1/25 scale Transtar 4300 exhaust: Part 3 - Flex pipe & band clamps

At the conclusion of Part 2, exhaust system for this Transtar 4300 model had pipe installed from engine to back of cab and muffler/stack completed. "Missing link" was pipe connecting muffler/stack to rest of system.

0:17 Take advantage of opportunities for photos when they occur! This Transtar 4300 was spotted on a drive back in April 2012. It has a single exhaust similar to the truck I am building a model of...

0:27...with section of flex pipe connecting muffler/stack pipe to pipe along frame. Although not the exact configuration of the model I am working on this photo provides a good reference for basic flex pipe installation.

0:37 Exhaust flex pipe is usually made from stainless steel, tightly wound from flat material to keep exhaust gases in while maintaining flexibility. Visual cue we are looking for in model form is the ribbed or grooved appearance.

0:49 Some truck kits, including the Transtar 4300, have molded-in flex pipe texture on the exhaust pipe parts. Italeri's "Superliner" has this detail, and so does AMT's Mack R.

1:16 Revell Germany's Kenworth W900 conventional provides good flex pipe detail, although the pipes are molded in two halves which requires a lot of fussy clean up.

Flex pipe detail is easily added to any model truck exhaust system with a very simple material...paper!

1:35 From Part 1, use a small candle for heat source...

1:42...and bend styrene rod (taken from a 1/25 "snap" kit exhaust stack in this example) to shape pipe as required.

1:57 Placing model on its side can make this bend-and-test-fit process easier.

2:25 A narrow strip of paper will be what creates flex pipe texture. X-Acto's "12" Compact Rotary Trimmer" is a useful tool for this and not overly expensive. I already one which sees a lot of use trimming decals and photos.

2:35 Paper strip is cut .040" (1 mm) wide, from the long (8-1/2" or 216 mm) edge of paper sheet. Attach this to pipe at end which will connect to the frame-mounted pipe...

2:45...then wind tightly around. Every 6 wraps or so use thin CA glue to lock the strip in place. Thin CA will soak into paper and not build up excess thickness.

3:01 Continue wrapping and gluing until desired length of flex pipe is added. This installation used almost the full 8-1/2" long strip.

3:19 Two band clamps are needed. I did a separate video on creating exhaust band clamps:    • Make 1/25 scale band clamps for model truc...   , the basic steps are to use aluminum tube that will fit over the exhaust pipe (for this model 7/32" or 5.5 mm) and cut a piece the required length. A 4" (100 mm) long band clamp in 1/25 scale works out to .160" (4 mm). Glue a piece of .040" x .040" (1 mm x 1mm) styrene strip to the tube...

3:39...trim styrene strip to same length as tube and add nut/bolt/washer castings on one side and rivet heads on other side to replicate fasteners. Tichy Train Group #8016 nut/bolt/washer and #8019 rivet head are the ones I use.

4:10 Slide band clamps into position and secure with CA glue.

4:21 I painted flex pipe and band clamps Testors bright silver and weathered with wash of brown India ink. Rusted pipe got Tamiya XF-10 flat brown base coat followed by dry brushing with lighter and darker shades of brown.

4:44 Now there is just the stack pipe, which on this truck isn't the usual vertical chrome piece, instead it looks like a 90 degree exhaust elbow.

4:55 Another "snap" kit stack is heated and bent, then drilled out progressively larger until hollow end is achieved. Final clean up with hobby knife smooths out any rough spots and thins down edges for more realistic appearance.

5:35 Tamiya flat brown and drybrushed highlights are also done for rusty appearance on this pipe.

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