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Old 30th November 2014, 05:49 AM   #11
edi
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Default Re: Going from AC3D to .stl

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Back to the original thread...

I know that number of cm per meter divided by number of cm per inch equals 39.37. (100 / 2.54 = 39.37). However, if ac3d units are in meters and Afinia printer units are also metric why should the use of any imperial units be required at all?
Maybe somehow the settings of your computer manage to interfere? I know they shouldn´t, but do you have imperial units set as a default somewhere in the system?

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Edi
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Old 30th November 2014, 09:05 AM   #12
bfeaver
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Default Re: Going from AC3D to .stl

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Maybe somehow the settings of your computer manage to interfere? I know they shouldn´t, but do you have imperial units set as a default somewhere in the system?

Best

Edi
Hi Edi,

I have used AC3D for 3D cockpit development in X-Plane for a number of years... always metric units. I've not run into any need for scaling up by 39.37.

I've found AC3D intuitive and easy to use. I recently used AC3D's Revolve function for 3D printing a 2 cm dia, 5 threads/cm nut and bolt.

Blue side up,
Bob
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Old 16th May 2018, 04:23 PM   #13
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Default Re: Going from AC3D to .stl

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Hi Edi,

I have used AC3D for 3D cockpit development in X-Plane for a number of years... always metric units. I've not run into any need for scaling up by 39.37.

I've found AC3D intuitive and easy to use. I recently used AC3D's Revolve function for 3D printing a 2 cm dia, 5 threads/cm nut and bolt.

Blue side up,
Bob
I know this is an older thread but I think I have it figured out. I've used AC3D myself for making planes for Flight Gear. Everything is modeled to the meter so if a plane is 10 meters long with an 8 meter wingspan and is 6 meters tall AC3D measurements would be 10 x 8 x 6 .

I made a model for something I wanted to 3D print as usual using meters and it came out way too small. The key I think is the scaling in AC3D acts like a percentage or it has to do with microns. Any how this does work. Take 39.37 and multiply by 100 to get 3937. Put 3937 in your scaling xyz hit scale and viola! Now when you export your model to .STL it should be the correct size.

It works! I have verified this by scaling up a model and uploading it to Sculpteo.

Last edited by jonbourg; 16th May 2018 at 04:40 PM.
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Old 16th May 2018, 05:37 PM   #14
bfeaver
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Default Re: Going from AC3D to .stl

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I know this is an older thread but I think I have it figured out. I've used AC3D myself for making planes for Flight Gear. Everything is modeled to the meter so if a plane is 10 meters long with an 8 meter wingspan and is 6 meters tall AC3D measurements would be 10 x 8 x 6 .

I made a model for something I wanted to 3D print as usual using meters and it came out way too small. The key I think is the scaling in AC3D acts like a percentage or it has to do with microns. Any how this does work. Take 39.37 and multiply by 100 to get 3937. Put 3937 in your scaling xyz hit scale and viola! Now when you export your model to .STL it should be the correct size.

It works! I have verified this by scaling up a model and uploading it to Sculpteo.
Hi Jonbourg,

Coincidence, I received a letter this very morning from a fellow who is using one of my AC3D exported .stl files for 3D printing 3 1/8" instrument bezels. He is saying that he needs to scale up by a factor of 1000. ?? (When using AC3D i convert all Imperial lengths to mm.)

Every thing I produce in AC3D and export as .stl needs to be scaled by a factor of 39.37 on my Afinia printer. (39.3701 is the number of inches in a meter)

So, it looks like there are differences in 3D printers and perhaps also differences in AC3D settings.

Recently I have been using SketchUp for my 3D Printing development work. SketchUp .stl's print correctly without scaling.

Blue side up,
Bob
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Old 16th May 2018, 06:45 PM   #15
jonbourg
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Default Re: Going from AC3D to .stl

Oh yeah there is definitely a difference depending on what scale you start off with. With aircraft meters is what is used for Flightgear. If you start off with mm than yup the factor will be different!
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Old 16th May 2018, 09:18 PM   #16
bfeaver
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Default Re: Going from AC3D to .stl

All aircraft components, cockpit objects, scenery objects in X-Plane are in meters. However, the instrument bezels etc in the photo are not used by X-Plane. These AC3D object are only designed for use by the 3D printer.

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Bob
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Old 17th May 2018, 12:42 AM   #17
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Default Re: Going from AC3D to .stl

Your right it depends on what measurement you want. I wanted to know this for myself so here it is.

AC3D Model Scaling for different measurements

Make a Rectangular box in size of 6 x 4 x 3
Lets call this inches to make it small for an object that will be printed on a 3D printer


Inches Meters Conversion Milimeters Conversion
x 6.0 0.152 152.4
Y 4.0 0.102 101.6
Z 3.0 0.076 76.2


From inches to mm change scale to 2540 and click on scale button AC3D Size Result 152.4 x 101.6 x 76.2

From mm to inches change scale to 3.937 and click on scale button AC3D Size Result 6 x 4 x 3

From inches to meters change scale to 2.54 and click on scale button AC3D Size Result 0.152 x 0.102 x 0.076

From meters to inches change scale to 3937 and click on scale button AC3D Size Result 6 x 4 x 3

From meters to mm change scale to 2540 and click scale button AC3D Size Result 152.4 x 101.6 x 76.2
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Old 17th May 2018, 08:51 AM   #18
bfeaver
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Default Re: Going from AC3D to .stl

Good analysis. Thanks.

I've been working with AC3D since about 2005. I hope you enjoy many years to come too.

Blue side up,
Bob
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