I spent the weekends of 28/29 October and 4/5 November up at the shop building more tools for handling big molds. This time the topic was lifting hoists. We use these for the lift-and-rollover maneuver where you lift a 300 lb mold, roll it 180 degrees, slide another mold under it, and lower the raised mold so as to bond together the shells inside the two molds.
We've been using engine hoists for this work, and that sort of works out OK, but it's troublesome in a shop as small as mine. Engine hoists are far larger and heavier than we need, and are difficult to manuever into the ends of my shop. They also use up a lot of space.
So, anyhow, over the last two weekends I designed and welded up a couple of hoists. Each of these is nothing more than an 8-foot stanchion of 2" square steel tubing supported at the bottom on a simple 3-wheel base, with a pair of pulleys in a bracket at the top. A come-along bolts to the side of the stanchion, and its cable loops over the pulleys. The idea is that you station one of these hoists at each end of the mold, hook the cables onto the mold's rollover spindles, and raise the mold to rollover height.
All this stuff totals about $100 worth of stuff for each hoist, which is about what you can get a Harbor Freight engine hoist for, but it is far better suited to my available floor space, or lack thereof.
After building and testing two of these hoists, I went ahead and disassembled one of the three engine hoists I have hanging around. I saved all the steel tubing for future projects, but I dumped the leaky hydraulic ram into the trash.
One other thing I did was to reinforce the caster carriages that the wing molds rest on when I need to roll them around. The carriages were just strong enough to support one pair of wing molds, but it was pretty clear from the way they were deflecting that they wouldn't support all four wing molds. And one of the things I want to use my new stick hoists for is to put all four wing molds in one four-mold-high stack to maximize my floor space.
Here's the pictures:
The upper half, showing the bracket and pulleys. The cable goes up along one corner and down along the opposite corner. I used two pulleys because it was cheaper than one big pulley. The pulley wheels themselves came from cheap 2" pulley blocks from Harbor Freight. I just ground the heads off their 4mm axle rivets, popped out the rivets, and then drilled the bores up to 1/4".
The bottom half of the hoist, showing the base, three castering wheels, and come-along. All this junk is zapped together with my 125 amp MIG welder.
Lunch time! Yours truly in grungies and tempered-lens dork glasses.
A closeup of one of the bases. I made the bases out of 2-1/2" tubing left over from the wing spar jigs of an HP-18 project. If I'd had more of the 2" tubing I probably would have used that, but the 2-1/2" makes for a slightly more robust tool. The hardest part of the base was the fitting for the upper joints of the 1" square steel diagonal struts. It probably would have been more straightforward to make these out of round tube, but I didn't have any at hand. The 3" castering wheel units are welded right onto the bottoms of the tubes; for stuff like this I have no patience for drilling bolt holes. Two zaps and done.
Return to HP-24 page
page updated 6 November 2006 all text and graphics copyright (c) 2006 HP Aircraft,
page updated 6 November 2006 all text and graphics copyright (c) 2006 HP Aircraft, LLC