Additional Options for Joint Production Cost Allocation
Currently the only way to evaluate the cost of joint production items is to already know what you're going to sell it for, as both costing methods require you pick a Price Tier in order to calculate its weight distribution. This seems unrealistic for items that are priced based entirely off of production cost. Some more realistic ways of costing many processes in manufacturing are the Quantitative Unit method or the Weighted Average method. They are described in some detail here:
For DEAR, you're already 80% of the way to a happy medium between both of these methods.
It would be really nice if you added a weighted average method to DEAR that allows you to select which processes to apply the weighted average to. That way, by selecting only certain processes to be part of the weighted average, you'd have effectively created the Quantitative Unit method as well.
I'd image it would work by replacing the Sales Value field in the Finished Output section of the Production BOM with a Weight field per output when the new method is selected. Then, each Resources, Component, or Input would have a check box next to it on whether to apply the weight or not. If the weight is not applied to a specific line item, then it's cost would be calculated based on Quantities Produced instead.
As an example, we have Production BoMs in which two products share 90% of their production process and only the last step is different between the two parts. They are always made in tandem, so it doesn't make sense to split the Production BoM at all.
The Production BOM produces 60 of Part A and 12 of Part B. We start with a base component of a metal rod 4.6 inches in length. It is then machined into 5 parts each about .6 inches in length and 1 part that is about 1.6 inches in length. the 5 .6 inch parts will be turned into part A and the 1.6 inch part will be turned into part B. All 6 intermediate parts undergo the next step together.
Up to this point, operation costs from resources should be split 5:1 between parts A and B since for each cycle, those are the ratios of parts produced.
The material costs should be allocated in a more detailed way, namely 3:1.6 (the ratio of material used for each part).
For the final step, the process is different for each part and is represented by a split path in the Production BOM. Each path should be costed to its appropriate part only.
At the end of the day, this math is very similar to the NRV method already implemented in DEAR, but it is costed entirely independent of sales value AND it allows more precise control of variables.
Currently, I work around the issue by manually doing the above costing calculation myself and then entering the result in as a price tier for each resulting product which I then choose as my NRV method Sales Value. It is a very tedious process where I'm doing what DEAR is supposed to do so DEAR can do what it's supposed to do.