Can anyone point me to an article, how-to or video about resin casting very small, very detailed parts like an HO scale truck sideframe? I have never used resin casting so I'm a total neophyte.
What I've found so far are articles about molds and casting relatively large items like bridge girder plates or small items like a 1:48 scale airplane prop that has little to no surface intricacy.
Perhaps because resin casting isn't suitable for reproducing small, intricate details??
And before everyone jumps in asking "Why use resin casting when you can just buy any truck sideframe you need" I must say that the old Reading (early Alco) tender trucks I need aren't really available anymore. I've considered buying vintage Mantua Goats, but its crazy to spend the money on an entire loco, when you just need to harvest the tender trucks.There are also some Rivarossi models with tender trucks like those. I bought one on ebay but the plastic tender trucks are marginal at best.
However, I did recently purchase a vintage Lee Town CNJ tender kit and the truck sideframes are beautifully detailed white metal and I'm pretty sure they'd make the perfect originals to make a mold from, but again the intricacy of their (bolt and leaf spring) detailing gives me pause.
Soliciting advice from experienced resin-casters
cnjman721Perhaps because resin casting isn't suitable for reproducing small, intricate details??
Au contraire, resin will produce excellent details. Everything you have on your master can be easily reproduced with resin, including a finger print
I made some various masters for retaining walls using silicone molds and sometimes plaster, sometimes wood filler (Durham's) and other times resin, depending on use/strength needed.
Later I went on to begin building a resin model of the Hulett ore unloaders. Half-way through the project Walthers announced their styrene kit so I put the resin molding project on the back burner.
I have some cast resin trucks that are very nicely detailed and sturdy and they roll nicely, too. These were made for a B&O C-15 baggage car I have but right now I forget who made them. **
Your simplest method would entail making a flat, one piece mold. These are easy. You would then epoxy the sideframe details onto a previously fabricated (brass?) truck frame.
If you attempt to cast the whole truck out of one-pour resin you will need a two part mold and that can get tricky.
I bought most of my supplies from MicroMark:
https://www.micromark.com/hobby-supplies/casting-molding-supplies
I pretty much knew what I was getting into so I simply followed the included instructions. There are dozens, if not hundreds of "how-to" videos on YouTube.
https://www.smooth-on.com/tutorials/casting-custom-scenery-model-railroad/
Once you get started you'll find lots of neat stuff that you can make using silicone molds and resin epoxy. Before you tackle the trucks you can play around with some simpler "practice" pieces.
I'll see if I can dig out some photos of the stuff I did for the Hulett project.
Good Luck, Ed
** Found it: KitBits
https://www.bobthetrainguy.com/kitbits-ho-scale-b-o-four-wheel-express-trucks-one-pair-rtr/
Just to be sure, the Bowser 2987 ones are not appropriate?
http://www.modelrailroader.net/ho_tendertrucks.php
I’ve been casting with resins for years and yes it would possible to cast a truck side frame.https://www.alumilite.com/
For the most of my supplies I get my goodies at Hobby Lobby, large quantities I go to eBay and shop for the best price.I’m currently working on making 1:87 scale figures for a heavy weight lounge car.This is an older car finished.I have about 500 Mel made figures on my model railroad. Don’t expect great results for your first try, like many things casting has a learning curve.I have around 150 molds for casting all kinds of goodies.I built up a mold making box for making my molds, the Acorn Nut alignment thing works very good for making two part molds (explained on one of the Alumilite Videos). Have fun casting!
EDIT:I neglected to say anything about the downside of casting with resin, AIR BUBBLES. When you stir the resin and hardener stir thoroughly but gently so as not to create air bubbles. Use the same caution for mixing the Silicon Mold Rubber, an air bubble in a mold is the pits! Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
RR_MelI neglected to say anything about the downside of casting with resin, AIR BUBBLES. When you stir the resin and hardener stir thoroughly but gently so as not to create air bubbles. Use the same caution for mixing the Silicon Mold Rubber, an air bubble in a mold is the pits!
Even the original discussions of 'epoxy casting' going back to Bill Clouser in MR at the beginning of the '70s (which was my introduction to the joys of the technique) are still relevant and usable. We have vastly improved materials, and more evolved technique now -- all you have to do is decide to find them.
In addition to the sources Mel and others have mentioned, dental supply houses ... or friendly dentists or practices ... can be the source of materials, tools, etc. as well as best methods for use or storage.
Making sideframes from resin molding is pretty tricky. There are only solid "trucks" and "sprung trucks" in the hobby.
