Thread: Knob puller
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Old 20th May 2020, 1:09 pm   #1
Bobdger
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Join Date: Jan 2015
Location: Rustington, West Sussex, UK.
Posts: 189
Default Knob puller

I have an old Bush AC41 that the knobs are refusing to come off. Inspired by a post here about a American knob puller for musical instruments I designed and built a small puller.
The outer tube is a offcut section of 63mm clear plastic pipe. The claws I designed around some M8 coach bolts, this meant that I could slide the jaws open to pass over the stuck knob, slide the jaws together and then hand tighten the retaining nut. The jaws would stay at 180 apart.
I had the jaws punched and bent at my local sheet metal shop. They could not punch these until the following day so meanwhile I cut out a 68mm circle from a piece of 10mm thick poly prop sheet with a hole saw. This gave me a centre 6mm hole to place a bolt through so that I could hold it in the lathe chuck. I then machined the disk down to 65mm with a 2mm locating rebate that fitted snugly inside the clear tube. The next day the jaws arrived with me, the 8mm slide was a little tight so I opened this up with a file, now works well. The parts were assembled with a M10 nut as a spacer to allow for the end of the square on the coach bolt. On the puller outer end I fitted a m8 penny washer and a M8 wing-nut.

Bob.
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