# Heavyweight 6-wheel truck



## machiningfool (Nov 15, 2008)

I thought I would share one of my methods of making parts. I use Bondo to machine patterns. There are several reasons to use this medium. *Easy on cutters, fast cuts, mistakes are easily cured, just add more Bondo. *I will be adding some details on this pattern, but here is a picture of my rough machined truck. I don't have a 3D printer, yet, so here is how I render the pattern. Bob.


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## ewarhol (Mar 3, 2014)

Interesting. Are you then casting resin parts from the pattern?


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## machiningfool (Nov 15, 2008)

Ewarhol, yes, and I hope to make them to be sprung, but more designing is necessary. I am now trying to design some details to make them look more prototypical. Bob.


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## machiningfool (Nov 15, 2008)

Here are two more molds almost ready to pour the second part of the mold for the steps and the ends, also the two part mold for the sides. Bob.


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## machiningfool (Nov 15, 2008)

*Really, I will get back to the trucks shortly.*

Here is the second part of the molds poured and ready to make a part. Today I will get back to the trucks and program the spring arms for the truck, and am looking for bearing for the trucks, any ideas? Bob.


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## machiningfool (Nov 15, 2008)

*Tracing tool.*

Here is another tool that I made to trace an outline of a part on my mill. It is nothing more than a spring loaded refill cartridge. This way, I can check to see if the part is the correct outline. This happens to be a spring arm for the six wheel truck. Bob.


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## machiningfool (Nov 15, 2008)

Well, after making the pattern with my handy pen, I found a huge error and have to start all over. I have decided to not make them sprung for several reasons, one, being that the spring that would have to be used would be so small in gauge that it wouldn't look scale, and two, the solid side frames will be stronger, and three, it's too time consuming. I have designed for the fit of the bearings, I will design the hole into the mold, therefore, won't have to come back and drill the hole for the bearing. Bob.


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## machiningfool (Nov 15, 2008)

*Mold insertion*

I mentioned how I would tackle the problem of a sagging mold section. This ladder like brace will be placed in the top, second part of the mold, keeping it from sagging and therefore having a straight part. This is only necessary in long parts like the roof not the sides, since the window opening actually touch, therefore keeping the mold from sagging. Bob.


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## machiningfool (Nov 15, 2008)

*First parts from molds*

Here is the first two parts from the molds, the steps and the end piece. This is the first time that I have use plastic instead of epoxy and I am happy with the new material, seems as strong as the epoxy. I am almost ready to machine the new truck sides, waiting for rivets from Miami. Bob.


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## machiningfool (Nov 15, 2008)

*Side was poured.*

I am pleased with the side, although it does have a few flaws, but an 80 year old heavyweight should have a few dents, I think I will leave them. The rivets came out well, tomorrow I will pour the other side. Bob.


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## du-bousquetaire (Feb 14, 2011)

Very interesting results Bob, and a fascinating sequence of showing how it' done. By the way in scene design and props work we use Plaster "socks" (= chausette! that's the way we call them over here in our slang) or outer molds to keep the silicone one straight as it should be when the resin part is being cast. It may be interesting technique fo you to use or explore as it's cheap and easy to do. The idea is to put the silicone mold in a sort of plaster box that holds it straight while casting. I may just be "pushing an open door" and you probably know all about this, but just in case you didn't it does work well for long parts. We just cast some 3' sphinxes for Napoleonic style table legs we did for a show and it worked like a charm, at school before I retired.


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## machiningfool (Nov 15, 2008)

*New loco.*

I am sure that works, but I have developed a routine with pouring directly on my waxed granite slab and then all that I need is some plywood borders. After the pour is finished, I add the top with runners in it, the full length and a few round dowels to keep the urethane from stretching. When I turn it over, the mold sits on top of the board with the straight runners and then it is oriented and straight. I just got my MTH Hudson, and put one of my stretched mth smooth cars behind it, can't wait until I build another 9 cars to pull behind, so many cars to build, and so little time. Here are a few pictures. Bob.


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## machiningfool (Nov 15, 2008)

*Hudson repair and heavyweight side window fix.*

I ordered the part for the Hudson and I had to buy the whole lead truck, cost 25.00 plus 9.75 shipping. The broken stud was fixed with super glue, seems to be very strong, but I will have to remember to pick it up by the wheels and not the boiler. Here is something that I had to go through to get the correct thickness of the window frames because of the plastic setting up as I was installing the second part of the mold. The stuff was setting so fast that it made the window frames too thick so I had to machine them down on the mill. Next time I will try to work faster and use more weight. This probably wouldn't have happened if I had used the epoxy that I am used to, but I am trying new things. Here are some pictures of the setup on the mill, cutting the inside of the frames for consistent thichness. Bob.


