Casting kit business?

[GreenTwin]

One of the secrets of Stuart's success is that mold material that they used.
I forget the name of it now (JasonB will remember it), but it produced very accurate molds, using some sort of material that acted like thermoplastic, and they set it with heat, using permanent metal molds.
Like bound sand, the Stuart mold material was not reusable (I don't think it was reused).

One of the keys to succeeding in the foundry business is to have little or no casting defects/failures.
So far, I am to the point where I never have a casting failure (knock on wood).
I pay very close attention to what I do, in order to make sure the casting turns out defect-free.
Most backyard folks have a very casual attitude towards quality control, and that tends to produce some bad castings.
I basically use an ISO9001 approach for my hobby foundry work, which I find makes it easier than just a random approach.
My foundry work is not a casual thing, and my casting success is not an accident; it is well planned and researched.

I started my own business (consulting) and have been running that for almost 20 years, so I know how to run a business successfully and make a profit.

I chatted with Maury for a while, and watched what he did, and that convinced me to not get into the casting kit business.

The biggest problem now is the ever increasing regulations on foundries.
No foundry will survive in the US if they don't keep the regulations reasonable and achievable.

I have done a group build (on the green twin engine), where my Canadian buddy provided many of the 3D printed patterns, and I did the molding and casting. I made two sets of castings for the green twin, and so there are two of those engines out there.

A colaborative effort is what is needed in the hobby for those who want to recreate old engine designs, with one or more persons tackling the 3D modeling, and then others doing the molding and casting, or contributing other aspects, perhaps such as machining. It would not be a "for sale" thing, but more of a makers-space thing, with contributors spread around the country.

The colaborative thing JasonB is doing is a good example of what can be achieved through a team effort.

Once you make castings for sale, then you are considered running a business, and that would make it unworkable for many reasons.
I don't intend to ever sell any castings. It will remain a hobby activity for me.

If the pattern work could be done by muiltiple people, to spread the load, then the casting work could be farmed out to Cattail's.

https://goodsstores.com/blogs/a-goo...ndry-casting-iron-in-gordonville-pennsylvania
There is a way to recreate many of the old engine designs; people just have to step up to the plate and learn 3D modeling, and be willing to contribute to that effort, which is time-consuming.

I have one 3D printer (a Prusa MK3), and have ordered the Prusa XL.
The XL gives a reasonable print area (14 inches cubed) for a reasonable amount of money, and excellent product support.




https://blog.prusa3d.com/original-p...il&utm_term=0_4199f6d18b-70632dd1b1-123714041
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[GreenTwin]

The Frisco Standard is one of the engines that is high on my priority list to cast.
I would probably make one with a 2.5" bore (+ _-), and a flywheel no larger than 12" diameter.

JasonB has worked out the helical gears for this side-shaft engine, and I have 3D printed his design, and they mesh perfectly.
I owe Jason on this one.
My intent is to cast these gears, and I think I can do it.

I found the patent drawing on the head, and so I have that hashed out in 3D.

This is what I am talking about; colaborative effort, and spreading out the work.

I will be sending JasonB all the 3D models for this engine when I get it done, since he worked out the thorny gear design.
He can do whatever he wants with those 3D models.

 

[GreenTwin]

On a semi-related note (relates to castings), I read the magazine "Modern Casting", and one of the articles details a Japanese company that has started a foundry business in the US, and some of its molds are 3D printed.
The article details why they are finding success with this format, paraphrased as follows:

1. Supply chain problems are making it difficult or impossible to get castings from far-away sources.
2. There are many industries that cannot afford to shut down very often, and when they do shut down, they can lose thousands of dollars (or more) per hour.
3. Costs for a 3D printed sand mold and associated iron or steel casting is higher than far-away sources, but for time-critical industries, they have no choice but to get their facility or process back operating again as fast as possible.
4. This Japanese company mentions a 5 day turnaround, from the time they get the 3D model, to sending back a finished casting.
This quick of a turnaround is really unprecedented. They are reporting getting a lot of work, since many castings are often not available anywhere else.
5. Any changes to the 3D model will not alter the 5 day turnaround. No tooling has to be modified regardless of 3D model changes.
6. Extremely complex parts and cores can be 3D sand printed easily.
7. A part can be cast as a prototype, and then machined-tested very quickly, thus avoiding very costly mold rework if the design changes during the prototyping phase.

