Best Practices

[Cam's Bricks]

Hello,

I am working on a set of steam train driving wheels that I 3D print and I want to have LDraw parts to share. I know I can go the route of STL->Dat but the files are HUGE (10k+lines) and I would like to optimize a little better. 

So far my thought is to have a slice of the outer ring that is 1LDU thick but has the profile of the wheel then take and spin that 360 degrees. I can then create a center section of spokes and other features from there. The "problem" is that the largest size of steam driver I am looking to produce is 386 segments (123LDU diameter). Is that "too much" I see that there are other primitives that I can use to create some of the faces but I am worried that the resolution is not high enough for something so large. 

I have attached and example of this. 

I am really looking to make sure I am at least headed in the right direction and that I am not doing something needlessly over-complicated. 

I would think that the creation of a file would go something like this

• Create inner connection 
  
• Create rim(s) at sizes needed
  
• Create associated details
  
• Create the "final" wheel(s) which will have reference to the various pieces needed
  

Additionally, I have also developed a spreadsheet to calculate the ring positions and it would be easily adaptable to help fill out the circular primitives if that is helpful.

[Philippe Hurbain]

It's clear that you need (very) high resolution to 3-D print the wheel, and stl file is fine for that. But imho to make a LDraw part used for rendering and building instructions, 48-primives are really fine for a wheel that large.

[Gerald Lasser]

Hello,

While these details are necessary for 3D print, doing this way the file will end up much too details.

We usually use a circle of 48 divisions for this size.

So as an approximation with existing Primitives that would end up as:

0 BFC INVERTNEXT
1 14 0 0 0 45.75 0 0 0 14.8 0 0 0 45.75 48\4-4cylo.dat
1 14 0 0 0 2.54167 0 0 0 1 0 0 0 2.54167 48\4-4rin18.dat
1 14 0 0 0 48.29173 0 0 0 1 0 0 0 48.29173 48\4-4edge.dat
1 14 0 12.8 0 1.17785 0 0 0 -12.8 0 0 0 1.17785 48\4-4con41.dat
1 14 0 12.8 0 49.46958 0 0 0 1 0 0 0 49.46958 48\4-4edge.dat

1 14 0 15.5 0 8.24493 0 0 0 -2.7 0 0 0 8.24493 48\1-4con6.dat
1 14 0 15.5 0 8.24493 0 0 0 -2.7 0 0 0 -8.24493 48\1-4con6.dat
1 14 0 15.5 0 -8.24493 0 0 0 -2.7 0 0 0 8.24493 48\1-4con6.dat
1 14 0 15.5 0 -8.24493 0 0 0 -2.7 0 0 0 -8.24493 48\1-4con6.dat

1 14 0 15.5 0 57.71451 0 0 0 2.74 0 0 0 57.71451 48\4-4cylo.dat


Gerald

[Cam's Bricks]

Hello,

While these details are necessary for 3D print, doing this way the file will end up much too details.

We usually use a circle of 48 divisions for this size.

So as an approximation with existing Primitives that would end up as:

0 BFC INVERTNEXT
1 14 0 0 0 45.75 0 0 0 14.8 0 0 0 45.75 48\4-4cylo.dat
1 14 0 0 0 2.54167 0 0 0 1 0 0 0 2.54167 48\4-4rin18.dat
1 14 0 0 0 48.29173 0 0 0 1 0 0 0 48.29173 48\4-4edge.dat
1 14 0 12.8 0 1.17785 0 0 0 -12.8 0 0 0 1.17785 48\4-4con41.dat
1 14 0 12.8 0 49.46958 0 0 0 1 0 0 0 49.46958 48\4-4edge.dat

1 14 0 15.5 0 8.24493 0 0 0 -2.7 0 0 0 8.24493 48\1-4con6.dat
1 14 0 15.5 0 8.24493 0 0 0 -2.7 0 0 0 -8.24493 48\1-4con6.dat
1 14 0 15.5 0 -8.24493 0 0 0 -2.7 0 0 0 8.24493 48\1-4con6.dat
1 14 0 15.5 0 -8.24493 0 0 0 -2.7 0 0 0 -8.24493 48\1-4con6.dat

1 14 0 15.5 0 57.71451 0 0 0 2.74 0 0 0 57.71451 48\4-4cylo.dat


Gerald

Hey its a year later and I am finally getting back to this project. I'm slightly lost as to why n-fcon6 was used in the way it was. Is there some kind of calculation performed to show that I need to scale con6 by some amount to get the size I needed? 

Additionally if there is such a calculator or formula to determine what I need, then how do I used that to do the back of the wheel that is missing in the example you provided? 

Would I be better of creating 48 resolution primitives for my wheels and then just performing my original proposal?



As an aside to this, I am very interested in making some train track using a similar method where I can create the rail profiles needed and then calculate path points. When talking in circles that are in the 500mm radius range, is there a primitive set that is suggested or am I better off making segments that are 2LDU long and placing them all over?