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## Jerry Barnes (Jan 2, 2008)

Looking good Bob, as usual! How will you do the roof?


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## machiningfool (Nov 15, 2008)

I am set up for the first part of the 2 part mold for the roof and hope to pour it within a few days when I get some more urethane. The second part of the mold will have to have dowel stiffeners in it to keep it from sagging, since unlike the sides, it won't have any contact in the middle to keep it from sagging. I will post pictures when I get that set up. Bob.


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## machiningfool (Nov 15, 2008)

*Back on the trucks.*

OK, back on the trucks. Here are a few pictures of the pattern cut out of Bondo, in steps. The hole is the hole for the 6mm bearing. The journal bearing cap will go on later. I have marked the locations of the bolts and rivets. Bob.


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## Scott (Jan 29, 2008)

Bob, looks good mate. CNC milling another skill I need to master. Keep up the good work.


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## machiningfool (Nov 15, 2008)

Thank you for your encouragement Scott. I will never learn all that there is to know, but compared to where I was a year ago, I am improving. I use MasterCam, it is easy for me, now that I am getting used to it. I push myself on the programming of more challenging shapes and that is where I learn, slow but once it is in the machine, the machine does the work and I love to watch it machine, once I push the button. Since I am working with urethane and not a hard mold, I have to add items after the rough pattern is made. Today, I am adding some hex head bolts and some rivets. I had to scramble to find two drills, one, .020 and one, .040, I can't believe that I had them. Probably for some other job that I had at one time, can't even remember what it was, thanks again. The size of stuff that I am doing right now does not take a large mill such as I have, a 9x 42 Bridgeport, with Anilam controls. A very small 3 axis mill would easily do the job. In fact I had to build a 48x48 cnc router because my mill travel was not long enough to do the future passenger car sides that I plan to do. My travel on my mill is only 27 inches, I need 33 inches, so the router will work just fine. That was an adventure building the router, but very satisfying. Bob.


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## machiningfool (Nov 15, 2008)

*More truck*

Here is the result of the bolts and rivets installed for the mold. Boy, these things are small, I am talken tweezers. Bob.


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## Phippsburg Eric (Jan 10, 2008)

Bob--

your work is fantastic! I am impressed with the mold quality. using bondo as a raw material to mill is slick! good idea!


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## machiningfool (Nov 15, 2008)

Thanks for your comments Phippsburg Eric. I started using Bondo to build and model small parts and when I observed how strong it was and that it carved well, I realized that it could also be machined for use as a pattern also. The nice thing about using Bondo is that if you make a mistake, you just fill with more Bondo and re-machine, which I am very familiar with. There is one thing that has to be done when making a Bondo plate. The Bondo has to be applied in thin layers and built up to the desired thickness because of bubbles occurring in the pattern. When spread thin, the bubbles will show themselves and can be dealt with and then another ply of Bondo applied. I still have some carving on this pattern, cutting out some fillets caused by the cutting tool. After that, I will wax the pattern several times before making a urethane and hard mold. The hard mold will be made of epoxy. Bob.


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## machiningfool (Nov 15, 2008)

*Methods*

Here are some hints on my methods of installing small rivets and bolts. I used a popsicle stick to hold the rivets before cutting, turned it over and held, and then used a grinder to cut to size. I used Elmers glue to hold in place. The one photo is to remind that even cnc machines can have a brain fart. In Mastercam, there is a varify screen to see if everything is cutting as programmed. I run that, and if everything looks good, I put it on a floppy and install it on the Anilam controls and run it, without any failures, except on this one. The first copy of the truck frame cut without any errors, but I discovered, as you can see in the picture, the first program, out of seven, the outline which required two depth cuts, the first cut error, about .0265 inches varied from the program, not in the first truck frame, but in the second one. Very interesting, shouldn't have happened, but it did, so all that I am saying is to be aware of rare happenings that could occur. Since I didn't notice it while it was mounted on the machine, 0,0,0, was lost, so I couldn't just fill whith Bondo and recut, so I added a piece of 1/32 ply to repair the pattern, so, there you have it, I am now ready for some wax and then pour some urethane molds.


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## machiningfool (Nov 15, 2008)

I forgot something, to cut out the radii of the cuts, here is the final version before waxing and molding. Bob.