Many people in the US are re-shoring their castings, so as to avoid the supply chain and quality control issues.
The overall cost of re-shoring is said to be less in the long term.
Critical delivery dates can be controlled with local foundries doing the work.

There are definitely some major changes happening in the global casting world, and in the model engine casting kit world too, so it would seem.

I still don't see $23k as being even remotely in the ballpark.
Those are some high quality castings he is offering, but even when the cost of the castings is included, I still don't see anything near $23k.

I would offer $5k max for those patterns, and I would consider that being very generous, since I could remake then without much trouble.

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[GreenTwin]

One other thing I just picked up on while watching the Prusa XL introduction video posted above, you can 3D print water-souble supports.
And so what that means is that you could also print water-souble patterns, such as the helical gears I show above, and encase them in some sort of material that set, such as castable refractory, and then rinse out the pattern with water, and bake the remaining material dry on a relatively low heat, such as 250F.

This would produce a method as accurate as lost-wax, but without all the tedious high-temperature burn-outs.
I think the multi-slurry dip could also be eliminated.

I think this is a big deal, assuming the water-soluble material did not have a short shelf life.

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[GreenTwin]

The Prusa 3D printer is even being used in industrial foundries with good success, as can be seen in this video.

With a 14" cubed Prusa XL printer, you could print an entire pattern set, with the gates, runners, sprue, etc., and cast perhaps 20 small parts at one time, such as 20 model cylinder heads.

I continue to be amazed at how useful 3D printers are with foundry work.

 

[Steamchick]

Green twin. An "off-the-wall idea" = for a water soluble material, do you mean something like icing sugar? (or Salt?) - Or Jelly/ Gelatin (Jello in USA?). I thought of icing sugar, because cake makers create all sorts of shapes in it, and "extrude" it from their Icing bags through nozzles. SO maybe this would work in the 3D printer? - Or Jelly is poured into (rubber) moulds, and removed from the jelly-moulds after the jelly has set (in the fridge), and holds pretty good detail on the cast jelly. It melts away with hot water.
But I am not a foundry-man, so just watching the thread for fun. (And I like Cake and Jelly!).
K2

 

[Jasonb]

Sell Mould is what they use/used

https://web.archive.org/web/20051219221221/http://www.stuartmodels.com/cast_process.cfm
There is a big difference in the few backyard castings you have done Pat and producing them for even a small scale production. The amount of time and effort you put into the individual castings would simply not make sense if you were looking to get even a modest return. Things like working outside would make it weather dependant, single patterns and small furnace would not be economical and simply the time spent preparing those faultless moulds would not equate well in $/hour. You would also need to invest more to get a productive setup so your low cost foundry that you have now won't be so cheap.

No need for anything fancy for helical gears I have seen them cast simply by rotating out of the sand

 

[GreenTwin]

I have already stated that I don't think there is any way to get a return on producing casting kits.
I have a commercial metal building, and a hefty 3-phase electrical service that would support an induction melter, but as I said, the money does not add up, and I would not go broke for the enjoyment of making castings. If the money made sense, I would definitely do it, and could do it.

I think some of the folks who have been in the casting business have found sympathetic foundries who probably poured the casting kit molds at the end of their standard production run, when they had some extra metal already melted and in the ladle.
A commercial foundry would basically be doing you a favor by pouring casting kit molds.

A buddy of mine said the soluable printing filament idea would probably not work, since he said the mold would get too soggy before all of the filament dissolved.

An new induction melter can be had for not to much money (about as much as what someone is asking for patterns and some castings).
The problem is not the cost of an induction melter, but the electrical demand charge that you set when you use the melter.
One guy told me he was charged $5k per month by the utility company, even if he only used his melter once a year.
The induction melters from overseas are actually quite reasonable, but I am not sure about the reliability, and you have to have a chiller to cool the coil.
https://www.focoinduction.com/induc...-furnace/tilt-type-induction-melting-furnace/
There is a video online of a guy (perhaps the same guy who mentioned the $5k demand charge), who uses a diesel generator to power his induction melter. This is the second person I have heard of doing this.
I looked at used 480v diesel gensets, and the ones that have to be retired after so many hours from hospitals are typically in perfect operating condition, and can be purchased for not too much money (probably less than $50k.