Solid trucks (bolster and sideframes are molded as one piece) are very hard to make because they require atleast a 4 piece mold. And that mold has to be dead on or your trucks will be out of align (your axles wont sit squrely in the frames becuase the frame wont be square).
Multi piece trucks require a simpler molding method. They can be made with one piece molds and glass panes. Using glass (a non stick, see through flat surface) panes allows you to make the perfectly flat back side to the sideframe. Also allows you to see any air bubbles in the mix (which you can fish out or 'slide the glass' to wiggle the air bubbles out).
Resin molding, no matter the size of part, recreates in perfect detail. If you mold a set of Kadee sideframes that have lets say, "Bettendorf" written on them, this will carry over to your mold. Resin molding is so good you can recreate the lettering on a boxcar side. It can pick up print, rivets, and also.... imperfections! It will even pick up mold seperation lines from commercially made products.
Making trucks uses such a small amount of mix that it is almost impossible to get the mix amounts right. I recommend you either make quite a few trucks at a time (alot of mix) OR you invest in a weight scale. Weighing your ingrediants can give you better 50/50 ratios when using miniscule amounts.
Now, your biggest enemys are time and air. Dont get the "quick curing" resins the first time around. These set up so quick, as a newbie, you will ruin alot of stuff before you get the hang of it. Use the regular time elapsed resins. It will take longer but you will have time to see whats going on and learn from it. Youll have time to "get the air out' or make other corrections before it sets up - in other words.
If you watch Youtubers and Googlers youll see a thousand different ways to 'get the air out'. Then they go and pour from a foot above the mold - which defeats totally their purpose. Pour directly on the mold! Stir slowly! Use a small-metallic (not wood like a tongue depressor) stirrer!
For a closed mold, dont pour into the pour holes youve made, use a throw away plastic eye dropper (get on EBay) that can 'inject' the mix into the mold. They come graduated - get those. Treat it like a medical syringe - DONT suck up any air into it - just mix!
Also make sure that you have more air holes for air to escape than you do pour holes. This allows your mix to flow freely and push air instead of trap it in the corners. If air cant flow - neither can your mix. Air is lighter than your mix!
One trick you never see anyone do is once you get your mold poured, rotate it slowly (while covering pour/air holes). Then set it back down in its curing position. By doing this, you are trying to 'get the air out' of the corners. You may have to add more mix after doing so.
Another trick no one uses is during your mixing, and during your curing, place your mix or mold on a vibration table. While on, as it cures, the vibrations force air to the top of mold. While having ANY air is a bad thing, and your goal is to have NO air bubbles, placing it on the vibe table will atleast get the air you do have to one side (top) leaving your part solid within, and 5 sides looking ok. Doing this in the mix stage removes the air bubbles you put in while mixing it.
Last little trick - when you have your mold made and you wanna know how much mix youll need... fill mold with water. Empty and weigh that amount of water on a scale. Divide by two - now you know exactly how much "A" and "B" you need.
Resin molded trucks are very doable, not the best - 'first' project to start with in molding, but doable and fun.
Best of luck!
PMR
Overmod RR_Mel I neglected to say anything about the downside of casting with resin, AIR BUBBLES. When you stir the resin and hardener stir thoroughly but gently so as not to create air bubbles. Use the same caution for mixing the Silicon Mold Rubber, an air bubble in a mold is the pits! Serious zero-defects resin casting requires vacuum degassing; I believe even what a good vacuum cleaner can develop can make a material difference.
RR_Mel I neglected to say anything about the downside of casting with resin, AIR BUBBLES. When you stir the resin and hardener stir thoroughly but gently so as not to create air bubbles. Use the same caution for mixing the Silicon Mold Rubber, an air bubble in a mold is the pits!
Serious zero-defects resin casting requires vacuum degassing; I believe even what a good vacuum cleaner can develop can make a material difference.
