LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently August 11, 2020, 12:44 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 14 posts ] 
Author Message
 Post subject: Bending hood
PostPosted: May 16, 2009, 3:48 pm 
Offline

Joined: August 6, 2008, 6:19 pm
Posts: 356
Location: College Station, TX
I am getting ready to fabricate the hood, any pointers on how to bend it would be appreciated. What size pipe do you use to bend it around, and I assume the radius at nose is different that scuttle, so how do you deal with that?

_________________
TSuppa
"Alimony is like buying Hay for a dead horse"
'86 Alfa Spider Quad
'79 Alfa Spider Veloce
http://tomsuppa.blogspot.com/


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: May 16, 2009, 4:48 pm 
Offline

Joined: August 15, 2005, 10:13 pm
Posts: 7046
Location: Charleston, WV
Below is how I did it. Worked well, but it takes two people. Start by making a cardboard template and cutting out and transferring the shape and lines to the aluminum sheet. Cut it out and bend it. Don't forget to leave room for a 90 degree bend along the sides.


Attachments:
hoodbending.jpg
hoodbending.jpg [ 102.91 KiB | Viewed 6609 times ]

_________________
He is a wise man who does not grieve for the things which he has not, but rejoices for those which he has.
Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: May 18, 2009, 4:09 pm 
Offline
User avatar

Joined: January 14, 2006, 1:06 pm
Posts: 813
Location: Vista (north of San Diego CA)
These pictures show how I made part of the form for my one piece hood. The idea would be the same for bending a conventional hood. Same as Chet, I started with a paper template and marked where the bends started, stopped and midpoint. Then transfered the marks to the sheet metal to align the bends. The pipe is some sewer pipe that came with the house 25+ years ago. And my wife wonders why I keep all this junk/great stuff around. :P

John


Attachments:
File comment: Forming a bend
Bending.jpg
Bending.jpg [ 74.28 KiB | Viewed 9518 times ]
File comment: Fitted as it would be on a Locost
Bent_fitted.jpg
Bent_fitted.jpg [ 75.3 KiB | Viewed 9520 times ]
Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 9, 2009, 12:32 am 
Offline
Man of Constant Hazard
User avatar

Joined: February 20, 2006, 11:18 am
Posts: 3165
Location: Lexington, KY
I used Chet's approach with good success. Photos and a few more tips found here: viewtopic.php?f=35&t=2741&p=71199#p71199

-dave "hoodie infestation" hempy

_________________
...nowadays people are so intellectually lazy and lethargic that they can't build ANYTHING with their hands. They'll spend hours watching whiny people marooned on an island, but won't spend a second adding anything to the world. -weconway
Visit my [Locost 7 build log]


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 9, 2009, 7:20 am 
Offline
User avatar

Joined: September 22, 2005, 8:12 am
Posts: 1738
Location: 4AGE in S.E. Michigan
I have a couple suggestions. Make both sides about 2.5" longer then your template and the ends about .5" longer, That way you can made a slight adjustment if you end up off center. Make the final trim for the length after fitting it to the car. The 2.5" will allows you to put a "U" on the bottom of each side with the extra material after forming the radii. "used a 1" sq tube to form the bottom sub-flanges" It helps the hood keep it's form when you add the tension of the over center attachment clamps.

Dave W


Top
 Profile  
Reply with quote  
PostPosted: July 12, 2009, 2:11 pm 
Offline
Man of Constant Hazard
User avatar

Joined: February 20, 2006, 11:18 am
Posts: 3165
Location: Lexington, KY
I bent the two curves, tweaked to fit, then bent the flange for the passenger side. Tweaked the curves a bit more, then marked and bent the flange for the driver side from the inside with a Sharpie. Everything was looking spot-on up to here. Unfortunately, I didn't mark/measure/bend quite accurately. The center of the hood now stands 3/8" above the nose cone. :-(

Attachment:
hood.fit.front.jpg
hood.fit.front.jpg [ 29.03 KiB | Viewed 6599 times ]

Attachment:
hood.fit.close.jpg
hood.fit.close.jpg [ 31.15 KiB | Viewed 6596 times ]