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## machiningfool (Nov 15, 2008)

*A mold*

The mold is done and later today I will make some parts. It came out perfectly and will make some good parts, not finished yet, have to add some stuff. Bob.


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## machiningfool (Nov 15, 2008)

*Frame mold and truck frame*

I poured the truck faces and the frame and everything went well with the exception of some bubble around the bolts in the truck frame, I forgot to drag a toothpick in the holes where the bolt heads are to release any air, but I will next time and also, I used too much spray mold release, caused a rough finish. The frame mold turned out good. I have changed how I pour my molds in that I pour directly on the granite and border the soon to be poured mold with plywood and clamps. Lot easier, also can reuse the plywood borders and comes apart easier. The excess urethane on the table just comes right up in several pulls. I will pour some better truck frames and post them later. Next, tomorrow, I will pour the first part of the roof mold. Bob.


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## machiningfool (Nov 15, 2008)

*The bearings fit.*

Here is what I was after. The bearings slip right in with no back drilling. Bob.


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## machiningfool (Nov 15, 2008)

I mentioned in a previous post that a couple of bolt heads didn't come out because of bubbles, well the nice thing about using real bolts and rivets in the pattern is that I can grind the heads off, drill a hole and replace with a bolt or rivet, so the first side frames are saved. Bob.


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## machiningfool (Nov 15, 2008)

*Roof mold and more truck.*

Here is the roof mold about to be poured. Also continuing on the truck, making attach brackets for attaching truck sides. There will be a second mold to make these. Bob.


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## MGates (Mar 16, 2016)

Bob, I'm enjoying looking through your documentation of the milling and molding process. Very clean results. What type of casting materials are you using? I usually use OOMOO and Smooth-Cast by Smooth-On for my molds/casts. I figure there may be a better material for train modeling, maybe something more sturdy.

-Mike


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## machiningfool (Nov 15, 2008)

In the beginning, I was mixing epoxy resin with flox, cotton fibers, and it is very strong and allows ample time for casting. I decided to try Poly-tec urethane plastic and have been making some parts with OK results, but I am thinking about going back to epoxy resin because of the working time is longer and it is stronger, we shall see. I am not familiar with the mediums that you have mentioned, tell me something about those, I would like to hear about them. If you can, show me some examples. Bob.


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## machiningfool (Nov 15, 2008)

*More truck*

Here is the way I will attach the two sides together. The square piece lying on the spring bar will be bolted on each side with two bolts. Shortly I will make the second part of the mold to add these cross bars. Just the spring holders, bearing boxes, some brakes and the bolster bar and It's pretty much done.


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## David Leech (Dec 9, 2008)

Bob,
Just a little warning!
On nice flat track you should have no problems, but being a totally rigid truck, you may find problems on 'not so good' track.
All the best,
David Leech, Delta, Canada


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## machiningfool (Nov 15, 2008)

Two things, one, I will be using large flanged wheels, and second, the trucks will be flexible, at least that's the way I plan it, but thanks for your warning, also I hope to have flat track for that reason. Bob.


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## machiningfool (Nov 15, 2008)

*Second part of the mold.*

Here is the setup for the second part of the mold for the truck, waxed, sealed, and sprayed with 2300 mold release. Bob.


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## machiningfool (Nov 15, 2008)

I need some help with some wheels. I found three axles and wheels around my garage and they fit my 3mm bearing holes perfectly, but I have no idea what they came off of. The hole size of the bearing has to be .120 or .121, because the axle shaft size is .119, it fits perfectly. Can anyone identify what they might have come off of? If I can find these wheels to buy, I can save myself the trouble of turning the ones that I have down on my lathe. Well the revised truck sides and the roof are poured and in the morning, I will open them up, it's like opening up a Christmas present in June. Bob


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## machiningfool (Nov 15, 2008)

*Pics. of needed and unidentified wheels.*

I need some help with some wheels. I found three axles and wheels around my garage and they fit my 3mm bearing holes perfectly, but I have no idea what they came off of. The hole size of the bearing must be larger than .118, has to be around .120 or .121, because the axle shaft size is .119 and it slips right on. Can anyone identify what they might have come off of? If I can find these wheels to buy, I can save myself the trouble of turning the ones that I have down on my lathe. Well the revised truck sides and the roof are poured and in the morning, I will open them up, it's like opening up a Christmas present in June. The wheel measurements are: wheel: 2.657, with the flange:3.255, and the axle between the wheels is: .268


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## machiningfool (Nov 15, 2008)

*Second part of truck side mold.*

You are probably wondering how I will get the plastic up into the upper mold? Here is a picture. I first pour the bottom mold, install the upper mold and then fill with plastic through the hole. Bob.


