Anyone have a tutorial for scratch built exhaust stacks

[lmtdconnectivity]

I did some searching on the forums but could not find any info on scratch building some exhaust stacks. I am working on a 1/25th '41 chevy pickup and want some exhaust stacks for it.The 1/25th semi truck stacks look too large for what i want. If someone has a link to a tutorial or pics or something I would appreciate it. I would also be interested if there was a model that i could get that has stacks smaller than the semi stacks.

[Chuck Most]

Not really a tutorial, but for stacks I have used on semis and trucks I like to use K&S aluminum tubing. It's available in quite a few different diameters, cuts easily, and can be polished with just about any aluminum or wheel polish (I like to use Meguiars Hot Rims aluminum and wheel polish with a microfiber cloth), or scuffed for paint. They're also rather cheap- a buck and a half or two for a 12" piece, depending on what diameter you want. They look much better than any kit-based stack, because they have thin walls and of course they are hollow. Most well-stocked hobby shops could carry K&S tubing, and I've also seen it available online. Like I said, there are quite a few diameters available, so you should have no problem finding something the size you want.

Some people like to cut it with a purpose-made cutting tool, like you'd use on 1:1 brake lines, but I've had good luck cutting it by rolling it under a sharp #11 blade, or using a fine-tooth hand saw.

Edited September 16, 2012 by Michigan Madman

[lmtdconnectivity]

What about bending it?

[Chuck Most]

Best way to bend it is with a tubing bender, either the type you'd use on brake lines or one of the spring types. But it can be bent by hand without kinking if you insert a solid round rod into it first. I like to use pieces cut from the kit sprue, but sometimes I'll use K&S solid aluminum rod if the pipe is rather small in diameter and thus easy to bend by hand. You want the rod to fit into the inside of the tube as tightly as possible. Downside to this if you need the bend near the top of the pipe (where the open end will be visible) it doesn't work as well, as the rod will be visible inside the tube. In that case, using a bender would be the only option.

If you just need an elbow, say, something that comes out from under the cab and turns the pipe up 90 degrees to vertical behind the cab, you can just cut the bottom of the tubing flat and bend a plastic or metal rod, then slip the tubing onto that.

[lmtdconnectivity]

Any idea on what diameter to get for a 3in or 4in stack in 1/25th?

[Chuck Most]

Best part about K&S is that they also include the metric measurements for the diameter. 1/8" would be fairly close to 3" in 1:25 scale, but you could just use the metric measurements and find one listed as 3mm or 4mm in diameter, since 1mm is extremely close to 1 inch in 1:25 scale.

[southpier]

Any idea on what diameter to get for a 3in or 4in stack in 1/25th?

1/25 = 1 divided by 25 = .040 = 1" in scale

scale 1" x 3 = .120"

scale 1" x 4 = .160"

conversion tables from the www: http://www.hamuniverse.com/antfrac.html

.120" - < 1/8" or < 3.1750 mm

.160" - < 5/32" or < 3.9688 mm

some math guru could figure the exact conversion, but i model to 12" scale. if i can't see the discrepancy from 12" away, paint it!

[lmtdconnectivity]

Thanks for the info!

[Chuck Most]

http://www.hamuniver...om/antfrac.html

Had this site bookmarked, lost it when I switched computers, forgot all about it until now. Thanks for that link!

[crazyjim]

An alternative to bending the aluminum tubing would be to use solder or soft aluminum rod that sculptors use. It's available at Hobby Lobby or Michaels.

[Art Anderson]

Best part about K&S is that they also include the metric measurements for the diameter. 1/8" would be fairly close to 3" in 1:25 scale, but you could just use the metric measurements and find one listed as 3mm or 4mm in diameter, since 1mm is extremely close to 1 inch in 1:25 scale.

The common sizes of K&S tubing translate pretty easily to scale inches in 1/25. Just use the factor .040" to equal one inch, and do the long division (either on paper or with a calculator. For example, 1/8 equals .125. Divide .125 by .040 and you get 3.25, or in 1/25 scale, 3 1/4 inches. Now, who's going to see a quarter scale inch? Practically nobody.

Art

[Chuck Most]

Eh... long division sucks. I just go straight for the metric measurements.

[lmtdconnectivity]

thanks for all the info everyone!