As I mentioned, some sort of colaborative effort to make a few sets of castings between several folks is really the only thing that makes sense, if somebody wants an iron casting kit of an engine that is no longer made, such as the Ball Hopper Monitor.

There are two ways to make a lot of iron on the cheap.
1. Build a cupola and source some coke for fuel.
2. Build an oil fired reverb furnace, which is what you see in India and Pakistan (video below).

I am toying with the idea of building a reverb, but it would be only from the standpoint of proof of concept, since I don't need that sort of capacity.
A reverb furnace is a poor-man's induction furnace, but they do produce a lot of iron, and they seem to work well.





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[GreenTwin]

Large format 3D printers have come way down in price.
Here is a huge one that is about 1/2 the price of the ebay offer (lists for $11,500 US).
Last time I looked at large format 3D printers, they were over $100k.

 

[darwenguy]

Thanks Ken.
Greentwin they are Very nice looking iron castings. And some interesting ideas, thanks for sharing.
Unfortunatly as you sied its not a process that can be profitable on a small scale. I do use sodium silicate for cylinder cores but they dont make too much waste.
I can just about do iron castings with my foundry, but as im set up now with petrobond, it becomes more expensive as the petrobond gets realy burnt out with iron and it almost becomes a use once and bin it consumable and so i cast cylinders in bronze now as it works out cheeper for me in gas and sand. Buying and disposing of contaminated sand here in the uk on a small scale is too expensive.
Ive got my process quite well refined now and at best i can do 18 molds per day, thats 3 melts x 6 molds each and i get it to around £6 per aluminium and £15 per bronze mold in cost.
I have done a lot of maintenance work in a large foundry and they use a resin bond but require a large plant to mill it back down for reuse, i often had to work on the whole sand delivery sytem i never liked the place much, always come come with black sand coming out my ears.
They also did the lost foam/polystyriene with ceramic shell Process for the smaller castings that was interesting to see. Not a chance of getting any parts made for myself though every second of production was accounted for there.

 

[abby]

I am having difficulty understanding your last post darwenguy "i get it to around £6 per aluminium and £15 per bronze mold in cost."
Do you mean that each mould costs that price for Petrobond?
Petrobond IS a use once only material , a thin layer should be applied by sieve to cover the pattern , and then backed up with greensand.
After knock-out the small amount of burned Petrobond is simply mixed in with the sand bulk.
Before changing to lost wax investment casting I used greensand , half a ton of Mansfield sand collected from the quarry cost very little and lasted several years of daily brass/bronze casting.

Actually the market for model castings is quite small unless you are prepared to have a large inventory. Having supplied a large UK firm with casting kits I know from experience that for a single model 10 kits per year can be a good rate for sales.

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For this kit the customer paid me less than 1/3 of their advertised selling price and needless to say I have lots of bits in stock after several years.
I still do some castings but only for myself nowadays.
Dan.

 

[darwenguy]

Hi Dan,
That is a very rougth average guess at the material cost for me to make and cast each mold. Thats sand, gas, metal, electric, over overheads and workshop rent.
This does not account for any design, pattern making or cost per hour worked.

Petroband can be reused many times, it does eventually get burnt out, i find its best for me to remove some and mix in the new bags when it gets too burnt, adding oil and a little isopropyl extends its life.
I usually go through about 5 bags, 100gk a year and get around 1500 molds from that.
When knocking out the molds i do try to remove the most burnt bits to preserve it more. This is usually a cast of just tapping the casting over a bin and the black dust falls off the shiny castings.
I agree i would not advise making a bussiness out of it unless you realy enjoy it, ive been fortunate ive focused on a bit of a nich market making accssesories to run with engines. I also produce finished working models and that accounts for maybe half my turnover.
But ive made hundreds of models that are allover The world and i can barly afford to keep any for myself.

Ps your patterns look beutifull! very nice wood work.

 

[abby]

The photo is of the castings , not the patterns,it's a complete set less the wheels for a gauge 1 loco.
I mainly produced bronze sculptures for an accomplished dog and horse sculptor but also fashion work for Vivienne Westwood and for David Shepherd.
I found it hard to get any large scale orders where it may have been more profitable.
Dan.