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  #11  
Old 05-03-2012, 06:51 AM
Neptune Neptune is offline
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Creating formers, or a Little geometry for breakfast?

OK, here's a quick study on circles, diameter, radius, centerline, equilateral triangles and pythagorean's theorem..... Annnnnnnnndddd an actual application. You could say that this is applied engineering and mathematics and theory all rolled up into one little example. Please make sure to send copies of this post to the clown posse'... Thanks.

I said I didn't want to get into the whole pictues with circles and arrows on the back of each one, but here I am. (See Alice's Resturaunt for reference).

OK, we need to make formers, bulkheads whatever... I showed earlier and easy way, now comes a little more complicated way. First off, in an earlier photo I showed the cutout from what I had traced and on it was "1&1/8th."
This was the measurement of the OD, or outside diameter, (from the centerpoint, also known as the radius,) after having been trimmed slightly. To make a more accurate circle for plotting out that former, I set the compass at that measurement and created a circle with a total diameter of 2&1/4"

At the point we could have left it there, but I thought I would do a demonstration on how to find the centerline of a given circle and how to plot that out.

I used an old machinists trick on how to find a preliminary OD using a scale, in this demo though I used a steel drafting ruler.

You place one end of the steel rule right up to the very edge of one part of the circumference, then swing it back and forth in an arc, to come close to the OD. If you try this, you'll see that the line around the circumference of the diameter will change position with relation to the rule. This gives you an approximation of the longest extent of that line.

Look up these terms online.....

1) Extent.

2) Equilateral Triangle.

3) Phasor.

4) Circumference.

5) Arc, Arc Tangent... and so on.

6) Approximation.

7) Centerline.

After you have found your longest extent, place dots on each side. Use these dots to position your compass and swing the compass in more arcs as shown in the photos, until you come up with two centerlines that look like a reticle.

If you draw lines from one point to another and they do not perfectly match the length of the radius, try again. Each one of those regions inside the circle should come out perfectly even and create an equilatral triangle.

Any questions?
Attached Thumbnails
Tin Toy Rocket Toy Build and Directions-tin-toy-actual-31.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-32.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-33.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-34.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-35.jpg  

Tin Toy Rocket Toy Build and Directions-tin-toy-actual-36.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-37.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-38.jpg  
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  #12  
Old 05-03-2012, 07:24 AM
blaar blaar is offline
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Going back to my technical drawing years back in my school days, oh I would say the early 90's....okay........93.............

The method used below is really easy to find the center of the circle.

Finding the center of a circle or arc with compass and straightedge or ruler - Math Open Reference
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  #13  
Old 05-03-2012, 07:56 AM
Neptune Neptune is offline
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Quote:
Originally Posted by blaar View Post
Going back to my technical drawing years back in my school days, oh I would say the early 90's....okay........93.............

The method used below is really easy to find the center of the circle.

Finding the center of a circle or arc with compass and straightedge or ruler - Math Open Reference
Thanks for that, I guess it's like anything else, you go with what you know and there's more than one way to skin a starship, or.... whatever. LOL!
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  #14  
Old 05-03-2012, 08:05 AM
Neptune Neptune is offline
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Below you can see that I started creating glue tabs from a strip of cardstock to bind all of the separate sections together, with a bit of space left on either side. This is to make room for the formers to connect the separate sections. The reason for doing all of this extra work is that I have to engineer (on the fly) these frames with an opening in the center and to add strength for a launch tube. I'm not just building a model and making directions, I'm going to fly the B.... er... baby. You can also see where I'm making formers and strengtheners for the fins, again, on the fly. I will incoporate these into the pdf of the instructions.
Attached Thumbnails
Tin Toy Rocket Toy Build and Directions-tin-toy-actual-39.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-40.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-41.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-42.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-43.jpg  

