plastic for casting pattern 1

[kenre]

What are the best choices for a machinable plastic for use as a casting pattern, used in sand castings.?

Wood is commom, but i would like something that is a little more robust.

http://www.retallickeng.com.au

Was told it couldnt be done, so
i went and did it!

 

[swall]

When a more robust pattern is required for sandcasting, it is common to use metal faced wood patterns or all metal patterns.

 

[arunmrao]

You can use epoxy patterns. You can also use polyurethane foam(commonly thermocole) material.

If you can give a little more information it will be helpful.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[kenre]

The patterns are small, approx 6 in Sq, and have quite a bit of detail in them. I would like to use metal but machining them will take forever, there being done on a homebuilt cnc mill.

I will be starting with petrobond sand molds and move onto a phenolic bonded sand if i need higher volumes.

http://www.retallickeng.com.au

Was told it couldnt be done, so
i went and did it!

 

[arunmrao]

You can use as mentioned earlier,araldite patterns,they are long lasting,easy to work with and economical.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[kenre]

arunmao, By epoxy (araldite being a trade name) are you saying to take a mold from the orgiginal wood pattern or machining from a block? ive never seen a solid block of epoxy.

My experience in epoxy is for laying up molds using carbon, kevlar and fibregrass.

http://www.retallickeng.com.au

Was told it couldnt be done, so
i went and did it!

 

[arunmrao]

Yes you are right. We often cast a solid block into near desired shape and then work on it to finish. This will be faster than metal patterns.

If you need one,send along a drawing I shall get one for you free,!

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[kenre]

Thankyou, interesting way to do it. do you use certain types of epoxy?

Are there any plastics that are also suitable? eg, nylon, acetel, as these are easy enough to source. I would be suprised if plastics arent used!

http://www.retallickeng.com.au

Was told it couldnt be done, so
i went and did it!

 

[arunmrao]

There can be others who might have tried,but I have been working with araldite for nearly 20 years.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)

 

[RPstress]

Something like Araldite AY 103 with an appropriate hardener should be castable in blocks.