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## machiningfool (Nov 15, 2008)

*Roof mold, first part*

The first part of the roof mold came out good and now I am preparing for the upper part of the mold. Bob.


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## machiningfool (Nov 15, 2008)

I found some more wheels in a box in my garage that I had ordered years ago off of Ebay and here is what I found. I found that the outside axle measurements varied from .115 to .121, but I found three that were within tolerances, so I am OK for now, thanks for your trouble. Bob.


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## machiningfool (Nov 15, 2008)

*Trying something new, to me.*

While pouring the sides, I noticed that since the plastic sets so fast, it doesn't allow the top part of the mold to seat properly. I think one reason for that is that it is restricted by the fit of the mold, nowhere for the plastic to go, so won't allow the weight to push it down. So, as you can see in the picture I have added vents or sprues to allow the plastic to go somewhere and relieve pressure and allow the top part of the mold to seat. If, after trying it this way, there is too much relief, I can always put some clay in the vents to restrict it some. I will know if this works either today or tomorrow, when I pour it. Bob.


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## machiningfool (Nov 15, 2008)

*Top roof mold*

I will be pouring the top of the roof mold tomorrow morning when it is cooler. The ladder that you see in the photo is to keep the top mold from sagging, it will be a part of the mold. The side parts of the ladder will be removed after the mold sets up, so the mold will actually bend longitudinally. This urethane is heavy, so this keeps the mold in the proper position. In the case of the side mold, the window portions of the mold contact each other, so no rigidity is needed.


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## machiningfool (Nov 15, 2008)

*Mold and parts came out excellent.*

Couldn't be a better day, the top roof mold came out perfect. Made two sides for the truck and they also came out good, ready to make some more parts for the truck. Bob.


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## machiningfool (Nov 15, 2008)

*More truck*

More solidity for the ends. Bob.


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## machiningfool (Nov 15, 2008)

*More truck*

Continuing to mock up, almost there, waiting for some more urethane. Bob.


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## Tomahawk & Western RR (Sep 22, 2015)

do you plan to use these molds to make more than 1 car? i think the wheels could be the lionel g scale ones from the 80's. not sure though.


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## machiningfool (Nov 15, 2008)

Yes, If I can find the time. I am having good luck just turning down the axles of any 36" wheels. Thank you for the info. The axles, inside the wheels seem to have a rubber like material on them. Bob.


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## machiningfool (Nov 15, 2008)

Hey guys, I am the proud owner of a Fine Arts PRR diner chassis and trucks that I won on Ebay, boy what detail, can't wait to put something on top of it. OK, who was bidding against me? Bob.


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## Tomahawk & Western RR (Sep 22, 2015)

any chance you could start making and selling them?


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## machiningfool (Nov 15, 2008)

So far, I don't sell anything, just build for myself, but If I ever get ahead with my building of parts, and make a good enough truck, we shall see. With all of my interests, I never have time to build extra parts to sell. I am in it for the enjoyment, not to make money. Bob.


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## David Leech (Dec 9, 2008)

machiningfool said:


> Hey guys, I am the proud owner of a Fine Arts PRR diner chassis and trucks that I won on Ebay, boy what detail, can't wait to put something on top of it. OK, who was bidding against me? Bob.


Well done Bob.
But WHAT will you put on it?
By the looks of it, you were bidding against someone in Germany, or Europe.
Cheers,
David Leech, Delta, Canada


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## Tomahawk & Western RR (Sep 22, 2015)

machiningfool said:


> I am in it for the enjoyment, not to make money. Bob.


so youre saying you could give them to us for free? just kidding


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## machiningfool (Nov 15, 2008)

Yes, I got that feeling too. From what I can tell, these trucks were used on the Broadway limited, maybe others. I saw a picture and statement in one of my Pullman books that these trucks could be changed over to the type of equalizers that are on the other type of 3 axle trucks and with the coil spring. I don't even know who made them. Did Pullman or PRR, U.S steel (Commonwealth), make them? I will have to do some detective work. Bob.


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## machiningfool (Nov 15, 2008)

To Tomahawk and Western Railway, maybe, when I have nothing else to do and all of my other projects are done. And, I found out that this truck is probably a Type: 3D-P1 or 3D7P2. Bob.


