October 11, 2005

Today was a big day.  I finished test fitting for a new grave jumper.  This one has a few new features.  The new design is stronger than the old one and has quite a bit longer throw than the model I built for the toxic barrel.  it goes from under 24" to 54" tall in a matter of about 1 second.

Side by side the two latest designs.  Both of them are shown in the down position.  The one on the right is taller and has a much shorter throw because it has to fit inside a barrel.  The one on the left is the same design, but with a much longer throw, so the head can be tucked behind a gravestone.
A big new feature of the latest design is the addition of a wood dowel to the inside of the PVC pipe where the piston attaches at either end.  I have not had a failure in the original design, but I just didn't feel like it was as sturdy as I would like it to be.  With the addition of the hardwood dowel in the center, the bolts and screws that hold the force of the piston have a lot more to bite into.
The new dowels are held in place with 2 screws that I set in flush with the pipe.  They'll keep the dowel in place while I drill and mount the bracket to hold the piston.
I redesigned the piston mount on the bottom.  It's screwed into the PVC and dowel and is extremely strong. I had to make the 2 L brackets from some aluminum stock that I picked up at the local metal supply shop.  It took about 30 minutes of grinding with my angle grinder to get 2 perfectly matched pieces with rounded edges so that the piston could swivel when activated.
I took some time to test out the design with all of the PVC pressure fitted together.  I still need to glue all of the joints so that this prop will last for years and years. You can click on the image to the right to see the new design in action.  I used a chair in place of a grave stone...	(click on image to see the grave jumper in action)

I keep improving the design with each build.  Unfortunately, the time to build one is also going up.  This last one took me 6 hours to get to the point you see in the video.  I still have about an hour or so more work to do to glue it all together...