In my hobby of restoring old bench planes, the hardest task for me is flattening the back of plane irons. I currently use an extra coarse DMT diamond hone which works quite well but can be time consuming (I follow this with a Trend 300/100 2-sided diamond hone and then extra-fine sandpaper). However, I have some arthritis in my fingers that makes grinding on the extra coarse hone for any length of time quite painful.
So, I have considered buying a “Work Sharp 3000” sharpening system for the flattening process, which uses a 6” flat tempered glass lapping plate with PSA sandpaper and runs at 580 rpm. I’m not sure if it would make flattening an iron any faster, but would hopefully be kinder to my fingers.
But really, I don’t need the other bells and whistles offered by the Work Shop machine – I’m happy using my CBN wheel to cut a hollow-ground bevel followed with several flat stones to cut a secondary bevel – not hard on my fingers. So, I’d like to avoid spending the $200 on the Work Shop machine if there’s another, cheaper way. (I know there’s also a Veritas MK machine out there, but that’s beyond my budget).
So, here’s one idea and a few questions:
- I have a benchtop drill press that I can adjust the speed down to 740 RPM. Would it be feasible to chuck one of the Work Shop tempered glass discs to my drill press and use that with the Work Sharp coarse sandpaper discs to flatten plane irons? (The glass disc is 5/8” thick and available as a Wood Sharp accessory for $20 + the cost for sandpaper discs).
- I’d need to get some kind of mandrel or arbor to adapt the glass disc to use in my drill press (does anyone know the hole size of that disc?). Would that mandrel/arbor need to be anything special to hold the glass disc (e.g., without cracking it and without adding wobble)?
- I assume my drill press speed of 740 RPM would be ok for flattening plane irons with coarse sandpaper on the glass disc. Am I correct?
- Is this just a bad idea (if so, why)?
- Alternatively, is there perhaps a completely different solution for easily flattening plane irons and avoiding painful fingers?
Thanks in advance for any comments and suggestions!