Sunday, April 25, 2010

Bolt cutter repairs

Bolt cutters, aka "The keys to the city"

Long story short, I bought these ages ago - a generic set of 900mm (36") bolt cutters with a nominal capacity of 3/8". I bought them for cutting up expanded aluminium to drop in the furnace for melting.
I loaned them out so someone could cut up some 1/4" and 3/8" reinforcing rod, and there was a hard spot in one of the 3/8" rods - the paper thin handles didn't stand up to the use and tore.

So as a result, I had to repair this tool. I cut the remaining handle piece from the head castings by careful use of a sharp cold chisel. I tested the other handle by trying to cut some 3/8" rod
and a temporary handle, it failed as well - most likely find the other handle was weakened, but not visually damaged.

I tested some of the pipe sizes in my rack and found a couple which gave good slip fits, with wall thicknesses around the 2-3mm mark.
I made some replacement handles about 8" (200mm) longer than the originals, drilled some 11mm holes and welded some 10mm nuts on so some 10mm bolts can be used to retain the pipe handles onto the head castings.

I painted the pipe handles up since they wouldn't be used too often.

Once the replacement handles were made, I built up a "tool" to hide in the end of one handle. Made from 25x6mm (1" x 1/4") flat bar, the tool serves two purposes...

a - open ended spanner to tighten/ loosen the 10mm bolts

b - a 3/8" slot to serve as a "go-no go" gauge for testing material to be cut.

Removing the tool from it's storage in the handle end.

Testing the spanner on the retaining bolts

a piece of 3/8" rod passing the "go" gauge.... compared to

a piece of 1/2" reinforcing rod failing the "no-go" gauge.

I've since loaned the colt cutters back to the guy so he could finish his job, and it worked well.

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