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Conquering the fear of hot hide glue.

June 10, 2012

I finally got around to drilling the holes for clamping the ribs, later…  Hopefully I’ll be happy with where I put them.

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This was with a borrowed hand drill from my dad.  Fun to use.  ;)  And I loved getting to smell the aromatic cedar of my mold, again.  (Incedentally, I kept trying to google for pictures of where to place the holes when you use the tangential style of mold…  And I kept getting pictures from my own blog.  Haha,  weird!  So the answer is: I don’t know. ;) )

I also finally tackled the daunting task of using hot hide glue!  For the past year and a half, I’ve been dreading this task.  But I read online about someone’s cheap way of making a hot glue pot:
1)  Buy a $20-30 hotpot at Target (must have adjustable heat)
2)  Buy a glass jar of something small at the grocery store.   I bought a 2oz jar of pimentos.  I tried to find something that could withstand heat. So look for something that has already been sealed by heat and has the little popup indicator that tells you if the can has been opened or not.
3)  Manufacture an aluminum stand to set the jar on to [reliably] hold it up away from the main heating element of the hotpot.  I started with a rain-gutter leaf filter thing (it’s aluminum mesh) from the hardware store, and shaped/cut it how I needed.  I’m sure there are many ways to do this.
4)  Buy a cooking thermometer.
5)  Buy a 1 inch paint brush.  I’ve heard that you don’t want it to have a metal ferrule…  I don’t know why.  Perhaps to keep it from rusting? Or, I heard someone suggest that it would affect the color of the glue.

Here’s my end result:

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As it turns out (after some patient temperature experiments), it really works!  :)
Be careful to check the temperature of the glue inside of the small jar often.  I find that it tended to vary by 10 or 15 degrees between the times when the heating element kicked on.  The glue granules melt into the water in your small jar at about 140°F.  I read somewhere that you don’t want to let the glue get more than around 160°F (supposedly it won’t form a very strong bond, if you do).   And I found that it started noticeably gelling at around 120°F.  So…  I would heat the new glue up to 140 to melt it and then turn the heat down a bit to keep it from getting too hot until I needed to use it again.  Then I’d decide whether to heat it up again.

Finally… I glued the blocks into the mold:
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First, I sprayed the mold with a couple of layers of varnish. Then I inserted three “spacer screws” to raise the mold up off the table so that the mold would be mid-way up the blocks. I did this experimentally, screwing or unscrewing the screws and drawing pencil lines on the blocks and measuring how much space was above and below the lines.

Once they were glued in, I improvised a sanding board by rubber-cementing some sandpaper to a piece of glass. Then I carefully sanded the blocks down to the suggested heights: 32mm for the bottom block, 30mm for the top block, and the others somewhere in between.

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Whew! It was a little stressful, because the blocks are really part of the final instrument. So my perfectionist worries started to kick back in. (I like to think that I’m a recovering perfectionist… But building a violin tends to cause a number of relapses… ;) )

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