Thanks for checking in Roger, and sorry for the delayed reply.
Hi Guys
Work continues the fan with making the fan cage. Below are two screen shots of my CAD design. My full-sized fan is missing the cage, but I have managed to collect some pretty good photos of an original so used that as a go by to design my ˝ sized one.
The cage is a rather flimsy mostly aluminum fabrication. It is designed to be easily split in two at its horizontal axis. There first screen shot here shows it assembled.
This shot shows how it is held together with clips at each end and split fasteners with knurled nuts to hold them together. The upper spoke is slotted where it slips over the pin on the hub. There is a captive nut and washer that will be shown later that when loosened allows the spoke to be lifted from the pin. The lower spokes are permanently attached to the hub with rivets. The blades and blade hub need to be removed before the lower assembly can be installed or removed.
Starting out the basic hub was machined.
Using a collet block for indexing the pin holes were added.
The pins were turned and added to the hub, I Had to make the heads on the pins smaller than I had originally planned because the 3rd pin would not pass through the other two, So they were trimmed down until I could get all three in place.
The pins were then silver soldered in place.
Back in the collet block the rivet holes and one tapped hole are added for fixing the spokes.
The front bearing stand needed to have the mounting hole added to secure the hub in place.
The dog bone parts were carved out on the CNC, here the first op has been completed.
Then flipped over and repeated on the other side.
The parts were then freed from the parent stock.
Then some fettling and a trip through the blast cabinet.
The boss to fit the ID of the aluminum tubing was machined next. One thing left to do was add the hole through the boss for the rivet.
Here are the spokes and dog bones ready for assembly.
Making the clips that hold the ends of the cage together was an interesting exercise. I designed a 3d printed tool that got me most of the way there. The material is .024” galvannealed steel, if it were any thicker, I wouldn’t have gotten away with the plastic tool.
The tool got the bends at each end started and before the part was removed the ends were bent up to 90 degrees which is as far as the tool would allow.
A new mandrel was made for my little bender so the loops at each end could be finished.
This made short work of finishing the loops.
Here is a photo of the mostly finished clips and associated hardware. They still need to have rivets installed.
The holes were drilled and rivets installed using the UPT.
The .093” aluminum hoops were formed using the slip roll, I have found that clamping an angle block square to the rolls helps keep the parts from developing a twist if multiple passes are needed to get the desired curve.
A template was made to help gauge the proper size and shape of the hoop; this was also used to help trim the ends to the proper length.
With all the parts made it is time to do a trial assembly. The upper hoops protrude slightly and engage into the lower clips; this keeps the hoops aligned with each other.
Here is the hardware that retains the upper spoke, I had made these parts when I made the hardware for the front sheet metal as I was already in the mode and they needed to match. These are slightly larger, being 2-56 vs 1-72 threads.
Here are all the pieces assembled for a test fit and photo op. I’m very pleased with how it all came together. The hub will be nickel plated so I haven’t attached the lower spokes for good yet.
More to come.
Thanks for checking in.
Dave
