Author Topic: Plan stretch (Read 3842 times)

Geoff Goodworth · « **on:** March 21, 2007, 04:40:07 AM »

I have received a copy of a plan that has a ruler along the bottom edge and it shows that the copy has grown 1.5%.

This might not seem much but on a 48" wing span it is almost 3/4"—0.72" t6 be precise.

I realise that in a game where we do our final sizing with sandpaper, it is probably not super critical in the total scheme of things but how do others deal with such issues?

Ralph Wenzel (d) · « **Reply #1 on:** March 21, 2007, 08:18:10 AM »

If you believe that the increased overall size may cause a problem, take the plan to FedEx-Kinko's and have them reduce the plans by 1.48% - - This will result in plans correct to about 4 significant digits. If you want to really fine-tune that road apple, the exact multiplier is .9852216748768472 - - ROFLMAO

Leester · « **Reply #2 on:** March 21, 2007, 09:45:05 AM »

I hope this is an apprropriate question for this thread. I have a set of plans on a 8.5 X 11 sheet of copy paper, by the scale on the plans the inboard wing is 27 3/4" can I just take this to Fed Ex Kinkos and have them make it full size ? or do I have to figure out the % of increase to have it done ?

rustler · « **Reply #3 on:** March 21, 2007, 06:34:34 PM »

A lot of copiers do distort an original plan, and frequently more in one direction than another. This leads to problems if you try to eliminate the distortion by taking a further copy adjusted to take account of this, if you get it right in one direction it's still wrong in the other. Sometimes (e.g. for plans associated with legal matters) it is essential to have exact copies. Over here in England one then has to ensure the copy service will do plans "True to scale".

Ralph Wenzel (d) · « **Reply #4 on:** March 21, 2007, 09:48:49 PM »

Quote from: Leester on March 21, 2007, 09:45:05 AM

I hope this is an apprropriate question for this thread. I have a set of plans on a 8.5 X 11 sheet of copy paper, by the scale on the plans the inboard wing is 27 3/4" can I just take this to Fed Ex Kinkos and have them make it full size ? or do I have to figure out the % of increase to have it done ?

It's a simple calculation. Just divide the wingspan desired by the wingspan on the 8½ x 11 page, and you have the correct ratio for enlargement. For example, if the Inboard wing shown has a span of 9", divide 27.75 by 9 and you get 3.08333. Therefore you would need a 304% enlargement to end up with the desired wingspan.

Marvin Denny · « **Reply #5 on:** March 22, 2007, 03:30:08 PM »

That "plan stretching" in one direction and not the other is quite common at Kinko's. I have run into it several times. When it occurs, it is always stretched in the direction that the plan and paper is pulled(rolled) through the machine but not in the cross direction. First time I noticed it, the stretch was 1 1/2 inches on a wing 54 inches long. And since the ribs were laid out with some of them lengthwise and others cross wise to the rolling direction, MANY did not fit.
I took the originals to a regular buleprint company (City Blue Print co) and told them my problem. They ran a single copy and it was off by about an inch. I showed that to them and in an instant, the operator went inside the machine and twirled a knob and Viola!! EXACT, in all directions. Internally, there are adjustments on most machines that can be made to correct those types of problems.

Bigiron

Ralph Wenzel (d) · « **Reply #6 on:** March 24, 2007, 04:09:58 AM »

BigIron's right, a Blueprint Service can do a better job, and often at a lower price, too!

phil c · « **Reply #7 on:** March 24, 2007, 08:06:09 AM »

Use the drawing like engineers use a construction blueprint. It's essentially a guide to build the thing. Especially building with any kind of a jig on a flat board, you put things in the proper place by measuring, not by lining them up with a drawing. Full size plans are a real anachronism in the modelling world for anything larger than a sport rubber free flight plane.

minnesotamodeler · « **Reply #8 on:** March 24, 2007, 08:13:45 AM »

Also a good idea to include, as mentioned, a "ruler"--6-inch segmented line, or some such--in both directions on the drawing, to use as a check for "stretch". Then, as also mentioned, the print machine can be adjusted to compensate.

But I also agree: Trust dimensions over drawings. If you're gonna trace patterns, check the dimensions first!

--Ray

Bill Little · « **Reply #9 on:** March 24, 2007, 08:42:05 AM »

Quote from: phil c on March 24, 2007, 08:06:09 AM

Use the drawing like engineers use a construction blueprint. It's essentially a guide to build the thing. Especially building with any kind of a jig on a flat board, you put things in the proper place by measuring, not by lining them up with a drawing. Full size plans are a real anachronism in the modelling world for anything larger than a sport rubber free flight plane.

HI Phil,

Thanks for helping my old demented brain here. I use "plans" just as you say, I measure everything out to build. I have very seldom ever built "over the plans".

Bill <><

Robert McHam · « **Reply #10 on:** March 24, 2007, 11:05:56 AM »

Leester, For plans like that and ones that I have (or others for me) that are digital files like .jpg, .gif, .tiff and even .pdf there is a wonderful program that will scale your plan to whatever size you want and allow you to accuratly print it out on your printer.

For instance if you have a plan from a magazine and you scan it into your computer and save it as an image file, you then open it with this program and lets say you know the stabilizer is 18 3/4' across. You clic on the scale and place a point on one side of the stab, then draw a line across to the other side of the stab. then in the box in the toolbar you assign that value as 18.75 and then clic print. The program will calculate and print onto however many sheets it will take and the result is that all values will be exactly to that scale.

