some casting projects

[FJ and G]

decided to try my hand at metal casting so I picked up some supplies from Ace hardware: a $10 cast iron pot; a $10 5lb bar of lead; and a $10 1lb bar of solder.

I haven’t yet tried the lead out but did some castings with the solder. With that bar, I should be able to create a number of wheels. The bar says 50/50, which I take to mean 50% lead and 50% tin (would be cheaper if I could learn how to combine those 2 materials myself). Unsure what the 4 in 1 means (stamped on the bar). The solder is certainly cheaper than white metal and I can’t really think of any disadvantages it has compared to white metal.

Used propane torch to melt the solder and a work glove to hold the pot when pouring. Incidentally, the pot stays really hot for about an hour. Pretty amazing pot.

My initial fear was that the solder would solidify on contact. That fear was unfounded, however, as the molten blob stays molten for around 8-10 seconds, giving enough time for it to settle in the mold.

My biggest disappointment was that the molten solder for some reason didn’t settle in a few spots. Of course the spoked wheel offered a challenge, as there are numerous crevices to fill. I tried shaking and tapping and blowing, but try as I might, it wouldn’t settle completely (but it still got into more than 95% of the mold). A more simple mold should give better results.

So what to do now? Plan B and C.

I haven’t yet (but will) try plan B, which is to build a centrifuge. My plan would be to set my power drill in a heavy vice with the drill pointed straight up. Attach a platter to the drill, ensuring it all is level. And then place the mold on the platter. Quickly cover the molten solder and then spin the platter on high speed, thus creating a sort of poor man’s spin casting device.

Plan C was the easier to execute, thus the chosen path of least resistance for me. I simply recast the mold with the already cast solder by lining the mold with a thin layer of epoxy. I’m familiar with JB Weld but found a somewhat less expensive product that I believe has the exact characteristics of JB Weld called PC-7. PC-7 is a 1:1 product in 2 cans that when the black and white substance is mixed, turns a sort of grey. Drying time is about 12 hours.

Plan C worked well, with just a couple of areas needing touch up. I purposely didn’t use casting resin or the smooth-on product resin, as there’s a warning that it doesn’t bond with lead or steel and some other metals.

The trick to removing flashing or drill holes in solder is to use tin snips for the big pieces and a hand file or sandpaper for finishing work. Hi speed power tools shouldn’t be used because could cause remelt. For drilling, you can either use a hand drill or a speed drill, but drill fast before heat can build up.

Summers in Virginia get hot but not yet (I think) hot enough to melt solder.

I’m not sure all this work I did was really justified, as metal powder would have made the job a whole lot easier. However, the solder method (and perhaps lead), will find a useful place in my repertoire of casting methods as it might just be the thing I need for a certain part.








beginning rumbles of a “squash” tipper

now that my wheel castings are coming along fairly well (with some ups and downs), I thought I’d start a 7/8n18 O gauge tipper, built from a composite of tipper prototype photos, taking the best of what I have in mind. The freelance based on prototype approach seems relevant, as tippers come in so many varieties and not a few have seen their own modifications in the name of field expediency.

My goal is to create a master tipper and then make a whole mess of fascimilies from a 2-piece silicone rubber mold, creating in effect tipper hatchlings from the mother.

To do this, I printed out a mess of tipper photos to work from and then did some cardboard mockups. Once satisfied with the mockup, I cut some heavy gauge steel to form the V chassis and locked the sides into place with PC-7 epoxy, followed by some touch ups with Bondo. I would have used cardstock for the body, except for the fact that to make a squash mold, one needs to emplant non-sulfurous clay inside the body, and I was fearful that the mother tipper would become pregnant as the clay would bulge her out. OTOH, the heavy duty steel will withstand the clay implant.

Next come rivets. I spent an inordinate amount of time trying to duplicate the rivet effect in the pictures. A number of punches and pointy devices did not work to my satisfaction so I took a large nail and spent some time filing it on the bench grinder until the impressions left me satisfied.

I then measured and made rivets in cardstock (3x5 index cards) and affixed the rivet strips to the body with Welder adhesive. Eventually, I’ll add a coat of shellac over everything to fill in any miniscule gaps and pores in the paper. Remember, the mother can be ugly but the babies need to be beautiful.

I thought about adding the angle irons on both ends which allow the tipper to tip, but decided against it because of the likelihood of mechanical locking, the bane of casters. I’ll likely cast separately a number of items to prevent this from happening. I plan to make all of the other master parts from card stock or steel, depending on what works best. The nwb’s will likely be cardstock or perhaps real nwb’s.

Incidentally, I’ve never before done a squash mold but I know to make keys to line the 2 parts of the mold up. I may also use clay around and inside part of the tipper to save on silicone rubber, which is pricey. But there will be at least ½ inch of mold around everything.

