Heavyweight 6-wheel truck

[rbrown7713]

I am doing Larry a favor advertising his wheelsets. Glad to know this is a good buy.  I mentioned these in the classifieds for him. If anyone wants any, send me a private message and I will give you his number. Bob.

[rbrown7713]

Here is another pattern done on my mill in Bondo for some more parts for the truck and another project. Bob.

[rbrown7713]

I received the Fine Arts chassis and trucks and am amazed at the detail in the trucks, the brakes on all six wheels articulate with the levers and rods, amazing.  Too many moving parts for anything but a static model, not practical for outdoors, too many loose and delicate parts, but it is beautiful though. Well have to get back to my trucks, as urethane is arriving tomorrow. Bob.

[rbrown7713]

Here are some more molds of the f-7/e-8 cab and parts. Tomorrow, I will pour the third part to the mold for the cab and the front skirt. Bob.

[enginear joe]

Beautiful. 

[rbrown7713]

Thank you Engineer Joe and I have an additional photo to show.  The mold is ready to pour the third and final part of the mold set.  You experienced mold makers probably already knew this, but I had to find out the hard way.  A means of reducing pressure when installing the top of the mold set is needed so that the two mold section can seat, thereby reducing the chance of making too thick of a part and not retaining the desired shape.  Note the two channels glued to the highest part of the mold allowing the excess plastic to escape.  Not all is lost on my previous molds, because I can still cut a channel in the top pieces of the molds to achieve the same thing, which I will do on the side molds where that was a problem, so I just thought that I would pass this along in case any one out there is making molds.  In case someone is wondering if the the thickness of the walls will be retained, and the answer is, yes, note that the cab pattern is in the first part of the mold and by pouring the third part of the mold the walls will be retained.  The only reason I shared this is that someone asked if I was going to pour it solid, he didn't see that the cab pattern was still in the mold. The third part of the mold is to establish the thickness of the walls.  This mold set has three parts to allow removing the part once the pour hardens, it would be difficult to remove if only using a two part mold. Bob.

[enginear joe]

I noticed the cab was in the mold to form the missing third piece of that mold. I like channels to help air to escape. It helps minimize the chance of trapped air. I like to see how you do it to adjust what I have stumbled on.

[rbrown7713]

Hey guys, you forgot to tell me to put the bridge dowels in the third part of the mold, but that is OK, I remembered.  They might not have been necessary, but any help to prevent say in the mold is good, even a 1/32 of an inch is too much.  It also helps, when the plastic is poured in and the mold is compressed downward, it is solid and prevents compression, here is a picture. Bob.

[rbrown7713]

Joe, while it may serve to expel air caught at the top of the mold, but the main reason is to allow somewhere for the excess poured plastic to go so that the top mold will seat without compressing the excess plastic.  If there is no where for the plastic to go it would not allow the top mold section to seat properly, therefore an improper part shape. Bob.

[enginear joe]

Thank you!

[rbrown7713]

Here is the first side rail out of the mold. Still making more parts for it, spring holders, leaf spring etc. Bob.

[Sean]

Funny It looks sorta like a key board! 

[rbrown7713]

If you weren't lurking in the background, you would have seen my truck. Nice to hear from you again Sean. Bob.

[rbrown7713]

Half of the front skirt and all of the cab mold completed, Bob.

[rbrown7713]

A mock-up for fitting some more parts. Bob.

[Jerry B44]

Really coming along Bob!  Cab looks like it will work good.

[rbrown7713]

Yes, your cab was well done, but after I produce a couple of cabs from this mold, I will add some of my parts and use yours for even a better cab., that means making an entirely new mold or two, but I know how to do it now.By the way, who made that cab? It looks different than a Ralph Brown cab. Bob.

[rbrown7713]

 Here is a picture of one my hard cab molds and you can see there are 5 parts of the mold that I had to make just to get the part out of the mold, as compared to the urethane, just 3 parts of the mold of a cab in the previous post. My cab evolved from a very rough pattern out of wood and then from many evolvments, and making 5 or 6 more molds, I got here, but not perfect. I am still trying to get the perfect shape of the bullnose cab, and I will until that happens. The urethane mold that you see in the previous post is just another step to that end. When I started making the hard molds for the cabs, all I had was pictures, no blueprints, so everything that has been shaped has been by eye. The windshield shape is very important, so one day I went down to the train museum at Parrish Florida where they had an F-7 loco and I asked them if I could climb up and take measurements of the windshields after telling them that I was a model builder and they said OK. I laid a piece of thick paper on the shape and marked the shape and then came home and laid out an XY grid on my garage floor and then took those numbers and transferred them into Turbo-cad, much like Autocad, so I have the exact shape. I then scaled these numbers to 1/32 and somewhere in my old computer, those numbers lie. So, to sum up, I still have quite a lot more work to do, as I want to be able to cast the glass pieces in the pour, real glass, and have the correct shape, I know, I have too much time on my hands, I know that, but maybe within the next few months, I will have gotten my true shape of the cab. Bob.

[rbrown7713]

Here are some pictures of the completed cab part from the mold.  I will also have to make a pattern for the straight type pilot. Note the amount of flashing, minimal, it just fell off and that's good, shows that the mold parts are fitting tightly. Bob.

[rbrown7713]

Engineer Joe, you were right about expelling air.  You can see in the top rear area of the cab, two air bubbles in the picture above.  The area that I did not have a vent, I got a bubble.  I minimized the air problem, but you were right, the channels are necessary to also expel air, so I will cut a channel in the top mold, easily done, to mitigate that problem. Bob.

[rbrown7713]

I found out that the Fine Arts chassis I got is not a diner, it is a 70'  RPO.. Bob.

[Jerry B44]

Bob, I got the cab with a bunch of left over Great Trains parts I got from the club in Grand Junction. His wife donated all he had left after he died. Club sold it to raise money. I think it's all gone now. I still have some metal castings but that is about it.

[rbrown7713]

Jerry, any metal castings relating to the F cab? any window frames, etc.?  If you do have, what are they and may I barrow them? Bob.

[enginear joe]

Sorry Bob, I may have jinxed you!

Are you pouring and then squeezing? (that's what I call it) or pouring into the mold already assembled?

[rbrown7713]

I am pouring the plastic into two parts of the mold and then I put the top part of the mold on, which has the inside shape in it,  and then, squeeze the plastic to the top, and then put weight on top of  it. Bob.