OK, I've been busy working on the crane, then we got a break in the weather, so I kinda slacked off. but here's what I'd been up to. In order to make straight accurate boom sections, a better way was needed than doing my best at pinning the components to a board. I designed and built, and modified this jig until it worked.
One side of the boom is constructed on each side of the jig. Then it is bolted together, and the edge lattices are added in. The big holes are actually recesses so that the aluminum doesn't sink the heat away from the joint.
This makes assembly go pretty fast, and accurate. The time consuming part is marking and drilling the holes in the brass tube where the lattices solder in place. Building this monster was a pretty big task in itself. It's 2 feet long.
I built 2 new 40 foot (20 inches) boom extensions and put the original one in the jig for a chiropractic adjustment of some warpage. It's much better. The connecting ends weren't done, but that's when the weather got nice...
It seems winter came back, driving me back to the workshop.
For about 4 years now, I've had nothing but trouble with the base boom on this crane. It was warped and bent, and I've gone to lengths to fix it, with actually favorable results. But one more tweak was needed for an alignment issue with the other sections, and in so doing, it warped way out again. It was time to do what I'd been putting off. I built a new one. The new one is built on the assembly jig too, but set up a bit differently.
It is lacking the large sheet metal spans at the bottom, something that I discovered after building the original rather back dated it about 30 years.
So with a shiny new straight and modern base boom, I need to be able to attach the extensions. The original connectors on the existing sections were difficult to work with and really fragile. New ones were fashioned more in line with 1/1 practice.
The old ones were kind of like stinger and receivers, you had to stuff all 4 corners at the same time.
The new ones can be connected jut 2 at a time, and they allow pivoting, as in 1/1 cranes. Stronger, easier, and more forgiving of necessary handling.
Making those connectors all fit accurately is just plain hand labor extensive, and time consuming, tedious. But it paid off. Now I can much more easily pin them together and take them apart as needed.
here's a look at all 7 feet, four inches of the boom, including the new base and 2 new extensions.
This shot is from a ways back, and then zooming the lense. It condenses the look, showing the number of lattices. (there are exactly 100 peices in a scale 40 foot section) I just like how it looks.
The day after I got it this far, I took it over to a friend's house where we played with it for a couple hours. It comes to within about 1/2 inch from his ceiling! Guess who forgot his camera
The mechanisms all work fine with the extended length, and the outriggers and counterweights really do their job well.
A few more pictures...
These spacer-retainers keep the ends at exact tollerances when the connectors are being soldered in place.
The brass tube is clamped into place on the jigs by screws and wingnuts.
I intend to eventually build a couple more smaller extensions, a scale 10, and 20 footer. But at this point, I'm almost burnt out on boom construction, I'm moving on with getting the cabs built and other cosmetic improvements. More pics as progress is made. Dan