I don't know how many of you here will be familiar with the name Brian Briggs, but several years ago, he built a Pullman-Standard Mini-Hy Cube boxcar in 1:29 scale. As far as I know, he only built one. I tried to get him to offer it as a kit, but he never would give me a definite answer.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2FMILW4609.jpg&hash=9203c42fd1f87b3ed24739fdd765a928f9478507)
Unfortunately, he passed away about a year ago. To my surprise, his wife, Margaret offered me patterns, molds & extra castings he had made for various projects. Among them were the patterns for his PS Mini-Hy Cube boxcar. He made it as a flat kit, with no patterns for the underframe. It was my intention when I acquired it (with Margaret's blessing) to produce a kit from it. Lately, I spent a little time working out the design of the underframe. I think I can make an operating cushioned underframe, with sliding center sill.
I am working primarily in Sketchup:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe.jpg&hash=9b705b5f1cc4de3d3f444c988b256d6625b8876b)
Since Brian cut up USAT boxcar ends & used them as his pattern, I felt it best to re-make this part. I am learning Autodesk Fusion 360 to draw these, since it has a filet function that I like better than Sketchup.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Fend1.jpg&hash=f5756646097396b921d3675a9a4ac812c61fe702)
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Fend2.jpg&hash=ef20499734856c8ad6162973e4da7c33f22a36a5)
I drew the end ladders in Sketchup. Old habits die hard. Here's my first attempt at marrying them in Fusion 360. I needed to do this to get the mounting holes aligned.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Fend3.jpg&hash=96948a30ca7bbc57b6671e89d78df95b36c17905)
Most impressive and inspirational. -- Russ
Burl, That looks like it's going to be a good kit. And the operating cushioned underframe will be a unique feature. Good luck with the project !
Very cool!
I remember seeing that on one of the forums when he first built it.
A little closer to having all the parts worked out for the underframe:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe2.jpg&hash=31b8b49b1611d564ad8a16fce781bfdfdd648445)
Well, that probably took a few hours .... -- Russ
If I'm not careful, I get bogged down in details here. I borrowed some of the components from prior projects, so that sped it up a little. These are low-poly stand-ins of details I had already made.
This might have been a better candidate for Fusion 360, since it supports collision detection, but I'm not comfortable enough with it yet to attempt anything very complex.
My inexperience in F360, coming to light, I ended up redrawing the end from scratch. Watching their tutorials, they put an emphasis on making everything components.
When I started cutting the mounting holes for the ladders, I realized making each rib a component was not going to work. Making a hole in one, resulted in a hole in every rib.
When it was time to scale it down to 1:29, I also encountered odd behavior in how it handled what they call "patterns". Where I had distributed rivets every 2 inches, it maintained the 2 inch spacing after the scale operation.
Redrawing it also allowed me to correct something I missed the first time. The ribs are not completely straight, but slope gently from the middle to the end.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Fend4.jpg&hash=84e11bf6201dc4be89a1f2d30ed6270553933828)
Impressive attention to detail. Sounds like you're figuring out Fusion 360 in the process.
Nice work.
All these different apps each have their own quirks.
Got everything broken down & arranged for a Shapeways order.
I'm taking a different approach on the ladders this time.
In the past, I have had them 3d printed in SLS nylon. The texture was a little rough that way, but I could live with it. However, Shapeways has a habit of revising their printing guidelines. I guess they're still going through growing pains. I have sometimes found things I printed 6 months ago, they say are no longer printable. Occasionally, things have also arrived broken (I assume they were handled too rough during cleaning).
This time around, I'm going to try making the ladders in brass. I'll use the acrylic prints (below) to make a mold for waxes. These waxes will be sent off for investment casting. The rungs (with NBW) will be one piece, and the rails will be a separate piece. I made them with locating pins to make assembly easier. I will find out in a few weeks if this is a better approach.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2FFUD1.jpg&hash=376112b6dcce143beb53e6236857d949574ae848)
These parts will be used as patterns for resin casting:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2FFUD2.jpg&hash=e66d14272f9e04d1f9550ef278c9e13516012081)
Laser cut parts came in today. I had these made at http://ponoko.com/
Kind of like Shapeways, but for laser cutting. I have not taken the paper off yet.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe3.jpg&hash=83f250c57a0190b1ba6bae0cdf1d3f7736e68d39)
Laser cut Plexiglas? -- Russ
Acrylic
My prints came in last week:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Fend5.jpg&hash=d9bd14508867664939cd19bfc96789c55cc4d076)
Those little rivets along the top and side -- printed or applied later? If printed, can you shoot a close-up? Your posts are providing a good tutorial. -- Russ
Is this close enough?
