I thought I’d share my first trial at doing the Camel/Dreadnaught doors for an auto car, ca 1935 or so. The photo below shows what I hope will become the master for a resin mold, and is patterned after a Union Pacific car that appears in the 1940 Car Builder’s Cyclopedia. Two ideas here: first, to try once again to resin-cast the dart-and-rib pattern as the main challenge, and second, to provide some variety in the appearance of the rolling stock.
VERY nice. I need to figure out how to make a stamped steel car end for a hybrid steel/wood boxcar. Care to share you techniques for getting those ribs?
Thanks, Bob. I can describe what I did–hopefully there are some better ideas floating around! The basic idea is to start with the smallest repeatable segment of the pattern. Here is the initial pattern–this is just a chunk of styrene formed by hand with files. Naturally, this single piece is the make-or-break for the whole job, and I found it to be something of a ‘guess’–you roll the dice and pray, unfortunately:
The piece shown above is about to be used as the master for a small mold. I made two castings, CA’d them end-to-end, then filed the joint between them for a smooth match. That makes the second pattern:
I then repeated the process, making a small mold of the new pattern and casting a bunch of parts I then assembled into the panel masters:
A better, more tedious alternative would have been to take the second pattern above–the full-length one–and split it in two lengthwise, then use THAT to make a mold. From that mold then, cast two pieces that are in turn assembled to form the Real second, full-length pattern. That would ensure better symmetry on the ribs. Maybe next time. This is the panel as it now stands:
Ah, very neat. It had the look of a cast or vacumn form piece, not a bunch of little ones. Hrm… I may have to give that a shot…
Yes, so what you’re looking at in the photo is the pattern for the final mold, not the final product itself.
Per the advice of Mark Horstead, this pattern will not include the hinges and safety latches cast from the pattern in the top photo–they will be CA’d on after the end panel is cast. That’s just to avoid the problem of trying to get bubbles out of all those hinges, which tend to bubble with 100% certainty.
Do you do vacuum forming?
Kirk, Wow, now THAT is impressive. I’ve thought about doing some wood sheathed steel framed boxcars, but I would hate to make those modern ends like we saw at the museum in Strassburg.
But, they had this other version that had wood sheathing all around.
And, in MR this month they had this riveted end. Admittedly on an all steel car, but still intriguing.
Now, I guess if I could make one good “rib”, I could make a whole end, but just getting it symetrical seems like an issue. How did you manage that?
Im thinking that a sacrifical boxcar is needed to make a master for the ends. I may have to rummage on ebay for a cheap one. Hmm
I didn’t read your message carefully enough–my last photo is of the final pattern (not quite finished), but yes your’re right, it too is actually a casting. Or at least the corrugated panels are castings. There are 4 castings in that master–two of the upper panel for the R and L, and two of the lower panel for R and L.
Each time you assemble the piece parts to make the next master patern, you’re given the ‘opportunity’ to clean up seams, finish and other irregularities. It also is the time to check your overall dimensions, squareness, etc.
The stamped end you show in the first shot would be very easy, I think. I did a Dreadnaught panel that of course has more taper in the ribs, and it didn’t go too badly.
The only reason for doing all this incrementally with 3 masters and 3 molds was to get the symmetry, within reason. But I didn’t do the Dreadnaught that way because you only have to make one single rib and one dart, and eyeball was good enough.
However, the idea still works. Take your steel-end car above as an example. This could be done by taking a single piece of styrene strip and simply fashioning the left half of one rib. Make a mold from that, then cast two of them and stick them end-to-end. Get the joint benched out so it doesn’t show, check all the dimensions, put a sweet finish on it (I’ve been using Scotch-Brite followed by a T-shirt buff). This becomes the second pattern of course, from which you make your 2nd mold.
Then cast all the ribs you need, assemble them on a sheet of styrene, add your edges and rivets, etc., then use that as pattern #3. Make your final mold from that pattern and cast away.
For the Dreadnaught there were some extra challenges with filets around the ribs, etc. I’ll post a separate thread showing how that happened, and I think you’ll find the Big Red Car above wouldn’t be too hard. Not cheap, but not hard.
I’m surprised to see a wood-sheathed car with a cushioned underframe–I wouldn’t have thought the two would go together, not that I’m any kind of era expert or anything. That’s an interesting car.
Kirk ,
I am impressed with what you have done . Although you say it’s tedious , I can’t help but think that the technique is pretty well foolproof and will give repeatable results . I am inclined to give it a go myself , thanks for going to the trouble of giving a good explanation .
