Crown Guard and Riving knife

[dicktimber]

What thickness should the riving knife be?

Should it be thicker than the table saw blade thickness, or the same thickness?

I realise that the riving knife helps to stop binding and kickback while ripping timber due to releasing inbuilt stresses in the wood, but what happens when cutting ply sheet, and the sheet won't spread over the riving knife?

I was taught that on no account should the crown guard be removed, and have always used alternative methods to cut timber when, Norm works exclusively WITHOUT the crown guard in place. For example, tenon shoulders etc

It would be nice to know what approach other members use when difficulties arise with the crown guard in place?

Mike

 

[jasonB]

The knife must be thinner than the blade kerf but thicker than the body of the blade.

An SUVA type gaurd will solve all your problems together will a riving knife that sits just below the top of the blade.

Jason

 

[OllyK]

The riving knife just be just slightly less than the kerf of the blade IIRC, otherwise, as you have discovered it binds.

I try not to remove the crown guard but there have been odd exceptions, ripping very deep stock that has required two passes, i.e pass through then flip and pass through upside down.

My old saw had neither a riving knife nor any guard - now that was a scarey beast

 

[stuartpaul]

The knife must be thinner than the blade kerf but thicker than the body of the blade.

An SUVA type gaurd will solve all your problems together will a riving knife that sits just below the top of the blade.

Jason

I seem to remember under the old Woodworking Machine Regulations the riving knife had to be 10% thicker than the saw plate (i.e. not as thick as the kerf but thicker than the body of the blade as mentioned by Jason).

 

[Niki]

As for the riving knife thickness

I'm not sure that the riving knife can "save" you from a "Reaction wood" (the workpiece springs out and presses on the fence but...the fence is "stronger" so, it will press on the blade and from here...only a split of second is required till the UFO will fly...

Maybe, that's the reason, that HSE, shows and recommends the use of "Short fence" when ripping solid wood...

As for the crown guard, the regulation is "Riving knife and crown guard must be installed for any operation on the table saw"...I think that it's very clear...

Regards
niki

 

[devonwoody]

No guards only riving knife.
What are forum members feelings on ripping slender pieces around 8 to 12 mm thickness and from timber perhaps only 25mm wide. (you cant get a push stick between fence and blade on this sort of stuff)

Any serious stories to tell?

 

[p111dom]

No guards only riving knife.
What are forum members feelings on ripping slender pieces around 8 to 12 mm thickness and from timber perhaps only 25mm wide. (you cant get a push stick between fence and blade on this sort of stuff)

Any serious stories to tell?

I've tried on my last saw and it was scary enough for me not to do it again. Worked out ok I guess but that was only because that saw had no knife or guard. My current Jet saw has an adjustable fence which you can flip round to the 'thin stock side' although that means your measuring scale is out. That gives more access for a push stick. In theory even with the guard in place that's about 10mm to the side of the blade and with a 10mm wide push stick my minimum comfortable cut between blade and fence is 20mm. If I have to cut anything thinner I use the bandsaw.

 

[devonwoody]

Yes I suppose a thinner piece of timber to the fence means the top guard could then come down, I sometimes use a pushstick/offcut around 1 mtr. long and push my strips through. Grit my teeth when the blade hits the push stick for the couple of inches necessary.

 

[Rob_H]

I was taught that on no account should the crown guard be removed, and have always used alternative methods to cut timber when, Norm works exclusively WITHOUT the crown guard in place. For example, tenon shoulders etc

It would be nice to know what approach other members use when difficulties arise with the crown guard in place?

Mike

I think Norm has mentioned once or twice that the guard was only removed for television purposes - so the camera can get a better shot. I have to say my Kity 618 came without a crown guard and I've been meaning to buy one - a 5 week delivery time from Kity so I'd better get on with it.

 

[Niki]

No guards only riving knife.
What are forum members feelings on ripping slender pieces around 8 to 12 mm thickness and from timber perhaps only 25mm wide. (you cant get a push stick between fence and blade on this sort of stuff)

Any serious stories to tell?

On those cases. I don't use "push stick" but "push tray"...of course, you can use a push stick to push the "tray", I just screwed to it a trowel...

For ripping narrow and short pieces, I use the sled that I made lately.

Regards
niki

 

[jasonB]

For narrow stuff I have a push plate made from 3mm MDF and also have an attatchment for the fence that is only 8mm high but puts the main fence 40mm further from the saw.

Jason

 

[devonwoody]

Thanks for ideas above.

 

[hpl]

Those pictures of your 'tray' are great Niki, very easy to understand what you do. Thanks very much for the idea, I'd never thought of that before but will now make one up for those narrow strips.
On the use of the Crown Guard, Many years ago I had a smallish saw and often ripped thicker timber and thought nothing of removing the guard, I had often done it at work and was comfortable with it. Now I am very wary of using a saw without a guard as I so rarely do it and have very long pushsticks if I do. When I see an American site showing unguarded machines it makes me nervous for them. I guess that it is what you are used to, you get used to the risk and so it doesn't seem a risk any more.
For me I'll use the guard and keep my fingers

 

[Niki]

Thank you Hpl

Actually, I call it "strips sled" and I'm using it also for "thicker strips" up to 70~80mm wide.
Just change the "Pusher" to the width you need (you can make it longer so the first pass will cut the pusher to size).

As for the crown guard on the American TV, Videos etc....it makes me mad...I still don't understand about what "clarity" they are talking and what exactly one have to "see"....

I used to work without guard/riving knife for 10 years but with a "Left fence" that in my opinion is much safer than the "Right fence"...I was always standing on the left - beyond the fence and my hands where never over the blade...

But, no more...it's much more safe and relaxed to work with the guard installed...

Regards
niki

 

[hpl]

I do like the sled idea, much safer to have the hands away from the blade.
Thanks for the further pictures Niki

 

[joiner_sim]

Now and again the crown guard gets removed, but I don't like using the table saw this way.

 

[Steve Maskery]

I've replaced my crown guard with a home-made SUVA-style guard, which is currently my avatar. It is easily lifted for blade access, or removed completely if it gets in the way of jigs (which have their own guarding built-in).

Cheers
Steve

 

[Niki]

Good day Steve

Can you tell me what is this SUVA stands for

The "Acronym finder" says;
"Specific Ultraviolet Absorbance" but I don't think so....

Oh yes, and it's also the Capital of Fiji islands

Regards
niki

 

[Steve Maskery]

SUVA - Schweizerische UnfallVersicherungsAnstalt
(Swiss National Accident Insurance Organization)

I can't remember where I originally saw it, but basically it takes its name from the company which sets the standard for permitted safety regs in Switzerland.

Or something like that.

S

 

[devonwoody]

Does anyone think the Chinese will have a safety/standard icon anytime in the future that we could trust?