Lost Foam

[ShedBoy]

I wanted to kill some time today so I thought I would give some lost foam casting a go. Found a plan for a high speed steam engine from 1933 with a 1 inch bore so I cut and sanded some foam and buried it. Sorry I forgot to take a pic of the foam as I was fairly excited.

Bucket of hot dirt

Fresh fro the sand, still warm

Fresh fro the sand, still warm (another view)

Small lump on the end which wll be cleaned off anywho

Inside bit ordinary but still useable

Pourer removed

Cut off the sprue and it looks good.
Real happy with my first attempt, Can only get better from here ay.
Brock

 

[metalmad]

Good going mate
looks like a lot of fun :big:
Pete

 

[Herbiev]

Great for first casting. Do you have a picture of proposed engine ?

 

[xlchainsaw]

looks good ..i must give lost foam ago sometime....im not sure the neighbours will like it tho. how bad does it smell???

 

[ShedBoy]

Herbiev, Here is a picture of the engine which I will be basing it on

I will be changing it a bit just to make it easier like bearing carriers for main bearings and lip seals and the obvious block difference.

xlchainsaw, there was hardly any smell from the foam melting, my neighbours never complain about anything I do. Next toime I do it I am going to spend more time sanding down to shape to get a better finish and maybe find some denser foam with smaller beads. But what a simple process. Hey what is with the name xlchainsaw, do you have a thing for large chainsaws because I have an old McCulloch saw, quite large just missing the bar if you want to save it from the furnace? Still turns over with good compression.

Brock

 

[tel]

Yeah, lost foam is the duck's guts for quick one-offs, and the better you make your pattern the better the result. Can't say I've ever noticed much of a smell.

 

[ShedBoy]

Decided to have a go at making a hot wire foam cutter, this is my first atempt but it needs some refinement.

12v transformer, and a light dimmer through a bit of mig wire. Crude but useable.

Cylinder template

Gluing together with pva wood glue

Sump and block on a common sprue

Time to heat

Hot bucket

With the common runner I could not pour quick enough and the sprue was empty for a split second causing this cooling and slowing of metal I think. Could have been the common sprue. Anyhow it was sentenced to death by fire.
Back to the foam cutter.
Brock

 

[ShedBoy]

Okay the second attempt had a boss added to it for and oil fill

Seperate runners/sprue (can''t remember which it is) this time

Same problem again but not as bad, I think it will be okay :-\ might touch it up with a bit of tig weld.
Foam is quick and sort of easy.
Brock

 

[dalem9]

Hi Is this just regular foam or is it a special kind .I would like to learn more about this .Thanks .Dale

 

[ShedBoy]

Yeah Dale it is just regular foam, easy to get. Give it a go and show us what you come up with. Denser would be better but too dense can cause issues.
Brock

 

[tel]

Your foam cutter is very similar to mine - the only difference it that I is that I power mine through a cheap battery charger (automotive) after the dimmer

 

[dalem9]

What keeps the foam from burning up ,or does the metel cool that fast Thanks Dale

 

[stevehuckss396]

try coating your foam with some plaster and it will improve the finish.

 

[ShedBoy]

Steve investment casting is on the list (I think that is what they call it). I have some lrger parts that I only want to do once.
Dale the metal displaces the foam which disapears.
Brock

 

[stevehuckss396]

I'm not talking about investment casting. I'm just saying if you coat the foam you will get a better finish.

 

[fltenwheeler]

try coating your foam with some plaster and it will improve the finish.

Take a look at this.

http://www.buildyouridea.com/foundry/lost_foam_howto/lost_foam_howto.html

Tim

 

[tel]

What keeps the foam from burning up ,or does the metel cool that fast Thanks Dale

That's the point of it - the foam burns out and is replaced by the molten metal

 

[ShedBoy]

Steve I have sen sheet rock mud and drywall mix mentioned. Do you think this would be the same as gyprock? We have gyprock base coat which set as hard as anything. mixed from powder. I will give it a go next time I am home.
Brock

Anyone got any pics of lost foam parts they have done?

 

[stevehuckss396]

Steve I have sen sheet rock mud and drywall mix mentioned. Do you think this would be the same as gyprock? We have gyprock base coat which set as hard as anything. mixed from powder. I will give it a go next time I am home.
Brock

Anyone got any pics of lost foam parts they have done?

Mix it watery so you can dip it and give it a try.

I tried to post pics but it failed.

 

[tel]

A word to the wise, however - the plaster, tape or whatever jiggery pokery you apply will only conform to the surface of you foam pattern and give you the same thing as you would have had without it, so you foam pattern still needs to be well made and finished. Apart from that, the plaster can add to your woes by sealing the pattern in the sand, which in turn will not allow the gasses from the foam to dissipate as readily. IMHO the plaster is just a security blanket for those who doubt the process!