Mike M
Good to see your online activity again Mike–what a pleasure. Actually, I was a little timid about posting so much on the topic and about making such a big thread–I hope there’s something you can use here. Thanks. The Dreadnaught project thread here also provides a slightly different perspective. It was my first attempt at doing an end panel and my first dive into casting–with all the behind-the-scenes drama that I thankfully left out. What a flippin’ blast though.
Hey, I hadnt noticed it was a cushioned underframe… another cool detail.
This is what it currently looks like after making a casting and adding hinges and door latches:
This is just stuck on the end of an incorrect car I had sitting around–to provide a pleasing effect.
Bruce Chandler said:
Now, I guess if I could make one good “rib”, I could make a whole end, but just getting it symetrical seems like an issue. How did you manage that?
It looks like I didn’t respond to this question, so I’ll do my best. I’ve tried this two ways. The first effort was to simply hand-file one HALF of the rib. Actually, for the Camel end door panel, it is one half of one of the repeating sections. It’s shown in the 2nd photo above, I think. This piece is a little weird–it includes a complete dart in the center, at the top of the pattern is the bottom left quarter of a rib, and at the bottom of the pattern is the top left quarter of a rib. The ‘repeating section’ I’m talking about is outlined in the yellow rectangle below:
NOTE: This is the project I’ll describe below, but for the approach in the Dreadnaught project, just check out that thread in this forum. There, I simply filed down a stack of laminated styrene strips until both ends looked right. They are not perfectly symmetric, but at a few feet with a paint job, I sure can’t see it. So from the pattern just describe, I made two castings. These are then butted together to form the single repeating section of the overall panel as shown above. That’s how I ensure some symmetry. Because the top and bottom of the original piece is NOT perfectly symmetric, when the two castings are assembled, there’s some hand work to be done at the seam where they meet. A second effort, not shown, was to go even further in decomposing the part. Imagine the first piece I just described being cut along it’s long dimension. Now we’re talking about a pattern that represents 1 QUARTER of a a repeating panel section. It includes one half of a complete dart, and one quarter of a complete rib. I cast two of these pieces and assembled them end-to-end to form a full-length, half-height strip that includes a) the top half of two opposed darts, and b) the bottom half of a complete rib. This attempt ensures end-to-end symmetry of a single rib and symmetry of the two opposed darts. This assembly then was used as the pattern for a 2nd mold, from which two castings were made. The two castings were assemble along the long edge, forming a single piece having a) one complete rib and b) two opposed bottom halves and two opposed top halves of the darts (four half-darts, one in each corner of the part). All of this work ensures left-to-right and top-to-bottom symmetry of the entire single panel section–more or less. Finally, I made a mold from this part after benching it out, and then cast as many pieces as needed to assemble a panel. It looked like crap so I threw it away. Brilliant in concept, brain-dead in execution. Actually, it would work great if assemble very, very carefully. But in this particular case, the final contour just wasn’t that much better than what you see above. Finally, you might notice that the final panel shown above in my 4/17 post is NOT the same as the pattern shown in the 4/5 post. In the earlier post, the left and right ends of each rib-dart section is flattened as it approaches the adjacent styrene. To make the final pattern, I hand-contoured that entire area with my little die-maker’s rifflers to take out all the flat surfaces to get what you see in my last photo above.
As mentioned, I worked with the first casting to develop a little better pattern for a second run at this. Here’s what we have right now:
To get this one, I took a casting of the pattern shown above, removed all the rivets and the center, vertical strip. I then benched-out as many visible seams as I could (or had the patience for), and fixed the bad spots at the top of the door panels. In addition, I worked on the corrugations a bit, where each pattern feathers out to the flat door panel. I also leveled out two small notches at the door panel bottoms to admit the door latches. Finally, what I show here includes all the rivets replaced with brass Galtran rivets, done as close to scale as possible for me. I have a Badger abrasive gun on the way, and the plan is to give this entire pattern a light blast to even out the texture mostly. It will then go into the goo pot to form the Final Mold.
Nice work , Kirk , now don’t blow it all away , will ya ?
Mike
Wow, awesome work!
Jon.
The mini-blaster came yesterday and it did leave a nice, uniform finish on the styrene, if held close enough. Not quite what I had in mind and probably not worth the effort. I’m not whining–at least it didn’t tear a hole thru the master in 2 seconds. This is the final master pattern just before going under. You can see two leveled recesses at the bottom edge of each door to accomodate the door safety latches. The door latches, hinges, placard board, ladder, etc., will of course be added on later. If I ever get that far it will be as part of a 50 ft car, which sounds to me like a winter project (i.e., next month). The finish is actually Polly flat Israel Gray and it looks pretty good to my eye–however, the photo shows it with a good layer of release agent sprayed on, and the glossy finish detracts a bit (i.e., shows every single little error).
