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PRR T1 kitbash from 2 Hudsons


rbrown7713
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I consider my rivet head maker a success.  First picture is the rivet head indention, the second is what it will look like on the model, an impression in clay, and the third, the tool itself.  The main thing is that it allows me to place the tool where the rivet head belongs and the second and most important is that it has an adjustment to control the depth of cut so that it is uniform, works well.  I still have a little more machining to do, but for the most part, it is done. The tool was purchased at Harbor Freight and is advertised as an engraver.  It has a little motor that spins a round head mill that fits into a holder.  I had to grind straight the rubber and then glue my mechanism to it.  It is spring loaded, so I put it in place, push the button and then plunge it into the mold. Bob.

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Actually, when it comes to making the mold of the shell for the T1, all of the steps that I used is the same in making any of my molds.  Same procedures, just a different shape. The only difference was to mix a rigid mold with a urethane mold for the purpose of being able to add details to the shell. The most important thing about making a mold are simple steps such as waxing, sealing, claying, and design of the mold to insure the one doesn't have mold lock, that means that the part or pattern won't come out of the mold,  and crisp fence breaks for good fitting parts of the mold.  If any of the basic steps are forgotten, the whole process suffers and believe me, I have, in the past, forgotten  steps and that  wasn't fun.  Now to add several hundred rivet heads and then I can make a part. Bob.

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Here is the final machining of the rivet head mill.  I milled away part of the mandrel around the tool so that I can see where the tool will land.  I am waiting for the Loktite to dry and then I will commence grinding the rivet heads into the mold. Bob.

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Bob, today I received a Tug kit that I ordered in Feb, posted it on the Live Steam section of this forum.   

   From the pic's I have attached are they using the same method to cast the hull as you are??      thank you

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Yes, except they didn't use an inside mold, in my case, it was the urethane portion.  They laid up resin and glass from one side against the mold.  Looks like they used a gel coat and then laid glass over the gel coat, only a one sided mold. Bob.

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Screwy Nick, here is the type of mold that I made for the rc model, Stars and Stripes, that I dug out of my archives.  Most likely your tug boat mold was made almost like this. Mine splits in the center.  This was a model of the 1987 Americas Cup race entry. I still have the sailboat, sailed well.  Here also is a video of the Vertigo VTOL that I scratched built a few years back in which I made several molds for parts for it.  It is best to skip to about to the 9:00 minute area because it was cold that day and the engine took a long time to get started. This was the first test hover, flew well. Bob.        

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Bob thank you very much, plane is really something, you are truly a craftsman.    I think I better understand bits and pieces of the process.   The claim is that the material they used on the hull will be able to withstand the heat of the burner and boiler, i have no intention of taking their word for that.  I  intend to put some heat shielding material between them and the hull.  

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Thanks Screwy Nick, and yes, I agree.  It doesn't matter whether the hull is made of epoxy or polyester, you would be wise to use a barrier.  There are brush on types, and there is a product called, I believe Fiberfrax, sold by Spruce aircraft that is used as a barrier on plywood firewalls along with an aluminum sheet on homebuilt aircraft.  I have used it when building Long EZ aircraft, a Burt Rutan design and works well.  It is a cloth like fabric and can be installed with a rubber like cement, Spuce Aircraft would know about that. Bob.

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I wouldn't worry about 212 degrees, but you know steam gets quite a bit hotter than that.  In my way of thinking, an air gap would be sufficient, so if there is a sufficient air gap, you might get away with no insulation, just where a steam line is close to the glass hull. Bob.

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 Bob, I appreciate your advice.  In this case I'd rather lean toward the side of caution.  What with the expense and the time that will be involved I want to take no chances.  I can even install a small battery operated fan that I used to install in network equipment if I get that crazy.  

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  Bob, since you are familiar with this material, I'd like to ask your advice.   All of the info included with the kit refer the hull as 'FRP Hull'.  Does that refer to the material it is made of??   Also in many places I will have to adhere wood frames and braces to the hull.  The instructions advise using 5 minute and 30 minute epoxy.

    Can you advise me of a specific kind or brand of adhesive to use in these circumstances.  Any advice you offer will be greatly appreciated.    LG

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From the picture that you sent me, it appears to be FRP, fiberglass reinforced plastic, not ABS.  They probably use a set of plans or directions used for both abs and FRP.  5, 10, or 15 minute epoxy is available from any hobby shop, the brand is not important. You can also use CA.  If you use epoxy, make sure you rough up the area to be glued. Bob.

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Well I poured the shell and it is a reject.  I was about 4 oz. shy and ended up with a short pour.  Just as well, I am testing the paints.  Here is what it looks like with flat black, a poor, hurried paint job, but in the end, I think it will look good. Bob.

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This part is trash, also, I don't engage in selling any of my work, It's just my hobby for something to do.  Besides, when I total up what I have spent on this engine, I could have bought the brass one on Ebay for 3800. not including labor and 8 months work.  I have about 1800. in it already and it is not done yet. Bob.

 

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Thank you for the kind response. I know you don't sell stuff as I have tried repeatedly, so I apologize. I may also have an unfair advantage at knowing just how much you are spending on this engine. At least, I could guess on the rest!

I still would always offer to buy, what could be leftover. Sorry for the bother though.

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I am waiting for some more plastic to be shipped and here is the first setup for one of the pieces of the mold for the cab.  This is the most challenging mold that I have made so far, and still haven't got it completely figured out. Bob.

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Thanks Jerry, and in fact, I did figure it out.  The problem was that the part of the mold that forms the inside of the cab has an under cut due to the protruding windows and would not be able to be removed from the mold.  I have solved the problem by having a removable section of plywood  in the center of that portion of the urethane mold, and  when it is removed, I can then bend part of the urethane away from the inside of the part, therefore being able to get the inside portion of the mold out of the center.  It will make more sense when I finish constructing the mold in a few days. Bob.

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For those of you that are following the mold building for the cab, here is the first part of the mold poured and it went well after a catastrophic mistake.  I also use epoxy 2 part resin and when reaching for the part B, hardener for the urethane, I mistakenly grabbed the epoxy hardener instead of the urethane hardener.  They are both clear, so it didn't look any different than any other pour, even mixed well, but when I came back 3 hours later, there was nothing but liquid on the table and in the mold.  Oh well, after cleaning up the mess, and pouring the correct mixture, it came out good.  I am aware of the different chemicals that I use and usually check, but this time I was in a hurry and made this mistake, won't happen again, I hope. Bob.

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Bob, don't beat your self for making a mistake.  Did I mention in another thread on this forum that I ADJUSTED the frames on the Tug build twice?   I could use the excuse that the translation was poor, that would not be totally accurate.    Still watching in awe.   LG     

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