# Riving knife higher than the blade! - Potential Mod?



## bp122 (26 Aug 2019)

Hello there

On my new Axminster AC216TS Table saw, the riving knife provided sits above the top of the blade. 
Lots of people who cut rebates and dadoes have riving knives that are slightly lower than the top of the blade so that the workpiece slides over them when cutting rebates etc. 

Are there any aftermarket riving knife upgrades out there or is it a matter of cutting off the excess using a hack saw after carefully marking it? (as many people here, I prefer to not buy the upgrade if I can do it myself)

Please let me know your thoughts.

best regards
bp122


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## ManowarDave (26 Aug 2019)

On my old bench top saw, that's exactly what I did. I took it to about 2mm below the top of the highest tooth with and angle grinder (knife removed from saw for modification obviously )

Dave


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## ManowarDave (26 Aug 2019)

I should probably add that following a "full risk assessment", I also modded the crown guard so that it could still be used when cutting through.

Dave


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## Steve Maskery (26 Aug 2019)

I would caution against modifying your existing RK. Once cut up you can't go back.
Instead, if you really do want to make non-through cuts like rebates, make a replacement RK, it's not difficult.

You can get a piece of Ground Flat Plate from people like Cromwell, in both metric and Imperial sizes, so you should be able to find something suitable. Don't try to use mild steel, you will have great difficulty in keeping it flat.

If you really don't want to start from scratch, buy a replacement RK and mod that, keeping the original for normal use.

Don't forget that you will need to make other guarding arrangements. I have several different guards for different operations. My normal guard is a SUVA-style one, mounted at the far RH corner of my saw and is supported by a shoe on my fence.

When that is unsuitable I have a magnetic stand-alone guard.

I have a dedicated rebate/ dado fence, with 2-way feather boards, which guarding built in to the unit. My Ultimate Tablesaw Tenon Jig has built-in guarding and so does my TS mitre jig, which I am going to film today, actually.

Lots to consider for such a small proposition!


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## Jacob (26 Aug 2019)

The riving knife is supposed to be higher than the blade as it is intended also to hold the crown guard, which is the single most important safety feature of a TS and should not be altered beyond use! It is highly effective and should be the default guarding system. I don't rate the flimsy SUVA type guards unless they are built in to an industrial standard on an industrial machine.
If you want to cut slots etc over the blade then just remove the riving knife. This is much deprecated but can be done if you are careful enough and use the fence and two push sticks.


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## Rorschach (26 Aug 2019)

I made a second riving knife, set very slightly lower than the blade for just this purpose.


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## Steve Maskery (26 Aug 2019)

Jacob":2r4vqix2 said:


> If you want to cut slots etc over the blade then just remove the riving knife.


And just how do you recommend that he guard the blade for this operation, Jacob? Remember that this gentleman is a beginner.


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## Jacob (26 Aug 2019)

Steve Maskery":16z0kh77 said:


> Jacob":16z0kh77 said:
> 
> 
> > If you want to cut slots etc over the blade then just remove the riving knife.
> ...


It's deprecated as I said. He shouldn't do it. He should use a router instead.
But if he chooses to ignore the warnings he should use the fence and two push sticks.
He also shouldn't bodge up a flimsy imitation of a SUVA guard. They are potentially more dangerous than no guard at all, whereas the crown guard is very safe.


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## Steve Maskery (26 Aug 2019)

Jacob":nwsdi2xt said:


> He also shouldn't bodge up a flimsy imitation of a SUVA guard. They are potentially more dangerous than no guard at all, whereas the crown guard is very safe.



I agree. He should make up a good robust SUVA guard, like mine. I don't know where you get the idea that SUVA guards are always flimsy, I really don't. They are only flimsy if they are inadequately made or supported. Mine gives excellent protection AT THE SIDES AS WELL AS OVER THE TOP. Come over and see for yourself. Ah yes, you haven't seen it have you, you are just assuming for the sake of an argument.

