Detailing the cab vents on AMT's 1/25 scale Mack R600 kit

AMT's "Mack R685ST" is a favourite kit of mine, and while it is quite well done overall one detail that is not present is the roof mounted air vent fitted top many 1:1 scale Mack R's - although the two air scoops at leading edge of roof are are provided.

0:12 MPC (later Ertl) did provide the roof vent detail on their DM series offset cab Mack kits, and this can easily be added to AMT's kit with styrene sheet and strip.

0:24 I used an MPC cab for dimensions, .010" styrene sheet was cut .460" long x .300" wide and forward edge of this piece was located .425" from front of raised portion at centre of cab roof.

0:45 With .010 styrene glued in place the vent cover is cut from .030" x .156" styrene strip, .350" long and corners and top edges are rounded. Gluing vent cover onto cab completes a closed roof vent...

1:04...however it is not a lot harder to model this vent in the open position. Lay out a hole in cab shell that is 5/16" (.312") x 3/16" (.188") and located .475" from front of raised roof section.

1:21 Cut out and clean up hole...

1:30...and glue the .010" styrene piece (.460" x .300") onto roof centred over the hole.

1:48 From inside of cab shell cut a smaller hole (.300" x .125") in the .010" styrene.

2:07 This provides a ledge into which K&S 1/32" square brass mesh is glued to complete the vent opening.

2:15 Vent cover is .300" x .156" styrene strip, .350" long with rounded edges and corners same as the closed version, with small triangular pieces cut from .020" styrene at the ends.

2:40 This cover can be installed with open side forward as shown here, to "scoop" air, or with open side to the back to draw air our of the cab.

2:55 Whether you model roof vent open or closed the kit provided scoops are a little on the coarse side being molded as a solid piece.

3:11 Removal of molded on mounting pins and short flat projection on the back end...

3:26...two parallel razor saw cuts partway through...

3:50...and cleanup with file results in a much better appearance for the air scoops.

4:02 The hollow appearance is much better than solid, especially if model will be painted a light colour such as this example which will be white.

4:26 Side vent in front of diver door is also easy to model in open position.

4:36 Drill around perimeter of opening...

4:45..."connect the dots" and remove material with hobby knife...

4:55...file smooth...

5:07...and glue K&S 1/32" square brass mesh in place on inside of cab shell.

5:15 Inset mesh is correct for this application because vent cover is flush with surface of cab, requiring vent assembly to be inset slightly on the real truck.

5:30 .030" x .156" styrene strip is again used for vent cover, cut and sanded to match opening with corners and edges rounded...

5:41...and glued in place along back edge at approximately a 45 degree angle.

5:51 .020" styrene triangles glued in place top and bottom, similar to how the roof vent was made, complete the installation.

6:04 Tapered walls of cab interior "tub" work well for this open vent installation, providing clearance for the brass mesh and a realistic open area behind the vent.

6:30 Same technique is equally useful to model sleeper cab vents in an open position, so this detail item is not limited to the Mack R kit alone!

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