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Riving knife higher than the blade! - Potential Mod?

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bp122

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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
 

ManowarDave

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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 :D)

Dave
 

ManowarDave

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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
 

Steve Maskery

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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! :)
 

Jacob

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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.
 

Rorschach

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

Steve Maskery

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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.
 

Jacob

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Steve Maskery":16z0kh77 said:
Jacob":16z0kh77 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.
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.
 

Steve Maskery

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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.
 

Jacob

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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.
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, .....
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.
 

Steve Maskery

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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.
 

Jacob

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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.
 

Trevanion

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

Doug71

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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.
 

Steve Maskery

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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."
 

Yojevol

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

Steve Maskery

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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.
 

Doug71

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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
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."
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.
 

Steve Maskery

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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.
 

Jacob

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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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