Tin Toy Rocket Toy Build and Directions-tin-toy-actual-44.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-45.jpg  
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  #15  
Old 05-03-2012, 08:35 AM
spaceagent-9 spaceagent-9 is offline
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i still think its completely awsome!
and this is just the beggining of retro and replacement models!
i think that paper modelling has reached a whole new level , and the modellers as well!
i wonder if 3-d printers could make a vaccuform like sheet, with all those details you did with the pen, slightly raised with rivets and indentated portholes and such, paper thin?
in color now too.
makes ya think.
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  #16  
Old 05-03-2012, 09:57 AM
Neptune Neptune is offline
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Originally Posted by spaceagent-9 View Post
i still think its completely awsome!
and this is just the beggining of retro and replacement models!
i think that paper modelling has reached a whole new level , and the modellers as well!
i wonder if 3-d printers could make a vaccuform like sheet, with all those details you did with the pen, slightly raised with rivets and indentated portholes and such, paper thin?
in color now too.
makes ya think.
I'm sure they could, but I do know one thing for a fact. I know that I can do it by hand and no lathes will be harmed in the process. LOL!
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  #17  
Old 05-09-2012, 06:44 AM
Neptune Neptune is offline
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Weell.... I ordered a new rocket and a handbook to get ready to launch this. I can't really finish it until I get the measurements for the launch tube, so it's just been kind of laying around while I wait, so I thought I would stack all of the parts and do a check and it looks to me that once I get everything together, it's going to look pretty good. I really like the print job, but naturally, I want to make it better.....

Amazon.com: Estes 1261 Baby Bertha Flying Model Rocket Kit: Toys & Games

Amazon.com: Handbook of Model Rocketry, 7th Edition (NAR Official Handbook) (9780471472421): G. Harry Stine, Bill Stine: Books
Attached Thumbnails
Tin Toy Rocket Toy Build and Directions-tin-toy-actual-46.jpg   Tin Toy Rocket Toy Build and Directions-tin-toy-actual-47.jpg  
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  #18  
Old 05-09-2012, 06:55 AM
jleslie48 jleslie48 is offline
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Quote:
Originally Posted by Neptune View Post
Weell.... I ordered a new rocket and a handbook to get ready to launch this. I can't really finish it until I get the measurements for the launch tube, so it's just been kind of laying around while I wait, so I thought I would stack all of the parts and do a check and it looks to me that once I get everything together, it's going to look pretty good. I really like the print job, but naturally, I want to make it better.....

Amazon.com: Estes 1261 Baby Bertha Flying Model Rocket Kit: Toys & Games

Amazon.com: Handbook of Model Rocketry, 7th Edition (NAR Official Handbook) (9780471472421): G. Harry Stine, Bill Stine: Books

from:

http://en.wikipedia.org/wiki/Model_rocket

Rocket motors:

13mm A10-0T,
18mm C6-7,
24mm D12-5,
24mm E9-4,
29mm G40-10.


You really don't have to worry about this too much Joe. Make them slightly larger and instruct the user to shim the motor with masking tape.

I take a used motor, cut it down to around 3/8" tall, hollow it out (take out the hard cement stuff) and glue it inside the launch tube as the part that the rocket engine pushes against. BC I removed the cement stuff, the ejection charge passes right through this block.

actually I just use the actual motors and roll my launch tubes around them to make the tubes...

path of least resistance.
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  #19  
Old 05-09-2012, 07:46 AM
Neptune Neptune is offline
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Quote:
Originally Posted by jleslie48 View Post
from:

Model rocket - Wikipedia, the free encyclopedia

Rocket motors:

13mm A10-0T,
18mm C6-7,
24mm D12-5,
24mm E9-4,
29mm G40-10.


You really don't have to worry about this too much Joe. Make them slightly larger and instruct the user to shim the motor with masking tape.

I take a used motor, cut it down to around 3/8" tall, hollow it out (take out the hard cement stuff) and glue it inside the launch tube as the part that the rocket engine pushes against. BC I removed the cement stuff, the ejection charge passes right through this block.

actually I just use the actual motors and roll my launch tubes around them to make the tubes...

path of least resistance.
Thanks for all of the info, but I do not have any engines yet. I haven't launched a rocket since I launched the TOS Enterprise Estes Rocket back in.... 75-76, so it's been awhile.
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  #20  
Old 05-09-2012, 08:20 AM
jleslie48 jleslie48 is offline
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just use a 1" diameter dowel as a guide, and roll the tube. - JL
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