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Old Dec 10, 2005, 12:11 PM
Martin X. Moleski, SJ
Martin X. Moleski, SJ
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Re: Acetone used to transfer photocopy parts to balsa

On Sat, 10 Dec 2005 16:02:05 +1100, "The Raven" <swilson150@yahoo.com.au> wrote
in <439a614f$0$20235$afc38c87@news.optusnet.com.au> :

>> Some copiers used to routinely shrink the copy 1% or 2%
>> in one direction.


>A valid point but given you're rarely dealing with A3 sizes or larger
>(metric paper here folks, not that US weird stuff) you won't get much
>inaccuracy.


I became aware of the problem when I was trying to tape
four or five pages together to make a pattern for an
Ultra Sport 40 fuselage (if I remember correctly).

The deviation was enough to be visible to my eye and
led me to find out about the auto-reduction on our
copier. It didn't make any difference to the construction
of the fuselage. I think I used a yardstick to
straighten out the lines and--of course!--sanded and
sanded and sanded until the fuselage looked OK.
It's still flying--after I broke the wing that went with
it, I sold it and a TT .46 to a friend who had a good
wing and no fuse.

>Another point to consider is how accurate such a transfer
>process will be on the balsa, will the transfer be 100% and how accurate are
>our cutting skills.


Yes. I'm sure I can't cut and sand to 99% accuracy. )

>I used to work in the printing industry so I could also suggest to measure
>the paper before and after copying. While this is unlikely to yield any
>measurable difference large printed sheets can stretch by up to 5mm. So, for
>the big plan boys consider how accurate your plan really is.........


If I've got the terms in the right order, what we need is a certain
amount of precision so that parts that are supposed to fit
together do fit together, while accuracy doesn't matter so
much (except in scale judging).

Marty