I'm sure that yours, Jacob, is not flimsy, but I have seen flimsy crown guards. Not all machines are built to a very high spec.


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## Jacob (26 Aug 2019)

Steve Maskery":23oqw6tb said:


> Jacob":23oqw6tb said:
> 
> 
> > He also shouldn't bodge up a flimsy imitation of a SUVA guard. They are potentially more dangerous than no guard at all, whereas the crown guard is very safe.
> ...


Sorry Steve it was your post a few years back - with your exploding SUVA guard! the-importance-of-practising-what-one-preaches-t88029.html
Put me right off them!
The crown guard is totally superior in that it moves with the blade, up, down, tilt, but the SUVA doesn't unless it is highly engineered and costing 1000s. One here with a price cut; https://www.scosarg.com/suva-s91-narrow ... d-complete
Crown guard is also dead centrally mounted so that even if it touches the blade there are no consequences other than another bit of the guard being gouged out.
Suva guards are sideways mounted so if they touch they can skew around with alarming effect, as your post showed.
Basically even the simplest crown guard is very sturdy and can resist heavy handed treatment. Not so with a basic SUVA guard. Unsafe safety devices can be more dangerous than no device at all.


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## Steve Maskery (26 Aug 2019)

And if you read the post thoroughly you will have read that the fault lay not with the guard or its design, but with the fact that I had not adjusted it correctly. It was entirely my own fault, not the guard's.
If you didn't tighten up your crown guard properly, you could have an accident with it too.
Tell you what Jacob, why don't you just keep using what you are happy with and I'll do the same, eh?
The difference between us is that you are happy to tell a beginner to "just remove the RK" (and with it the guard), and I'm not.


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## Jacob (26 Aug 2019)

Steve Maskery":3eawmszt said:


> ....
> If you didn't tighten up your crown guard properly, you could have an accident with it too......


Er - not really. If it was adrift you'd get plenty of warning as it touched the blade but it would most likely stay in situ, though I expect accidents have happened
They are very safe and should be used whenever possible.


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## Trevanion (26 Aug 2019)

Jacob":3jgyd4ff said:


> Steve Maskery":3jgyd4ff said:
> 
> 
> > ....
> ...



A good friend of mine who's been around machinery for donkeys almost had his head taken off when the crown guard on a Sedgwick rip-saw fell down onto the blade, threw it across the room narrowly missing his head and pulled the riving knife out with it. To this day he does not know for certain what went wrong, My guess is over years of use the riving knife worked its way loose.


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## Doug71 (26 Aug 2019)

Quick question while we are on the topic.

My friend has a table saw with a proper suva guard on it, as you push the wood through the guard lifts up and then drops down again after the cut. All very nice keeping the blade covered but it gives the impression that if you ran the timber through with your finger on top of it the guard could just lift up over your finger and let things get a bit messy with the blade. Is that how they work or are they locked off at a certain height? 

Our old Wadkin had the crown guard on an arm, the guard had a nose piece that you pulled down to within a few mill of the timber (obviously we did this every time :roll: ) so you couldn't fit your finger and the timber under the guard at the same time, kind of felt safer even though part of the blade was exposed if you were not cutting anything.


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## Steve Maskery (26 Aug 2019)

Doug71":18szw9dg said:


> if you ran the timber through with your finger on top of it the guard could just lift up over your finger and let things get a bit messy with the blade



Quite frankly, if anyone did that, they deserve to lose their fingers. It would be an insane thing to do and I don't see how anyone could that accidentally.

"Well, yes, I did feel the guard go over my fingers but I didn't think it would be a problem."


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## Yojevol (26 Aug 2019)

What does SUVA stand for?
Is it South Utah Vollyball Association or maybe
Sydney's Unique Venues Association or even
Schweizerische Unfallversicherungsanstalt


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## Steve Maskery (26 Aug 2019)

Of the three it would be the latter. I don't know the litteral translation, but it is something to do with a Swiss insurance company. It's a standard of guard of which they approve.


