The Home Machinist!

Suppose you are building a Chopper (custom motorcycle). You need to fabricate up a gas tank for your chopper. How would you do it (from start to end).

I know there is some sort of sheet metal bending machine. You push the sheetmetal through rollers and hold it and move it back and forth into the shape you want. I think you may control the machine with foot pedals???? What is this machine called?

How thick of a sheetmetal would you use for the gas tank?

After making the final shape, would you use bondo to make it smooth and sand it smooth?

So far I have found this forum VERY helpful and i am slowly learning as I go along. I have read lots of posts, and went to get some books from the libarary.

I believe the machine you are referring to is an english wheel. As for the rest of your request - I will be waiting to see the answers posted too. [img]/ubb/images/graemlins/wink.gif"%20alt="[/img]

The metal thickness would depend on the metal (aluminum versus steel) If it were me I think I'd go at least .060" on steel and probably a little more for aluminum (.090ish). Of course this still leaves the alloy to be determined - my guess is that you can get away with 3003H14 but you might consider 5052H32 might be a good choice as well. Not sure what the Pro's use.

The English Wheel would be good but all depending on the tightness of your shape the (standard) rollers might be a bit wide. Certainly narrower rollers are doable. I think a lot of guys just use a planishing hammer instead since the dies are relatively small. The easiest way to start this would be to rough out your shape - keeping in mind the surface area is the key - once you have that it becomes a simpler job of just "positioning" the metal where you need it. For example starting with a shot bag (or even a hunk o urethane) and a large mallet beat the panel until it looks like a sack of oranges in the general shape you desire - it will look like a lumpy disaster and you mgith be tempted to quit - but keep goign as your headed down the right path. Next work on smoothing out soem of these lumps. Some hammer and dolly work is fine for this. Next you just keep refining your surface finish - smaller and smaller lumps until you finally have a decent looking finish - given enough patience this can be close enough to paint with NO FILLER but also keep in mind THAT is not necessary but rather a point of bragging rights. Most "production" custom work employs a good dose of plastic filler. Shoot for perfection and develop your skills as you go. You will soon be surprising yourself.

The "fancy" tools only allow you to work FASTER. And when you're learning this means it will only allow you to make a mess faster. Learning and "doing by hand" are good companions - don't be fooled into thinking you need expensive equipment. Ewheels are majorily cool - I think EVERYONE should have one - just not absolutely necessary.


Your mileage may vary

Ever see the Discovery channel with Jesse James there is a segment about building a gas tank if you can catch it. The seem to re run it all the time. He makes gas tank building look eazy. West coast choppers is the place he owns. and I think Monstor garage is the show name, (correct me if Im wrong) Preston. [img]/ubb/images/graemlins/tongue.gif"%20alt="[/img]

That big machine I was reffering to was the enginsh wheel and another cool machine I found, a Power Hammer.

I know of Monster Garage. I also like American Chopper. Ill have to keep watching Discovery and hope I catch the gas tank fabrication one.

I have loaned some pretty sick books on sheet metal fabrication. I will be reading them tonight and Ill let you people know what I find out.

Tomorrow maybe ill drive by a shop and see all the tools of the trade and maybe some pros at work.

Erik:

Check out http://www.metalshapers.org/ for pics and advise on gas tank fabrication, etc, etc. You'll spend hours on this site - trust me...