I am using an undamaged and sharp Freud SD508 dado set (on a 3HP General 350 cabinet saw). I use it now and again for 1/2" box joints in ¾’ stock and for off-sized plywood. It has worked fine in those applications. The other day, for the first time, I needed to plough for some T-track extrusions. To be safe, I first measured the Lee Valley T-track material at 3/4” wide. As such, I stacked the dado set accordingly. The result was an exceedingly sloppy fit. It was an easy 1/64” too wide.
I went to work making the strips needed to fill the gaps and save the drill press table fence I was making. With the fence saved, I moved on to discovering why the dado set was unable to plough a clearly standard width. Suspecting first that I had a blade or a chipper cockeyed on the shaft or debris in between blades, I removed the setup, cleaned the mating blade surfaces and arbor face and remounted the stack. No change. A 3/4” setup (A-E-E-E-E-A) produced a groove that was an easy 1/64” too wide. I then looked at the saw. My arbor and flange runouts were about +-.0015 as best as I could measure. Moreover, my saw has been preforming quite well with my other Forrest and Freud blades.
Freud is telling me to use the supplied shims to achieve desired widths, but I’m having trouble understanding why an obviously standard with cannot be achieved without the tedium of shimming. Sure, I've used the shims for plywood and other off-sized material thicknesses, but 3/4" x 3/8" extrusion seems a standard width that would not require odd chippers and or shims for a snug fit.
Has anyone else had a similar experience and/or can anyone shed any additional light on this? Are my expectations out of line?
I went to work making the strips needed to fill the gaps and save the drill press table fence I was making. With the fence saved, I moved on to discovering why the dado set was unable to plough a clearly standard width. Suspecting first that I had a blade or a chipper cockeyed on the shaft or debris in between blades, I removed the setup, cleaned the mating blade surfaces and arbor face and remounted the stack. No change. A 3/4” setup (A-E-E-E-E-A) produced a groove that was an easy 1/64” too wide. I then looked at the saw. My arbor and flange runouts were about +-.0015 as best as I could measure. Moreover, my saw has been preforming quite well with my other Forrest and Freud blades.
Freud is telling me to use the supplied shims to achieve desired widths, but I’m having trouble understanding why an obviously standard with cannot be achieved without the tedium of shimming. Sure, I've used the shims for plywood and other off-sized material thicknesses, but 3/4" x 3/8" extrusion seems a standard width that would not require odd chippers and or shims for a snug fit.
Has anyone else had a similar experience and/or can anyone shed any additional light on this? Are my expectations out of line?