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please give me some bulkhead building tips
http://t18.net/thorpforum/viewtopic.php?f=36&t=7620		 Page 1 of 1
Author:  Ryan Allen [ Wed Jul 23, 2014 7:36 pm ]
Post subject:  please give me some bulkhead building tips
I have now trashed 4 #574 bulkheads. I can not get the bulkheads to lay flat after I cut them and bend the inside flanges. Once I take them out of the form blocks, I can not flute them to get them to lay down. I end up fluting (and more bending) until it cracks at the inside flange in the curved portion.

I am missing something. Please help this idiot. Shouldn't I be able to flute the bulkhead flanges until it lays flat???
Author:  dan [ Wed Jul 23, 2014 7:41 pm ]
Post subject:  Re: please give me some bulkhead building tips
Shorten up that flange just a bit on the curves Ryan, this is the inside curve your having trouble with? Dan
Author:  Ryan Allen [ Wed Jul 23, 2014 7:47 pm ]
Post subject:  Re: please give me some bulkhead building tips
yes, its the inside curve that always cracks. But, I cant get the dang bulkhead to lay flat after I take the form blocks off. I always crack the inside radius while attempting to get the bulkhead to lay flat.....
Author:  fytrplt [ Wed Jul 23, 2014 8:59 pm ]
Post subject:  Re: please give me some bulkhead building tips
Like Dan says -- Allow for no more material for the flange than it requires. Polish the edge so there are no nicks or other stress risers. You must stretch the metal on the inside. Start in the middle of the curve with a plastic hammer and knock it down a bit, then work on either side 'til you get to the straight part. Work a little at a time. don't worry about getting a full 45 degrees. If you are successful in getting the edge stretched, the bulkhead will lie flat. While you are at it, do not stretch any of the straight parts of the flange. This will make the edges longer than the parent metal and it has no choice but to raise up and not lie flat. You should not need to flute any of this.
Author:  Ryan Allen [ Thu Jul 24, 2014 2:05 pm ]
Post subject:  Re: please give me some bulkhead building tips
i'll give both of yalls suggestion a try. thanks for the input.
Author:  Bill Williams [ Thu Jul 24, 2014 2:29 pm ]
Post subject:  Re: please give me some bulkhead building tips
I'll give you another...........I used a finger break and bent up the outside flange. Cut the center out and as Bob suggest, filed and sanded the edge to eliminate any stress risers. Clamped one side of the flange with a 1" board, leaving the cener protrude out from the table. Now, using 1" roller bearings on a 16" flat bar rolled the inner flange.
Author:  Ryan Allen [ Thu Jul 24, 2014 4:00 pm ]
Post subject:  Re: please give me some bulkhead building tips
thanks Bill.
Author:  dickwolff [ Fri Jul 25, 2014 7:55 am ]
Post subject:  Re: please give me some bulkhead building tips
https://www.tinmantech.com/html/workshop_courses.php
Author:  bmooresbm [ Sun Jul 27, 2014 7:57 pm ]
Post subject:  Re: please give me some bulkhead building tips
After reading this topic I was motivated to give it a try myself. I used the 2 form block method with the bulkhead sandwiched in between. I cut a 45 degree chamfer on the inside flange of the form with a router and used a hard rubber mallet to form the inside flange, starting in the corners and then the straight sections, forming a few degrees at a time. After a few passes it was forms all the way down against the chamfer minus a few degrees for spring back. When I removed it from the form it was nice and straight, no warping or waviness at all. I credit it to the helpful tips here or just dumb luck, but I couldn't be happier with the results. The only problem I see is that it's not quite 45 degrees per the drawings do to the spring back.

947

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Author:  fytrplt [ Sun Jul 27, 2014 9:31 pm ]
Post subject:  Re: please give me some bulkhead building tips
Nice job! Remember to make the 45 degree flange on the bagage compartment bulkhead bend to the rear instead of forward. This will make installing the luggage compartment rear panel so much easier.
Author:  bmooresbm [ Mon Jul 28, 2014 10:00 am ]
Post subject:  Re: please give me some bulkhead building tips
Bob, thanks for the tip. I think you told me the same thing when I posted the video the forms being cut. I have it it in my notebook so I won't forget.

Brad Moore
Columbus, IN
Author:  Ryan Allen [ Mon Jul 28, 2014 12:31 pm ]
Post subject:  Re: please give me some bulkhead building tips
now that aint right! dang!.......im kidding, of course. That does look nice.

Dick-I got your PM and I appreciate the tips.

I regret posting my bulkhead attempts. I am not really building a Thorp. I just bought the sheet of aluminum ($11 from spruce) so I thought I would try it. After I screwed up several times I got frustrated. After I thought about it for a while, I didn't understand why I got frustrated since I'm not even building anything.

But, now I gotta get the 574 done just to say I did it.....I have another $11 sheet on the way.....
Author:  jrevens [ Mon Jul 28, 2014 10:10 pm ]
Post subject:  Re: please give me some bulkhead building tips
Ryan Allen wrote:
now that aint right! dang!.......im kidding, of course. That does look nice.

Dick-I got your PM and I appreciate the tips.

I regret posting my bulkhead attempts. I am not really building a Thorp. I just bought the sheet of aluminum ($11 from spruce) so I thought I would try it. After I screwed up several times I got frustrated. After I thought about it for a while, I didn't understand why I got frustrated since I'm not even building anything.

But, now I gotta get the 574 done just to say I did it.....I have another $11 sheet on the way.....

One piece at a time, Ryan... one piece at a time.
Author:  James Grahn [ Wed Jul 30, 2014 9:52 am ]
Post subject:  Re: please give me some bulkhead building tips
Ryan,
That's what this hobby is all about. We all like to learn new skills. Keep going!
Cubes
Author:  Rich Brazell [ Wed Jul 30, 2014 5:27 pm ]
Post subject:  Re: please give me some bulkhead building tips
You should have seen the pile of scrap/incorrectly made parts that I took to the aluminum can recycler ! :P BOOM !

RB O0
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