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post #1 of 10 (permalink) Old 05-13-2014, 06:33 PM Thread Starter
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I would like to read more on making patterns in wood for both foundry work and for carbon fibre and fibre glass molds.

Do forum members have experience in this work, or know of good sites to visit? Thanks.
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post #2 of 10 (permalink) Old 05-13-2014, 07:26 PM
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Click Templates &
Templates II
Might help.
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post #3 of 10 (permalink) Old 05-13-2014, 08:13 PM
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The only templates I have used are flat templates for router use. Not sure where you would find making molds...

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post #4 of 10 (permalink) Old 05-14-2014, 09:13 AM
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AJ, Wood isn't often used in Foundry Molds where molten metals are cast - due to the propensity of being burned in the process. Each successive casting with a mold would yield a slightly different part(s). For small runs, you may wish to investigate "sand molds".

Molds for carbon-fiber reinforced epoxies or fiberglas can be and often are made of wood. I am an inventor and have numerous molds in use for these products and we use wooden-reinforced translucent grade silicone molds, or in some cases with extremely simple profiles we'll use UHMW PE molds or mold liners.

In the past, I've owned manufacturing of specific-application ceramic molding - it may be that for your foundry work a high-strength and very durable ceramic mold may be workable. Ceramics that are cast from "slip" are cast-into molds made of Plaster of Paris.

Plaster of Paris cannot handle high temperatures, typically - but making positive to negative molding and changing materials as one goes is one approach.

Native Americans (and quite likely Aboriginese) made bridges across huge ravines, rivers, gorges, etc. beginning with thread shot with bow and arrow. From the opposite side, a coworker would tie-on a string and the shooter would pull-back the thread, followed by the string, the shooter would remove the thread and tie-on a thicker string, bla, bla, bla. Eventually a heavy "rope" would be stretched across the ravine - using several workers on each side to pull the increasingly heavier thicknesses of ropes.

This same principle can be used in many things having to do with manufacturing - it just requires someone to "think creatively" and use progressing materials along the way. Every big man-made production begins with something smaller than the tiniest seed - an idea. For one to be a successful inventor, one must be willing to be a successful failure. To me a successful failure is when something logical is attempted and then fails. Success often is when something is learned through failure of a logical process and then experience becomes wider. And don't ever be chicken to try something logical just because a friend said it cannot be done - but has no good reason. Just always be mindful of safety procedures along the way.

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post #5 of 10 (permalink) Old 05-14-2014, 07:39 PM Thread Starter
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Hey, Otis, thanks.

The wooden patterns are made to create the profile in damp sand in the flask. The wood is removed and the molten steel is poured into the flask. It is the skill of making these patterns that is one of the things I am interested in: the subsequent cast must be accurate to an amazing degree, even before it is machined.

Your other comments are pure gold. I have not come across the silicon molds before, and will chase this up. Some of my reference books are for carbon fibre auto body parts, and musical instruments, and they don't mention silicon molds.

Thanks for your insights: very helpful with just a few words.
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post #6 of 10 (permalink) Old 05-15-2014, 03:47 AM
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Quote:
Originally Posted by OPG3 View Post
AJ, Wood isn't often used in Foundry Molds where molten metals are cast -
Well... Sort of.

Years ago, in High School Metal shop... we learned to do foundry works. We used wooden frames that looked like boxed sides, where we used two of them - filled them with sand, with an item between the two, to create two sides of a mold, with pour and vent holes in the top side.

So, yes, the wood was not the mold itself, but wood was used as the frames for the created molds. I remember I used to cast aluminum counterfeit "Hurst" shift knobs... because back then, I couldn't afford to buy those, but they were the thing to have...

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post #7 of 10 (permalink) Old 05-15-2014, 05:55 AM
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Quote:
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The wooden patterns are made to create the profile in damp sand in the flask. The wood is removed and the molten steel is poured into the flask. It is the skill of making these patterns that is one of the things I am interested in: the subsequent cast must be accurate to an amazing degree, even before it is machined.
Which is exactly why pattern making is a skilled trade.

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post #8 of 10 (permalink) Old 05-15-2014, 06:32 AM Thread Starter
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Yes, indeed: pattern making is a skilled trade. And I have to respect those skills to the point that I can do my projects with sufficient accuracy that the castings are serviceable.

And so I seek to learn (without putting skilled pattern makers at risk of being displaced, I assure you).

Anyway, I will have some fun, will probably make a success of the projects, even if my casts are not the neat and tidy products trades people would achieve, and will make plenty of mistakes.

Hence the "jack".

But please help, if you can. Thanks.
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post #9 of 10 (permalink) Old 05-15-2014, 07:41 AM
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AJ, you are very welcome! Mike is absolutely correct on the wooden mold part - what I should have said is "wood isn't a commonly-used product for moltens to be cast against". Sometimes molds are made to create other molds! Negatives form positives and at this point (or the reverse) material changes may take place - but certainly not always, because compensation must be allowed for things such as: expansion, contraction and/or adhesion! My products which are injection-molded HDPE are molded with a 3* mold draft, because another problem in molding some products is similar to adhesion - but is actually suction. Kinda like the taper of a flower pot - which is properly referred to as a "frustum of a cone", that slight (or more) taper makes all the difference when products are extracted from molds.

I used the term "frustum of a cone" for an important reason. Many people will laugh and say, "Who the heck needs to know that?" Among others with their same IQ, they may get a good laugh - but where the "rubber meets the road" is in trying to find information for calculations of volumes, weights and taper values. I'd love to see those same "geniuses" try to find "flower-pot-shaped thingy" in an engineering reference book.

Quote:
Your other comments are pure gold. I have not come across the silicon molds before, and will chase this up. Some of my reference books are for carbon fibre auto body parts, and musical instruments, and they don't mention silicon molds.
Also (and not to be picky), here's where SPELLING is critical! Silicon and silicone are two completely different things. That little "e" at the end makes all of the difference in the world. Here's a website that is very helpful on the subject: Rubber-Cal - A Comprehensive Source for Sheet Rubber, Rubber Mats, Rubber Flooring

Good luck!
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post #10 of 10 (permalink) Old 05-16-2014, 09:01 PM Thread Starter
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Thanks, Otis. Now I will be busy.

Cheers.
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