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## Doug71 (26 Aug 2019)

Steve Maskery":2s0llnzg said:


> Doug71":2s0llnzg said:
> 
> 
> > if you ran the timber through with your finger on top of it the guard could just lift up over your finger and let things get a bit messy with the blade
> ...



I realise it would be very unlikely and a very stupid thing to do but I picture someone cutting up sheet material on a sliding panel saw, getting distracted and sliding their fingers with the sheet straight under the guard and in to the blade. Just wondered if this could happen or if the guard would physically stop your fingers getting any further.

Had a quick google and I get the impression some of the guards can be locked off but some are just floating.


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## Steve Maskery (26 Aug 2019)

Mine just floats, so it is always in contact with either the table or the workpiece. I really cannot imagine anyone who is authorised to use a TS getting their fingers underneath it and carrying on without realising it. It is an unbelievable scenario.


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## Jacob (27 Aug 2019)

Steve Maskery":u9wmxz21 said:


> Of the three it would be the latter. I don't know the literal translation, but it is something to do with a Swiss insurance company. It's a standard of guard of which they approve.


Or "manufactured by SUVA, the Swiss safety executive" . Presumably they can be approved if made by others to their standard.
https://www.scosarg.com/suva-s91-narrow ... d-complete
You can download a brochure from the above. It's a very sturdy and expensive bit of kit. 
Over complicated perhaps - fussy to use, too many things could be left loose etc.
Feeble imitations of SUVA guards would not and should not be approved!

The other thing a crown guard does is prevent things being thrown up. They may get thrown out if something jams but the trajectory will be horizontal and at waist height!

PS guarded or not, most TS accidents would be prevented if people simply used two push sticks. One push stick is not good unless you keep your other hand behind your back, which would be silly.
PPS had a closer look at the expensive SUVA variations and must say I'm a bit doubtful. They look very much like clumsy 'designs by committee' - intended to relieve management of responsibility for accidents rather than protecting the users?


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## bp122 (3 Sep 2019)

Thank you all for the responses, suggestions and the caution!

I have started a new job, two weeks ago, which has extremely minimal internet access for outside stuff and quite fast paced than my previous place. hence I am a little slow on the responses.

It is a shame, as my previous place had a laser cutting machine where I could have designed and get a riving knife cut out of pretty much any thickness wanted. Maybe I'll call in a favour  

Since the riving knife on mine has a slot (as almost all of them do) for the adjustment bolts, I thought if I should extend the slot upwards, I'd be able to position it further down to get underneath the cutting height line of the saw blade. But no matter how much I played around with it, the curve on the RK wasn't concentric or had enough clearance with the blade curve. Hence I have to get a new knife or make (get one cut- as I don't have any metal cutting tools other than a hacksaw and a drill, not even a bench vise)

On another note, for people who have seen using cross cut sleds etc take the RK out and use a perspex guard across the sled (along the full length of the blade slit) - Is this still safe? - reason I ask is because I am building a sled myself, was wondering if it had the merit.

Thanks guys!


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## Steve Maskery (3 Sep 2019)

Perspex is not a great choice, actually, as it can shatter. You are much better off using Polycarbonate or even a thick piece of HDPE. It is soft, yes, but it doesn't shatter.


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## SamTheJarvis (21 Oct 2019)

I second using a harder steel for a riving knife if you're making your own. Mild steel will invariably end up bent and is surprisngly difficult to get adequately flat again.


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## bp122 (24 Oct 2019)

SamTheJarvis":1iawtahy said:


> I second using a harder steel for a riving knife if you're making your own. Mild steel will invariably end up bent and is surprisngly difficult to get adequately flat again.



Thanks, Sam.
Would you know of a place to buy flat hard steel? My current RK is 2.2mm thick, any thicker and the workpiece won't push through as easily. And I don't have a milling machine to bring standard thickness to my size. Any suggestions?


