Thursday, October 6, 2016

Chair Repair 2

My friend had offered to give me his broken chair to see if I could fix it, so I jumped at the opportunity.
I discovered that the back had fallen off due to two of the bolts failing in tension. It looked like the other two had come loose at some point, so the entire load was placed on the ones which broke.

Seems like an easy fix, just get new bolts.... though drilling out the old ones doesn't look like too much fun.
The bracket removed.
Might as well tighten the rest of the screws on this thing while I'm at it.
Drilling out the bolt pieces taking care to not mess up the threads. The trick is to not use the same drill size as the bolt itself!!! That would be like those people in my lathe class who thought they were supposed to drill a 1" hole before cutting a 1" internal thread, and then the bolt just slides right through. Now of course, in this case I could have just drilled the threads out, bought longer bolts, and nuts for the other side, but that would be a last resort. I guess it would've also helped if I knew where my screw extractor was at the time...
For the new bolts, I figured I should get the strongest available which were socket head cap screws (SHCS) which I've been told are even stronger than grade 8 or whatever the metric equivalent is.
All bolted up with lock washers so they won't come loose as easily.
Connecting it back together.

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