Raw Stock

 

SAE 5160 Steel Flat Bar, 1.25 x 0.25 inches

ASTM A36 Steel Round Stock, diameter = 1.00 inches. 

 

 

Necessary Equipment

 

Manual Lathe

CNC and Manual Mills

Drill Press

Ball-Peen Hammer

 

Link Construction

 

The links are constructed in a CNC Milling machine by drilling the necessary through holes and then milling the counterbore on opposite faces. Next, the ends are rounded on each end with a diameter of 1.25 inches. Next, the holes are put in a drill press to be reamed to the exact dimensions. The final step in construction of the links is adding the fillets, however in order to do this a fixture plate is needed which would allow the parts to be clamped and located from the holes, rather the outside edges. The fixture plate was manufacted out of scrap steel from the CWU Machine Shop, and was cut using the CNC mill to ensure that the clamping holes are located correctly. Finally, the links were clamped using 5/8 inch shoulder bolts and the fillets were added. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Rivet Housing Construction 

 

The rivet housing parts are constructed using a manual lathe to form the two differing outside diameters. Then, several drill bits were used to step up to the 5/8th inch diameter inside diameter. The end of each part is given an edge break and finally each piece is parted off of the same stock. The same procedure is repeated for the remaining rivet housing parts. 

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After the original bike lock was created, it was apparent that the counterbore could not generate enough shear resistance to prevent the bars being pried apart. The solution to this was to recreate a new rivet housing design. The original design involved using two identical parts on either side of the joint. However the new design involved one long part with a countersink in the head, and a flat washer-like mating part that sits flush on the other side. This allows the rivet to fill the entire countersink rather than sit above the rivet housing. This mistake was caused by a lack of experience with solid rivets, as well as a misunderstanding of the information found about solid rivets.

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Washer Construction

 

The washers are constructed from the same round bar stock as the rivet housing. The outside diameter is turned down on a manual lathe, and then center hole is drilled and reamed to 5/8 of an inch. Each washer is then parted off with a thicknes of 0.10 inches. 

 

Chain Assembly 

 

The links were joined together, by placing a washer between the holes of two seperate links, then feeding the rivet housing into the holes to align the links. FInally, the solid rivets are placed into the hole, and the tail end is beaten with a ball-peen hammer until the tail end is flush with the top face of the links.