Vertex-foot cast in aluminium

Today I sand-casted for the first time.

Wooden pattern cut on CNC:
Wooden pattern 1
Wooden pattern 2

Raw casting:


Sanded down:



Blue wooden pattern and finished side by side:


My setup can be seen here, a couple of bricks and a propane torch:
http://i.imgur.com/JUROR.jpg

Only need 5 more

Edited 4 time(s). Last edit at 05/16/2012 06:56PM by flashnet.

Looks good, flashnet. I'm likely not the only one interested in reading what you use to make the mold.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Looks great. Perhaps you could revise the part so its easier to cast.

1) Reduce the thickness in certain areas. Aluminium casts better when the part has uniform wall sections.
2) Have raised bosses around the holes. This way you can flash machine them off quickly to make a very accurate part.
3) Re engineer it so it uses less material. You could drill the wooden master and rework it.
4) Increase the corner radii to improve casting.
5) Extend the casting along the rods, so it increases the rigidity of the reprap machine.


As you have CNC facilities, have you considered machining a tool directly and casting the aluminium directly in the steel mould?

What sort of gas lance do you use and what cupola. Where do you get this from?

Very cool.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

Quote
Traumflug
Looks good, flashnet. I'm likely not the only one interested in reading what you use to make the mold.

I made a wooden cope and drag (2 wooden frames basically) and made a negative in sand with the wooden pattern. 'myfordboy' on YouTube has excellent videos on the subject.

Quote
martinprice2004
1) Reduce the thickness in certain areas. Aluminium casts better when the part has uniform wall sections.
2) Have raised bosses around the holes. This way you can flash machine them off quickly to make a very accurate part.
3) Re engineer it so it uses less material. You could drill the wooden master and rework it.
4) Increase the corner radii to improve casting.
5) Extend the casting along the rods, so it increases the rigidity of the reprap machine.
As you have CNC facilities, have you considered machining a tool directly and casting the aluminium directly in the steel mould?
What sort of gas lance do you use and what cupola. Where do you get this from?

The part about wall section is a pretty good idea. Not sure what raised bosses would do to the accuracy could you elaborate?
I actually tried to use more material than a standard 13mm prusa because I want the extra weight to get less vibration hopefully, so I made it 18mm.
First drawing I made the radii were bigger, but I wanted the washers to be flat against the part so I reduced them.
Not sure about steel mould, but the CNC I have access to is for soft materials like wood, acrylic and maybe aluminium sheet at most. If I had the option I would've CNC'ed it from alu stock.
Don't really have the proper tools yet, what I used can be seen in the last photo. Because of the small amounts, I'm melting in a stainless steel cocktail shaker and using pump pliers to lift and pour. For my next pour I'd like to make more than one vertex so I'd have to make some improvements to this.

Thanks for suggestions,
- Nic

"Raised bosses"



When you need a flat surface to bolt to, you produce casting similar to as show above. You then machine just the tops of the bosses only and you get a very accurate and square surface to run the nuts up to. It saves you machining the whole surface. Spot facing is another alternative.

By doing things this way, you may be able to machine them on your CNC as the metal removed is much less (maybe leave 2mm stock for maching). Of course if your happy to bolt to a cast surface this is OK, but for a machine frame its nice to keep things square.

As your part now has a hard surface you could get away without washers or use flanged nuts



This is really good work though and gets me thinking a cast set of parts would be a real neat. What sort of volume / weight of aluminium can you melt in one go? Could you cast a pair of parts in one mould?

Edited 1 time(s). Last edit at 05/17/2012 04:07PM by martinprice2004.

Here's a video where I cast the rest
[youtu.be]

Didn't change the dimensions this time - maybe if I cast another set.

Heve you tried to reprap the pattern for sand casting. It might be easier than making it from wood. You could add draft angles and maybe finish the surface by hand.

I don't have a RepRap.

Heres a little update: