How do i do it?

[Dr.dieseljr]

how do i draw a straight line on the bowl end of a propane tank i need it straight so i can frame the hole with flat stock.

[MAC702]

Please actually use the subject line for the specific subject.

I had to think about your question for several minutes before assuming you are trying to duplicate the item in the picture, and want to draw and cut out the square for the door. Maybe I'm dense.

I would do it by rolling a straightedge along it as I drew the line with a pencil. If I slipped, I'd wipe it off and start over. You ain't making a piano. It'd be even easier if the cylinder was resting against a flat surface of the right height and the straightedge was long enough to always be flat on it on the side away from where it touched the cylinder.

If you secure the tank vertically, you can jig up a fence and use a metal-cutting circular saw with the depth at the right level to do most of your line, too.

What cutting processes do you have available?

[Dr.dieseljr]

i will use a 4.5 inch cutting wheel metabo. i think if i hold the tank and find a spacer to hold a sharpie at a set distance and slide the spacer it will draw a straight line following the contour of the tank.

[Goodhand]

You might consider cutting a template out of cardboard to fit the curve, then just scribe the edge of the template while against the cylinder.

[Aeronca41]

I use that "rubber" magnetic "tape" from the crafts store. Pull it taut, lay it down around the curve, and draw your line.

[ryanjones2150]

I did not know such a creature existed.

[Aeronca41]

I did not know such a creature existed.

It's roughly about 1/2" wide by 1/8" thick, and pretty sturdy. Magnetism is strong enough that it stays where you put it. Works great.

[ryanjones2150]

Hmmm....sounds useful.

[FusionKing]

how do i draw a straight line on the bowl end of a propane tank i need it straight so i can frame the hole with flat stock.

Assuming you took all the proper precautions here.....a lot of idiots could read this....... and then just dive into their tank withwhatever and

You should always post a disclaimer

[aametalmaster]

Use a string. Tape one end to the tank where you want it. Then pull the string to the other side and tape it. Then use soapstone, sharpie or whatever to mark the line. Simple...Bob

[ryanjones2150]

I have a disclaimer....took me years to finalize it....probably legally binding too....<br />
<br />
If I do something stupid and hurt myself, I promise not to blame others for said stupid action. <br />
<br />
Seems reasonable to me.

[MAC702]

Use a string. Tape one end to the tank where you want it. Then pull the string to the other side and tape it. Then use soapstone, sharpie or whatever to mark the line. Simple...Bob

Might be close enough, depending on the degree of curvature, but the shortest line between two points on a 3D curved surface will not be a straight line. This is why pilots and sailors use a Great Circle route instead of what we would think of as "straight" between two cities with similar latitudes.

[aametalmaster]

Might be close enough, depending on the degree of curvature, but the shortest line between two points on a 3D curved surface will not be a straight line. This is why pilots and sailors use a Great Circle route instead of what we would think of as "straight" between two cities with similar latitudes.

After I hacked the end it would be straight. You mean it wasn't supposed to be LOL...Bob

[ryanjones2150]

Great thing about metal, most of the time at least....you hack the wrong end off, just weld it back on.

[Metalburner]

Draw a straight line on a curved surface. Use a laser level that you can project the line on the cylinder and trace it with a pencil or soapstone. Just make sure the cylinder and laser are square and level with each other.