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## Steve Maskery (24 Oct 2019)

You can buy 2mm stock from places like Cromwell's.


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## AJB Temple (24 Oct 2019)

This kind of topic always gives me the heebie jeebies. I really think table saws are fundamentally dangerous for beginners with no training. I have seen site carpenters (who are supposedly professionals) do the most amazingly stupid things with table saws). Fiddling about with RK and guards is not great if people are not very careful with a safe and robust set up. Examples of experience on property developments: 

Cutting 8 x 4 sheets on portable TS with no support
Cutting mitres with guard off and leaning over the saw to see the line
Removing RK because the wood gets stuck on it 
Forcing wood through because it is binding on the blade
Dropping stuff on an unguarded spinning blade
Dispensing with inconvenient or missing push sticks
Standing right in the path of the kick back
Trying to shove tiny bits of wood through (parquet)

etc....


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## Trainee neophyte (24 Oct 2019)

AJB Temple":34h4lxie said:


> This kind of topic always gives me the heebie jeebies. I really think table saws are fundamentally dangerous for beginners with no training. I have seen site carpenters (who are supposedly professionals) do the most amazingly stupid things with table saws). Fiddling about with RK and guards is not great if people are not very careful with a safe and robust set up. Examples of experience on property developments:
> 
> Cutting 8 x 4 sheets on portable TS with no support
> Cutting mitres with guard off and leaning over the saw to see the line
> ...


I

I am pleased to say that I only managed one on your list - dropping a piece of wood on the blade - I won't be doing _that_ again!

However, I do cut rebates on the saw, and to do that I have to remove both guard and riving knife. Could someone correct my ignorance if necessary, but I was under the impression that a riving knife serves no useful purpose in a rebate, because the wood is a single solid piece, so nothing is going to move and bind on the blade. All my knowledge is from here, or YouTube, and this little nugget is definitely of YouTube provenance, so a definitive ruling would be nice. 

Thanking you in anticipation...


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## Steve Maskery (24 Oct 2019)

A rebate involves _TWO_ cuts...


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## doctor Bob (24 Oct 2019)

Steve Maskery":1o4h53sm said:


> A rebate involves _TWO_ cuts...



Well that depends .............. i could do a rebate 4mm wide with one cut ..........


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## MusicMan (24 Oct 2019)

That's true for a small rebate, but if using two cuts, as Steve implied, there is a possibility of binding on the second one.


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## Steve Maskery (24 Oct 2019)

doctor Bob":y1wotymb said:


> Steve Maskery":y1wotymb said:
> 
> 
> > A rebate involves _TWO_ cuts...
> ...



Yes, that is fair enough.
And I could do a rebate up to 3/4" in one pass because I have a dado head, so nah, nah, na-na, nah!

But I'm sure you take my point.

The fact is that there is an increased chance of kick-back with a two-cut rebate, even with a short fence, than there is with an ordinary rip cut.

For anyone who is still in the dark about it all, there is always YouTube

Yes, yes, I know. The videography is very dated, but it was a long time ago. The content is still relevant.


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## RobinBHM (24 Oct 2019)

Ive spent the last 20 years using an industrial panel saw with an overhead guard - the guard is mounted on 70mm square hollow section steel so it is proper solid.

I have to be honest the guard is almost never adjusted for height :shock: , but any small work is done with 1 or 2 push sticks -always.

I dont see a cut down riving knife as dangerous when rebating, although I would clamp a piece of timber to sit above the blade to prevent hands getting near the blade at the beginning or end of the cut.

My biggest concern with a cut down riving knife is thoss machines where the riving knife is the crown guard mount. -the danger I see is the temptation to use the saw with no guard just because 'its not worth swapping the RK back just for this cut'..........


