[theastronaut]

Got the Heck unloaded, need to build a table for it and the new bandsaw.




It matches the big bandsaw pretty closely.






Back to the hinges. The arms were out of alignment, none of the pivot points were parallel from one end to the other. Some had high and low spots along the friction surfaces.












After straightening.







All of the areas that were worn were welded up and ground/filed smooth. The holes were all reamed to make the exactly round again.












Flatness was checked against a block of steel with a machined face.




The pins were machined from 1" steel bar. I sized them for about .002" clearance for minimal play and room for grease. I also added .030" length to the shoulder so I could add a washer cut from UHMW. This will slightly cushion the joint, space the arms apart so they don't rub the paint off each other, and will reduce friction and wear in the joint.




.030" UHMW sheet from McMaster Carr.





Drilling/tapping for 5/16-24 hardware to hold the joints together. The original pressed rivets are not a precise way to hold the joints together so I didn't want to copy that aspect of the hinge pins.






Milling the square ends that set the depth of the pin. This determines how tightly the joint is assembled so it was critical to measure the arms, UHMW washer, and on the main frame the offset of the raised friction surface. Too deep and the joint froze up, and the joint was too loose and wobbled if the depth wasn't cut deep enough. I ended up cutting the step slightly too low on purpose so I could remove material from the arms to incrementally loosen up the joint until it there was no play but no binding.




Compound set to 12.5" to cut a bevel in the head of the pins.




One of the pins on each arm were longer with a groove to mount the spring. I used the Delta carbide grinder with the table set to 7* to reshape an old/broken 60* threading bit to match the shape of the original groove.