The advantages with foam are simplicity of pattern making.
Draft -- dont need it.
Undercuts and weird shapes -- not a problem..
Foam is relatively cheap.
Easy to work with the most basic of tools.
If its a 1 of piece foam may often be easier.
It you need 100 of them thats a different story...
Yes you loose a pattern if there is a problem.
So start with simple patterns till you learn to cast foam...
On 4/2/2011 12:43 PM, Wonk wrote:
> I don't see the advantage with foam over wood patterns unless you don't want to ram sand moulds! Also the other problem if something goes wrong your pattern is also gone, where-as with wood you can cast many times! I agree with the previous post that if you can figure how to machine metal, wood should be easy? I used the hobby store bass wood which seems to be dimensionaly sound and easy to cut with hand tools, glues great and once sealed with several coats of varnish seems to hold its shape well even when packed away for several years.
> I'm making my third set of castings from the original patterns starting in the 70's to present. I rarely hear that someone is sharing patterns or selling - works of art and should be kept for show and tell! Ha!
>
> Cheers
>
> --- In gingery_machines@yahoogroups.com, Ron Thompson<ron@...> wrote:
>> On 4/2/2011 11:47 AM, Wonk wrote:
>>> Ron how do you maintain accuracy with lost foam? would seem you would
>>> have to cast a bit oversize and machine until your there? I guess CNC
>>> comes into play but then you have to start somewhere!
>>>
>>> Wonk
>>>
>> No cnc needed for simple patterns. If you can cut wood to dimension, you
>> can do the same with foam. you can glue it together just like wood.
>> Some patterns may need bracing to keep them straight, but that isn't a
>> huge problem.
>>
>> Another thought is for people with the patterns. Maybe you might want to
>> sell casting kits. Works for steam engines.
>>
>> --
>>
>>
>> Ron Thompson
>> On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA
http://groups.yahoo.com/group/gingery_machines/app/peoplemap/view/map
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