The Bucket Foundry

[F5 Dave]

I hope you're going to put a young fella on that as the crash test dummy rather than risk your own good self.

[WilDun]

Makes the supercharger look small.
Sitting on the doorstep this evening.
Lots of work to trim this down to a less sizable lump. I should weigh it as is, before and after as it were.
It was almost free thankfully.

Neil, I'm sure it's probably going to be an experiment of course, but what is your aim? - (bikes or aircraft?) - will you be fitting a balancer as well? (assuming it doesn't have one or two of those!).

[Flettner]

For Vinduro use, new class. I want to enter something..... unexpected but within the rules. This is it.
Im having trouble finding someone to grind the bigend journals at 15mm wide. Ive ordered a new wheel for my cylindrical grinder, Ill grind it myself, the centres are still in place thankfully.

[husaberg]

For Vinduro use, new class. I want to enter something..... unexpected but within the rules. This is it.
Im having trouble finding someone to grind the bigend journals at 15mm wide. Ive ordered a new wheel for my cylindrical grinder, Ill grind it myself, the centres are still in place thankfully.

I think that was what used to stop the 250 four engines
Grumph will confirm
i think they have many size shells but not for regrinds.

[Flettner]

A new grinding wheel will just work if I thin it down to 14.5mm. At 305 dia it is just big enough to reach in.

[Grumph]

A new grinding wheel will just work if I thin it down to 14.5mm. At 305 dia it is just big enough to reach in.

Generous radii in the corners please. And take the edges off the oil holes where they break out onto the shaft surface. The rpm and load you're going to give it means taking great care prepping the crank and rods. Going to nitride it ?

[Flettner]

Yes, it has to be nitrided. Im copying the FZR bigend journals, including the radius. Wayne (Blackwood Yamaha) is getting me some new bigend shells.

[Grumph]

Yes, it has to be nitrided. Im copying the FZR bigend journals, including the radius. Wayne (Blackwood Yamaha) is getting me some new bigend shells.

If he suceeds, let us know where he found them please.

[husaberg]

If he suceeds, let us know where he found them please.

Plenty for sale in China but from what i understand you need to buy all sizes and selectively fit.
if the bearing metal is as soft as they fasteners and have as much lead as they kids toys paint, they should do well in service.

[Gradella23]

Hello guys, i'm new here. My name is Andrea and i'm from Florence, Italy.
I'm trying to cast my first 50cc cylinder, which i designed from 0, mainly thanks to all the knowledge i got here and on pitlane.
I'm looking for advice about core boxes design.
Since i'm too poor to pay someone to study and manifacture all the necessary stuff for casting, i'm trying to model and create the core boxes by myself via 3d printing.

I've already tried some prints and coated them with a special filler, and the results were good: optimal roughness, perfect alignment and coupling.

The problem is that since this is my first try with castings, i'm experiencing some difficulties at "reverse thinking" to obtain the right planes and angles and all.
I'm a mechanical designer with skills on Creo 7, so the software part is not too much of a problem (even if i needed to learn some surfaces features i wasn't used to).
I thought that maybe an expert eye can solve in 5 minutes what i'd need 5 days to understand.
-First of all: i know that i usually need a min 2-3° draft angle to extract the cores, but can i just ignore that where i don't need a strict dimensional control? For example on the outside shell or in some liquid pattern surfaces? i don't care if the sand rubs on the walls a little. The local foundry man said that he's not using my boxes if they're at 90°...
-there are some surfaces, especially those in the ducts, than i can't reshape to avoid a negative draft: how can i design the core boxes in these cases? (The green core)
-any suggestion on how to divide the box for the fuchsia core? if i divide it in two halves on the vertical plane i always have negative angles (see the yellow and orange models)
thanks for your attention
Andrea

[lohring]

Attached is my method for creating a 3D model of the various passages in a 26 cc race engine. I use Fusion 360, but other 3D modeling programs should be similar. I model the passages as solids then subtract them from the solid shape of the engine. That method should also work for creating core boxes.

Lohring Miller

[Flettner]

Not exactly sure what you are asking but if I understand the question, I make my transfer core boxs like this. Split edge to edge, this way the transfer cores can have straight sides, no taper and yet still pop out cleanly and easily, with no sticking.

[Gradella23]

Attached is my method for creating a 3D model of the various passages in a 26 cc race engine. I use Fusion 360, but other 3D modeling programs should be similar. I model the passages as solids then subtract them from the solid shape of the engine. That method should also work for creating core boxes.

Lohring Miller

thanks Lohring, it's interesting. My method is very similar, i also use surfaces blends to control shapes. And of course i subtract cores from a solid, my main concern is how to divide properly the boxes to avoid negative drafts.

Not exactly sure what you are asking but if I understand the question, I make my transfer core boxs like this. Split edge to edge, this way the transfer cores can have straight sides, no taper and yet still pop out cleanly and easily, with no sticking.

mm so the only way i have to make the c transfer pop out is to create a single core box for the duct without having it already tied to the central core, right?

anyway, at the moment i found a fairly cheap alternative in voxeljet 3d printed sand cores: the full core with tranfers, cooling core and exhaust duct comes at 100€ for the single piece, and 26€ each if i buy 5. I'm going to try this for the prototype and then evaluate if this tecnology is good enough from a tolerances and roughness perspective.
thanks for your help guys! will post update if you're interested.

[Flettner]

These cylinders cost fu%^^k all, just some bondifill, wood from the wood shed, plastic beads, sand and some molten metal. Also a wee bit of time. Now I can make as many as I want with just a bit of sand consumables.
Sand printing is wonderful, but that cost is each time, can add up to be expensive once you want more and more cylinders with detailed changes.
Transfers are keyed and glued in place.

[Gradella23]

These cylinders cost fu%^^k all, just some bondifill, wood from the wood shed, plastic beads, sand and some molten metal. Also a wee bit of time. Now I can make as many as I want with just a bit of sand consumables.
Sand printing is wonderful, but that cost is each time, can add up to be expensive once you want more and more cylinders with detailed changes.
Transfers are keyed and glued in place.

no doubt, that remains the absolute best. I plan to continue the development of traditional core boxes once i got a taste of what I'm doing.
After all if you consider that I don't have the space and the tools to build a proper home foundry, it sounds nice to me to pay a batch of 10 full cores 19€ a piece! (even with 10 different adjustments if needed, that doesen't affect the print cost). I think the local foundries would charge a similar if not bigger price to form sand cores from my own boxes.
I've already changed the outiside shell core to add 2° drafts since the outer boxes will be still done the old way:

don't pay attention to the channel and sprues, it's just an hypotesis without too much thinking.