GeeBee R2 Sportster (Huge Scale)

[Monkey]

This design and build is an experiment first and a model design/build second. i chose a very large scale because my fingers don't work as well as most people and I cannot handle the small parts well enough to accurately glue them.

Scaling up to 1:13 has presented me with some very unexpected challenges. I started with an old Modelik kit and tried to scale it up with my scanner. Though the model fit together well at 1:33 scale i have been told, the up-scaling intensified the flaws. Minor issues became major fit problems!

Also, I found that the parts were not strong enough when scaled up. The paper/cardstock buckled and deformed under its own weight in places, I like my models to be more sturdy. This led to some major experiments in laminating cardstock.

Due to a lack of funds I had only cardstock and Elmer's Glue All to build this model. I will not bore you with the details of my research, but I finally found a way to laminate cardstock with white glue that did not deform the material! You should be able to see the method in some of my pics. There is a trick to it that makes it all work. I will share this later in the thread.

The model itself was designed using AutoCad. I took the formers from the Modelik kit and redesigned the model around them. I found it was necessary to do this in order to accommodate my laminating process. I will show all this as I continue the build.

Meanwhile, here are some picks of the first two sections successfully assembled.

[Robotaleem]

Originally Posted by Monkey

This design and build is an experiment first and a model design/build second. i chose a very large scale because my fingers don't work as well as most people and I cannot handle the small parts well enough to accurately glue them.

Scaling up to 1:13 has presented me with some very unexpected challenges. I started with an old Modelik kit and tried to scale it up with my scanner. Though the model fit together well at 1:33 scale i have been told, the up-scaling intensified the flaws. Minor issues became major fit problems!

Also, I found that the parts were not strong enough when scaled up. The paper/cardstock buckled and deformed under its own weight in places, I like my models to be more sturdy. This led to some major experiments in laminating cardstock.

Due to a lack of funds I had only cardstock and Elmer's Glue All to build this model. I will not bore you with the details of my research, but I finally found a way to laminate cardstock with white glue that did not deform the material! You should be able to see the method in some of my pics. There is a trick to it that makes it all work. I will share this later in the thread.

The model itself was designed using AutoCad. I took the formers from the Modelik kit and redesigned the model around them. I found it was necessary to do this in order to accommodate my laminating process. I will show all this as I continue the build.

Meanwhile, here are some picks of the first two sections successfully assembled.

Could you attach .dwg files? This is fascinating. Great work!

[MichaelS]

Woo! Hoo! Let me get my popcorn. I will be in the front row for this build young fella

[C9B]

Looking forward to watching this come together and to reading about how it goes.
Jon

[Rata]

Way to go Monkey. Love these 'engines with wings'.

[Monkey]

Originally Posted by Robotaleem

Could you attach .dwg files? This is fascinating. Great work!

Well. . . Allow me to clarify something. I am using AutoCad LT for the design work. It has all the 2D functions of AutoCad but very limited 3D commands. The ones it has are very cumbersome to use. However, I was drafting when we still used boards with parallel bars and triangles to draw on velum. So, I still have to use some of my old tricks to get things done.

Since I am actually designing the skins in 2D the only thing that I have when I am done designing the part is the finished drawing. Instead of posting the .dwg or .dxf files which would be useless to most people unless they wanted to plot or print them out, I will post some screenshots of the process as I am doing it so you can get some idea of how to do things with precision without using 3D.

Once I figure out the exact placement of the formers in relation to each other, I employ a little trick we board drafters use to "unroll" cylindrical or conical objects that are constructed out of sheet metal or any other flat material; air conditioning ducting is a good example. This is shown in the attached pictures. Believe it or not, this gives me all the information I need to actually draw out the skin and it will be accurate to .0001 of an inch.

With this level of accuracy, I have to figure in the thickness of the cardstock (.00782") when matching the circumference around the former to the newly drawn skin piece.

