Good reason to leave your table saw guard on

[Doug71]

I generally think the main reason to leave your table saw guard on is to save your fingers but it also prevents kickback as I experienced today.

I was just ripping down a 2' length of Walnut when without warning there was a bang as the wood was thrown violently upwards into the guard, normally you can feel the wood tighten around the blade and back off but for some reason the tension was suddenly released in this piece gripping the upward spinning back of the blade and flipping it up. If the guard wasn't on the timber would have been flying across the room (if my face didn't stop it).

Some may say my blade is set too high but when it's set lower the wood can be thrown straight back (not up) and the guard wouldn't stop it.

I have been doing this for years and this was by far the most violent kickback I have experienced, it really went with a bang. I do think one of the reasons could be that I was using a shortish piece of wood which made me think of people on here who may generally deal with shorter pieces which is why I'm posting it.

The wood really got a good grip on the riving knife.

Leave the guard on

 

[mikej460]

Many years ago I was using an elektra bechum site saw and had kick back that threw the piece backwards like a dart. Luckily I was angled slightly to the left and it missed me but it didn't half put the wind up me.

 

[RobinBHM]

The tension on some boards of iroko can be incredible - I’ve had boards tighten so much on the diving knife the machine has to be turned off and a club hammer used to move the board.

The knack is to watch out for the board closing up - and if it does, pull the board out, adjust fence by 2mm then go in again.

Ive even had the last 18” of an Iroko board crack with a big bang.


riving knife and guard saves lots of injuries

 

[Inspector]

Doug I can't tell from the picture but does the guard have anti kickback pawls? Ot did the board stop because it jammed up? Always a good reason to stand to one side when ripping.

Pete

 

[Sandyn]

Is the blade the correct width for the riving knife? previous thread here. Could it be caused by stress in the wood causing twisting when it's cut?

It's scary when it happens. In the early days of ripping wood, before I knew what anti-kickback pawls were for, I was ripping a bit of wood, there was an almighty bang and the wood came out of the saw and hit my thumb. The thumb instantly went numb, but I was too scared to look to see if it had been removed. I had to go find my wife and ask her if my thumb was still there.

 

[Doug71]

@RobinBHM back in the day I spent many hours stood behind a big old Wadkin ripsaw hammering wedges into the kerf to keep it open so know just what you are talking about.

@Inspector I think the board stopped when it hit the guard and tightened up on the blade and riving knife, I don't think anti kickback pawls are really a thing here.

@Sandyn yes correct riving knife for blade, it was just the tension released in the wood which made it grab.

I always use riving knife, blade guard, push sticks, short fence, safety glasses etc so know not much can go wrong. I just thought of some hobbyist who had learnt his craft from the internet, no blade guard on, leaning over their Dewalt 745, he would have got it square between the eyes

 

[Nick Laguna UK]

Doug I can't tell from the picture but does the guard have anti kickback pawls?

Hi Pete I often get asked about why Laguna saws in Europe don't have the anti-kickback pawls along with the USA style drop down plastic guard flaps - reason is the USA guard design couldn't pass pass CE inc. the pawls.
I don't know the exact specifics why we couldn't use USA style but I do know CE testing is far more stringent than USA ref breaking/shattering tolerances and tensile strength / thickness of material etc.
If USA guards would have been OK here, then we would have used them as we wouldn't have changed factory production for more cost. Pawls to me make sense, but I guess only if they are specced to not turn into flying missiles shattering the guard in a kickback,.
There were several aspects with the USA crown guard design that necessitated a whole new EU style change is all that I know.
I only see it as a good thing if more safety in fairness - I guess America can catch up when they feel like it. I do think we are way ahead on safety in some aspects & have been for some time (sub fences also)
Looking at Doug's image I can only wonder what the outcome would have been with a non-CE spec thinner guard that shattered & hi @Doug71 glad you are OK too
Cheers all, Nick

 

[David Young]

I generally think the main reason to leave your table saw guard on is to save your fingers but it also prevents kickback as I experienced today.

I was just ripping down a 2' length of Walnut when without warning there was a bang as the wood was thrown violently upwards into the guard, normally you can feel the wood tighten around the blade and back off but for some reason the tension was suddenly released in this piece gripping the upward spinning back of the blade and flipping it up. If the guard wasn't on the timber would have been flying across the room (if my face didn't stop it).

