Riving knife thickness

[Daniel2]

Hello,
After a bit of advice or opinions.
Looking at available circular saw blades on line, I see that the kerf
on the blade I would like to buy is 2.8 mm. My riving knife measures
2.52 mm.
I'm concerned that this may increase the chances of kickback.
Do the collective think this concern is justified ?
Thanks in advance for any input.

 

[Sachakins]

Do you know the blade body thickness?

This is from a thread on here a while back..

 

[Peter Sefton]

The kurf of the blade (teeth) should be wider than the thickness of the blades plate and the riving knife, so my guess is this would be fine. The important thing is that the riving knife is thicker than the plate of the saw blade, does the description mention this thickness?

If you buy the blade from a reputable dealer you should be able to return it if you carefully unpack it to check the blade thickness, if its returned unused and undamaged you should get your money back.

Cheers

Peter

 

[Sideways]

Buy a decent blade and the details will all be specified up front.
This as an almost random example :

Blade Diameter	168 mm
Bore Size	20 mm
Hook Angle	10°
Kerf	1.8 mm
Maximum RPM	9,500 rpm
Plate Thickness	1.2 mm
Teeth	42
Tooth Format	ATBR

 

[niall Y]

The riving knife has to be fractionally smaller than the kerf otherwise the saw will bind, I can't see that a 0.28 mm difference is significant enough to cause problems.

 

[Daniel2]

Thanks guys for the concise and rapid replies.
Very helpful.

 

[Cabinetman]

Yes can’t add to that, hope nobody minds me hijacking, having to make a riving knife for an oldie but goodie table saw, I have a sheet of brass the correct thickness and it will be a lot easier for me to cut than steel plate. Will it work? I’ve only ever seen steel ones
Ian

 

[Distinterior]

.....having to make a riving knife for an oldie but goodie table saw, I have a sheet of brass the correct thickness and it will be a lot easier for me to cut than steel plate. Will it work? I’ve only ever seen steel ones
Ian

Not stiff/ rigid enough in my opinion Ian.........I also made a couple of riving knives recently out of an old table saw blade.
Nice and flat and not too difficult to cut up.

 

[bp122]

One of the hacks I had seen was this person who was fed up of cheap steel bendy riving knives that he traced the outline of it on an old saw blade plate and cut it out with an angle grinder. It was a perfect fit as the new blade had the same plate thickness and allowed the kerf to cut without kickback. And the plate is super strong compared to the cheap metal the stock ones comes with.

 

[bp122]

Not stiff/ rigid enough in my opinion Ian.........I also made a couple of riving knives recently out of an old table saw blade.
Nice and flat and not too difficult to cut up.

Damn it, @Distinterior , you beat me to it!

 

[Distinterior]

One of the hacks I had seen was this person who was fed up of cheap steel bendy riving knives that he traced the outline of it on an old saw blade plate and cut it out with an angle grinder. It was a perfect fit as the new blade had the same plate thickness and allowed the kerf to cut without kickback. And the plate is super strong compared to the cheap metal the stock ones comes with.

This is pretty much exactly what I did....!!

Started with a thin cutting blade in an angle grinder, then onto an oscillating spindle sander, then finished by hand with a couple of files. Last job was to really clean it up and then chemically blackened.

 

[Hornbeam]

The riving knife is one of the fundamental safety features of a table saw ( particularly if using a knife mounted crown guard). Use the right grade steel plate

 

[Cabinetman]

Ok, well thanks anyway, and your quick answers. It would have been silly as well as I will be mounting a guard on it too. Hadn’t thought of using a grinder lol.
Ian

 

[Distinterior]

TBH, a hacksaw with a couple of really good quality blades fitted to it,would do a good enough job of cutting out the shape.
I just found it a bit of a laborious task, so opted for the thin blades in my angle grinder.
I've got a couple of pictures of one of them somewhere....!

 

[hlvd]

One of the hacks I had seen was this person who was fed up of cheap steel bendy riving knives that he traced the outline of it on an old saw blade plate and cut it out with an angle grinder. It was a perfect fit as the new blade had the same plate thickness and allowed the kerf to cut without kickback. And the plate is super strong compared to the cheap metal the stock ones comes with.

That sounds like an excellent idea!

 

[Distinterior]

Here is a picture showing the original riving knife off a Startrite 145 saw on the RHS and the replacement I made from an old saw blade on the LHS. I actually managed to get 2 out of 1 x 250mm dia blade.

I checked the thickness of the original with a digital vernier to ensure the thicknesses matched before cutting up the old blade.....

 

[David Lloyd]

I used a worn out saw blade to make two riving knives for my ancient Metabo 10" saw that I bought without any riving knife at all. I made two from one blade - one with bolt holes for a blade guard and the other just lower than the top of the blade for use with my sled. The work perfectly.
The old saw blade was easy to cut and shape with thin cutting discs in a grinder finished with a flap wheel.
The guy I bought the saw from was making staircases and ripping huge pieces of wood with no riving knife, the saw was balanced on four milk crates! It looked "exciting" when he demonstrated the saw for me!

 

[budgie98]

Here is a picture showing the original riving knife off a Startrite 145 saw on the RHS and the replacement I made from an old saw blade on the LHS. I actually managed to get 2 out of 1 x 250mm dia blade.

I checked the thickness of the original with a digital vernier to ensure the thicknesses matched before cutting up the old blade.....

View attachment 172990

I really don't want to be negative, but, on another group, some time back, there was a lot of discussion about riving knives of the same pattern as yours. Apparently, a riving knife of that style was accidentally knocked onto the running blade, and was dragged from under the securing bolts and thrown into the operator's body, or head. The consensus was, only riving knives with a full fixing loop should be allowed: that is, the knife should not be able to be removed unless the fixing bolts were removed. A number of members of the group had had 'C' shaped extensions welded to their knives soon after, although a piece of straight flat strip would have been perfectly adequate.

 

[Distinterior]

I really don't want to be negative, but, on another group, some time back, there was a lot of discussion about riving knives of the same pattern as yours. Apparently, a riving knife of that style was accidentally knocked onto the running blade, and was dragged from under the securing bolts and thrown into the operator's body, or head. The consensus was, only riving knives with a full fixing loop should be allowed: that is, the knife should not be able to be removed unless the fixing bolts were removed. A number of members of the group had had 'C' shaped extensions welded to their knives soon after, although a piece of straight flat strip would have been perfectly adequate.

I appreciate your concern Budgie, but as you can see from the picture, I just copied the original riving knife.....It is still possible to buy new identical riving knives, but if someone wanted to modify their own knife, that is their choice.
This particular saw dates from the late 50's/ early 60's and will be up for sale within the next few weeks.....

 

[ColinDeVelen]

For what it's worth, the safety standards (admittedly from 2-5 which is for hand held circular saws including track saws) call for a riving knife to be thicker than the plate, but thinner than the kerf.