To paraphrase Vane Jones, "Knowledge is of little value until shared with others."

Saturday, August 4, 2012

AEFRE 49 - #4B The Flat Car with Decking

Next comes the adding of 2 brass tabs to hold the power truck in place. The tabs need to be 3/32” thick. Each tab has to clear the "top" flange of the “I” beam in order to butt up against the web of the “I” beam. Making the tab from 2 pieces of brass provides this.

Each tab is 2 pieces of brass, 1/16” and 1/32” thick. The drawing shows how long to cut each piece of brass.

The 2 pieces of brass have been soldered together and filed, if required. Note the stepped area to clear the flange of the "I" beam.

Before adding the 2 tabs, the location of the where both power and trail trucks  needs to be marked. Locate the center point of both trucks on the beams. On the end where the power truck is to be installed, measure the width of the flat plate bolster of the power truck on the set of beams. I filed the beams to make the markings noticeable.

Always try to “tin” the pieces of brass to be soldered. Then clean up the area. Place the tabs in location. You may have to “eye-ball” the exact spot. To aid in the soldering, cut 1/16” long pieces of 6% silver solder and carefully place pieces next to the beam and tab. Apply only enough heat with a propane torch to melt the solder.

The brass frame is designed to have pieces of styrene glued to it – this includes end and side pieces. Place the frame on its side on a flat surface. When this is done the frame should not rock back and forth. If it does this means the tab is sticking out too far. The tabs should not stick out beyond the 2 end pieces. If a tab does stick out file it down.

After the tabs are soldered on and filed down, if required, carefully file down the web of the “I” beams where the power truck is located. When the filing is completed the flat plate bolster should fit into the filed out “slot”.

The flat plate bolster of the power truck will stick out further than required. Center the power truck in the frame. Mark where the excess of the flat plate bolster needs to be cut off plus the location of the 1-72 mounting screws in the tabs.

Here you can see both the power and trail trucks before they are mounted to the frame. The body bolster provided with the trucks is of the correct height.

Cut off the excess flat plate bolster material. Drill and tap the holes for the 1-72 mounting screws in the brass tabs on the frame. Drill or file out the 2 holes in the flat plate bolster so 1-72 screws will pass through them.
Normally the flat plate bolster is attached from the top. That's why the holes in the bolster are already tapped 1-72. IN our application the mounting screws are attached from the bottom.

I ran into problems with my 30 year old 1-72 tap – it broke in the brass tab. A new hole had to be drilled and taped. This is the reason the tapped holes on my frame do not match and line up.

File the screws flat with the top of the brass tab if you have to use longer screws like I did. Remove the power truck and screws and store them is a safe location.
On to applying the styrene.


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