Cost Determination, Section 5.3.4.4

[Madison]

Originally Posted by KenWittlief

Richard - your SLA example is excellent. But I think you have reached the wrong conclusion.

Go back and read the rules I quoted from FIRST. You only have to account for the amount of material you actually use, whether it comes in 1Qt cans, 55 gallon drums, or 20,000 gallon tanker railroad cars.

That's not how the rule reads at all, Ken.

Originally Posted by The Rule

• The cost of items purchased in bulk or large quantities may be prorated on the basis of the smallest commonly available unit that satisfies the need for the item.

If the smallest commonly available unit of resin that is available for the SLA machine is, as Richard says, 10kg and $2500, then the team must account for that whole cost on their BOM regardless of how much of that 10kg they use.

However, if a team buys an 8' long piece of aluminum tube and uses only 3', they can account for the price of a 3' piece instead as aluminum tube is commonly available at shorter lengths.

Our team has an SLA machine on its way to the lab we borrow, so now I'm curious what sort it is and what material it uses to see if it'll be at all helpful to us.

[Andy Baker]

Originally Posted by Richard

I've been reading this part of the rules carefully for several years now. It does not say that you only have to account for the amount of material you actually use. It says that you have to account for the cost of the smallest commonly available unit that satisfies the need for the item. In the example above, the smallest commonly available unit is a 1' x 1' sheet, so the team must include the cost of that sheet, not just the 10" x 10" they actually used.

In the case of SI40 resin, the smallest commonly available unit is 10kg. When a smaller unit (e.g., one liter for $250) is commonly available, I'll gladly fire up the Viper to make parts for 931.

Another option for this example, Richard...

If a company who sells the service of making rapid prototypes can give you a quote for making 1 piece for under $400, and that is the commercially-accepted price, then a team could make a custom part on one of these machines.

For instance, I made our first plastic Omniwheel for AndyMark on a dimensions 3D printer that used ABS plastic as the material. The company who made this part for me charged me $250 for each side of the omni wheel. This cost covered their material usage, labor, and overhead costs. Anyone off the street could take a similar design, of similar size and get approximately the same price. As long as it's done during the build season, this would be legal, in my interpretation to the rules stated above.

Andy B.

[Richard Wallace]

Originally Posted by Andy Baker

Another option for this example, Richard...

If a company who sells the service of making rapid prototypes can give you a quote for making 1 piece for under $400, and that is the commercially-accepted price, then a team could make a custom part on one of these machines.

For instance, I made our first plastic Omniwheel for AndyMark on a dimensions 3D printer that used ABS plastic as the material. The company who made this part for me charged me $250 for each side of the omni wheel. This cost covered their material usage, labor, and overhead costs. Anyone off the street could take a similar design, of similar size and get approximately the same price. As long as it's done during the build season, this would be legal, in my interpretation to the rules stated above.

Thanks, Andy. For the record, Emerson does account for actual material and labor used when we make SLA parts, so the costs can be allocated to the appropriate project. Others had suggested that 931 could use those calculated costs, maybe adding a profit margin, to account for SLA items on its robot BOM. I rejected that because Emerson is not a vendor of SLA parts as defined in the FRC rules.

I should start looking for a free-lance SLA operator that can fabricate with the same resin that Emerson uses, and is willing to quote parts.

[KenWittlief]

Originally Posted by The Rule
• The cost of items purchased in bulk or large quantities may be prorated on the basis of the smallest commonly available unit that satisfies the need for the item.

Prorated on the basis.... it does not say the smallest unit cost is the cost

this is a very common issue with electronic parts. you can get the gyro sensors that many teams use from places like Digikey.

If you buy one they are $50. If you buy 10 they are $45 each. If you buy a thousand they are $20 each.

The rules are saying you cannot take adavantage 1 thousand quantity pricing and only charge $20 to your BOM, you have to use the lower quantity pricing if you only use one.

But its still pro-rated by the amount (number) you actually use. If they only come in a box of ten for $450, and you only use one, then you only used $45 worth the parts on your robot.

[Cory]

Originally Posted by KenWittlief

Prorated on the basis.... it does not say the smallest unit cost is the cost

this is a very common issue with electronic parts. you can get the gyro sensors that many teams use from places like Digikey.

If you buy one they are $50. If you buy 10 they are $45 each. If you buy a thousand they are $20 each.

But its still pro-rated by the amount (number) you actually use. If they only come in a box of ten for $450, and you only use one, then you only used $45 worth the parts on your robot.

I don't see how you think this is correct. If the only way you can get them is to buy a box of 10 (ie: they don't sell them individually, then you have to account for the entire box of 10, even if you only use one.

This example is very clear:
Example: A team purchases a 4' x 4' sheet of aluminum, but only uses a piece 10” x 10” on their robot. The team identifies a source that sells aluminum sheet in 1’ x1’ pieces. The team may cost their part on the basis of a 1’ x 1’ piece, even though they cut the piece from a larger bulk purchase. They do not have to account for the entire 4’ x 4’ bulk purchase item.

I don't see any room for interpretation. If he uses one teaspon of his 10 kg drum, it doesn't matter. He can only get them in 10 kg drums, and therefore must account for an entire 1 kg drum.

Originally Posted by KenWittlief

The rules are saying you cannot take adavantage 1 thousand quantity pricing and only charge $20 to your BOM, you have to use the lower quantity pricing if you only use one.

That's not what it's saying at all. If it was, it would say so. It's saying that if I go out and buy a 4'x8' sheet of polycarbonate, and cut one part out of it that's 1'x1' and then use the rest for non FIRST stuff, as long as you can find someone who sells 1'x1' sheets of polycarb, you can put that as your cost, so that you do not end up "paying" for material you don't use.

