toque than the
screw can take, but they often fail in this way (especially after many
years of environmental exposure (corrosion).
For purpose of restoration this (weak weld) is not necessarily a bad thing,
especially if you have broken bolts or damaged female threads. You can
usually hit a weld nut hard on the side with a cold chisel and heavy hammer
to remove it from the frame. If the frame is not badly rusted you might
remove a little rust and promptly install a new weld nut in it's
place For reconstruction it is generally easy to punch a hole in a newly
formed rail (or drill it). For original mass production the punch and
projection weld is very fast.
Barney Gaylord
1958 MGA with an attitude
http://MGAguru.com
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