I see several options:
  • Good enough -- I'm a pretty lax builder, but this would bug even me. I might end up running this hood temporarily to get licensed and stuff, but not long term.
  • Build a new hood -- Yeah...except I'm cheap, and might find another way (or the same way!) to screw up the next one.
  • Fix the flange -- Can I do this? Maybe hammer it flat, re-anneal it, and bend it again?
  • Ditch the flange -- I could cut it off, and rivet on some aluminum angle inside.
  • Raise the nose -- This would be easy. I think it would only need 1/8" or so to take the slack out of the hood. Tempting, but I hate to fix a bug with a hack.
  • Lower the rails -- Okay, not really. But I could remove the foam tape. That would only get me maybe 0.5mm, probably less, and then I'd lose my rattle inhibitor. Might just try it since it's so easy and cheap, though.

I'm hoping for Door Number 3 - fix the flange. Anyone have any guidance on this?

After hammering it back flat, would it be too work hardened to get another bend? Would I need to re-anneal it? I've read about the Sharpie/acetylene soot trick for annealing. Guess I'll do a little Googling and practice on some scrap first.

Help, please!
-dave

_________________
...nowadays people are so intellectually lazy and lethargic that they can't build ANYTHING with their hands. They'll spend hours watching whiny people marooned on an island, but won't spend a second adding anything to the world. -weconway
Visit my [Locost 7 build log]


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 12, 2009, 3:01 pm 
Offline
Always Moore!
User avatar

Joined: November 9, 2007, 3:40 pm
Posts: 3993
Location: Pittsburgh, PA
Did I read somewhere that you are using 3003 1/2 hard?

Don't take my word for it but it seems to be a very malleable and very crack resistant alloy. I had a few flanges that were bent (incorrectly), unbent, then bent again and the aluminum couldn't have cared less.

Can you do a few test pieces with some scrap?

_________________
-Andrew
Build Log
Youtube


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 12, 2009, 4:07 pm 
Offline
User avatar

Joined: September 30, 2005, 1:28 am
Posts: 1281
Location: Sunny-Okanagan, Canada, eh?!
Right now, you don't like it, and you might have to redo it.

I would anneal the edges and re-bend it.

Best case - you like it and you're done.

Worst case - you mess it up and have to redo it. But you have to redo it anyway, so you're really no worse off than you are right now. You have everything to gain, and really nothing to lose.

G

_________________
The Lethal Locost
The Lethal Locost 2 - Even More Lethalerer


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 12, 2009, 4:30 pm 
Offline
Locostering Legend
User avatar

Joined: December 27, 2005, 8:13 pm
Posts: 787
Anneal it before you flatten. The material is old and may have age hardened.

Use Sharpie and propane. It's slower but less likely to overheat. Concentrate heat on bend only. Don't go wider than 3/8" either side or you may warp the flat sides above.

Flatten with soft hammer so you don't stretch it. Use steel body hammer only at the very end with light strokes.

Make hood radii longer (flatter) than the mating surfaces at the nosecone and scuttle. That way when you tighten done the fasteners, the hood will spring a little and seal against the mating surfaces. You need to think like and "be" the metal............


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 12, 2009, 6:09 pm 
Offline
Automotive Encyclopedia
User avatar

Joined: December 22, 2006, 2:05 pm
Posts: 6656
No need to start over.

It looks like the hood is too high all the way to the pax side bend.

Pull the pax side edge outward so it can overlap the frame rail. Does the hood lay flat? If so, put a straight edge across the overlapping portion and trim it off.

Also, bending the pax side leg beyond 90 degrees will force you to spread the corners when installing, which lowers the center.

_________________
MV8

https://www.youtube.com/watch?v=Om3C1Ep ... D3E18BB447


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 27, 2009, 11:35 pm 
Offline
Man of Constant Hazard
User avatar

Joined: February 20, 2006, 11:18 am
Posts: 3165
Location: Lexington, KY
Thanks, everyone, for the advice.

I decided I'd try to fix the bend.
If that didn't work out, I'd cut it off and (if needed), rivet an aluminum angle inside.
If that didn't work, I'd buy a new sheet of aluminum and start all over.

Fortunately, I didn't get past step one.