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## doctor Bob (24 Oct 2019)

Steve Maskery":30z92xbb said:


> Yes, that is fair enough.
> And I could do a rebate up to 3/4" in one pass because I have a dado head, so nah, nah, na-na, nah!
> 
> But I'm sure you take my point.



I do, just being a smart pineapple.


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## Doug71 (24 Oct 2019)

Trainee neophyte":6m4076a9 said:


> However, I do cut rebates on the saw, and to do that I have to remove both guard and riving knife. Could someone correct my ignorance if necessary, but I was under the impression that a riving knife serves no useful purpose in a rebate, because the wood is a single solid piece, so nothing is going to move and bind on the blade. All my knowledge is from here, or YouTube, and this little nugget is definitely of YouTube provenance, so a definitive ruling would be nice.
> 
> Thanking you in anticipation...



You still need a riving knife really depending on how deep you are cutting. The wood can still move because of internal tension and try to grip the blade even if you are not going right through, especially if it's case hardened.


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## doctor Bob (24 Oct 2019)

This is my set up.





The guard just pulls/ pushes up and down. I like to see what I'm doing, but it needs to be low enough to extract efficently.
The riving knife is set 1mm lower than the blade.

I have found over the years the biggest culprit for errors on a saw is firstly user complacency and secondly a dull blade. If you can drag your finger over a blade without it properly catching the skin then it's blunt. 
I do a lot of cutting and can easily get through 4-5 saw blades a week.

If you've never used a sliding panel saw it's just a pure luxury compared to a table saw. 
Most hobbyists will have the fence between them and the board, I like to have the fence at the end of the board. i.e. most people would have the fence at the other end of the sliding table. Not that unusual in the commercial world.

What ever your set up, take it seriously


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## Trevanion (24 Oct 2019)

doctor Bob":i014nl0x said:


> I do a lot of cutting and can easily get through 4-5 saw blades a week.



I can tell just by the single piece of foam matting by the saw, someone spends *a lot* of time standing in that spot :lol:.

I personally prefer having the fence/arm behind the workpiece but I seldom do work with sheet material, 95% of the work is with solid wood usually over an inch thick so I feel the fence helps to carry the workpiece through the blade whilst I would think if the fence was set up the way yours is it would be more prone to coming away from the fence and binding on the blade. I've never had it set up that way mind so it might be just as easy.

How do you find the Altendorf to use? I only hear good things.


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## doctor Bob (25 Oct 2019)

The WA 80 is a great mid way size saw. We've had it about 10 years now and i've probably realigned it twice in that time. Rock solid.
I think Altendorf and Martin are the bentley and rolls royce of saws, Martin is probably edging it, but budget is always a consideration.
If I got another I'd stick with another WA80 but with electric fence and a control screen to speed things up a bit.


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## Trainee neophyte (25 Oct 2019)

Well, I can't compete with the size of Bob's tool, that's for sure. No wonder he needs to wear those special glasses.

However, realising that I know nothing, I have decided to rectify the problem by purchasing Mr Maskery's excellent video tuition guides. I reckon at £5 per finger, it's got to be a worthwhile investment. All I need now is some international internet banking, which is proving trickier than you might think. Money in the post, Steve, I promise!


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## Trevanion (25 Oct 2019)

doctor Bob":3fqn0shy said:


> I think Altendorf and Martin are the bentley and rolls royce of saws, Martin is probably edging it, but budget is always a consideration.



Saws aren't really my bread and butter, but I've used almost all the makes of spindle moulders like Kity, Jet, Sedgwick, Felder, SCM, Wadkin and Martin. The absolute *best* machines I ever used were the Martin ones when I was working for another company, which were a large T-25 and a pair of smaller T-12s. The build quality was second to none and was leagues above even the high-end SCM machines in my opinion, they were far better thought-out as well and definitely designed for a very heavy use, high production environment. I loved them very dearly and it was a shame when I had to leave them behind, I think if you can afford it, they are worth *every* penny more than any other high-end moulder.


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