An Easy Guide
Converting scales in 3D printing software is essential for accurately resizing models.
Every 3D printing “Slicing” software I’ve ever used has a really easy way to increase or decrease the size of your model based on the scale you want. You just need to know the percentage (%) amount to scale up or down by.
You can also use online tools like the Scale Calculator
- Find the Original and Target Scales:
Identify the original scale (e.g., OO scale at 1:76.2) and the target scale (e.g., HO scale at 1:87) - Calculate the “Scaling Factor”
Divide the original scale by the new scale:
{Scaling Factor} = {Original Scale} / {New Scale} - Let’s use the example of converting OO to HO
Original Scale (OO): 1:76.2
New Scale (HO): 1:87
Scaling Factor = {76.2} divided by {87} = 0.876
note that you only use the last digits, not the number 1 before the :If the scaling factor you end up with after your calculation is less than 1, you’re scaling down; if greater than 1, you’re scaling up.
- Convert the Scaling Factor to a percentage (%)
- Multiply the scaling factor by 100:
{Scaling Percentage} = {Scaling Factor} times 100 = 87.6%In the popular CURA software, you would use a scaling factor of 87.6% with “Uniform Scaling” enabled.
Uniform scaling means that all 3 dimensions of your model will be scaled correctly.
Common model scales:
- N (2mm – 1:152)
- N (standard – 1:148)
- HO (3.5mm – 1:87)
- OO (4mm – 1:76.2)
- O (USA – 1:48)
- O (UK – 7mm – 1:43.5)
Common conversion factors:
- OO -> N (1:152) 50.13%
- OO -> N (1:148) 51.49%
- OO -> HO (1:87) 87.59%
- OO -> O (1:48) 158.75%
- OO -> O (1:43.5) 175.17%
Happy 3D Printing !!!