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## machiningfool (Nov 15, 2008)

*More parts for the truck.*

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


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## machiningfool (Nov 15, 2008)

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.


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## du-bousquetaire (Feb 14, 2011)

Yes Bob, I have a friend who has one of their engines in a glass case, since I also run electrics with analogic and track power, I offered him to come and run it on my pike. He told me that every time he takes it out of the showcase he has to pick up one or two detail parts that fall off... And declined the offer. So much for these high end shelve queens. I like to run my models. David has found a neat way to articulate six wheel trucks and I can vouch that they work very well as my Diner is equiped with them and has actually never derailed in about four years. You might want to check it out.


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## machiningfool (Nov 15, 2008)

I would like to know, for my own information, when your car is sitting on the track, are the bearing blocks forced all of the way to the end by the springs? And if they are, how much force is necessary to begin to have spring movement. For a model, that doesn't weigh, say 30 lbs., the axle block would have to be loaded for the bearing journal to be around the center of the motion, in other words, supported , and floating by the spring. I have never seen a model truck where the springs actually support the load, they have always been forced to the end of travel. If they are forced to the end of travel and not able to move both ways, up and down, then all that you have is a rigid truck. For that reason, I have chosen to make my trucks rigid so that I can use more real looking spring gauge. If anyone has a sprung truck that actually supports the weight of the car and can move both ways, I would very much like to see the setup. If this situation exists, the wire gauge of the spring would be too small for scale. Bob.


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## machiningfool (Nov 15, 2008)

I have been doing some thinking on how to make a truck that actually works as it should, like when one wheel is lifted because of a bump on one rail, and all of the other wheels stay in position on the rails. As some of you have seen, I redesigned, stretched the MTH passenger truck by about 1/2 inch, to make it look a little more true to the prototype. The spring system that they use to make it, so called "sprung" is close, but no cigar. My idea, which I haven't tried yet, would be to use two of the springs that sit on top of the journal and make them with a better spring rate, in other works weaker and smaller so that the journal sits in the middle of the movement. Then the truck could truly be called sprung. Maybe I will try that when I get a little further with the projects that I have going on now, just a thought. A test that I may use. is to put two or three plies of tape on one rail and when the car is pushed horizontally across the bump, if the all of the wheels stay on the track and don't lift off of the track, then a "sprung" truck has been created. Bob.


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## Burl (Jan 2, 2008)

When I built mine, I wound the load-bearing springs out of music wire. The cosmetic springs were 3d printed in nylon, and were very soft. If you look closely at the picture below, you can see two sets of springs, one behind the other. Don't know if that would work for your application or not, but it might give you some ideas.


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## machiningfool (Nov 15, 2008)

That is a good looking truck, but I am not knowledgeable enough on freight trucks. It looks like the weight of the car will compress the springs collectively, but it looks like the bearing journals are bottomed out. How does each wheel move independently?. or is it supposed to? Like I say I don't know anything about these trucks, so a little more explanation would be wonderful. Bob.


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## Burl (Jan 2, 2008)

The axles don't fit tight in the bearings, there is a little play. It lets the whole thing flex.


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## David Leech (Dec 9, 2008)

Bob,
On a typical four wheel freight truck, the journals do not move at all, they are fixed in the side frames.
It is the side frames that can in effect pivot on the centre springs when a wheel needs to drop or rise, as well as the whole weight of the car allow for suspension on those springs.
I hope that helps, and doesn't confuse even more.
All the best,
David Leech, Delta, Canada


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## du-bousquetaire (Feb 14, 2011)

What that is called is equalised trucks. And that is how you did it on your six wheel trucks. Freight trucks pivot around the Bolster with springs on equalised trucks they pivot around a screw that acts as a pivot. This is a good solution so that all wheels stay on the track in case of small differences in rail height. Just trying to help Bob.


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## machiningfool (Nov 15, 2008)

OK, that is for freight trucks, but all I am trying to say is that on passenger model trucks, the springs are so tight that there is no compensation for bumps, so they might as well be solid and not sprung. It is nice to say that I have sprung trucks, but they don't work on passenger trucks, they are for show only. I see how the freight trucks conpensate and that is good. If one could use a very light spring to put the bearing journal in the center and actually support the weight of the car, then you would have a sprung truck that works and not just cosmetic. That is why I am not wasting my time to engineer sprung passenger trucks. I will be doing some experimenting with my stretched MTH passenger trucks to make them actuate even though they will not be like the prototype because the tiny springs are on top of the bearing journal and could possibly be made to actuate properly and independent of the other wheels. I appreciate the tutorial on the freight trucks because I had no idea on how they worked, so now I do. Bob.


