Jake and I worked on the trebuchet some more today and were actually able to dry fire it.  Here are a couple of pictures after we got it put together.

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We then did some adjustments to make sure the arm was swinging how we wanted.  Every looked good.  So we loaded it with some weight.  We used a couple of cinder blocks.  In hind sight I think we should have used something lighter since the blocks were about 50 lbs each.  So with 100 lbs or more we lifted it up as high as we could which was only about eye level.  That should have been our clue.  We counted to 3 and let it drop.  It dropped much much faster than we expected.  The arm rollers unfortunately went off the front platform and onto the ground with such force it split the arm in half lengthwise.  It was a little scary how fast it moved.  We thought the weight would keep the arm from going too far forward.

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The next step is to rebuild the front with longer 2x4s and replace the broken arm with a 2×6.  I think there was enough force to throw a bowling ball a long ways.  Live and learn.

Jake came over today and we were able to light up the furnace again. We were pretty confident we’d have some good results with our new design. Our last attempt fizzled pretty bad. We shorted out our fan motor and had to quit. It turns out that the fan isn’t powerful enough for our new setup any way. We went back to the vacuum cleaner set to blow.

We used cinder blocks to enclose the coals with a cookie sheet dividing the furnace from the plenum underneath. It got super hot this time. We were actually able to pour some decent ingets. We still have some things to work out but we are moving along.

We poured in to a plaster mold and that seemed to work ok. I think we might need to heat it or something to help the aluminum cool more evenly.

In other news, Kami is at her 2nd to last performance of “You’re a Good Man Charlie Brown” along with my brother Alex and his girlfriend.  I’m going to go see it tomorrow with my friend Tyson and Jake and Carolyn.  I already saw a preview and it was really good so I’m sure it will be good tomorrow in full production.  I think she has a week off and then starts rehearsal for “To Kill a Mockingbird”  That should be good too.

Just a quick update on the “furnace project.”  We built a very small charcoal furnace.  We connected our vacuum to blow air into the coals and build a small steel crucible to hold the aluminum.  We were a little too impatient in getting the charcoal going so it ended up taking longer than we wanted and we ran out of time.  We did manage to get a small amount of molten aluminum however.  Jake took a bunch of pictures, I’ll post a slide show soon.  So bottom line is that it looks as if we will be able to pull this off.  We may attempt to melt some more again tomorrow.  Next up…Mold making.