Some may say my blade is set too high but when it's set lower the wood can be thrown straight back (not up) and the guard wouldn't stop it.

I have been doing this for years and this was by far the most violent kickback I have experienced, it really went with a bang. I do think one of the reasons could be that I was using a shortish piece of wood which made me think of people on here who may generally deal with shorter pieces which is why I'm posting it.

The wood really got a good grip on the riving knife.

Leave the guard on

View attachment 119230

The reason your piece of Walnut got thrown back was your rip fence shouldn't pass the centre point of the blade, from the front of the blade to the centre the blade is holding your timber down. After that it's only going to launch it skywards. The saw blade should ideally be set with the tooth gullet 10mm above your timber thickness. Hope this helps. Contact me direct if you need a one to one chat.
Cheers David

 

[Inspector]

David it is not a good idea to post your phone number, email address or mailing address in forums and the like. You never know who will use it to bug you to buy junk, ask or scam you for money etc. If you still have the edit button showing I would delete it otherwise ask a moderator to remove it. People can use the conversation feature to send you a private message that you can if needed give the more personal info.

Pete

 

[MikeK]

The reason your piece of Walnut got thrown back was your rip fence shouldn't pass the centre point of the blade, from the front of the blade to the centre the blade is holding your timber down. After that it's only going to launch it skywards. The saw blade should ideally be set with the tooth gullet 10mm above your timber thickness. Hope this helps. Contact me direct if you need a one to one chat.
Cheers David

I'm not answering for Doug, but he has the SCM Minimax SC4 sliding saw (I have the SC2 Classic). Unless one is familiar with the SCM sliding saws, it is not obvious where the end of the rip fence is, but I can see the fence does not appear to extend past the centerline of the blade. The rip fence on the SCM saws slide in a clamp attached to bar on the infeed side of the saw table and can be adjusted to fit the width of material being ripped. The far end of the rip fence can be seen near the fire extinguisher in the photo.

The SCM operator's manual for my saw and the SC3 instructs the operator to set the outfeed end of the adjustable rip fence so it follows a 45-degree path away from the blade as the width of the material increases. I think the same is true for Martin and Altendorf sliding saws.

 

[Sgian Dubh]

The reason your piece of Walnut got thrown back was your rip fence shouldn't pass the centre point of the blade, from the front of the blade to the centre the blade is holding your timber down. After that it's only going to launch it skywards. The saw blade should ideally be set with the tooth gullet 10mm above your timber thickness. Hope this helps. Contact me direct if you need a one to one chat. 07886451319
Cheers David

Looking at Doug71's photograph I'd say the rip fence wasn't set beyond the centre point of the blade, or too long, as I think you're suggesting was the cause of the kickback. So, if fence position (too long) can be discounted, the most likely cause is stress release in the wood leading to the wood pinching on the upward rising part of the blade, i.e., the part of the blade beyond the centre point.

Interestingly, regarding your other point, the HSE PDF document Circular saw benches - Safe working practices WIS16 doesn't seem to define the height that the tooth (or the gullet height) at the top of the blade's described arc should be set higher than the thickness of the wood being ripped. The document states:
"Saw blades should:
■ be set so that the teeth project through the surface of the material during cutting;
■ not, however, be set higher than necessary"

This would seem to leave operators to determine for themselves what is, in effect, "not ... set higher than necessary". I've always interpreted this to me quite often preferring to set the blade higher rather than lower for ripping operations, especially with powerful saws and thicker material, because I don't like the tendency of rearward thrusting low set teeth near the top of the arc tending to push the wood back towards me. Generally I prefer the front teeth chopping downwards as vertically as I can arrange it, which naturally leads the rear teeth similarly wanting to lift the cut wood, should the wood pinch.

I'm not sure where the commonly espoused guide to limit the height of a saw tooth or gullet above the the wood during ripping operations came from, but your 10mm limit guidance for the gullet above the wood is similar to suggestions given by other trainers of my acquaintance. I suspect the primary reason for height limits of this sort of order came about because this also allows a crown guard attached to the riving knife to be set close to the wood thus preventing fingers getting at the spinning blade. Yet, similar sawblade height guidance isn't replicated at the HSE website where an example in a video they endorse as illustrating good practice shows ripping where the the blade height is set substantially higher than the wood: perhaps 35 - 40 mm of blade is exposed at its highest point during the demo, see my link in post #14 below.

