Left = Right - making parts symmetrical

[rudy d]

I love this hobby, really. I find a place to 'go' that takes my mind off of all the daily tribulations. I re-discovered it when my daughter wanted a snap together Mustang. We worked on it together and it rekindeled the enjoyment. Anyway, enough of the reminicing. The bane of all my attempts to fabricate parts/scratchbuild is, as the topic states, left the same as the right, know what I mean? HELP! I've got quite a few ideas, but the results are always unsatisfactory (to say the least) . I would appreciate any advise you could impart. Thanks for your time.

[silentsage418]

I think I know what you mean - how do you keep the parts perfectly symmetrical (left - right symmetry).

 

My son and I spent many years scratch-building RC aircraft. You have the same problem there - how do you keep the left and right sides of the fuselage symmetrical in cross section, or the wings symmetrical. In RC it's important, because asymmetrical aircraft don't fly straight.

 

The trick is to build the left and right sides at the same time, and on top of one another. For a fuselage former, you split the former down the vertical axis and stack the left and right sides on top of one another and cut them both at the same time.

 

Typically you make a sketch of one side of the fuselage former (the left or right side, doesn't matter). Then use rubber cement to glue it to a sheet of balsa. You then put a second sheet of balsa under the first. Usually I drill two holes through the stack of drawing/sheet of balsa/sheet of balsa. Two small flat head screws and nuts are used to keep the two sheet s aligned while you cut them with an exacto blade, or sand them. When you're done, you should have two perfectly symmetrical halves, then just glue them together. When I build wing ribs, I build the left and right ribs together as a stack.

 

The reason many scale aircraft drawings only show 1/2 of a cross section is because many builders work this way.

 

Another trick is to use calipers to make sure the left and right wing ribs are positioned exactly the same difference from the fuselage center line.

[rudy d]

Thank you Silentsage 418 for the tip. It's a great help for larger parts like control surfaces, wings , etc.. Many of my problems deal with smaller parts. For example (this is for you Krow113) rudder pedels, throttle quadrants, things of that nature. It's difficult to get the size correct. Do you guys 'eye ball' the sizes? Do you take measurements? How do you scale parts for 1/24, 1/32 etc. I know I went off on a tangent. From matching left to right, to getting the scale correct. Just bear with me guys. Like I said in the begining, I love this hobby and I want to get better. Thanks for all your help and your patience.

[LSP_Kevin]

On 11/8/2012 at 12:06 PM, rudy d said:

For example (this is for you Krow113) rudder pedels, throttle quadrants, things of that nature. It's difficult to get the size correct. Do you guys 'eye ball' the sizes? Do you take measurements? How do you scale parts for 1/24, 1/32 etc.

 

I struggle with this aspect of the scratch-building process too, and I too wish for a better or more reliable method. I've just finished scratch-building a new control column for my Spitfire build, and while I'm happy with the way it came out, I managed to make the spade grip overscale, which you can see in the photo below:

 

 

I mostly just eyeball things, which is obviously part of the problem, but I have no idea how to arrive at dimensions more precisely (leaving aside for the moment any question of my ability to actually produce something to a precise dimension!).

 

Kev

[Out2gtcha]

I faced this same thing on my current build for the Horner wing tips I had to scratch. I found the only way was to get two patterns for what I wanted (in this case brass), make those identical before gluing and shaping them, then just plain and simply, put them side by side and did the old "stare and compare"

 

 

 

 

Edited November 8, 2012 by Out2gtcha

[dodgem37]

'Many of my problems deal with smaller parts. For example (this is for you Krow113) rudder pedels, throttle quadrants, things of that nature. It's difficult to get the size correct. Do you guys 'eye ball' the sizes? Do you take measurements? How do you scale parts for 1/24, 1/32 etc.'

 

The most important thing to understand is this: The problem dictates its' own solution. And, it's all about relationships. How do the shapes relate to each other.

 

First, study the problem. What do you want to make? Then, How do I make it? Break the object down into its' simplest forms. Square, rectangle, circle. Everything is made from these three shapes. If it's too complicated to figure out how to do mentally, then draw it. Write notes.

 

You can take measurements from the kit parts to build finer renditions of that part.

 

If you don't have a part from which to work, then you'll need to work from reference drawings or photos. Within the drawings or photos will be imagery of parts surrounding the item with which you want to scratchbuild. These are your knowns. By looking at them, and visualizing the size of what you want to build to them, you know what you want to make must be 'this' big.

 

An example: Throttle quadrant: You want to remove the kit handle and shaft and make your own. Measure the part, then make the part, then remove the part from the quadrant. This way, if you mess up you will not have destroyed the kit part.

 

Otherwise, first you evaluate the size of the handle and shaft against a known. In this case the quadrant body. You compare the photo to the kit part and find additional knowns. Additional knowns are the details similar between the two, the kit part and the image. It/they may be a rivet location, a panel line location, a molded on detail.

 

Then you compare your stash of scratchbuilding supplies to the part and the reference until you find the right relationship. Is the handle .025 diameter rod? .030 rod? .035 rod? Or some wire diameter you have? Then you compare the length. 1mm? 1.5mm?

 

Sometimes you match right on, sometimes you don't. If you don't, you use a different diameter/length/thickness and make another until you are satisfied with the relationship between what you've done and the kit part, and the kit part with what you've done and the reference.

 

When making an entirely new part, you use a similar technique. Within the body of the image you use as a reference there will be knowns. You just have to find them. You find them by comparing the model to the photos. You measure the space in which you want to place the new part. This too becomes a known. Then you build the part to match the relationship between all of the knowns.

 

The more you do the better you become at 'eyeballing' material and size, because you've done that condition before. In many cases, the smaller the better. You just make the part as many times as necessary until you solve the problem.

 

Just my view of things.

Sincerely,

Mark

Edited November 8, 2012 by dodgem37