This program is called Tile Print and is one of the best programs you can buy. Presently it is $15.95 USD. Link here:
http://www.blackflight.com/tileprint/

This is the most useful program I own besides Windows.

It was once free from the developer but as he improved it and updated it decided it was really worth something.
You can download the program and try it for free and if you like it just pay the fee and he will email you a key to unlock the program entirely.
All upgrades are free. There is a huge thread fore it. just google "tileprint".

Robert

Bill Little · « **Reply #11 on:** March 24, 2007, 11:31:44 AM »

Thanks for the info, Robert!
Bill <><

Robert McHam · « **Reply #12 on:** March 24, 2007, 01:09:14 PM »

Bill, You won't be dissapointed. The people who have this program love it.

Accuracy is the keyword for this proghram. You can take for instance a plan for a large stunt ship and scale it down to half A size.
Lets say the original wingspan was 45" and you want a ship where the wingspan is 32". Just put your reference line from one wingtip to the other and assign the value as 32.00 and tell it that these are inches and there you go!
You can use metric mesurements as well. Take your pick!

For everything this program will do it is worth far more than what it it sells for.
I printed a CD lable to store the file and code so that I would have a hard copy!

Robert

phil c · « **Reply #13 on:** March 26, 2007, 07:36:47 AM »

If we're getting into programs, Turbo CAD will print plans as strips, up to 44 in. long, using the standard Windows printer driver for a dot matrix printer. Or it will print the plan in 8x10 pieces on an inkjet, but I find the longer strip much easier to work with. Using the printer, if the lines are narrowed down to the narrowest pen, you can print pieces, like ribs, that are accurate to <.005 in. Works great for jigsawing parts out. You can get pieces as accurate as a laser cut part, without the waiting.

Dennis Vander Kuur · « **Reply #14 on:** April 03, 2007, 02:29:32 PM »

Phil,
What version of TurboCad do you have? I have TurboCad v.6. I'll have to check it out and see if it has this tile print feature. Thanks for the heads-up.
DennisV

Robert-Jan · « **Reply #15 on:** April 08, 2007, 12:41:53 PM »

EXCEL can also do the tile job.
Just load it as a picture.
You can scale it if you want.
Tiling is done automatic

Greetings Robert-Jan

Paul Smith · « **Reply #16 on:** April 09, 2007, 09:09:52 PM »

The habit of photocopiers enlarging copies goes back to the beginning of time. We had some of the first Xerox machines when we stepped up from Thermofax and Mimeograph. They enlarged the copies.

Setting the machines to 98% went without saying. Otherwise, later-generation copies "grew" the text right off the page.

Fortunately, with stunters a little extra wing area never hurts, and you can always blame the copier.

Geoff Goodworth · « **Reply #17 on:** April 10, 2007, 05:01:16 AM »

Thanks for the comments gents.

I spent over an hour with my printer today and they could not find a solution. I didn't spell out the problem in the initial post but a 24" wing panel became over 24 1/2". We tried reducing marginally; no success. We tried recalibrating the printer; no luck, we tried printing from a scanned tiff; same result as direct copying.

The result—my plans and the output are sitting in the shop waiting for the printer tech to visit

One of the real difficulties that has been touched on is airfoils and wing areas. In my case, did the designer really use 7 1/8" as his tip chord? He may have but my plan cannot confirm either way.

Thanks again, and I will report back when I have some news.

Cheers, Geoff

Paul Smith · « **Reply #18 on:** April 10, 2007, 08:22:37 AM »

No doubt, somebody upstream of you allowed a copy to grow without taking into account the usual 2% photocopy growth factor. Your efforts may have prevented further growth without fixing the previous error.

Geoff Goodworth · « **Reply #19 on:** April 13, 2007, 05:15:09 AM »

Hi guys

I heard back from my print shop. They had their machine technician look at the machine and they found both the scanner and the printer out of whack.

Both grew the plan a couple of percent such that even when we were copying a few percent under—say 97% or 98%, the prints were oversize.

The shop is all apologies but a critical issue is that the vast bulk of their work is fully dimensioned and does not rely on paper copies for templates.

The lesson—check the size before you print too many copies. I also found that the printer/plotter at the local shop allows you to reduce by fractions of a percent. Obviously, a moot point if the machine is out of adjustment.

Thanks for the input. Geoff

Air Ministry . · « **Reply #20 on:** April 22, 2007, 06:52:53 PM »

Have a drink of water.

Leave it in the sun !

as a draftsman, one comes to work in the morning,

and has to retension the Drawing, after lunch , at about 2 oclock all the tape pings of.,

as its shrunk again in the sun.

So some silly twit ivents plastic paper which is more thermally stable, and wears out pen nibs and has other foibles.

then someone invents air- conditioning 7 legioneers disease.

Its caused by Moisture temprature variations.

the plan bit.

Legioneers disease is like worn out automotive engines.Its caused by dirty filters.

You could put the Air co unit from the printers in your workshop, and the plan should be the right size.

Or visit differnt states with the plan, a steel ruler, and a calculator and log of expansion rates for steel rulers,

If you want to get it spot on .. . . .
Ananamus.

( Gees, it takes a bit to get you blokes to bite , doesnt it )

a bit of latteral thinking encourages alterative solutions ,

development of the concepts etc. . .