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Fend5b.jpg&hash=3b24b5d399a23f991db5daa458f333ce44730208)
Everything is printed on. The tops of the ribs (the easiest part to get to) got a light sanding to remove the layer lines. Then I cleaned, sealed and primed.
Very impressive! I have a three-month old grandson who was on life support for a couple weeks and I haven't been able to do much work on my own stuff, so I have been living vicariously on all the wonderful projects you and the others here have been up to. The little guy is now on the mend and doing much better, so hopefully I can get back at it. I am especially interested in your use of Fusion 360 and how that is working out.
Thanks!
Greg: sorry to hear that, but glad he's getting better.
Thanks, Burl. That photo works well and answers some questions I've had. I guess I should try a test print one of these days.
Greg, glad the little rascal is getting better. You, he, and the entire family must have been wrecks for a while. I hope that's the last time his health is a concern.
Russ
Progress on the underframe pattern:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe4a.jpg&hash=1c14c531e4a6a38e2971db75e43960d8cb71a885)
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe4b.jpg&hash=4347b26da7e26751fd3694d8901107d1439fe090)
The printed parts are only there for reference right now. I will be making resin copies of them later.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe4c.jpg&hash=ba2540f9aaf7bbfbfc8a297d5ac5e7fec042063e)
Burl, the rivets look good even in the extreme closeup view and the underframe is coming along nicely.
Poured the molds for the underframe this weekend, and I immediately saw some things I wish I had done different.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe5a.jpg&hash=23dc605d9ee75d372657b979368308b12c86e99e)
Since this car has a cushioned underframe, it has four beams for center sills, instead of the usual two. I had planned on making the outside center sill as two pieces. I could see right away they were going to be too floppy to glue in place and get a proper alignment. My goal was to make the sliding underframe operational, so this would be critical.
I also had all the bearings aligned to take vertical load only. I can see now, it will function better if I added some to maintain the clearance between the inner & outer center sills.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe5b.jpg&hash=7975f8bc7543becdd1ac8c2dea9a01bf485831a1)
The other problem I see is that one beam has to be cut to make clearance for the trainline piping. I'm afraid this will be easily broken if its made out of resin. Brass would be much better.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe5c.jpg&hash=ae28e6e5c0721e348c3ae82878a8ecd62f3abac1)
So, I think I'm going to revise it to make the outer center sills part of the floor casting. Just wish I had figured this out before I used four pounds of RTV, but you live & learn.
All is not wasted. Chop it up and add it to the rubber for the new mold. When you do it, first pour a fairly thin layer of new rubber and then add the chopped pieces, then as soon as the mold is poured, evacuate it to remove the remaining air. Old molds can be repeatedly diced and reused over and over.
In a model as large as your, do you find it necessary to reinforce the frame by embedding brass rod or bar? A friend has built many 1:32 scale cars and felt it necessary to do that. -- Russ
I generally find some other way to brace it up internally, with resin bulkheads, or similar. I have always shied away from embedding metal in castings because of the differing expansion coefficients.
After stewing on it a couple days, I have found a design I like better. Funny how simpler designs seem like they are harder to come up with.
