- Joined
- Dec 25, 2011
- Messages
- 10,552
The best way is to measure the diameter and groove width of the shaft. Of course, that requires at least partially removing the shaft from the gearbox.
If you can't do that, first determine whether the machine is inch or metric. Then look at the appropriate tables noting that they are sorted by material diameter. Determine what the nominal material diameter of the old one is. Note that they only come in certain diameters, so determining which yours is should be simple. The tables give both nominal diameters and actual.. Then find a cylinder (a socket set may supply one) that the O-ring just fits without stretching. Measure the OD of the O-ring while on the cylinder and pick the nearest diameter from the section of the table for your material diameter. The flat on the OD of your old one is probably due to wear, so the original OD was probably slightly larger. The actual ID of the O-ring should be a few thou smaller than the ID of the groove so that it is a snug fit and doesn't have to bunch up during assembly.
Parker sells rubber lubricant in small tubes. This will aid in assembly. McMaster won't call it Parker but whatever they have will work.
If you can't do that, first determine whether the machine is inch or metric. Then look at the appropriate tables noting that they are sorted by material diameter. Determine what the nominal material diameter of the old one is. Note that they only come in certain diameters, so determining which yours is should be simple. The tables give both nominal diameters and actual.. Then find a cylinder (a socket set may supply one) that the O-ring just fits without stretching. Measure the OD of the O-ring while on the cylinder and pick the nearest diameter from the section of the table for your material diameter. The flat on the OD of your old one is probably due to wear, so the original OD was probably slightly larger. The actual ID of the O-ring should be a few thou smaller than the ID of the groove so that it is a snug fit and doesn't have to bunch up during assembly.
Parker sells rubber lubricant in small tubes. This will aid in assembly. McMaster won't call it Parker but whatever they have will work.