Brick – FAIL!!

I wanted to see if I could make a mold so I could cast bricks in 1:48. First thing I model a standard brick in Sketchup including a 3/8″ deep frog.

That was easy enough. There are all kinds of different sizes of bricks when you start looking but the 4x8x2-1/2″ shown here is near enough a ‘standard’ or ‘common’ brick.

I arranged 11 bricks by 10 bricks in a grid and then surrounded them with a wall and a base. The idea was to create a master that I could pour RTV into and create a nice mold.

I wanted to test out WSF as a material – I haven’t done so in the past as I’ve kept myself to using FUD.

WSF – or – White Strong and Flexible is a laser sintered nylon plastic. It’s high strength is offset by it’s medium smoothness and less detail then FUD.

So. Here’s what I got. Hmmmmm. The minimum embossed/engraved detail that WSF can be printed at is 0.2mm .. about 0.008″. If you look back at the first illustration with dimensions that 4″ full-size brick width is 0.075″ in 1:48. That 0.008″ minimum detail is a full 1/10 that width. That means I got bricks with rounded edges.
A close-up of the RTV mold and a couple tries at casting bricks shows the results.

There’s a couple of things that can bee seen in this photo:

  • Pin-Holes in the RTV. That’s one of the things that I will fix at some point. The RTV needs to be de-gassed in a Vacuum chamber. I have the vacuum pump and need to purchase a couple more items to build my own vacuum chamber.
  • The bricks show well the rounded edges. Those edges would be much less if the master was printed in FUD – but that would be quite a bit more cost then the WSF print. I wanted to see how well the WSF printed and am confident that it would probably be fine to represent something like a truck sideframe.
  • The yellowish colored bricks were cast in Durham’s Water Putty and the reddish colored bricks is a plaster’ish floor leveling compound colored with Terra Cotta cement color. Neither of these made good bricks.

The bricks were a ‘FAIL’ IMO .. pretty much. If they would cast better I might could use them as old bricks. I will still use the mold to experiment with other materials to see if I can some nicely cast bricks from it. One problem is if you look close .. the backs of the bricks .. the side opposite the frog is slightly dished on many of them. That’s simply that the plaster didn’t completely fill the brick mold and surface tension pulled the edges up. I need to play around with it but I think that the answer is that I need to overfill the mold and at some point I need to scrape across the surface.

This entry was posted in Casting, eTraxx, MicroMimesis by etraxx. Bookmark the permalink.

About etraxx

Retired from the Army in 2006. Served during Vietnam - 1969-1972 as as 72B - Communications Center Specialist (Teletype Operator). Got out .. and went back in 1987 as a 19K - Armor Vehicle Crewman - (M1/M1A1 tanker) getting out in Korea in 1999. Went into the Reserves .. got mobilized in 2001 .. stayed active until my retirement with 20 years in 2006.

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