The outer center sill (green) will now be part of the main floor casting. It will have a channel that the bearings will ride in. The inner center sill (pink) will have slots for the bearing shafts. This should lock the whole thing in & keep it from sagging vertically. It also means I only have to reprint the center sill, and I can use the rest of the floor pattern with no further modifications.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe6c.jpg&hash=bdcf013445b68df5d9a14677da5766cdcf09b31a)
This also allowed me to change the orientation of the pattern in the (eventual) RTV mold by 180 degrees. Now I can also model the spring for the cushioning unit as part of the casting.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe6d.jpg&hash=ae93939b9ad42fcd01884bdfa2e927e8b73abd05)
Simpler always is harder. Excellent engineering. -- Russ
While I'm waiting on my revised underframe parts to come in, I decided to work on the side patterns. Started with the vertical panels. Looks odd right now, because the glue shows through in places where the castings are very thin. It should all even out when its painted though.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Fside2.jpg&hash=94f0a79224af3e61991d6a1c881b083e4c3fc798)
How thin are those castings?
Ray: in the thinnest sections, probably paper thin (0.005" ?). Thicker parts might go up to 0.030" in the middle.
My revised underframe prints came in last week. When I started to glue them in, I was having trouble keeping them even. After some double checking, I realized I had some variance in the I-beams. So I stripped out the old glue, and made up this sanding stick out of aluminum C-channel & 220 grit sand paper:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe7b.jpg&hash=f15fa05e16d728e71b3dbffeab3618804e243857)
With that, I was able to fine tune the fit & get a fairly straight line. When I got ready to try gluing them again, I made up a spacer to represent the sliding part of the centersill (cut the same width), and added .015" styrene for clearance:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe7c.jpg&hash=cd6afb0fd765f43379939bb83d599d51be015561)
With that in place, I could tack it from the outside, remove the spacer & finish gluing from the inside.
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe7a.jpg&hash=3c306d24d0c4051a85621ccab775199860df4716)
Now everything looks like it fits well. I don't want to get in a hurry on this step, so I'll look at it for a while. If I can't find anything wrong with it, I'll pour another mold tomorrow (I have found sleeping on it helps me avoid mistakes due to haste):
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe7d.jpg&hash=ee681e90f186a17e18ef4ee7bdc03cb6088559f4)
Continuing to follow along with this impressive project. Very neat work.
I applaud you for sleeping on it. I'm at my absolute best when I'm asleep. -- Russ
Very interesting!
What is the purpose of the small styrene strips outside of the frame? Is it to "lock" the two halves of the mold, or to permit excess resin to flow out? Or something else?
Ray: that's exactly what they're for. It helps me get a more even thickness over the length of a large, open-faced mold.
Poured my molds for the revised lost wax parts yesterday, only to find the two I really needed had refused to completely cure. I was about to write them off as a total loss, but then I realized I could still get patterns out of them sufficient to finish the underframe casting.
I think the last thing I need on it is the divots for the new mounting holes:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe8b.jpg&hash=f35d66f4039ed0050a94c616b2a0df2808da51f8)
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe8a.jpg&hash=b15c3eca808d9d3378a3a9f9dffa2335ea6f1f52)
I will remake the lost wax molds later. Still trying to figure out what inhibited the RTV, but they say platinum-based silicones are very touchy. When this has happened before, I cleaned the patterns, applied a fresh coat of paint, remolded, and they were fine the next time.
Finished the centersill pattern & molded everything. Made up some castings to check the fit:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe9a.jpg&hash=36dc80a6f5d536707f5f517e992a44b822c80ce7)
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Funderframe9b.jpg&hash=7301928d67d3cef0a0124c1fdce5c58a55265214)
That should suffice. -- Russ
Sweet!
Sort of got derailed on this project. Shapeways took their sweet time on my last order (3-4 weeks). When it did come in, I got covered up at work.
Anyway, I got back around to working on the sides again. I've re-done some more work here. What I had before was OK, but I felt like I could get it closer. I had previously used my old trick of using Aluminum tape to imitate oil-canned sheet metal. Sometimes it worked well, sometimes it was hard to control the effect. And there was always un-evenness between the panels that made it hard to apply the weld bead decals later.
