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BTromblay 06-05-2018 07:41 PM

Beech Debonair access panels.
6 Attachment(s)

A sheet metal project for a 1960 Beechcraft Debonair. The panels are spar inspection plates that mount under the pilot and co-pilot seats. The originals were bent up, cracked and damaged from years of abuse. Not a structural component, but critical as they keep debris out of the retractable landing gear system.
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Both panels made out of .040" 5052-H32 aluminum.
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It's a deep draw, about 3 inches in the deep end of the pool.

I wish I had taken more photos of the form process, but I do have a couple. I had pre-stretched the area with the Pullmax, using a urethane dock bumper and a delrin lower doming die.
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Once I had the general shape, I wheeled out the dish area with the E-wheel. To finish the corners, I made a 3"dia ball roller for the English wheel. I have one of Peter Tommasini english wheels and I love it. One great feature is, I can adapt the machine for many different ideas. The ball bearing allows you to roll in any direction and great for finish work.
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The ball bearing idea is from Cass Nawrocki Book "Any impossibility in shaping metal". If you don't have the book, get one, it's a great reference to have in your shop. I have a nice planishing hammer now, which I didn't have when I formed these panels. A P hammer, would have made the corners easier, but the ball and wheel worked fine as well.

To finish the panels, once the dish area was formed and wheeled out, I tipped the edge in a bead roller and trimmed to size. I don't have any photos of that process. I can post more pictures of the urethane die in the pullmax and the 3" dia ball for the e-wheel if anyone is interested.

Thanks for looking,


Onemorehammer 06-05-2018 08:49 PM

Nice work Bill, Thanks for sharing your process, Dan

longyard 06-06-2018 01:02 AM

Really nice photos and explanation. Thanks Bill :)

skintkarter 06-06-2018 06:05 AM

Wow! Thanks for posting Bill. Really like the ball bearing idea. Does this just sit in a cup somehow?

Steve Hamilton 06-06-2018 07:08 AM

Hi Bill

Clean results, thanks for sharing the process


Marc Bourget 06-06-2018 08:40 AM

More pictures, please?

What, you couldn't find replacements at your corner Beechcraft Store? hahahaha!

Kevinb71 06-06-2018 10:38 AM

Nice work Bill!
It would be great to see more pics on the Urethane die and ball bearing. Thanks for the post!

MP&C 06-06-2018 11:40 AM

Beautiful results Bill!

Charlie Myres 06-06-2018 05:14 PM

Nice work Bill!

I would love to see some detail of the ball and mount please,

Cheers Charlie

BTromblay 06-07-2018 09:20 PM

9 Attachment(s)

The ball roller for the E-wheel is using a 3" dia ball bearing from Mc Master Carr. The holder I designed and machined, the ID matchs the ball radius for only 1/8" contact area. The ball rolls on another conventional ball bearing so only the two tangent points are touching, to reduce friction. The ball works great for finish planish work, but it is easy to put furrows in the material if you have the pressure to high.
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The loading dock bumper is from McMaster Carr as well, part number 9546K53. I machined an adapter to mount in my Pullmax (SMV Presses Nibbler Medium). My tooling uses a 25mm dia round shank, instead of the Pullmax square. I prefer the round as it is a fast way to make tooling. I did machine a set of square hole collets for my machine so I can run purchased Pullmax tooling in my machine as well.
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Dan Pate gave me the idea of building a lower die holder that will accept my lower CP planish hammer dies.
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The urethane die is a stretching Mad Man. What I like is, it is fast, but very controllable. All of the stretch is only happening in the work area, look how flat the rest of the material stays. For the spar covers, the stretched area tapers down to 3" deep. As it gets deeper, you stretch more and more, layering one stretch pass onto the next stretch pass.
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It works well, and as Dan Pate says, "we have electricity, so let the machine do the work"


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