# A model design overview

Discussion in 'Armory & Military' started by jimm.30300, Mar 28, 2012.

1. ### jimm.30300New Member

:car1:
My son asked me to make a pair ofdueling pistols for him and his friends to use as props and I've been readingsome of the posts about design questions so I thought I would start a threaddetailing the model from concept through final product I hope at least some ofyou will find this interesting. Comments and suggestions along the way would begreatly appreciated
2. ### jimm.30300New Member

I start by looking at real blackpowder pistols and deciding what elements I want to put in the model. Bing isyour best friend at this stage. The more photo reference you have the better.

It is also important to decide beforeyou begin how complicated you want the finished product to be. My son is at amedium building skill level so I will make the model complicated enough to befun to build but avoid complex curves and seams that are too difficult for him

I do my designing in auto cad butthese techniques work just as well with a T square and triangle which is all wehad when I first started back in the dino days before computers projectedgeometry hasn't changed since Pythagoras.

So to begin

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3. ### jimm.30300New Member

I started with the barrel and drewit as shown. I always draw the isometrics as I design the parts. I'll need themlater for the instructions and they help establish fit and scale.

One of the most important partsof a build is the tabbing. Nothing influences the ease of a build more than thesize and placement of the tabs. I try to never make a tab smaller than 3 to 4mm also I try toshape my tabs as you see below. For bent parts, there is a basic equation toremember (length of bend divided by #of tabs /2. With this your tabs willalways fit

Inthe case of the barrel this comes to length 62.83mm/30 which is the desirednumber of tabs so the tab base is 2.0943 divided by 2 to get 1.047 which is thepeek offset see picture.

Atthis point I transfer the parts I've made so far to my graphics program I useneo paint and adobe, but any graphics program will work. I arrange them in a part sheet and print whatis called a production white this is an unskinned line version of the modelused to test fit and scale before skinning the model which we will discusslater after I've made all the parts.

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4. ### ZathrosGuest

Very interesting, I'm watching!
5. ### jimm.30300New Member

Theproduction white of the barrel turned out perfect so I continue on to the nextpart.

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6. ### jimm.30300New Member

Thefirst piece of the stock was a challenge I thought it was fine but when Iprinted the production white I found that the tabs weren’t sufficient and it wasn'tstructurally sound it keeps trying to collapse then the real disaster thebarrel is to tight a fit and the top rips badly

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7. ### jimm.30300New Member

Solution1. Fix the tabs then 2. scale up the part by 1.025 ae 1/4mm larger all aroundmaking a better fit for the barrel then 3. I made two structural supports tobrace the parts then reprint and rebuild and bingo it fits.

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8. ### ZathrosGuest

Is that barrel made of rolled paper? Looks great. The Tab information is great!
9. ### jimm.30300New Member

SorryI’ve been gone so long. Health issues but I’m back and the build continues.
Thebarrel is hollow and consists of 4 parts the outer wall the inner wall and two end plates
10. ### jimm.30300New Member

Nextwe create the bevel on the front and back of the barrel the front bevel is madeby using two truncated cones of opposing angels and capping them with a ring. Itried using clipped cones for the back but they didn’t look rite on the modelso I decided to cut the stock and use a full cone.

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