I’ve experimented with a vacuum cleaner and while it helps it’s a PITA. I have found by careful mixing and a bouncing the molds against the workbench works pretty good for 5 minute resins. Most of my pours are very small, using eyedroppers for making 1:87 figures.I’ve been casting resin since the 70s and just being careful when mixing makes a huge difference, the larger the pour the more bubbles. For large pours I use a 30 minute mix and slow mixing using a Mel mixer. I made a mixing device for large (10oz) pours, a 5 RPM 2” diameter boat propeller on a long shaft works very good. Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
PMRVery good info!I’m into restoring Old or Clunker Rivarossi Articulateds and most need some sort of missing detail parts. Over the years I have been able to make molds of every detail part on the Cab Forward and most of the details on Y6Bs. Sure makes restoral super easy and cheap compared to buying parts off eBay.Making detail parts is super easy, even the tender steps come out great. Even the cab roof mold works good but requires a lot of clean up out of the mold.Tried making the cab side walls for the Y6B but they require a lot of work. The Rivarossi Y6B motors seriously over heat melting the cab walls, I keep an open eye for Y6B cabs. Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
Detail parts, body castings, heh you name it, resin molding brings it own to the table! Especially for restoration work where parts can sometimes be hard to come by, or overly expensive. Resin molding is perfect for this.
Im concerned to hear your having motor heating problems with your Y6B. Rivarossi are some of the best products out there (for their era of manufacture). I would recommend that you check your driveline, electrical connections and pathways, of your Y6B. Gotta be something wrong there.
Ive had a few Riva's get a 'tad warm' before, buts thats because i load mine down and make'm grunt. I also run proto-speeds and use momentum... very hard on lil DC motors! Never melted anything on a Riva before. You shouldnt be experiencing this problem.
Prolly make a good post if other forum readers experience same problem.
I don’t have any problems with over heating Rivarossis, I buy clunkers and several of the Y6B have had melted cabs. Part of my restoral is new can motors.Early on I went with the Faulhaber 2224RS but they got pretty pricy. I used Canon EN22 motors until they also got pricy. I make new Mel brass frames for the Cab Forwards and use a pair of EN22 motors, after they got to expensive I went to the Mabuchi SF266.The Mel dual motor Rivarossis with added weight are really smooth runners with almost triple the drawbar at less than half the current. Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California I'm beginning to realize that aging is not for wimps.
Impressive! Ive hacked, resined, and printed plastic. But i havent gotten around to forming metal yet. Still on the todo list. There are soooo many things i need metal for.
Nice job on the remotoring. Id like to load those up for a good drag. They look good!
I started casting resin several years ago. The bubble problem seems to be the most annoying thing in casting resin. After watching many videos and reading threads on resin casting saying one can purchase a vacuum to eliminate bubbles. I looked into purchasing a vacuum pump. The price of one of those items nixed it right there for me. By accident I came across using a refrigerator compressor/vacuum pump. I always wanted to know what was in those enclosed cans that made a refrigerator work, so I cut one apart to find a motor and a piston in a cylinder. The whole compressor works on the Scottish yoke mechanism. There is also an amount of lube oil in there. That's why they tell you to leave the fridge standing up for 24 hours so all the oil drains back down into the enclosure of the motor/pump. Anyway a fridge compressor supplies both pressure and vacuum. Easy to find out which pipe has the vacuum and which has the pressure with a touch of the finger. So I made my own small vacuum system for doing small parts. It consists of piece of plywood with a slot mill in. A brass tube is epoxied into the slot. A piece of counter top material is the glued on top. I bought a set of Pyrex bowls. Remember they used to do commercials of dropping Pyrex on the floor to show it won't break. Plus a couple of feet of the proper size tubing. That's all that's needed. I used a silicone caulk on the rim of the bowl so it would make a good seal on the board. I checked out how much one of these compressors would pull on a vacuum. I got 27Hgm, which quite bit. The first time I used it on a resin casting it looked like a pot was boiling. By the time I shut off the pump and the vacuum had dissipated the resin had started to harden. I had a mess but it didn't have any bubbles in it. Here's the whole set up.
New York, Vermont & Northern Rwy. - Route of the Black Diamonds
protolancer(at)kingstonemodelworks(dot)com
Many thanks PMR. Thanks for taking the time and effort to post in such detail. With such good advice, I'm starting to feel confidant enough to attempt it.
OK Bernd. You absolutely win the response to my request for guidance. I'd heard about using vacuum to eliminate bubbles but your detailed and well-photographed set of instructions is the best. And that homemade shaker table! Awesome!
Thank you for your time and effort in the reply!
cnjman721OK Bernd. You absolutely win the response to my request for guidance. I'd heard about using vacuum to eliminate bubbles but your detailed and well-photographed set of instructions is the best. And that homemade shaker table! Awesome! Thank you for your time and effort in the reply!
Hey you're very welcome. I find it's nice to have pictures to explain how something is done. Good luck in your casting adventure. Remember that it's take a while to learn the tricks of what will work for you and what will not. Don't get discouraged if the first few don't come out to your expectations. You'll learn many different ways on how not to do resin casting.
Bernd