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## machiningfool (Nov 15, 2008)

*More molds.*

OK. 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.


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## machiningfool (Nov 15, 2008)

*Ready to pour third part of cab mold.*

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 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.


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## machiningfool (Nov 15, 2008)

*Sag rods*

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 sag 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.


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## Burl (Jan 2, 2008)

So this is a squish mold?


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## machiningfool (Nov 15, 2008)

Is that the proper name? I don't know. I have never heard of that term. I have heard of a displacement or compression mold though. Bob.


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## machiningfool (Nov 15, 2008)

*More truck*

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


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## Scott (Jan 29, 2008)

Nice mate


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## machiningfool (Nov 15, 2008)

Thank you Scott, I appreciate it. I am almost done making parts for it, more to come. Bob.


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## machiningfool (Nov 15, 2008)

Hey, if you are still here Du-Bousquetaire, I am sure you already have one, but I found on Ebay-Volumn 36, No. 1 of Keystone, the entire publication on the D78. I bought this for pictures of the D-78 after winning the Fine Arts D-78 chassis and trucks on Ebay just to get an idea on what the rest of the car looks like. Maybe some day in the far future, I will finish the car, long ways off. One thing that I would have to do it greatly modify the trucks because with everything they have on it, the car will hardly roll, brakes binding, etc., fine detail, but not practical. Bob.


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## machiningfool (Nov 15, 2008)

*More molds.*

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


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## machiningfool (Nov 15, 2008)

*More truck*

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


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## ewarhol (Mar 3, 2014)

Bob-

What brand of supplies are you using for the molds, wax mold, plastic casting material, etc? I reviewed previous posts and not seeing that. All though after 8 pages it's possible I missed it.


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## machiningfool (Nov 15, 2008)

I buy my materials from BITY mold products. Brick in the Yard., easily found. They are in Texas, I believe. The urethane that I use is 74-20, medium soft urethane, one kit, 24lbs. cost 185.00. The plastic is called Poly 1512X, for part B. Part A is Poly 1512X. I use Mequiers carnuba plus for the wax because I can brush it on to surfaces, about 14.00. from Discount Auto. I use alot of 3/4 inch plywood, good stuff for the bottom, sides and tops of the molds, some is reusable and some is not, so I go buy some more. Before I started using urethane for the molds, I made hard molds out of fiberglass and epoxy, and the disadvantage to that is, when building the mold, you have to make sure you don't back yourself into a corner and get mold lock, then your part won't come out of the mold. You don't have that problem as much with urethane, but you do have to watch how your mold is constructed. One disadvantage to the urethane is that you can't go back and change the mold, let's say. to add rivets. after the mold is made, but you can with a hard mold. The hard epoxy mold will last forever if properly maintained, but not the urethane, but that is probably after many, many parts, many more than I will ever produce. The parting spray, I believe is Pol-ease 2300, a silicone based oil, care has to be taken when cleaning for paint, hard to get off of the part, and is very good. All of the wood surfaces must be waxed, or the urethane will stick. When making a two part mold, make sure the first part is fully cured or the second part of the mold will stick to the first urethane surface. Parting spray is necessary on all operations to ensure that nothing sticks. Once all urethane is cured, after about two or three days, you won't have a problem. If you have any more questions, feel free to ask, and if I know, I will tell you my experiences. As with any mold maker, I am waiting for more urethane. There are many sources for almost the same stuff, but these products are the only ones that I am familiar with. I will say this, that the Poly 1512X says that it is a 5 minute working time, and that is a bunch of crap, as I can barely mix it and get it into the mold and for that reason some of the parts come out too thick because it starts to harden as you squeeze the mold together and add weight. On some parts, I might go back to epoxy resin, because I have more working time and because of the mix that I use, I can make sure that all of the little details get filled. I had to machine the sides for the windows because the stuff started to harden before I got the mold closed and caused the window sides to be too thick. The other thing that might have cause that problem is that I didn't have any relief channels for the excess plastic to escape, so all of my molds have relief channels as I have shown is previous posts. I can still go back an cut channels into the urethane top mold sections and accomplish the same thing, and I will try that before going back to epoxy.


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## machiningfool (Nov 15, 2008)

*Hard mold.*

Ewarhol, 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 evolutions, 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 alot 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.


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## ewarhol (Mar 3, 2014)

Wow Bob, thanks for all the great info. The urethane cab mold, do you have a mold that fits inside? Trying to picture how you don't end up with a solid block.


