Spar bending jig

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Spar bending jig

Postby Archer123 » Mon Jan 08, 2018 8:40 am

I'm doing the "due diligence" for a Sonex build. I would be using the "B" model complete air frame kit, not sure which tail just yet..

One concern I have ( may not be justified..), are the bends required for the HS and VS forward spars.

Seems like these bends are critical to the dimensional integrity/fit. I may be overthinking this... but any links to a jig/process for this would be appreciated.

Thanks !
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Re: Spar bending jig

Postby Bryan Cotton » Mon Jan 08, 2018 9:09 am

Mine came pre-bent, and with pilot holes. I believe yours would too.

I scratch built those for my Hummelbird. The proper jig is a good sheetmetal brake!
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
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Re: Spar bending jig

Postby lstinthot » Mon Jan 08, 2018 8:44 pm

If you are buying a kit, those parts are prebent. I am scratch building and those parts were not too bad to bend. I ended up making the Dave Clay brake. It does adequate. If I had the space, i would have a nice big 8' brake with its own space. Are you looking at buying a started "A" model kit and converting to the "B" Model and said kit does not have the spars?
Scratch building #1604
Tail dragger
Thinking Turbo Aerovee
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Re: Spar bending jig

Postby Archer123 » Mon Jan 08, 2018 10:51 pm

lstinthot wrote:If you are buying a kit, those parts are prebent. I am scratch building and those parts were not too bad to bend. I ended up making the Dave Clay brake. It does adequate. If I had the space, i would have a nice big 8' brake with its own space. Are you looking at buying a started "A" model kit and converting to the "B" Model and said kit does not have the spars?


Not looking to convert an A to B. Considering a new B kit. I’m new to the Sonex world....

I didn’t realize how responsive the factory was to questions.... super quick response... refreshing...

Official word from Sonex with regards the tail kit advises the HS forward spar “heavy aluminum” center spar bracket does come pre bent on the straight tail, the forward spar on the VS needs the lower “paddle bracket” bent.

With regards the V tail, none of the heavy aluminum spar brackets like the “hockey sticks”come pre bent.

Appreciate you guys replies - Thanks !
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Re: Spar bending jig

Postby wlarson861 » Mon Jan 08, 2018 11:41 pm

Bill Larson
N861SX
Sonex, polished, tail wheel, Generation 4 Jabiru 3300
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Re: Spar bending jig

Postby Bryan Cotton » Tue Jan 09, 2018 8:47 am

There is a picture of my first hockey stick bending jig on the first page of my thread:
viewtopic.php?f=39&t=578

Later I made a different jig. I had two pieces of oak screwed to a piece of plywood. I would set the gap between them to be equal to the rod I was using to press in the bend. For my later efforts you will need the photobucket embed fix to be able to see the pictures.
Bryan Cotton
Poplar Grove, IL C77
Waiex 191 N191YX
Taildragger, Aerovee, acro ailerons
dual sticks with sport trainer controls
Prebuilt spars and machined angle kit
Year 2 flying and approaching 200 hours December 23
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Joined: Mon Jul 01, 2013 9:54 pm
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