CHJ
Established Member
One of the limitations with my "economy" table saw was the design of the Riving Knife and top guard/dust collector hood.
The Knife protruded above the blade to facilitate the support of the guard/hood.
This of course prevented the cutting of part thickness channels for plywood cabinet backs etc. (a case of quick meeting of EU safety rules overriding original design essential of adjustable blade height maybe.) And meant the temptation to operate without the knife and risk kickbacks.
Also the supplied Riving Knife was some 0.6 of a mm thinner than the blade kerf, and without constant re-shimming of knife to the required side of the blade for job in hand, resulted in chipping of edge especially of laminate surfaces on anything passing the rear teeth.
Although I always plane the edges of any boards cut on my Router Table (don’t have a Jointer) the mere fact that the saw was not producing a better job niggled.
Solution: Manufacture new Knife of increased thickness to spread cut and prevent chipping.
Checked Dimensions:
Existing Blade kerf: 3 to 3.1 mm dependant on material, feed rate etc.
Existing Riving Knife: 2.4 mm thick
New Knife material: 3.2 mm thick (selected from scrap bin, been there 5 yrs+)
Having marked out new material using original as template, cut it out with judicious use of drilled holes, hacksaw and file. A trial fit determined the max height by lowering the blade alongside a scrap of wood on the saw table and marking off the new knife.
A trial run with some cheap paper veneered chipboard proved that the rear teeth no longer caused as much surface damage and a run through with a piece of hardwood proved that the spread of the cut did not produce binding.
On trialling a partial thicknesses channel, the binding of the new knife in the cut proved to much for comfort and unusable.
Solution: Reduce the thickness of the new knife over the top 20 mm or so to be an easy fit in a channel but still provide the spread in through cut boards.
The final result, which relies totally on careful use for finger retention and IMOHO no more dangerous than the view impairing, jig blocking guard supplied.
The Knife protruded above the blade to facilitate the support of the guard/hood.
This of course prevented the cutting of part thickness channels for plywood cabinet backs etc. (a case of quick meeting of EU safety rules overriding original design essential of adjustable blade height maybe.) And meant the temptation to operate without the knife and risk kickbacks.
Also the supplied Riving Knife was some 0.6 of a mm thinner than the blade kerf, and without constant re-shimming of knife to the required side of the blade for job in hand, resulted in chipping of edge especially of laminate surfaces on anything passing the rear teeth.
Although I always plane the edges of any boards cut on my Router Table (don’t have a Jointer) the mere fact that the saw was not producing a better job niggled.
Solution: Manufacture new Knife of increased thickness to spread cut and prevent chipping.
Checked Dimensions:
Existing Blade kerf: 3 to 3.1 mm dependant on material, feed rate etc.
Existing Riving Knife: 2.4 mm thick
New Knife material: 3.2 mm thick (selected from scrap bin, been there 5 yrs+)
Having marked out new material using original as template, cut it out with judicious use of drilled holes, hacksaw and file. A trial fit determined the max height by lowering the blade alongside a scrap of wood on the saw table and marking off the new knife.
A trial run with some cheap paper veneered chipboard proved that the rear teeth no longer caused as much surface damage and a run through with a piece of hardwood proved that the spread of the cut did not produce binding.
On trialling a partial thicknesses channel, the binding of the new knife in the cut proved to much for comfort and unusable.
Solution: Reduce the thickness of the new knife over the top 20 mm or so to be an easy fit in a channel but still provide the spread in through cut boards.
The final result, which relies totally on careful use for finger retention and IMOHO no more dangerous than the view impairing, jig blocking guard supplied.