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## machiningfool (Nov 15, 2008)

Eric, if you count back 5 or six posts, you can see. in the picture. the urethane outside mold and the urethane inside mold. The mold on the left is the inside, and the one on the right is the outside. There are three pieces to that mold. Now, in the case of the epoxy hard mold, that only has one side, so it is laid up with an epoxy, peanut butter type consistency and then glass cloth is laid over to give strength and the wall thickness. If you have anymore questions, please let me know, Bob.


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## ewarhol (Mar 3, 2014)

Ah ha, got it. Thanks!


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## machiningfool (Nov 15, 2008)

*Cab part good.*

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.


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## machiningfool (Nov 15, 2008)

I found out the the Fine Arts chassis is a 70' RPO and not a diner. Bob.


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## Scottychaos (Jan 2, 2008)

Wow, beautiful work Bob! very nice..

(I just searched this entire thread, and amazingly, this question has not yet come up!) 
What scale are you working in?

Scot


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## machiningfool (Nov 15, 2008)

I work in 1:32 only and thanks for the kudos. Please, what question are you talking about in these threads? Bob.


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## machiningfool (Nov 15, 2008)

*I don't have any machines.*

I wanted to share this with you. Back in the days when I didn't have any machines, such as, a lathe, a mill, a cnc router, or a 3D printer, which I still don't have, I made patterns out of wood with just a hand held router and a band saw. While this 1945 Pullman observation is not perfect, in my estimation, it still looks good. The fluting was made with a bullnose 1/8th inch router bit, spacing with different thickness plastic spacers on a jig that I made. The roof shape was made with 1 inch sections of wood. After the patterns of the sides and roof were made, an epoxy mold was made. I made the mold long enough for the round end and a straight roof, which I still use today. My point is, one can still make models without all of the fancy machines. Bob.


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## Scottychaos (Jan 2, 2008)

machiningfool said:


> I work in 1:32 only


cool! thanks..



> and thanks for the kudos. Please, what question are you talking about in these threads? Bob.


I dont know what you mean..I wasnt talking about any question, I asked a question!  which has now been answered..

thanks,
Scot


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## machiningfool (Nov 15, 2008)

*Added some relief grooves.*

Some bubbles occurred in the last pour of the cab, so I added some some relief channels. cut in the shape of a "V" with an Xacto knife, to the upper most part of the mold where the bubbles occurred, so I hope this cures the problem, I will know later on today, and also I have been taping paper, with vinyl caulking, since the tape won't stick to the waxed wood, to make the cleaning of the molds easier, works good. Bob.


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## machiningfool (Nov 15, 2008)

OK, done for today. I poured a cab, a heavyweight chassis, heavyweight roof. *I put quite a few relief channels in the roof mold, so we shall see if they work. *The experts say that I can de-mold after four hours and while you can, the plastic is still soft, so if you did, after that time, you would have to either put it back in the mold or make sure you put it on a flat surface so that it wouldn't deform. I prefer to wait 24 hours and then it is hard. Bob.


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## machiningfool (Nov 15, 2008)

*More parts*

I couldn't wait, so I pulled the parts out of the molds, the chassis and the roof came out perfectly, but still having some small bubble problems in the cab. *None of the bubbles are bad enough that they can't be repaired, but I would like a bubble free part, here are some pictures. Bob.


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## machiningfool (Nov 15, 2008)

Just an update. Poured another 15 lbs. of urethane today for another heavyweight side, some parts for the truck, pilot for the cab,**and*reduced a*three part piece for the truck to one piece, starting the mold today. I keep forgetting to tell you this. *I don't know how many of you are using urethane, but if you do, this procedure was recommended to*me by the seller. *Part A, that is the hardener, to keep water vapor in the air isolated from the urethane, after opening, a shot of nitrogen should be shot into the bottle to preserve the hardener and to give it more shelf life. I found out the hard way, without that shot of Nitrogen, the hardener will gel much faster. *The part B doesn't need this step. When they ship it, a shot of Nitrogen is already in the bottle, but once opened, you have to do it again. *The Nitrogen is heavier than air, so it isolates the urethane from unwanted moisture in the air. *Urethane, in contact with air, causes the moisture to get into the urethane and causes air bubles in the urethane, just something that I had to find out the hard way.*Bob


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## machiningfool (Nov 15, 2008)

*Still mocking up.*

Here are some more parts for the truck, still mocking up. *I combined the spring cross bars with the mounting plate, so it makes it a little easier to assemble. Bob.


