Dimensions

When uploading stl files, my model dimensions are different to shapeways. In blender my radius is 5cm and when I upload my files in mm then my model is way too small. .. And when I upload it in meters then my model is about four times the size it should be. Can someone help me get the dimensions right. I don't want to arbitrarily size my models.

Can you share the file? If it's private you can email it to me and I'll take a look. Sounds like your work space units and export units aren't aligned, but I don't know how to fix that in blender.

Thank you. I will do in the morning.
Also, perhaps do you know whether shapeways has an FDA approved plastic for 3d printing. .?

If its in blender, try to set metrics to none if you haven't already.

http://www.katsbits.com/tutorials/blender/metric-imperial-un its.php

No, Shapeways does not have FDA approved plastic. The only material they have that is applicable for contact with food is their ceramic material. But I never saw anything that stated it was FDA approved though.

One thing you might try regarding the size issue is to get a piece of free software called Netfabb Basic. I'm pretty sure the default settings are millimeters being that the software is German, if not go to the settings menu and set it as mm. Then, load your file and go to the part menu and select scale. This brings up the scaling dialog, which is very good for scaling as well as finding out exactly what your main software is exporting. Whatever you scale and export with this software is rock solid for doing any kind of real life 3D printing operations. You can trust what this software tells you. It also shows you information about your file in the lower right hand corner immediately after loading the file.

When I run into your situation, and I do on rare occasions, I go straight to this software to see what the heck is going on with the file.

Thanks for that.. i have tried creating a simple cube 2cm by 2cm by 2 cm. Whether I select none or select metric in blender, shapeways seems to disregard the measurements and assign it to inches, even though i select upload in mm.

I work in Blender, but I always send my file through NetFabb first before uploading to Shapeways. It's a good way to fix any problems, and when the dimensions are correct in NetFabb, they are always recognized correctly by the Shapeways uploader.

thank you. I will upload via nettfab in the future. regards M

I opened the files you sent me, and your scale appears to be off by 100x. The cube that you made 2cm comes up as .2mm. So if you uploaded it as meters it should be the size you intend.

Your uploads may be switching to inches when you upload as mm because they are uploaded smaller than is possible to print. The software assumes that you uploaded in the wrong units and is incorrectly assuming inches.

With Blender you don't need NetFabb for scaling.

If you have set up the units (Metric or Imperial) in Blender, and you export with .x3d, the units will be respected by SW: in fact you will not have the option of specifying upload units at all. If you do not have the units set up in Blender, 1 Blender Unit (B.U.) is treated as 1 meter for .x3d

If you export as .stl, then whether or not you have units set up does not matter: stl files do not carry unit information. The BU values will be taken and then modified by the scale you choose on upload to SW (mm, inches, meters). If you have set up the units in Blender to be Meters, a 2cm cube will have sides length 0.02 BU - so if you choose Meters as the upload you will be correct (as Michael has said, although I'm not sure abou the maths), whereas if you choose mm, or inches you will be way off.

It is also worth noting that if you upload a file with a size that SW considers unfeasibly large or small, it will try to use the other scales, in order. I.e. if your model seems too small and it was uploaded as mm, SW will try to apply inches and then meters until it gets a valid size. If this occurs you will see a message somewhere in the poorly designed and over-cluttered Edit Model screens. See below:

This is really helpful. Thank you. I will export as 3ds in future.