Elements of a Detailed Materials Cost Estimate
A materials list should give all the details needed to accurately estimate costs and to accurately determined budgets. It should be done with a spread sheet and contain the following columns:
Number: The number of units to be ordered Quantity: The size of a unit. For example dozen, box, carton, 10-pack, each, etc. Price: The cost of one unit of the item Item: A detailed description of the item to be ordered including part or model numbers. Vendor: where the item is to be purchased. It's not necessary to list all the details on each vendor for each item. A code can be listed with the details can be footnoted. Total: Number x Price the amount to be paid. Shipping and taxes are usually listed as a separate item. If shipping is unknown estimate it at 8 to 10%. See example below: |
Major Purchases - These are typically any item which makes up 5% or more of the project's material cost. Tax - should be added where appropriate. Shipping - should be added when known except for local pick up and delivery items. If shipping is unknown, use 8% Misc. - small items like fasteners, paint wire, etc. can be lumped together but should not be ignored Contingency - for items like unforeseen price increases. Contingency should not be used to cover for a sloppy or hasty cost analysis. |
Cost Estimate Example
| Num | Quantity | Item | Vendor | Price ($) | Total ($) |
| 2 | each | 1/4 x 2 in bolts | Acme Hardware | 0.13 | 0.26 |
| 4 | each | 1/4 in nuts | Bob's Hardware | 0.05 | 0.20 |
| Tax | 0.01 | ||||
| Shipping | 1.00 | ||||
| Total | 1.47 |
Materials sources:
McMaster Carr - has a huge selection of industrial components.
ER-1 Robot - the basis for SAM jr.
Robot MarketPlace - a good source of parts and ideas for robotics applications