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Old Mar 03, 2011, 01:02 PM
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Chev's FBL head and custom mainshaft

Chev's FBL head and custom mainshaft

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Seeing as how I'm a do it yourself kinda guy I figured I would try my hand at making a custom mainshaft and my own version of the FBL head.

Using materials I purchased from Mcmaster Carr I was able to make these parts fairly inexpensively.

I'll start with the mainshaft which is a 5/64's precision polished rod made of A2 tool steel costing 2.69$ for 36" so cost per unit minus labor and tools is 19 cents each. The diameter is .0006" larger than the stock mainshaft so it fits with absolutely zero play going through the swash and bearings. This mainshaft runs smoother than the stock one and I'm very pleased with how it turned out.

I drilled the holes using a #61 .039" drill. I simply stacked the old mainshaft on top of the new one using tape to hold them together, this allowed me to use the holes as a guide and to keep the drill from wandering. You have to make sure the holes are exactly straight and perpendicular before you clamp them tightly into the vise. My mainshaft is also hardend and tempered which turnes it blue.

To make the mainshaft even better I drilled and tapped the original Walkera head using a #50 .070" drill, drilling right through where the pin was. I used some 1/16" long 2/56 cone tip set screws to hold the head on, the tips of the set screws go right into where the pin was and hold it very securly. This allows you to remove the head while the shaft is still in the heli which is very convienant for things like using a swash leveling tool. I just needed to drill straight through the head and tap for 2/56 which only took a few minutes. I already had the taps and drill for this job but the set screws were about 70 cents each. Any of you guys can do this mod.

Now it's time for the more complicated mod which is much harder to make than the mainshaft or the removable head.

Yes it's my own version of the FBL head as in no Walkera stablizer required. This part is not easy to make because the tolerance is very tight for this part to actually fit in and function without binding anything.

I'm using a stainless collar which is drilled through to fit two pieces of #61 .039" drill rod which allows it to attach or plug into the Delrin upper part. The drill rod is locktighted into the stainless coller then the coller is pressed into the Delrin piece for an extremely tight fit. Total material cost for this part is less than 10 dollars and most of that was for the expensive stainless collar, you could probably use one of the cheaper stock aluminum collars for this but I wanted the part to be as strong as possible.

This new FBL head and hardend mainshaft works perfectly during testing with no binding problems and firm control.

In the lower set of pictures I added a second set screw to the stainless collar and trimmed down the delrin to reduce weight and wind resistance.

This is just a roughed out proto type that I finished last night. I may be selling a batch of the mainshafts later after testing them out. I might even make some more of my FBL heads for sale after more complete testing.

The pictures will make it more obvious how these parts were made in case you want to make them yourself. I also mentioned drill sizes and hole sizes in other places.

All parts were made using hand tools, dremal, drill press no CNC equipment is used but experience is required. The pictures show the more difficult steps in clear detail cept for the fuzzy one with the mainshafts stacked on top of each other in the vise.
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Last edited by chevell; Mar 25, 2011 at 08:40 PM.
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