Fusion 360 Prints - Scale off?..

[WillBellJr]

Hi folks, trying to understand why a model I bring into S3D (STL file) is off in scale. I've searched and seen similar issues, but didn't notice any fixes / workarounds?


I'm making a replacement plate for my doorbell (moving over to a SkyBell HD) so I created an F360 model that matches the rectangular width / height of the 2-button doorbell along with groves underneath to allow wiring to snake to the new bell.

In particular, using a caliper, I measured the distance between the two screw holes - 3.96 inches apart.

The first time, the holes didn't line up but I had other things I needed to change - scratched my head, wondering why the holes didn't line up, but didn't ponder the issue much, thinking I measured wrong or sketched the hole centers wrong etc.

Second time around, I had the doorbell in my hand at my desk, measured, measured and sketched / extruded etc. Definitely correct.

Loaded STL into Simplify3D "Model is extremely small convert inches to MM" I accepted - printed this out - SAME issue??

First time, screw holes were short, this time, the length of the plate is slightly larger than designed - the bottom hole is long instead of short?

Feels to me like the inch to MM conversion is off, or some measurement bits are flapping in the wind (first short now long?)

Not sure if I had this problem w/3.x version, I'm using the new v4 now.


If I can't depend on the scaling between F360 and S3D I'm basically dead in the water - any suggestions are truly appreciated; I'd hate to waste another 2-hours printing and the associated plastic...

Thanks!


-Will

[rrdavis]

Try setting the unit system in Fusion360 to millimeters. That way you know what the values should be.

Then when you import it into S3D, it should already be in millimeters.

Also, you didn't mention this in your original post, but how far off was the actual printed part? It was supposed to be 3.96mm? What did it end up being?

[wirlybird]

I agree on the scaling. In Fusion you can model in inches then set it to mm and export. Ran into this the other day for a guy.
IF this isn't the case then you need to give more info.

[rojaljelly]

Hail to the imperial system....
There are sooo many countries still using this complicated system...

Conversion: 1 Inch = 25,4 mm

[WillBellJr]

Hi guys, thanks for your replies, after posting, I remembered I forgot to mention what printer I was using - I have a Monoprice Select Mini; love this little printer. I don't use it often but when I have odd jobs like this, it really comes in handy!

I guess I should print the 1x1x1 cube test to get a metric on how well dimensions are being matched, but for now I'm trying to get my doorbell finished...

I'll create a simpler model - just one or two millimeters tall with the hole spacing and try changing back to millimeters in Fusion before export to see if that helps.

Admittedly, I've always used millimeters in the past with my models, but this project I figured I'd use inches since I was using a tape measure, when measuring around the door and wall etc.


Thanks!

-Will

[WillBellJr]

Okay printed a test piece and then, the final - changing Fusion 360 to mm before export was definitely on point - thanks for the tip, Wirlybird!

Sorry to say this sounds like a bug or at least a rounding error or something - if Simplify3D is going to offer to convert from inches to mm, one would hope it gets the scaling correct?? Otherwise don't offer at all.

Out of all my prints, this was the first time I used inches in a design; I couldn't get my calipers to fit around all the weird shapes and tight spaces, so I pulled out the trusty tape measure and went with inches.

Glad to see F360 doesn't barf when switching between units - the more I use the program, the more I LOVE it - amazing program with great pricing for hobbyist!


Thanks folks for all your assistance!


-Will