STL import on dome shape, totally wrong size

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WanaGo
Posts: 10
Joined: Wed Jan 09, 2013 4:14 am

STL import on dome shape, totally wrong size

Post by WanaGo » Thu May 22, 2014 9:28 pm

Hello,

I have a UP Plus, and design parts with Solidworks.
Never had any issues up until today, when I need to print a small dome part, 4mm diameter half circle with a slight extrusion of 0.8mm off the base of the circle.
Import it into UP Software, and the part comes out the size of the whole print bed, rather than the 4mm diameter as it should.

All other parts I have made are the correct size, just not this one.
I started from scratch and made another one, and the same result.
I cant figure out why it is coming out so large.

Using the latest UP Software.
See attachments

Please assist
Thanks
WanaGo
Attachments
64_Dome2.zip
STL File zipped
(145.48 KiB) Downloaded 333 times
Screen2.png
Screenshot from Solidworks showing its 4mm diameter
Screen2.png (139.58 KiB) Viewed 9738 times
Screen1.png
Screenshot from UP Software showing how large it is coming out
Screen1.png (112.99 KiB) Viewed 9738 times

WanaGo
Posts: 10
Joined: Wed Jan 09, 2013 4:14 am

Re: STL import on dome shape, totally wrong size

Post by WanaGo » Thu May 22, 2014 10:25 pm

Managed to scale it down with the UP Software, to get it the right size.
Saved the part as a UPP file.
duplicated the part, it came back as the original large size.
Opened the UPP file, it was the original large size.

Something odd going on here.

When I first reduced the size with the scale, I could copy it and make a few more copies, as I need to print 4 of these. That works.
But then after I saved, it no longer worked, it copied but each copy came out the original large (incorrect!) size.

Is this a bug?

caesar
Posts: 64
Joined: Sat Feb 22, 2014 1:32 am
Location: Romania

Re: STL import on dome shape, totally wrong size

Post by caesar » Thu May 22, 2014 11:51 pm

Make sure that you export the part with sizes in mm.
Your problem seems to arise from the fact that it was exported in inches instead of mm.

Anyway, find attached your file corrected to mm.
64_Dome2.zip
(41.94 KiB) Downloaded 348 times

WanaGo
Posts: 10
Joined: Wed Jan 09, 2013 4:14 am

Re: STL import on dome shape, totally wrong size

Post by WanaGo » Fri May 23, 2014 4:40 am

Hello

Part was designed in mm and exported in mm, this I am certain and just reconfirmed.
The part you attached reacted exactly the same way, it was huge in UP software.

Regards
WanaGo

doraemon
Posts: 94
Joined: Wed Sep 19, 2012 3:37 am

Re: STL import on dome shape, totally wrong size

Post by doraemon » Fri May 23, 2014 5:13 am

The UP software will try to autoscale really small parts up by 25.4 and really big parts down by 25.4.

WanaGo
Posts: 10
Joined: Wed Jan 09, 2013 4:14 am

Re: STL import on dome shape, totally wrong size

Post by WanaGo » Fri May 23, 2014 5:26 am

Gee thats a bit strange isnt it?

Whats the point in spending time to CAD design a part if UP Software mucks with the dimensions...

Seems very odd to me.

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: STL import on dome shape, totally wrong size

Post by roller » Mon May 26, 2014 11:34 am

It's intended as a safety net presuming that you didn't really want an item that small and the units are really inches rather than mm. Using the STL format for 3D printing is part of the blame for needing such a mechanism. So you scale your print by 0.03937 - I think the windows software has a preset for this "inch -> mm" or "25.4 -> mm" or something like that.

To explain why they would do this in the Up software is simple - the STL format deals with units poorly and these are often poorly recorded into the file by exporters. If you meant inches and the software is millimeters the print is impossibly small - often so small the user can see it sitting on the platform. This can cause all sorts of confusion. So when this is a risk of this happening (to small an object to see ) the software scales up by 24.4 presuming you will understand and correct it if you get something big when it's supposed to be small. It would be better understood if it's in the manual but I've never noticed a reference to it.

Neal
Posts: 32
Joined: Sat Oct 06, 2012 2:26 pm

Re: STL import on dome shape, totally wrong size

Post by Neal » Thu May 29, 2014 6:52 pm

I was looking at the release notes on some of the older versions of the UP software and I came across this note from release Version 1.16:

"1. Automatic Unit Conversion. The loaded models are automatically enlarged 25.4 times if the sum of XYZ size is less than 15."

At least now you have a way to check when this phenomena is going to occur.

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: STL import on dome shape, totally wrong size

Post by roller » Fri May 30, 2014 12:39 pm

I find it easier to work out ...if the model turns out to be massive... no calculation required and hit the to inches button.

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