Post by oldtimer52 on Feb 15, 2020 1:41:20 GMT -5
Part 2: Part Preparation. Now we have to prepare the part that we
are going to makd a mold of. First we check the part for holes that
are used to attach parts.
On this piece we have holes for attaching the tool box covers, queen
posts, brake cylinder, truck mounting, coupler box cover attachment
and for the truss bar(string) on the bottom. On the top we have
small holes for the handrails and brake wheel shafts.
I started by finding out the size of drill bits needed to make these
holes. I used my drill bit set by using drill bits to check the size
of each hole and then writing down the size needed for each hole. I
came up with the following sizes:
Truss rod holes = #69
Queenpost/Brake Cylinder/Tool Box holes = #56
Coupler holes = #50
Handrail/Brakewheel shaft holes = #70
You will need this information to re-drill holes in the part once
it has been cast as the silicone will not completely make them for you.
One the bottom of the part most of the holes will allow a little bit of
silicone to settle in to create a small "dimple". This will mark the
pace where the hole is to be drilled. The truss rod, had rail and
brake wheel shaft holes are far too small for this so I had to
enlarge them a small bit. To do this, I used a smalll cone shaped
burr bit to slightly enlarge the holes so that the silicone could
create dimples to mark the spot where holes were to be drilled.
I did this by placing the tip of the bit in the hole and lightly
turning the bit 3 times for the truss rod holes and 2 times for
the handrail/brakewheel shaft holes. Just enough to allow the
Next I had to ensure that the "bolster" holes didn't get filled up
with silicone because the "bolster" holes are the end of a cup that
the studs on the body of the model fit into. When assembled, the
truck screws actually screw into the studs to hold the frame, body
and trucks together. I did this by filling the cups with clay and
cutting any clay that bled thru the holes even with the end of the
cups.
Now I had to deal with the steps. If I were to pour the silicone
now, the steps would be embedded in the silicone and there would
be no way to remove the part without destroying the mold. So, I
filled up the step space with clay and cut the excess even with
the edge of the steps.
Once this is done, we can mount the part into the mold box and finish.
I pressed the part (top side down) into the clay in the box. I used
enough pressure to push the part into the clay about 1/16th of an
inch. After doing this, I checked around the edges of the part to
make sure that the clay was up against the side of the part. I
did this to make sure that there were no "crevasses" on the edges
for the silicone to leak into. If there is the tiniest little
space, the silicone will find it and creep in.
Next step is pouring the bottom of the mold.
are going to makd a mold of. First we check the part for holes that
are used to attach parts.
On this piece we have holes for attaching the tool box covers, queen
posts, brake cylinder, truck mounting, coupler box cover attachment
and for the truss bar(string) on the bottom. On the top we have
small holes for the handrails and brake wheel shafts.
I started by finding out the size of drill bits needed to make these
holes. I used my drill bit set by using drill bits to check the size
of each hole and then writing down the size needed for each hole. I
came up with the following sizes:
Truss rod holes = #69
Queenpost/Brake Cylinder/Tool Box holes = #56
Coupler holes = #50
Handrail/Brakewheel shaft holes = #70
You will need this information to re-drill holes in the part once
it has been cast as the silicone will not completely make them for you.
One the bottom of the part most of the holes will allow a little bit of
silicone to settle in to create a small "dimple". This will mark the
pace where the hole is to be drilled. The truss rod, had rail and
brake wheel shaft holes are far too small for this so I had to
enlarge them a small bit. To do this, I used a smalll cone shaped
burr bit to slightly enlarge the holes so that the silicone could
create dimples to mark the spot where holes were to be drilled.
I did this by placing the tip of the bit in the hole and lightly
turning the bit 3 times for the truss rod holes and 2 times for
the handrail/brakewheel shaft holes. Just enough to allow the
silicone to make a small "dimple" to mark the spot for drilling.
Next I had to ensure that the "bolster" holes didn't get filled up
with silicone because the "bolster" holes are the end of a cup that
the studs on the body of the model fit into. When assembled, the
truck screws actually screw into the studs to hold the frame, body
and trucks together. I did this by filling the cups with clay and
cutting any clay that bled thru the holes even with the end of the
cups.
Now I had to deal with the steps. If I were to pour the silicone
now, the steps would be embedded in the silicone and there would
be no way to remove the part without destroying the mold. So, I
filled up the step space with clay and cut the excess even with
the edge of the steps.
Once this is done, we can mount the part into the mold box and finish.
I pressed the part (top side down) into the clay in the box. I used
enough pressure to push the part into the clay about 1/16th of an
inch. After doing this, I checked around the edges of the part to
make sure that the clay was up against the side of the part. I
did this to make sure that there were no "crevasses" on the edges
for the silicone to leak into. If there is the tiniest little
space, the silicone will find it and creep in.
Next step is pouring the bottom of the mold.
