Lost foam

[tel]

Somebody has to be first in here, so it might as well be me. Here are a couple of workshop projects using the lost foam method.

The body and detent bracket for this spin indexer (for the Douglas shaper)

Travelling steady for the Myford

How it came outta the sand

 

[PTsideshow]

Here is some info on it from a guy in Canada'shttp://www.theworkshop.ca/casting/casting.htm site along with other casting info

;D

 

[wmf138]

Hi there

Just a question can you use the foam they use in flower shops as this is light and fine in the texture I know the sand is what give you the finish

and do you spray the foam with some sort of heat proof paint to stop the dry sand from falling into the cavity

Cheers Wayne

new to this but would like to try this maybe lead first

 

[PTsideshow]

If you go to my other post he covers it pretty good, The sand is moist with an oil so it holds together. The foam burns out completely. so any foam works just about.
Problem with lead may be getting it to burn out the foam completely replacing it with lead with lead having a relative low temp compared to aluminum, brass and iron.
glen

 

[wmf138]

OK

Cheers for that I did read the thread and found it interesting in that he didnt use anything apart from the dry sand

some other sites Ive looked at said to use a barrier to hold the sand like painting it

and some say to use clay base ????

but i think Ill try this one

as for the lead it was only to try on small pieces (fishing weights) just for practice on small shapes as this I have lots off and doesnt take to long to see if I stuff up ;D

Cheers Wayne

 

[rickharris]

there are quite a few recipes for casting sand if you search around.

Commercial casting sand is often mixed with Bentonite a sore of clay as a binding agent. If you can't find Bentonite it is the main constituant in Kitty litter you can buy in any supermarket.

http://en.wikipedia.org/wiki/Bentonite

[ame=http://www.google.co.uk/search?hl=en&q=casting+sand+recipe&btnG=Search&meta=&aq=f&oq=]http://www.google.co.uk/search?hl=en&q=casting+sand+recipe&btnG=Search&meta=&aq=f&oq=[/ame]

 

[PTsideshow]

Here are a number of books that cover all things casting
Metalcasting
C W.Ammen
It is Craftmaster imprint
of McGraw-Hill
Trade Paperback
copyright©2000

Is the godfather of small shop castings. http://madmodder.net/index.php?topic=84.0 Is the start of the books on casting and foundry work I have posted.

Any of the books by Ammen are good. In the postings are also books on wax carving wood pattern making. And related small shop skills.

http://worldcat.org/ is an online catalog which comes in handy for finding books that are in a member library close to your home.

 

[mu38&Bg#]

I saw a Chevy engine block recently that was produced from the lost foam method. They use expanded bead foam to make the pattern and the beads were clearly visible in the casting. I had never actually seen it before and it gave the impression of a styrofoam part, that's how well the beaded foam detail was passed to the casting. So the finish is very dependent on the part and method. If you dip your foam pattern into a plaster slurry a few times prior to packing it in sand the finished part will have all the detail of the pattern. I've seen this mentioned before on forums and also on "How it's Made" on Discovery Channel. Of course that might be easier said than done, as I have not attempted to cast anything yet, maybe one day.

 

[PTsideshow]

The ceramic slurry is a silica based high temp slurry not just a plaster based. Most important thing is all the moisture is removed from the plaster. Generally the slurry dip method is used for shell casting with a wax master pattern. And you have to take into account the shrinkage of the wax and expansion of the slurry so the part comes out to the size or tolerance you want.

A lot of brass/bronze hardware parts and harness hardware is cast by the wax/ceramic slurry method.