Simple 3D dimensions not printing as designed

Hello everyone! My first post and foray in 3D design.

I designed a simple headset spacer 15mm high about 34mm OD and 26mmID but when i printed it it was way bigger than the dimensions i drew. What did i do wrong?

Thanksin advance.


It seems like you made a different measurement than mm “cm maybe”
That or you enlarged it on your slicer.

You might be right however if cm vs mm then the final model to print would be 10x size, right?
I’ll wager a guess that the original model was dimensioned with a ‘diameter’ measurement when a ‘radius’ dimension was needed. Just a guess.

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I used prusa slicer and i don’t i changed anything. I just thought i changed a setting or so.

I will try again later. Thanks

Ooh wait a minute!!

Sure you did not made a circle and made the OD 34mm… Right?

Because that’s a radius…

This could be it…

This brought back some memories. Decades ago I made the radius vs diameter dimension mistake. I designed some headphones for Big Jim and the parts came out way too big. Luckily the parts were not production parts but rather engineering samples. Guess what, I never made that mistake again!!!

Big Jim


No, smaller. It scales the cm down mm. If I’m working in inches my part imports into slicer teeny tiny. You have to change the scale to mm.