What I did different this time was to model the oil-canning in Fusion 360. I started with an image like this:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2FPS_oilcan.jpg&hash=30f92b1e17e2422fe2c7db55fde598b15ca67aef)
I run this through a script that interpolates the z-coordinate based pixel lightness/darkness. Sort of imitates the result a 3d scan, without all the expensive hardware. I do some mesh reduction & smoothing on the raw image, and scale it to get the print to the thickness I want. Which looks something like this:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Foilcan3.jpg&hash=8022754cb67cf10f8f4e50b4c754bd7387f79ed0)
To avoid obvious repetition, I had three prints made: one regular, one flipped horizontal, and one flipped vertical. The prints came in with obvious scan lines, which I expected. I sanded them with 220 grit sandpaper until they no longer looked like topographical maps. Then I made an RTV mold, and cast copies in resin. Using a combination of castings, some rotated 180 degrees, I built up the side pattern:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Fside3.jpg&hash=0262cd46806147728664d8a1d4dd54c79362f0a1)
Satisfactory. -- Russ
Burl, Rippled sheet metal panels has always been a detail I've wanted to add to my (HO) scale boxcars. Quite awhile ago I experimented briefly with lightly carving and sanding the faces of the thick panels on some kits or applying metal foil (real) duct tape with ripples on top of panels. Neither produced the desired effect. I thought about removing the panels between the ribs on some cars and replacing them with something that could be randomly rippled, but still stay strong enough that it wouldn't badly distort if someone picked up the model by its sides. Your panels have me thinking about trying something again. Thanks.
Bill: I think the key will be removing the panels, or printing the whole side from scratch.
The first project I did that I would call "successful" was a 1:29 scale Airslide, probably 15 years ago. I used Aluminum tape to make the patterns, and the waves were somewhat exaggerated. Every car I've done since then, I've tried to tone down the effect, and control the rippling more. Difficult in 1:29. I never felt like I had enough control over it to go smaller.
Up until now, I had tried to build the side pattern, then apply the sheet metal casting over that. But freight cars aren't built that way. When there's a wave in prototype car sides, if it pops out 1/2", it also cavitates 1/2" in the negative axis. Not sure if I'm articulating that in English well, but here's an illustration:
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fburlrice.com%2F_LS_MiniHyCube%2Foilcan_compare.jpg&hash=672b64e03061002a927fef5dd4afe5de3489c13b)
I won't be able to say for sure until this project it painted & weathered, but I may still have the waves exaggerated too much. On this one, I restricted the wave to [-.25", .25"], which may still be unrealistic. Don't know how I could actually measure such a thing on a prototype car without getting in trouble for trespassing.
Thanks for the additional information and ideas, Burl.
Burl, very interesting approach. Did you ever try to use 0.1mm brass or copper sheet, clamped tight at the later 'welding area' with some aluminum blocks and then heat it with a torch?
Cheers,
Volker
Volker: not for this. Don't know how I would mold something during clamping. Material thickness also has a big effect on how it ripples. Stuff that behaves "to scale" is usually very easily damaged when handling.
I have used thin copper sheet for stamping roof panels, and waffle sides.
This is sophisticated stuff. Of course Volker already is familiar enough with it to offer suggestions. (And here I am, messing around with primitive paper structures ....) -- Russ
Burl,
to start of with, no, I didn't try it myself. Please excuse that sloppy artwork, but it shows the idea behind it. Annealing the sheet between the angle sections should make it warping while the clamped areas keep cool and stable. I thought of using the brass sheets for building the car (or then making a mold of the whole sidewall ...)
(https://www.finescalerr.com/smf/proxy.php?request=http%3A%2F%2Fwww.buntbahn.de%2Ffotos%2Fdata%2F9000%2F5715Clamp.jpg&hash=d928c2021942727ea09e07881a42daa383193b49)
So far for theory. For the Rollwagen project (Codename Rosebud ::)) I had to solder a rather large sheet of 0.5mm brass sheet to an solid 7 mm brass core and people told me, that it doesn't work without having the sheet warp. It works with some clamping during soldering http://www.finescalerr.com/smf/index.php?topic=2355.msg51524#msg51524 (http://www.finescalerr.com/smf/index.php?topic=2355.msg51524#msg51524). Maybe the principle works the same if you want a not clamped area to warp.
Cheers,
Volker
Sounds like the fundamental theorem of scratch building: that which should stay flat, will warp; and that which should warp will, will remain flat.
If it's that easy just backflip the part :D.