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String Trimmer Bump Knob

We have a string weed trimmer that requires the operator to bump the trimmer head on the ground to feed out more cutting line. Over time, the original plastic knob wore out, and wouldn't work any more.

I turned this replacement knob on the lathe from Delrin®. It was a fairly simple project. In addition to turning the Delrin rod to size, I drilled a hole for the bolt that holds the bump knob to the trimmer, then used a boring tool to create the shallow "cup" for the bolt head and washer.

Bump knob


Updated October 12, 2017