[Robotaleem]

Originally Posted by Monkey

Well. . . Allow me to clarify something. I am using AutoCad LT for the design work. It has all the 2D functions of AutoCad but very limited 3D commands. The ones it has are very cumbersome to use. However, I was drafting when we still used boards with parallel bars and triangles to draw on velum. So, I still have to use some of my old tricks to get things done.

Since I am actually designing the skins in 2D the only thing that I have when I am done designing the part is the finished drawing. Instead of posting the .dwg or .dxf files which would be useless to most people unless they wanted to plot or print them out, I will post some screenshots of the process as I am doing it so you can get some idea of how to do things with precision without using 3D.

Once I figure out the exact placement of the formers in relation to each other, I employ a little trick we board drafters use to "unroll" cylindrical or conical objects that are constructed out of sheet metal or any other flat material; air conditioning ducting is a good example. This is shown in the attached pictures. Believe it or not, this gives me all the information I need to actually draw out the skin and it will be accurate to .0001 of an inch.

With this level of accuracy, I have to figure in the thickness of the cardstock (.00782") when matching the circumference around the former to the newly drawn skin piece.

Brilliant! I have been trying to use Inventor to use its 'convert to sheet metal' functionality, but boy, does that take a while. Could you share this trick?

[Monkey]

Originally Posted by Robotaleem

Brilliant! I have been trying to use Inventor to use its 'convert to sheet metal' functionality, but boy, does that take a while. Could you share this trick?

Honestly, what you are doing in inventor is probably way faster. My trick is really tedious, and it takes me forever to do, but back when I was board drafting, nothing was easy or fast! That's why CAD was such a godsend! It cut production time in half! I keep telling myself that it is super accurate and that is why I keep doing it. I wish I could afford AutoCad with Mechanical Desktop because it has an unroll function built in. All you have to do is click the command and tell it which object to unroll, and it does it all right there!

Basically, what I have to do is draw the front, back and side views of the new skin as if I was looking at in 3D wire frame. From there, I can take the measurements of the four sides of each wire frame trapezoid and draw it out. I do this with each one and then assemble them to make the unfolded skin. it usually takes me a couple of days of work to get this done and cleaned up.

[Robotaleem]

Originally Posted by Monkey

Honestly, what you are doing in inventor is probably way faster. My trick is really tedious, and it takes me forever to do, but back when I was board drafting, nothing was easy or fast! That's why CAD was such a godsend! It cut production time in half! I keep telling myself that it is super accurate and that is why I keep doing it. I wish I could afford AutoCad with Mechanical Desktop because it has an unroll function built in. All you have to do is click the command and tell it which object to unroll, and it does it all right there!

Basically, what I have to do is draw the front, back and side views of the new skin as if I was looking at in 3D wire frame. From there, I can take the measurements of the four sides of each wire frame trapezoid and draw it out. I do this with each one and then assemble them to make the unfolded skin. it usually takes me a couple of days of work to get this done and cleaned up.

Oh wow. That really is quite a bit of work. I'm currently in 10th grade, so I like have all the licensing information. DM me, I can get you a license for Inventor or AutoCAD. I'm going to try this trick when I get some time. It is fascinating.

[Monkey]

Originally Posted by Robotaleem

Oh wow. That really is quite a bit of work. I'm currently in 10th grade, so I like have all the licensing information. DM me, I can get you a license for Inventor or AutoCAD. I'm going to try this trick when I get some time. It is fascinating.

That's interesting that you are in the 10th grade. I have a daughter in the 9th grade.

i am using a licensed version of AutoCad LT, cost me about $1200! I would love to have Inventor, but right now i don't have much time to learn how to use it. Thanks anyway though.

I use my CAD program to do house plans and industrial/structural drawings for a local architect and he has me booked up solid for the next six months. I get to do my paper modeling at night after I meet my day's deadlines.

Now that I know that you are wanting to learn some drafting tricks from the "old school" I will be sure to throw some of those in while i attempt to build this model.