NOw, how much did the foam cost? How many hours and workers were on this
project. How much does it cost to operate the CNC machine for the
required time to do the cutting (include the operator). How much time was
spent getting the tool path, and having it verified? Add all this time and
multiply by at least $50 per hour. And, how many models can you make from
this 'tool'? Aluminum will make a lot of planes. The foam not nearly as
many. How many do you intend to sell?
.........bc ([EMAIL PROTECTED]
http://www.widomaker.com/~conk
Williamsburg, VA 23185
On Thu, 10 Jan 2002, Bill Johns wrote:
>
> >What I found out is that CNC molds are VERY expensive! One gentleman is
> >working on tooling a design and was quoted $4,000 per wing. Tome Copp of
> >f3x.com said he could probably get the job done for about $5,000. Several
> >others estimated prices in the $20,000 plus range!!
>
> What material were the folks suggesting using? Aluminum would of course be
> most expensive. This has me wondering about exactly what we mean when we
> say a "molded" plane. Are molded planes molded into a female mold with
> vacuum bagging techniques, or are layers of fiber and resin sandwiched
> between matching male and female molds and then squeezed at high pressure?
>
> We have a CNC machine in the college of engineering I work with. The
> students did the programming, got some high density urethane foam, stuff
> specifically made for making tooling for composites, designed and machined
> all the models for 9 foot wing span electric-powered flying wing. They
> sanded and smoothed out the molds and with standard vacuum bagging
> techniques were able to pop out planes without a problem. I don't recall
> it taking very long to actually cut the molds on the CNC machine. With a
> brittle material like that foam we were using, you can cut at very high
> tool feed speeds. For a 9 foot wingspan flying wing, I think total machine
> time was a couple of easy days. Hey, the Civil Eng. students were in a
> concrete canoe competition and they CNC machined a mold for a 16 foot canoe
> in not too long a time?
>
> I guess all you need is the bizillion dollar CNC machine, huh.
>
> We had a lot of problems getting balance just right and it never flew as
> intended in the competition is was designed for. It just sits now. All
> the involved students graduated. What to do with female molds for a 9 foot
> flying wing?
>
> >Anyway, at this point I am not feeling very inclined to jump right in! I am
> >actually pretty amazed that we have as many molded airplanes to choose from
> >as we do, considering how expensive it is for manufacturers to market a
> >product of this type.
>
> With all the talent in this list, I'm surprised that someone hasn't figured
> out how to make a CNC machine out of an old washing machine and a Radio
> Shack TRS-80. When using the urethane tooling foam you are cutting
> something about like stale bread. You do not need a cast iron frm to make
> the whole mass stable. It is not hard on tools. It took a bit to get it
> smooth and then sealed, but once the molds are made.....
>
> I'll try to get some pictures of the plane up on the student's club web
> site if anyone is interested.
>
> Cheers,
>
> Bill
>
> --
> It is useless to show the gold piece to a cat. Zen saying.
>
> Bill Johns
> Pullman, WA
>
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