I'm aware that by saying what I've said this potentially opens up a whole can of worms, but hopefully not as wormy and sometimes contentious as a plane iron or chisel sharpening thread, ha, ha. Slainte.

 

[scooby]

@RobinBHM back in the day I spent many hours stood behind a big old Wadkin ripsaw hammering wedges into the kerf to keep it open so know just what you are talking about.

Exactly the same when I was an apprenticeship. They also had a big Wadkin. Intimidating to look at, but such a nice machine to use if you didn't take the water. At the even slightest chance of the cut closing up, wedges were knocked in.
They also had a Wadkin panel saw..complete with no guard or riving knife. That thing took no prisoners. On one occasion, I left (stupidly) the offcut piece next to the blade and it was thrown backwards an impressively long distance. Getting that in the face wouldn't have been fun.

 

[isaac3d]

I see you guys referring to a "rip fence". Is that the same as a "riving knife"? If not, then could you please explain what you mean by "..the rip fence shouldn't pass the centre point of the blade.."

 

[Sgian Dubh]

I see you guys referring to a "rip fence". Is that the same as a "riving knife"? If not, then could you please explain what you mean by "..the rip fence shouldn't pass the centre point of the blade.."

See this link for guidance: https://www.hse.gov.uk/woodworking/videos/ripsaw.mpg When this link opens you'll need to wait for the video to download before you open and view it.
Also click on the Circular Saw Benches link in my previous post, #11 three above this one. Slainte.

 

[Jacob]

Rip fence is just short fence you use for ripping. Ideally the work piece goes free as soon as a possible after the fence guided cut is finished, so it can't get caught between blade and fence and flung back.
There was a vogue for home made overhead TS guards a bit back, sometimes referred to as "SUVA" guards, but were not built to SUVA spec and were dangerous. Gone out of fashion perhaps?
The TS prob is the slingshot effect - given enough room the blade can accelerate the work piece up to saw rim speed and shoot it off like a cross bow bolt. Restricting the sling shot throw by keeping blade low, hold-downs and guards set close, reduces this risk, if the workpiece does get snatched up.
And the riving knife and crown guard need to be sturdy and well attached so they don't get blasted off too.

 

[Ttrees]

That's on the list of things to make for me, and going to have a proper bash at it
sometime, now I have a welder.
Just don't know what the best one to copy would be?

Any other suggestions apart from this one Jacob?
I can't use an attached crown guard for a lot of the stuff I use the tablesaw for.

https://www.ukworkshop.co.uk/threads/overhead-table-saw-blade-guard.115782/#post-1268044

 

[Jacob]

That's on the list of things to make for me, and going to have a proper bash at it
sometime, now I have a welder.
Just don't know what the best one to copy would be?

Any other suggestions apart from this one Jacob?

It looks like a disaster waiting to happen. I wouldn't go near that saw with all that DIY bodged kit hanging over it. The guard itself looks like a greater hazard than kick back or the sling shot itself. Though the second one looks sturdier than many worse examples which crop up

I can't use an attached crown guard for a lot of the stuff I use the tablesaw for.

Why not - I think you should!
Get a proper riving knife and crown guard to fit the machine. A lot less trouble than that Heath Robinson contraption. Much cheaper, easy to fit, goes up and down with the saw blade automatically and stays in place, close to blade so restricts movement of flying woodwork

https://www.ukworkshop.co.uk/threads/overhead-table-saw-blade-guard.115782/#post-1268044

Daftest suggestion in that thread was to use an Angle Poise arm to hold it - perhaps he was taking the pi**ss!

 

[isaac3d]

Thanks for the video Sgian Dubh, that's much clearer. I have only ever really used a hobby table saw but I'm expecting a Charnwood 8'' Table Saw to arrive soon.
I normally use my bandsaw for pretty much all ripping and cross-saw operations. Whilst I'm aware of the general rules of safety when using a table saw, the original poster's experience is scary to say the least!
OK... off to watch some more videos on the correct way to use a table saw!

 

[Jacob]

If you do mount something over the blade the most important thing is to hang it in line with the blade so that if it does touch it won't be skewed sideways and twisted off its moorings. Also a material which can take a cut without getting snatched.

 

[Bristol_Rob]

If OP has a sliding table saw.

You could consider building a Fritz & Franz jig for cross-cutting & ripping small pieces