There have been a few planes I've fixed, where the rosewood front knob had a blowout on one side of the base. Not only that, but some bending of the threaded rod could be seen. Today was such a find, and I saw the knob wasn't ever really turned accurately in the first place. By using some bigger pen-turning bushings on a mandrel, I was able to re-turn / re-face the glued-base, and make the whole knob stand square (for the first time in its life!):
<img src="http://i32.photobucket.com/albums/d38/C66RUPPEL/Truing_Knob_zpsxigup2s5.jpg" border="0" alt=" photo Truing_Knob_zpsxigup2s5.jpg"/>
Thank you for suggesting a pen mandrel . While I don't need to turn any knobs right now ,I do need a sweep handle for a little 6" non ratcheting brace.
Looks good nice tip, thanks for sharing.
Steve
I've made a couple similar repairs using all thread rod as a mandrel. A jam nut and rod coupling will fit the live center. !/4" all thread will flex so its best to keep the unsupported parts as short as possible.
I've used a pen mandrel to turn drilled blanks into knobs. It works well, and is safe and an on hand tool most turners have.
If you don't have a pen mandrel, you can make a knob mandrel from a block of wood with a centered bolt. Just drill a 1/4" hole in the wood block on the lathe. Cut a shallow inset large and deep enough to accommodate a nut. Run a long bolt through it and thread a nut onto it and tighten. Holding the end of the bolt in a jacobs chuck in the tailstock will ensure it stays centered. Then you can slide the drilled blank on the bolt end and snug it up with a nut. As a bonus, you can turn the end of the block of wood to the desired diameter of the base of the knob and use it as a bushing to make sizing the base of the knob easier. Just don't cut into the block when turning the knob. Use due care with a home made mandrel to ensure the work doesn't exit the mandrel unexpectedly.