Even something as seemingly simple as a Mack truck hood can become a model in its own right - and along the way, minor inaccuracies are easy to correct.
0:18 Ejector pin marks are a necessary part of the injection molding process and AMT's Mack hood has eight large ones on the underside. Two hole locations provided for turn signals on fenders are one of the inaccuracies to correct as they are located on flat portion of fender top...
0:34...and, if the kit instructions are followed as they were for this model built about 12 years ago, place turn signals too far inboard.
0:46 Photos online and in books all show Mack R model turn signals on the rounded portion of fender, farther out than kit location.
1:07 Styrene disks punched from .020" material are glued into the holes.
1:24 Next step is roughening underside of hood for fiberglass texture. This is one time when the kit part is actually too smooth!
1:35 7/32" carbide bit in motor tool set at low speed is an excellent way to remove elector pin marks and create fiberglass texture by lightly drawing it across all surfaces of hood underside.
2:02 Use 1/8" carbide bit on inside corners with smaller radius where the larger bit will not fit.
2:13 AMT provides good inner fender detail as separate parts. Fill the ejector pin marks on these as well...
2:32...and add fiberglass texture. The improved appearance shows up well comparing upper, untouched part with textured one at bottom of image.
2:45 Another minor inaccuracy is molded on location of marker light, noticeably farther back on side of fender...
2:57...than it is on 1:1 truck. This raised circle is easily sanded off and marker light can be installed in correct location at final assembly.
3:12 Mold parting lines are present on any injection molded plastic part, here they are highlighted in red. A few minutes of sanding work will remove these and greatly improve appearance of finished model.
3:33 Horizontal ridges at back of fenders are not an error or parting line, these ridges are present on some real trucks...
3:53...such as J&F Trucking #111, a truck I drove myself nearly 30 years ago back in 1994!
4:22 Of the many Mack R models made, these ridges do seem to be relatively uncommon so if the truck you are modelling does not have them it is an easy matter to remove them with careful chisel blade work followed by sanding.
4:46 AMT has seven hood hinge bolts molded on kit hood. This is accurate for some years of trucks, I believe the earlier ones up to around the mid 1970's which makes sense for the kit as it would have been tooled close to the mid 1970's, representing a truck of approximately 1976 vintage.
5:02 Matching seven bolt pattern on this truck...
5:12...and this one, a pre-1973 "flat back" or "steel dash" version.
5:39 AMT's kit is based on a post 1973 "plus 3" version similar to the truck pictured which had 3 inches added at back of cab for more interior room. Note this truck also has the fender ridges.
6:08 Later trucks all seem to have four hood hinge bolts like this example hood.
6:36 Easiest, although not quite accurate, way to make a 4 hood hinge bolt hood is to tape off upper four bolts...
6:51...and sand off bottom three. This places the four bolts higher than they are on the real truck and not quite in the right arrangement but is certainly "close enough" for model purposes.
7:08 1:1 scale trucks with four hood hinge bolts have them slightly lower and not quite in a square pattern with bottom outer bolt further out than upper one.
7:23 In 1/25 scale I modelled these with Tichy Train group #8077 rivets, .060" diameter. Bottom outer bolt was located first using corner of tapered section below headlight opening as a location guide.
7:39 Once these were in, other bolts were located "by eye" and glued into drilled holes.
7:57 Contour of plastic rivet head projects farther than more flat shape of carriage bolt head so sanding was done to reduce profile slightly, followed by wash of Testors liquid cement to blend everything together.
8:12 Next installment will cover adding details to hood underside, and correcting the radiator shutters.
#scalemodeltrucks
#scalemodelling
#modeltrucks