[KenWittlief]

Originally Posted by Cory

I don't see how you think this is correct. ...I don't see any room for interpretation. ....

I disagree completely. The rules add the words "prorated" and "on the basis".

If I have to buy a box of ten gyros, and I only use 1, I can sell the other 9 on ebay to get the money back, or I can sell them to other teams, or I can use them for spares, or I can use them next year.

The BOM represents the cost of building one robot, the one that is on the field. If I have to keep buying off the shelf parts to replace after every match, that cost is not accumulated into the BOM.

If wire only comes in 100 foot spools, and I use 1 foot of wire, then I dont have 100 feet of wire on my robot - why would have to account as if I did?

Prorated means the cost of the whole sheet times the percent used.

On the basis - means based on the price of the smaller sheet, not on the largest sheet you can find.

look at it this way: If gyros only come in boxes of ten, and I buy ten, but use one, but I have to put the cost of ten on my BOM, then why not use ten gyros on my robot?

accounting that way makes no sense from an engineering perspective - the value (cost) of having ten gyros on my robot is clearly ten times the value (and cost) of only having one. The fact that Digikey decides to sell them on cut tape with ten per order, or 100 per reel, has nothing to do with the functionality or value of that part, except for establishing the price per part.

[Cory]

Originally Posted by KenWittlief

If wire only comes in 100 foot spools, and I use 1 foot of wire, then I dont have 100 feet of wire on my robot - why would have to account as if I did?

Prorated means the cost of the whole sheet times the percent used.

Ken, the example FIRST gives exactly addresses this situation.

Example: A team purchases a 4' x 4' sheet of aluminum, but only uses a piece 10” x 10” on their robot. The team identifies a source that sells aluminum sheet in 1’ x1’ pieces. The team may cost their part on the basis of a 1’ x 1’ piece, even though they cut the piece from a larger bulk purchase. They do not have to account for the entire 4’ x 4’ bulk purchase item.

I really do not see where we're losing each other. It clearly says that you must use the smallest whole unit you can find. If a 100' spool is the smallest unit you can find, it doesn't matter if you use 99' or 1'. You still account for it like you used 100.

[KenWittlief]

Originally Posted by Cory

I really do not see where we're losing each other. It clearly says that you must use the smallest whole unit you can find.

well, no. The word 'whole' is not in the rule. The words 'prorated' and 'basis' are.

I guess its time for some CD searching to clear this up.

[Richard Wallace]

Originally Posted by KenWittlief

... accounting that way makes no sense from an engineering perspective - the value (cost) of having ten gyros on my robot is clearly ten times the value (and cost) of only having one. The fact that Digikey decides to sell them on cut tape with ten per order, or 100 per reel, has nothing to do with the functionality or value of that part, except for establishing the price per part.

I think the intent of the FRC cost accounting rules is to capture the cost of building one robot. That cost includes the cost of buying needed components at minimum order quantities.

If my boss tells me to build a motor tester, and that tester requires three inches of 3/4" diameter shaft stock, then I might have to buy a foot of shaft stock in order to get what I need. Will I then tell the boss I bought three inches so he can reimburse me for that, while I pay for the whole foot? No, I won't. The cost of completing the assignment included buying the minimum quantity of that material.

[sanddrag]

The way I see it is that most teams' cost accounting sheets are so poorly done that all this argument isn't even relevant. We need teams to actually do their accounting before we ask them to do it perfectly.

[KenWittlief]

Originally Posted by Richard

I think the intent of the FRC cost accounting rules is to capture the cost of building one robot. That cost includes the cost of buying needed components at minimum order quantities.
....

I agree. And I think FIRST inlcluded the prorating accounting method so that students would be able to use things like Gleasons Gear cutting machines, and your SLA machine, without having to add the cost for a 30 foot long, 12" diameter steel rod, when they cut off 1/2" length to make a 12" gear,

or to put the cost of 10,000 gallons of SLA GobblydeeGoop on their BOM, when they only used 4 ounces for one part.

Remember, FIRST wants us to show students all this neat technology. Why would they cripple us with a non-prorated rule for materials usage.

Prorated means only listing the actual amount used, not the size of the drum it comes in.

[Madison]

Originally Posted by KenWittlief

Prorated means only listing the actual amount used, not the size of the drum it comes in.

Prorated means accounting for the smallest quantity of a material available for sale that is larger than what you used on your robot.

[Alan Anderson]

Originally Posted by KenWittlief

Prorated means only listing the actual amount used, not the size of the drum it comes in.

That's obviously what you want it to mean. But reading the actual rule for what it says makes the indended meaning clear.

The cost of items purchased in bulk or large quantities may be prorated on the basis of the smallest commonly available unit that satisfies the need for the item.

Note that it doesn't say "on the basis of the quantity used".

You can list the amount used based on the cost of smallest amount commercially available, rather than the cost of the amount you purchased. You do not get to list it based on only the amount you used, if that amount is less than the minimum available.

[Noah Kleinberg]

The word prorated seems to contradict the rest of the rule really. Prorated would mean, I think, that you just divide the price by how much you use, but the rest of the rule, especially the example, make it pretty clear that they mean just substituting the price of another product that could've replaced the part on your robot for the price of the larger product.

[Richard Wallace]

"When I use a word," Humpty Dumpty said, in a rather scornful tone, "it means just what I choose it to mean -- neither more nor less."

"The question is," said Alice, "whether you can make words mean so many different things."

"The question is," said Humpty Dumpty, "which is to be master -- that's all."

Alice was much too puzzled to say anything; so after a minute Humpty Dumpty began again.

-- Lewis Carroll, from Through The Looking-Glass And What Alice Found There (1871).

Some arguments endure.