Question about filament vs spool

[spyder007]

As I just started this, it occurs to me that some of the fields in the filament seem to be more "spool-specific." This runs into some very unique issues and I'm not sure how to get past it. I can see spool weight being a vendor property, and perhaps allow the filament to "override" the empty spool weight (maybe the vendor uses different spools for PLA vs ABS, etc). #307 is, I believe, a feature request for exactly that.

Likewise, perhaps weight can be set as a default on the filament, but, at the end of the day, every spool is a different weight. Issue #299 highlights this.

Would anyone be opposed to something like this:

1. Add Empty Spool Weight field to vendor (not required) and allow that value to "fall through" the filament to the spool. If you don't set an empty weight at the filament level, we will use the empty weight at the vendor level. This should solve Add vendor defaults, for example empty spool weight #307
2. Add Initial Weight field to the spool object. It will initially inherit from the Weight field of the Filament, but would be able to be changed, to support over-laden rolls. This fixes Unlock ability to create spool with "higher weight" than theoretically possible #299 and is also useful if you are transferring filament from bulk rolls.
3. Change the spool math as follows:
   Used Weight - If used weight is entered=
   1. remaining weight = initial weight - used weight
   2. measured weight = (initial weight - used weight) + empty spool weight
Remaining Weight - If remaining weight is entered
   1. used weight = initial weight - remaining weight
   2. measured weight = remaining weight + empty spool weight
Measured Weight - If measured weight is entered
   1. used weight = initial weight - (measured weight - empty spool weight)
   2. remaining weight = measured weight - empty spool weight

I also generally wonder if any of this belongs at the filament level, or if it should go straight to the spool level. Filament should just be properties of the filament, not properties of the spool. If the above was implemented, the next steps could be:

1. Remove Weight and Spool Weight from the filament
2. Add Empty Spool Weight to the spool itself as an editable field that defaults to the empty spool weight from the vendor. This would allow you to set spool weight based on the spool itself, not some value on the filament.

I realize that this means a little more data entry when entering a spool, particularly if your vendor uses a variety of spools. But it separates the filament properties from the spool properties and generally makes the math easier.

[BigTrikerTom]

That would be a good approach.