Superior & Seattle Railroad Build

Started by S&S RR, December 20, 2013, 10:27:49 PM

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S&S RR

First step is to make a box out of artist board. I hot glue these together. Make sure you where gloves. Hot glue burns hurt!





John Siekirk
Superior & Seattle Railroad

S&S RR

Here are a couple of pictures of a cutting tool a bought from Micro Mart a few years back that makes the slitting of the artist board real easy.  I highly recommend this tool.











Keeping the blade protected when not in use is also highly recommended.
John Siekirk
Superior & Seattle Railroad

S&S RR

Here is a setup picture showing the gloves I use for the hot gluing process.  Now I switch to latex gloves for the mold making process.


John Siekirk
Superior & Seattle Railroad

ak-milw

I bought one of those cutters a few years back, they sure work nice. I use it for making odd sized strip wood also.

S&S RR

Quote from: ak-milw on September 02, 2016, 09:07:44 PM
I bought one of those cutters a few years back, they sure work nice. I use it for making odd sized strip wood also.


I haven't tried it for strip wood.  Interesting. I have a small table saw that I use to cut my own strip wood. Except for the real small stuff. I may give this little tool a try for that.
John Siekirk
Superior & Seattle Railroad

S&S RR


Here is a picture of my setup just before I put on the latex gloves and opened the bottles.


I use 3 disposable cups for this process two that are small and exactly the same.  I pour equal parts of A in component in 1 cup and B component in the other. This is critical MUST HAVE EQUAL PARTS OF A AND B. I have had a few bad experiences when I was at the end of the bottles and tried to get away with just a little more of one of the components.


I always have the thinner on hand if the mixture is not liquid and hard to stir. For todays pour the A component was nice and thin and the B component was like tooth paste.  When I poured them into the big cup the mixture stirred nicely so I didn't use thinner. The key to this process is to combine the two components by pour both together without introducing unwanted air bubbles. The stir process must be very thorough but not fast so you make air pockets and bubbles. You have to mix so that the mixture becomes the same shade of blue.  No streaks of white or darker blue.  When I'm happy with the stirring I start pouring the mixture into the box - start in one corner away form the master casting.  Once you get a stream flowing out of the cup then cover the master casting completely.  You need enough of the mixture to completely cover the master casting and provide for a nice base to the casting.  I like about 1/8 of an inch above the casting.  More is better but expensive.  The key is to have enough mold material around the casting so the mold doesn't tear when you remove casting form it.




John Siekirk
Superior & Seattle Railroad

S&S RR

Here is a picture after the pour. And yes, I use the rubber hammer.  I gently vibrate the bench and tap the side of the mold box to make sure any air bubbles trapped in the mixture make their way to the top and away from the working surface of our mold. On this pour I didn't get any visible air bubbles. 


John Siekirk
Superior & Seattle Railroad

S&S RR

Next step - after you let it cure for about 6 hours - is to remove the artist board box.  The bottles say 4 hours cure - I give it 6 just to be safe.




John Siekirk
Superior & Seattle Railroad

S&S RR


I simply cut and tear the white artist board away from the mold. You need to be careful not to twist or crack
Tom's hard to find master casting.



John Siekirk
Superior & Seattle Railroad

S&S RR

This is what the back of the casting looks like after the box is removed.





The latex rubber seeps underneath the casting leaving some flash to be removed.





Most of this will come off by simply rubbing it off with your finger.  I use an exacto knife on the stubborn areas.
John Siekirk
Superior & Seattle Railroad

S&S RR

Then you simple peal the mold off the master casting.  Again, being very careful not to twist and brake the master casting.  I take this process very slowly.


Here is a picture of our finished mold.





John Siekirk
Superior & Seattle Railroad

S&S RR

This casting had some very deep mortar joints in some areas which did pull off in some random areas.


John Siekirk
Superior & Seattle Railroad

S&S RR

On this brick pattern I don't think it will make a difference but I'm going to clean up the casting and try using some release agent on the next mold to see if that helps.  I very rarely use release agent - because most casting don't require it.






John Siekirk
Superior & Seattle Railroad

S&S RR

I'm simple going to pick and vacuum the small pieces of latex left on the casting to clean it up.  I will be making a few more molds with the blue latex.  I'm then going to make some more durable molds out of the 10:1 latex mold material.  I plan on make many castings of this set of molds.  I have big plans for these casting as I described in a previous post.


I plan on making both plaster and resin castings using these molds.



John Siekirk
Superior & Seattle Railroad

S&S RR

On one of my trips under the layout today I took a few pictures of the rest of the tunnel system.


Here is a picture looking down the long tunnel at the back of the layout. 





It is 20 feet from one end to the other.  All of the old benchwork behind the mountains (above the tunnel in this picture) was what I cutout yesterday to make room for the loops between the four different levels of the layout. I removed some more today and I think I have plenty of room to work and haven't hurt the structure holding up the mountains.
John Siekirk
Superior & Seattle Railroad

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