# Estimating Final Part Mass

I am looking for a way to estimate the final part mass from the volume of resin used. I have read that the density changes during the liquid to crosslinked transition.

The reason I am looking for this is to determine the part density of hollow prints.

Does anyone have experience with this?

This should help:

Alternatively you could weigh a completed print and use the Preform-estimated resin volume to get a ratio to use for future estimates. If you print direct-on-base that would exclude the volume consumed by supports.

If you’re really keen you could print in Open Mode or with an empty cartridge installed, and measure the volume change yourself (or use before/after tank weights to calculate it). A holder like this could help you drip off as much resin as possible before removing the print.

you mean the averaged part density including the empty hollow space?

Because the density of the resin as listed is the density of the part excluding hollow spaces.

If you want the density of the overall hollow part ( for example- to calculate buoyancy ) there are a couple of ways-
Preform will tell you the volume of resin- and you know the density of the resin… plug any holes to the hollow part and simply immerse in a graduated beaker full of water to determine total volume displacement-
And divide the weight by the volume.

While modeling, create a version that is solid before using an offset surface operation to make it hollow.
That will tell you total volume displacement- with Specific gravity set at one- that will be the weight of water displaced.
Then query the volume of the hollowed version of the part, and set the specific gravity to the density listed in the prior posts.
This will give the the weight of the printed part.
Again- divide the total weight of the print by the displacement as ml of water and that will give you total part density.