I annealed the bend with propane and a sharpie. With that much aluminum, it took a lot of patience to get the heat into it with propane. I couldn't burn the Sharpie off from the other side, as I found recommended, so I hit it from both sides. I was tempted to get the oxy-acetylene out, but stuck with it.

I then bent it flat, by hand, with the broad leg in an improvised clamp. Then a plastic hammer to get it flat, followed by a light tapping with a steel hammer to get the last kinks out.

I meant to anneal it again at that point, but forgot or ran out of patience or something. In any case, it bent up just fine in the brake. My alignment is much closer this time...certainly close enough for the foam and clamps to accommodate.

Attachment:
hood.fixed.jpg
hood.fixed.jpg [ 24.72 KiB | Viewed 9248 times ]


The black mark is where it lined up pre-fix. The blue line (bottom) was my target alignment after the fix. It ended up about 1/16" low...certainly within tolerance. The front was marked similarly. It looks like a big, nasty gape below at the rear, but it's not that bad, really.

Attachment:
hood.fixed.2.jpg
hood.fixed.2.jpg [ 30.89 KiB | Viewed 6597 times ]


Next up I need to do the latches...but not until the side skins are installed.

Thanks again, everyone!

-dave

_________________
...nowadays people are so intellectually lazy and lethargic that they can't build ANYTHING with their hands. They'll spend hours watching whiny people marooned on an island, but won't spend a second adding anything to the world. -weconway
Visit my [Locost 7 build log]


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 28, 2009, 9:08 am 
Offline
Mid-Engined Maniac

Joined: April 23, 2006, 8:26 pm
Posts: 6049
Location: SoCal
dhempy wrote:
... I annealed the bend with propane and a sharpie. With that much Aluminium, it took a lot of patience to get the heat into it with propane. I couldn't burn the Sharpie off from the other side...

MAPP gas is your friend. You just have respect it, as it gets much hotter than propane.

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 28, 2009, 9:35 am 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 5501
Location: West Chicago,IL
Funny thing about MAPP gas. I have used it for years and have preferred it over the propane. But recently it has been taken off the market. It has been replaced by called MAPPro or something like that. I tried using this new gas a week ago or so and couldn't get enough heat into the piece I was working on. It doesn't seem to work for me. At least with my torch.

I switched to an old propane torch I had in my toolchest and hadn't used in years. This one that has a belt clip, valve, rubber tube and hand held nozzle that you have to light with a flint. Hands down there was more heat available even with propane gas. I refound an old friend in this torch.

YMMV

Chuck

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Top
 Profile  
Reply with quote  
 Post subject: Re: Bending hood
PostPosted: July 28, 2009, 11:26 am 
Offline

Joined: June 24, 2007, 6:04 pm
Posts: 1526
rx7locost wrote:
I switched to an old propane torch I had in my toolchest and hadn't used in years.
YMMV

Chuck


I also required the use of my propane torch, something that was sitting in my tool box for more than a few years. I fired it up and about 10 seconds later I had a huge ball of flame in my hand, luckily I had put on my leather gloves.
To say this little surprise got my old heart pumping like a marathon runner would be an understatement.
The first thing I did instinctivley was to throw the whole thing out of the garage onto the front lawn.
Well bad luck never seems to come by itself, but brings friends.
As I threw it out into the lawn I suddenly noticed that all the little kids from the local elementary school were walking by on the way to the park. I now had more panic, so I grabbed my leather welding jacket and leather apron and quickly ran out and threw them on top of the torch and then got enough sense to turn off the valve and unscrew the bottle.
One I did that the flame went out much to my relief.

It was then that the local fire chief who lives next door ran over to see if I was alright, which I was.

The point here is that the unit was quite old and had not been used or checked lately and basically the seals had let go.
I think there is a bit of a tendency to overlook the smaller units like propane torches as we dont necessarily put them into the same mental context as larger equipment like welders and such.
For the amount they cost I just disposed of it and will buy a new one when the time comes.
I just thought I would share this in case there are others out there that have similiar old torches sitting in their tool chests, if you haven't used it in a number years perhaps check it over in a safe place or just replace it.
Al

_________________
Super Seven 3.4


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 14 posts ] 

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY