Riving Knives On Table Saws
By Sean O'Hara
Fine Woodworking’s interesting article on riving knives has got us a little excited about new table saws. If you don’t know, last year Underwriter Laboratories made Euro-style riving knives mandatory on all new table saws. Fine Woodworking’s coverage of IWF shows how manufacturers are answering the new standard –- the short answer is “stylishly.”
Riving knives provide added protection from that dreaded adversary of all table saw operators, kickback — a nasty, devilish creature that can send boards back at you at astonishing speed or can drag your hands into the business end. A riving knife located right behind the blade in the kerf separates and cuts any material that might produce this horrid effect.
In general, aftermarket mods have been a bit clunky in past years — but with the new standard in effect, saw builders are getting the mod done right and with surprising grace. We like both the integrated style and the added safety.
Great News At IWF 2008 [Taunton]
September 8th, 2008 at 10:51 am
I have a General 650 and have heard that they will be coming out with a riving knife version that will also have backward compatibility to existing saws. Hope so, that would be a worthwhile upgrade. Would I sell my saw and buy a new one to get a riving knife? I kinda doubt it.
September 8th, 2008 at 12:18 pm
In the shop we use 2 cabinet saws (1 old Unisaw and 1 Shop Fox) both equipped with sliding tables - but no riving knife - we also use a panel saw.
We have 2 other Unisaws that we bring out to larger worksites. We have started purchasing the new Bosch work-site saws to replace older Makitas. The Bosch saws are a definite improvement - in part because of their safety features - including riving knife.
I think that the issue with backward compatibility for many saws will be the arbor geometry. If the arbor moves through some part of an arc to raise the blade - then I’d guess that fitting a riving knfe that keeps its position relative to the blade will be tricky. The other issue with riving knives also relates to the blade - or more precisely its thickness. To be 100% effective - You really need different riving knives.
One other thought is to use proper support (both infeed and outfeed) and maybe an external clamp (like the Pony Brand - Kerf Keeper) to help keep large panels from twisting and binding the blade.
By the way - I recall some of my old Black and Decker Super Saw Cats (7-1/4 saws) having both riving knives and electronic brakes - both way ahed of their time.