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## machiningfool (Nov 15, 2008)

*Correction.*

After 5 attempts at producing a flawless pilot, I discovered that one half of the mold had a pocket molded into it that was trapping air. I am filling that area with clay, and I think that will correct the problem. I just poured one with the clay, so we shall see. Bob.


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## machiningfool (Nov 15, 2008)

Yep, it worked, filling the void with clay eliminated the air from inducing into the part and now no bubbles. Still working on cloning parts for the truck, hope to have a finished one shortly. Bob.


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## ewarhol (Mar 3, 2014)

Bob- 

Did you fill the part with clay and make a new mold, or add clay to the mold and cast a new part?


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## machiningfool (Nov 15, 2008)

I did not make a new mold, so every time I make a part, I fill the void in the mold with clay, no big deal. I will be adding details to the cab to make it look better, so at some time, in the future, a new mold will have to be made. I will be refining the windows and the windshield. Bob.


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## ewarhol (Mar 3, 2014)

Thanks again for the tip Bob!


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## machiningfool (Nov 15, 2008)

*Truck mock up is finished.*

The mock up is finished, here is the truck. Bob


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## Tomahawk & Western RR (Sep 22, 2015)

very nice!


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## machiningfool (Nov 15, 2008)

Thank you Tomahawk & Western RR. The next thing is to start putting some of the car parts together, Bob.


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## Tomahawk & Western RR (Sep 22, 2015)

how many do you plan on making? and this is the 100th post


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## machiningfool (Nov 15, 2008)

Just enough to make an 8 car consist, but I don't know when that will be. I think I have too many irons in the fire. Bob.


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## ewarhol (Mar 3, 2014)

Nice looking truck Bob!


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## machiningfool (Nov 15, 2008)

*F cab windshield mold.*

Thank you Eric. I have been trying to get the perfect shape for the F cab windshield and I made a pattern for a mold. The shape has been scaled from the full size to 1:32 and is made with the seal.  Here is the beginning of the operation. Bob.


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## machiningfool (Nov 15, 2008)

*Heavyweight doors and E and F cab windshield molds.*

Here is what I have been doing in the last few days. I made a mold of the heavyweight doors so that they will open and be a split door. *I am still trying to make the perfect E and F series windshields. *I am trying to make the windshields, so that I may retro fit them into any one gauge E or F series loco. *I am designing them so that when installed in the loco, there will be no glass to make it easier for painting and then there will be a ring in the shape of the windshield, to be installed from the inside to hold the glass in. *I am using .020 Lexan for the glass, also making the side windows for the loco, and here are some pictures of the patterns and molds. Bob.


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## machiningfool (Nov 15, 2008)

*F cab glass was a success.*

*Well here are the glass panels. *I cut them with a tool that I made, a vinyl cutter. *This tool was made to cut just .005 material, but I ran it through twice and it scored the .020 Lexan enough so that it broke away clean. They came out just like I wanted them to. *I have to draw just one more part to complete the assy. then I will attempt to install them in an MTH cab and the other cab that I made the mold for. Here are some pictures. Bob.


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## Tomahawk & Western RR (Sep 22, 2015)

any more progress?


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## machiningfool (Nov 15, 2008)

I have been working on the elusive shape of the F cab windshield shape and after two molds and patterns, I think I have it. I now have to make an entirely new mold. I also, have been working on the heavyweight doors and splitting them and also hinging them. Also, the wind wing on the F cab, I am trying to slant it open, and also the side window will be half open, might help for ventilation for the electronics. I also have been removing grass for the layout, and almost ready to lay some concrete. The layout will be abou 160 feet long and of course the viaducts will be laid for that entire length, so that is what I have been doing, boy, it is sure hot here in Florida, Bob.


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## Tomahawk & Western RR (Sep 22, 2015)

machiningfool said:


> I have been working on the elusive shape of the F cab windshield shape and after two molds and patterns, I think I have it. I now have to make an entirely new mold. I also, have been working on the heavyweight doors and splitting them and also hinging them. Also, the wind wing on the F cab, I am trying to slant it open, and also the side window will be half open, might help for ventilation for the electronics. I also have been removing grass for the layout, and almost ready to lay some concrete. The layout will be abou 160 feet long and of course the viaducts will be laid for that entire length, so that is what I have been doing, boy, it is sure hot here in Florida, Bob.


sorry to bring up an old thread, but have you finished them bob?'


hope you are OK.


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