Following up on a post by MrRon concerning “Concerns regarding saw cutting accuracy” I thought I would show anyone interested how to achieve pretty close to zero run-out on any table saw equipped with a pressed on or integrally machined flange.
It’s worth doing. For this is the tool that for most of us makes or breaks the accuracy and satisfaction in our machining. If you run high quality blades (from any manufacturer) then this simple operation will enable you to get the best out of your saw.
It was taught to me by Rockwell service technicians in 1981 when they owned and made the Unisaw and others in the then and now Delta line. I don’t know if it was a technique they used to cure rotten quality control or maybe just the odd flier (if you’re a target shooter) that somehow slipped through their lines.
It was easy. You simply mounted a 3/4”, 1/4” shank coarse grinding wheel to your router and then offered it up to the inner flange of your saw while both were running. Both rotations work in the same direction so it is sort of a climb cutting with no digging in. With a light and careful touch you can machine in place using the dynamics of tools you already own and enjoy great results. I have done this trick on almost a dozen saws with tight readings resulting and much cleaner cuts.
Clean out your base and internals of all sawdust. Have a fire extinguisher handy. Keep an eye on the area for an hour afterwards.
Having said that there is very little danger here, but there is also real profit in careful and safe working. Sparks are tiny fires.
To begin you may use a dial indicator if you wish to check on your current state, or just a careful eyeballing will do and will tell you if there’s run-out.
Raise the arbor to maximum height,
Remove insert, nut, outer flange and blade.
Tilt arbor to 1 degree. The aim is to make the flange ever so slightly concave so that the pressure on the blade is at the outer edge at first, much like a well tuned vise.
Set the router depth with grinding wheel to fully contact the face of the flange.
Turn on saw and router with wheel away from the flange.
Slowly bring the grinding wheel into contact with the centre of the flange and tightly hold that position till it sparks out.
Always do a very light first pass, stop both machines and inspect your flange. It will probably show fresh grinding marks at points and arcs. Make another light pass, inspect again. Three grindings will usually do it for an average condition, giving a perfectly uniform scratch pattern. Stop and re-test your blade or use an indicator. I always black colour the flange with a Sharpie before grinding starts so as to easily show fresh metal.
It is helpful to position the fence near the insert opening so that you may rest your right hand against it and pivot the router into position.
This type of small wheel is rated for 25,000 rpm so there are no concerns about disintegration but I would pay attention to the quality on the shank seeing as it’s being used in a collet.
To complete, pass your outer flange over a diamond or coarse stone by hand till it shows the same effect.
-- firstname.lastname@example.org : dovetail free since '53, critiques always welcome.