I’m not in a rush so I don’t know when I’ll get this all completed but I’ll be sure to keep you posted with photos and updates.

[cacole]

If you intend for these to be actual wheels on rolling stock, I think you'll find that solder is too soft a metal that will quickly wear.

[FJ and G]

then good to have coated with epoxy!

 

(Actually though, model railroaders for decades have been casting frogs from solder and these seem to be holding up.) I'd like to hear from someone with solder wheels who has experienced problems. I'm still learning stage

 

Anyway, don't know if the time and effort is worth it. Might cast metal for other things and leave the wheels resin or epoxy 

[cabbage]

Melt the tin first and then SLOWLY add the lead. This will produce a eutectic combination -rather than an alloy.

A eutectic combination is one that has a higher melting point than freezing point. Salt and water is the common one.

The most famous eutectic failure was the first casting of "The Statue of David". The cheapskate Michelangelo used OLD bronze and tried to melt it... The furnace was yellow hot and it still hadn't melted, in despair he threw in several sets of tin dinner services and there was just enough molten tin to begin to dissolve the bronze. The molten mix by this time was "anybodys guess" and as it cooled the ends of the statue show the tin crystals bulging the head, hands and feet.

It is still a lovely work of art -it was just never supposed to look like that!!!

[FJ and G]

thanks! I'll have to look around for some tin. Not many tin cans around and not sure they're pure tin. Maybe some of my tinplate Lionel tubular rails?

I'll have to see if the propane is hot enough to melt the tin. Mapp might be better. So much work ahead of me!

 

Don't want to create another David but some pissing cherubs in the garden might be nice 

[cabbage]

I have a combination MAPP/Propane bottle torch. MAPP is quite a lot hotter than propane -but (for me) does have one horrible drawback.... I can only describe the smell of MAPP as a sickly combination of ripe drain and sweaty socks. It does say in the EU safety guide on it that the chances of unnoticed build up of MAPP gas to toxic levels is a room is deemed as REMOTE...

I think they mean by that everyone would have left the room!!!

However I like MAPP as a silver soldering and brazing gas -it is clean and VERY hot.

regards

ralph

[FJ and G]

hi, when you are taking apart propane; the smell of that is overpowering too; even outside; I think they add the smell to the propane so you know when something is horribly wrong

[cabbage]

No David,

Definately MAPP -Methyl Acetylene Propadine. EU gas cylinder colour coding is rigidly enforced. Propane is in ORANGE, Butane is in BLUE, and MAPP is in MUSTARD cylinders. I have small 0.45kg cylinders of each in my workshop. Our former home had Butane and the Propane cylinders in the back to provide gas for the house. You could tell when summer was comming -we switched from Propane to Butane!!!

regards

ralph

I know the US colour coding is different. I do know that Compressed Air in the EU is White on Grey -the US is Yellow -the colour used by EU for Chlorine...

[Anonymous]

Propane is in ORANGE, Butane is in BLUE, and MAPP is in MUSTARD cylinders. US colour coding is different. I do know that Compressed Air in the EU is White on Grey -the US is Yellow -the colour used by EU for Chlorine...

As I checked with the cans I use on the mini torch here, Oxygen is Red and Mapp is Yellow but I would think there all the same because they would want workers to know the colors when they work around these. I never thought they might be different around the world! Set standard I guess not!?

[cabbage]

These are only SOME of them...

http://ptcl.chem.ox.ac.uk/MSDS/cylinders.html

There are also colour confusions when EU electrical systems meet US electrical systems. Our 3 phase "Delta Star" coding is Brown Black Grey Blue with Green/Yellow striped as Earth.

Last year we (the company) got a contract for the US offshoot of a Canadian Bank. They ordered the computers for an initial site in Seattle, (there is a direct cable link to Vancouver Island there). It turned out to be a complete nightmare....

The standby diesel generators had to run on US 76 Cetane rated fuel, (which is illegal in the EU). The power supply had to be wired for US std connections (we use 415Volts 60Amperes here...) Plus the fact it all had to be correctly colour coded in TWO halves. The Std Power cabinet had to have US colour coding from the Transformers to the Mains. THEN the power cabinet had to have EU std cabing and colour coding to power the cabinets.

It got worse.

We test assembled it all in Berne (Switzerland) were it worked faultlessly. We air freighted the system to Seattle. The contractors to do the raw install (i.e. just assemble the cabinets out of the boxes) simply decided to go insane -there is no other word for it!!! After two weeks I fired the US contractors shipped a German team over there.

Since then the US construction team (we hired and trained a new one from Omaha) have worked flawlessly.

regards

ralph