Making a steel riving knife for a TS
A Scheppach table saw has served me very well for over two decades now. But just lately I’ve been trying out alternative blades to the standard 250mm (10″) 3.2mm (1/8″) blades for various purposes.
One problem remains – the standard riving knife (which is also the mounting point for the blade guard) is 3mm thick. If I use a 2.8mm or thinner blade, the workpiece can jam or become difficult to push through. A jam will always occur with an over cut (full depth cut in a workpiece thicker than the height of the bade).
This riving knife, by the way, goes up and down with the blade and also tilts with the blade. It’s profile allows it to be set just a couple of millimetres (around 1/16″) behind the curve of the blade as it rises out of the table.
Alternative riving knives of suitable thickness, as well as a different profile for smaller blades, could be fashioned and attached to the arbor in the same way as is the standard riving knife. But what steel plate to use?
Is mild steel sufficient? That would be easiest to cut and shape. And how thin can a riving knife be before it becomes too feeble to do its job, perhaps bending too easily if pressured side-on by a workpiece?
The blades I want to use include 10″ diameter blades of various teeth profiles but a lesser tooth-width of 2.8mm. I also want to use smaller diameter blades of 2.4mm tooth thickness; and one that’s even smaller in diameter with 1.6mm wide teeth. Basically, it saves expensive exotic woods and takes less power to cut the really tough stuff.
Any advice about the steels that would be suitable will be gratefully received.
Lataxe
Replies
There is a company in the US that makes aftermarket splitters and riving knives out of 304 and 316 stainless steel. No affiliation (I’m a Canukj, but I have one for my saw and it is excellent.
You may want to check them out to see if the have a solution that works for you.
https://www.thesharkguard.com/how-to-determine-splitter-or-riving-knife-thickness/
Hi Ox,
There's some useful information on that Sharkguard website regarding what thickness of riving knives will work best with which width of saw blade tooth. If such a vendor existed down the road here in West Wales, I'd get them to a make one or three but I suspect that them being in the USA makes for too many barriers to ordering - customs, VAT and carriage costs being one and their probable lack of familiarity with European table saws another.
I do have a hanker, anyway, to make my own. :-)
It should be possible to measure then create a tech drawing of what riving knives would have as the right profile for various blades I'd like to use in my TS. In general, that website seems to suggest that the riving knife should be around 0.2mm / 0.008" thinner than the blade tooth width. But it also seems to suggest that a riving knife can be slightly thinner again ... but not so much that the blade teeth could still catch and lift the workpiece.
One problem with making my own riving knife is to decide on the metal to use. I have standard hacksaws and files but no fancier metal working tools so mild steel has a certain appeal - if its strong enough. Hence my first question: is it?
But there'll be supplementary design issues such as how much thinner can the riving knife be than the blade teeth.
Does stainless steel plate take more cutting than mild steel? Will standard hacksaws and files cut it in a reasonable time; or at all?
I can’t say with certainty, but it appears my original splitter is mild steel and is easily cut with a file. If it we me, doing it by hand, I would use mild steel. Stainless being corrosion resistant and harder is a good choice but I suspect the supplier to Shark would be using CNC diamond tooling.