| Name and Model Number | Boykin RotaRule Model 510 |
| Country of Origin | USA |
| Date of Manufacture | ~1960 to 1970 |
| Front Scales | L, B, CT, T, ST, CS, S, CIF, CI, C, D, A, K |
| Back Scales | LL03, LL02, LL01, LL1, LL2, LL3, C(50"), V1, V2, DLL, D(50") |
| Scale Length | 50" (127cm) |
| Type of Rule | Disc |
| Construction | Plastic 5.25" (13cm) diameter |
| Area of Use | Other |
| Comment | For precision basic math calculations. Has unique modified spiral scales. The first image shows the optional magnifier. Another image shows RotaRule parts without ink and un-assembled. |
| Rarity | RRR |
| Donor | Collection of Richard Davis |
| Match Number | 52 |
| Thumbnail (Click Picture for Details) |  |
| In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen |
| (1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD. |
| • RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace. |
| • RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale. |
| • RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale. |