[jpd37]

I am new to the craft of forming sheetmetal. I want to form a vault shape for a new transmission tunnel. I have made a light cardboard shape template and I have a sheet of 18 ga. sheetmetal that I intend to use. The new tunnel shape will be welded to the original floor pan. What method should I use to shape the tunnel to result in a smooth rounded form as opposed to straight line breaks. I was thinking of somethong like a chunk of large steel pipe or telephone pole (neither of which I have) or something else. The method should be low-tech, because I don't have a lot of special tooling. Thanks for any help.

 

[lozinit]

If the object isn't too large, I usually use my knee to start the general shape.
Never done a tranny tunnel though, so it's just a suggestion.
I too would be happy to hear any tips and tricks anyone else would offer up in this area.

~Michael

 

[jpd37]

That was fast Lozinit. I think the knee idea may be a way to get it started but knees and hammers don't get along too well. But thanks for the starter idea.

 

[Dragon J]

For something like a trans tunnel I use a gas cylinder from the welder to start. Anything cylindrical of the correct diameter will help you get a beginning:the hot water heater,have a friend hold a bucket, stop along the road and use a telephone pole (!!!) and just start the bend slowly. I usually start a curve then move to another area and bend a little more, etc. so as not to get a ridge from too much pressure at once. Good luck- forming is fun!!! Look around your garage as many items will help.

 

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IF you want a simple curve, just bend it carefully over a 2x4, fence post or such. If you want a compound curve (curved in two directions)that takes a little more skill but can be done by a novice. May take a couple of trys to get it right. Do the first step to get the first curve then lay it cupped side up on a soft surface (piece of carpet, lawn, etc.) and begin GENTLY hammering (can use the peen of a ball peen hammer) back and forth, up and down to streach the metal and get the bulge you want. Need to cover the surface wiht a lot of gentle blows rahter than a few big bangs and you will gradually build the compound curve.

Any body work is hard to describe adequately with just words. Ths is the quintessential place for an apprentice program.

 

[lozinit]

Willys,
I have a question concerning the compound curves.
Let me preface by saying that I in no way am a bodyman, just a curious backyard fabber.

I've done some panel beating before on a floorpan patch, and it worked fine for the area under the carpet, but without a wheel to smooth the mallet/hammer marks out, how do you get a smooth surface? Is there some basic secret to it?

JPD37, I wasn't talking about beating the panel while it was resting on your knee (Ouch!), I was talking about forming the bend by pulling the metal over your knee with your hands. (I've done this before on a trike tank)

~Michael

 

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Loz; I understood your knee method. Should work fine, especially with relatively thin 18 gauge. Onde you get the compound curve near where you want it, you are right, it will probably be a little lumpy. At that stage, a good body and fender man can smooth it out with a hammer and dolly and body file to baby skin smooth. Hammer the highs with a body hammer (have to give up the ball peen here!) while holding the dolly under the lows which will level them out without streaching the metal, hammer on a localized high without a dolly which will lower it without streaching, hammer on a low with the dolly directly below the sheet metal which will streach the metal and raise the low. To shrink a high heat it directly in the middle with a gas tourch to a nickle sized red spot then lay the torch down and immediatedly tap (don't pound) the red spot down flat using rapid taps in a closing circular motion. The quench the spot with a wet rag and this will greatly shrink the spot. When the panel is near perfect, a skim coat of quality plastic filler will finish the job.

Again, it is harder to describe than to see and to do but an english wheel is definitely not needed to do a credible job on panel forming.

 

[lozinit]

Thanks for the info.
I've often thought about smoothing out a panel like you described, but figured that it was taking way too long and that I wasn't doing something right. You are right in that this is one of those areas where experience is the key.

Right now I'm healing from a finger injury that my project gave to me. (The dashboard pics in my album.) There was a high spot in the center of the dash, so I decided to do the heat/quench method to pull the metal back. It worked and I ended up with only a dime size high spot, so I grabbed the hammer and dolly and proceeded to pound it flat. Only one problem though - I suffered a "stupid moment" and forgot that metal bounces when not supported. With a dolly in hand and rough welded metal on the other side, I ended up driving a sharp weldment through my fingernail and out the other side. (Poor hand positioning, don't ask. Should've used a spoon and not a dolly.)
Oh well,Live and learn.

Thanks again for the forming tips and tricks.

~Michael

 

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Ouch!

 

[jpd37]

You guys are GREAT! I was only kidding about the knee thing. I will try your suggestions this weekend and let you know next week how I did. I particularly liked the suggestion to find a local telephone pole and start hammering on it. The neighbors will have something to talk about for weeks.

 

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Originally posted by jpd37:
<strong> I particularly liked the suggestion to find a local telephone pole and start hammering on it. </strong><hr></blockquote>

You aren't paying attention. <img src="graemlins/nono.gif" border="0" alt="[nono]" /> I specifically said FENCE POST. Telephone poles won't work properly. Too gnarley. <img src="graemlins/mwink.gif" border="0" alt="[mwink]" />

 

[jpd37]

I'm going one better. I have borrowed a bunch of steel tubes of various diameters to use for shaping the metal. The sheet metal I got is galvanized. Will that give me any grief when it comes time to weld the new to the old?

 

[[email protected]]

IT will hassle you a little more than un-coated steel. If you breath the fumes, thay aren't particularly harmful but will give you 'zinc fever' - feels just like you have the flu! Goes away over night. Work with good ventilation and things will be fine. DON'T take chances with cadmium plating though. That is really bad stuff.

If you weld with any zinc in the weld zone, it will pollute the weld and weaken the joint. Either braze instead of weld or grind all the zinc from around the weld on both sides of the sheet.

 

[jpd37]

Thanks Willys for the heads up. I'll take great care at this step.

 

[trees]

Couple of low budget tips that require a little effort. 1. Buy a $5.99 bag of SacCrete, add water slowly and mix fairly dry, form your desired shape and let dry a couple of days. Then use your knees, hands, hammers etc to form the metal to your creation. 2. Stich up a cotton burlap sack and fill with coarse sand. Modify until you can get your shape and go to work as above.

Trees

 

[jpd37]

The tunnel is formed and welded to the original remaining sheet metal. I used 18 gauge metal (thicker than original) and formed it using my knee at the start followed by the column in the garage applying controlled pressure at strategic pionts along the edges to be curved in a slow and methodical manner until the desired curves were achieved. Several layers of dense carpet were used as a spacer between the transmission and the tunnel sheet metal to maintain a decent clearance. Additional pressure was used to shape the tunnel over the carpet spacers. Once the parts were formed to satisfaction the parts were screwed together and taken to a welder. The finished pan has turned out GREAT! Preping for paint now. Thanks to all who helped with great advice and tips. It was fairly easy, just a little slow. This is the best site I have found for good advice. Cudo's to all!

 

[trees]

JPD37, congrats are in order. Also thanks for sharing with us what you did. I will never make a cement mold again!!

Trees

 

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You mean something I suggested actually WORKED?!?! Whodathunkit?