How can I change the units of measure to nanometers?

monroe_weber_shirk

I can't find any options for editing the available units. I'd like to create drawings of clay particles and I'd like the measurements to be correct. 

MBartlett21

@monroe_weber_shirk
Onshape's modelling kernel, Parasolid, does not work very well with tiny measurements (I think its smallest available measurement is 0.001 mm or 1 um). This means that you will probably have to draw your model as a scaled version.

elif

Sorry to negate Neil, but Parasolid is in fact dimensionless. We currently take it so that 1 = 1 meter. nm as a unit is currently not supported as it falls into modeling tolerances. 
I know that we are internally tracking an improvement request that would allow modeling on a smaller scale. Please check in Improvement Requests and vote or create one to collect votes from the community.

monroe_weber_shirk

I tried entering 100 nm in the dimension of a nanoparticle and Onshape claims it is an invalid entry.

MBartlett21

@monroe_weber_shirk
Onshape's modelling kernel, Parasolid, does not work very well with tiny measurements (I think its smallest available measurement is 0.001 mm or 1 um). This means that you will probably have to draw your model as a scaled version.

monroe_weber_shirk

This does suggest that Parasolid does its modeling using quantities that have dimensions instead of using a dimensionless modeling framework. Dimensionless modeling would have made it possible for the same modeling Kernel to handle any dimension with the limitation that within any model the range of dimensions would be limited to some maximum factor. 

NeilCooke

Correct - Parasolid has an absolute measurement system - 1 micron to 1km

elif

Sorry to negate Neil, but Parasolid is in fact dimensionless. We currently take it so that 1 = 1 meter. nm as a unit is currently not supported as it falls into modeling tolerances. 
I know that we are internally tracking an improvement request that would allow modeling on a smaller scale. Please check in Improvement Requests and vote or create one to collect votes from the community.