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  #11  
Old 08-11-2017, 06:41 PM
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Originally Posted by cfuruti View Post
Well, had you printed on A2, that would be exactly 200% the width and height of A4, therefore you'd get 1:36. However, an A3 sheet, having exactly 2x the area of A4, has only square root of 2 (about 1.4142) of its width and height*. Therefore your model's final length and width will be approximately 141.42% greater, and the scale will be about 1:51, because 72 / 1.4142 ~= 50.91.

Regarding sturdiness, if the gramature is the same, the weight scales with area, therefore is 200% of A4 and your model will be 50% as sturdy because sheet strength is roughly proportional to thickness, which is the same.

*remember, width x height = area, therefore if area doubles, linear dimensions increase only by sqroot(2)
so in english - floppy models
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  #12  
Old 08-11-2017, 06:49 PM
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John Bowden John Bowden is offline
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you can always add more formers to stiffen up the inside.

The 1/72 A32X series I've done is pretty fickin strong. All I did was double the formers......basically one in front and one behind every joint..........

Now you may have to come up with something for the wings..........
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  #13  
Old 08-11-2017, 07:08 PM
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you can always add more formers to stiffen up the inside.

The 1/72 A32X series I've done is pretty fickin strong. All I did was double the formers......basically one in front and one behind every joint..........

Now you may have to come up with something for the wings..........
will give it a go.if it works its going to be a beast of a model
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Old 08-11-2017, 07:16 PM
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go to your local bar and ask for beer mats, the round ones might just be the right diameter for the fuselage
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Old 08-12-2017, 12:38 PM
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Quote:
Originally Posted by John Bowden View Post
you can always add more formers to stiffen up the inside.

The 1/72 A32X series I've done is pretty fickin strong. All I did was double the formers......basically one in front and one behind every joint..........

Now you may have to come up with something for the wings..........
If you're wanting to actually triple the formers/spars, the quickest way is to do a rough cut of the part, then glue the extra layers to the backside, allowing you to cut the part using the printed graphics on the top piece. Only need to cut one part this way. You will need to verify the knife is 90 deg for straight edges, unless you want the edge tapered.

I might have read your post wrong, thinking you are cutting three pieces out and then gluing them together.


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  #16  
Old 08-17-2017, 05:43 AM
amoscarmel amoscarmel is offline
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I print my models on A3 paper and so far they are never twice as big, maybe 175% over the A4 models. The tissue paper stuffing is a great idea but nevertheless you should be careful not to press the body to hard.
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  #17  
Old 08-17-2017, 07:04 AM
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Originally Posted by amoscarmel View Post
I print my models on A3 paper and so far they are never twice as big, maybe 175% over the A4 models. The tissue paper stuffing is a great idea but nevertheless you should be careful not to press the body to hard.
175% is unlikely. If margins are proportional, width and height should increase by 41.42%, to a 141.42% total*. In practice, the printer might have set the margins to be constant (e.g., 1.5cm instead of 7%) instead of proportional, changing the fraction slightly.
I'm not sure about stuffing the model. In order to be of any substantial benefit, a weak material like TP should be packed fairly densely; wouldn't it add more weight than strength? I suspect a few cardboard strips, strategically laminated during the build, on pieces already folded/curved, would give a better cost (=weight) / benefit (=sturdiness) ratio.

* A4 is about 210mm on the short edge, and 297 on the longer one; A3 is 297 on the shorter edge, which is thus 297/210 - 1 = 41.4% longer. This ratio applies to all linear measurements of the model.
BTW in a previous post I wrote "141.42% greater"; that's obviously imprecise: I meant the A3 model would be 141.42% as large as the A4 version, therefore 41.42% larger.
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  #18  
Old 08-17-2017, 10:03 AM
John Wagenseil John Wagenseil is offline
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I've stuffed Fiddler's Green models printed on regular paper with TP, it does a good job adding stiffness. I think Chip recommended this as a cure for floppy wings after they were glued up. He did not care for formers.
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  #19  
Old 08-17-2017, 10:59 AM
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Darwin Darwin is offline
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Quote:
Originally Posted by cfuruti View Post
Well, had you printed on A2, that would be exactly 200% the width and height of A4, therefore you'd get 1:36. However, an A3 sheet, having exactly 2x the area of A4, has only square root of 2 (about 1.4142) of its width and height*. Therefore your model's final length and width will be approximately 141.42% greater, and the scale will be about 1:51, because 72 / 1.4142 ~= 50.91.

*remember, width x height = area, therefore if area doubles, linear dimensions increase only by sqroot(2)
One caution regarding this approach to figuring the effects of enlarging....it works for European paper, but fails for American paper size. Tabloid paper (11 x 17) is twice the area of letter size, but the the dimensions of the edges if the paper do not change as the square root of the area change. The height of tabloid paper is 155% that of letter, and the width of tabloid is 129% that of letter.
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Old 08-17-2017, 01:15 PM
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As a complete eejit when it comes to arithmetic stuff, this is the most useful explanation I have ever read on how paper sizes compare to scales. Thanks, cfuruti. This made it all a lot clearer for me, too.
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Last edited by Paper Kosmonaut; 08-17-2017 at 01:16 PM. Reason: I used the wrong name in my message and I changed it.
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