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Permalink Reply by John Austin on Sunday

Rainbow Aviation has a YouTube video on Low Cost Hydroforming .  Basically, you make a wooden form and use a hydraulic press to press the aluminum sheet down over the form with a thick rubber sheet between the press and the aluminum.  I know you said you don't have a press, but surely you could find someone with one that you could use apparently the pressing procedure is the easiest/quickest part of the whole process!  I bought a cheapo HF press years ago, and like many other tools, found numerous uses for it such as pressing bearings, breaking tires loose from rims on small wheels, pushing punches through rubber for clean-cut holes (works great for the cut-outs in the pads for Zenith landing gear!), etc.  I have zero experience with hydroforming - I suspect a dome is more difficult than bending a simple flange as in a rib? - and wonder if the 6061T6 would have to be annealed? - and would that affect the ability to polish it afterwards?  Hope someone can help you out who has been there/done that!  Interesting topic!  Sure would be nice if you buy one "off the shelf!"

John

N750A

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Permalink Reply by Gary Welch on Sunday

If I had a hydraulic press I would try it but I don't. I'm also suffering from a severe case of "builder burnout". I "finished" my plane 8 years ago but it seems the maintenance and repairs never end.

I hated building the plane and I hate, even more, working on it.

I love to fly but I'd rather stick a fork in my eye than work on it..

I'm just looking for the simplist, shortest way to get where I need to be.

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Permalink Reply by Patrick Hoyt on Monday

Gary, two ideas:

1.  Don't dismiss making fiberglass covers.  I recently had to make a bump like this (for clearance under a custom cowling).  

My suggestion would be to take a piece of thin plywood, cut roughly a 8" diameter hole in it (no need to get fancy, maybe use an old coffee can to trace a circle).  Layer up some fiberglass cloth between sheets of plastic (like cheap Home Depot drop cloth) and then drape the cloth over the hole, letting gravity pull it down into a natural "bump shape".

You could get fancy and try an aerodynamic shape if you're feeling ambitious.  Or maybe use the actual sender (with some padding) as a "mold'.

2.  Since you have a Zodiac it's possible that you also have a pneumatic riveting gun (like what the RV builders use for "driving" rivets).  Lot of the Zodiac guys have those from the upgrade saga a decade ago.  Try wrapping one of the larger flat nose pieces in a towel and using it to "massage" a thin plate of 6061 into the shape you want.  Would probably take some practice, and I suspect that you'd make several and then pick out the best two to use.  They'd look pretty cool if polished...

I understand the builder burnout.  Especially if there's any travel at all involved.  These ideas could be accomplished in your garage at home.

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Permalink Reply by Gary Welch yesterday

Thanks Patrick but I just have zero desire to try and make something. I can buy a plastic one for $15 which I will likely end up doing 

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Permalink Reply by Earnest Fontenot on Tuesday

Gary,

What about a 3d print of the dome?

I'm designing clamps to hold my brake line to the main gear for my 650.

I actually went and test fit my latest prototype to my gear today. It fit really well.

I'm going to have the rest I need printed now that I know it fits and will work.

Just a thought.

Earnie

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Permalink Reply by Gary Welch yesterday

I was hoping to get it in 6061 T6 aluminum so that I could polish it to match my polished wing.

Its looking like this is not available. After a lot of research (and knowing nothing about the subject) I've learned there are technical challenges, especially with this type of metal. 

It would be less challenging in softer aluminum. But even them it is going to take a hydraulic press which I don't have.

I may end up buying a plastic dome for it. 

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