Ceiling mounted crown guard.

[Jacob]

"too space hungry" is another way of saying "getting in the way".

No in the context of this discussion it clearly isn't, the distinction (which I don't think was that hard for anyone to understand) is where it gets in the way, i.e. at the blade or more generally in taking space up in the workshop. ...

It's in the way wherever or however it's in the way. Not semantics, just logic.

 

[Wizard9999]

Thanks to those that offered on topic answers. Riving knife mounted "safety" features? Not even once.

It does 4 things really well:
1 works as riving knife
2 prevents accidental contact with the blade from above. It's fairly sturdy and can take a big knock, though sides of the guard may lose a bit of plastic
3 prevents having stuff thrown up and off. Again it's fairly sturdy in this respect and if set close enough a thrown piece won't have gathered much momentum. It won't stop stuff being thrown out horizontally of course.
4 Can be connected to dust extraction

There are lots of fussier examples with lifting clear covers etc but the fussier they are the less safe they are . Keep it simple.

Jacob

As a newcomer all of that makes perfect sense. But my initial problem was with visibility, I didn't like not being able to see where the blade was entering the wood. Do you find any problems with this? The picture you included seems to show the guard mounted as high as it can be, do you recommend this approach, maybe that is why visibility isn't an issue or maybe with more experience the urge to see where the blade meets the piece being cut is simply not there any more.

The second issue is then of course when making non-through cuts. Is the removal of the riving knife mounted guard not an issue because the work piece is covering the blade? Or maybe you simply do not recommend using the table saw for this purpose?

As a newcomer I am keen to learn and appreciate you highlighting the strengths of your advocated approach, but what I would really value as well is your views on how to address the shortcomings of a riving knife mounted guard.

Terry.

 

[woodbrains]

Hello,

Disadvantages of the riving knife crown guard, which is why the enlightened find better alternatives!

Dust extraction is feeble or non-existent, since HVLP dust collectors, require large diameter ducts, reducing down to 32mm typical crown guard outlet defeats extractors.

A wayward whack to the crown guard with an unwieldy plank bends the riving knife and ruins it. Who hasn't come across a TS with a deformed knife.

Partial thickness cuts cannot be done without removing the whole thing, which is dangerous, obviously and a PITA. What is the point of having a massive hunk of cast iron machinery, and then hamstringing its usefulness with a safety guard. I make shoulder cuts for tenons on a TS, which I find fabulously accurate quick and convenient.

Crosscut sleds can't be employed with a crown guard, which are more convenient than mitre gauges and take up less space than sliding carriages, for people who don't have acres of space in their workshop.

Mike.

 

[DennisCA]

The second issue is then of course when making non-through cuts. Is the removal of the riving knife mounted guard not an issue because the work piece is covering the blade? Or maybe you simply do not recommend using the table saw for this purpose?

Some people argue this. I don't, I prefer to use my saw for several types of non through cuts, I constantly go to it rather than the horrid, screaming router table which I only ever use when the situation absolutely demands it.

If you got some cheap tinpot saw though it might be unsafe on the table saw too. I don't have this issue, I have a high quality machine and love to use it.

I might just keep my current setup out of spite.

 

[Jacob]

..... But my initial problem was with visibility, I didn't like not being able to see where the blade was entering the wood. Do you find any problems with this?

depends on the particular set up I suppose but it's not a prob on mine. It has two fitting holes - I use the rear one as the front one extends it to cover a scribing blade which I don't have

The picture you included seems to show the guard mounted as high as it can be, do you recommend this approach,

Random picture from the net. Mines pretty similar. I set it to just above the teeth

The second issue is then of course when making non-through cuts. Is the removal of the riving knife mounted guard not an issue because the work piece is covering the blade? Or maybe you simply do not recommend using the table saw for this purpose?

It's thoroughly deprecated but people do it anyway. The hazard here is kick back - the wood can pinch the blade as tension is released and the timber bends. Result; over-heating blade (gets warped) over loaded motor but at worst a big throw back

As a newcomer I am keen to learn and appreciate you highlighting the strengths of your advocated approach, but what I would really value as well is your views on how to address the shortcomings of a riving knife mounted guard.

Terry.

There are no particular shortcomings to address though you might try a different make if yours doesn't suit

 

[Jacob]

Thanks to those that offered on topic answers. Riving knife mounted "safety" features? Not even once.

It does 5 things really well:
1 works as riving knife
2 prevents accidental contact with the blade from above. It's fairly sturdy and can take a big knock, though sides of the guard may lose a bit of plastic
3 prevents having stuff thrown up and off. Again it's fairly sturdy in this respect and if set close enough a thrown piece won't have gathered much momentum. It won't stop stuff being thrown out horizontally of course.
4 Can be connected to dust extraction
5 stays in situ with all movements of the blade

There are lots of fussier examples with lifting clear covers etc but the fussier they are the less safe they are . Keep it simple.

and 6 - very quick and easy to remove and accurately re-set, if you have to.
NB the main dust extraction would be from below - the port on the guard is an extra for the small amount of stuff thrown up. I don't use mine but would if cutting mdf etc.

 

[Wizard9999]

..... But my initial problem was with visibility, I didn't like not being able to see where the blade was entering the wood. Do you find any problems with this?

depends on the particular set up I suppose but it's not a prob on mine. It has two fitting holes - I use the rear one as the front one extends it to cover a scribing blade which I don't have

The picture you included seems to show the guard mounted as high as it can be, do you recommend this approach,

Random picture from the net. Mines pretty similar. I set it to just above the teeth

The second issue is then of course when making non-through cuts. Is the removal of the riving knife mounted guard not an issue because the work piece is covering the blade? Or maybe you simply do not recommend using the table saw for this purpose?

It's thoroughly deprecated but people do it anyway. The hazard here is kick back - the wood can pinch the blade as tension is released and the timber bends. Result; over-heating blade (gets warped) over loaded motor but at worst a big throw back

As a newcomer I am keen to learn and appreciate you highlighting the strengths of your advocated approach, but what I would really value as well is your views on how to address the shortcomings of a riving knife mounted guard.

Terry.

There are no particular shortcomings to address though you might try a different make if yours doesn't suit

Thanks Jacob, most helpful. In terms of non-through cuts do you use a router for dados and rabbets, or is it the case that you don't actually use these types of joint given the issues you have highlighted with using the tablesaw for them?

Terry.

 

[siggy_7]

It's thoroughly deprecated but people do it anyway. The hazard here is kick back - the wood can pinch the blade as tension is released and the timber bends. Result; over-heating blade (gets warped) over loaded motor but at worst a big throw back

The hazard here is most certainly kick back - if you have one of those rubbish RK mounted crown guards where the RK sits proud of the saw blade, such that you have to remove or reposition the RK as well as removing the guard to perform such a cut (the alternative with a RK mounting being to have the RK sitting just below the top of the blade but lose depth of cut with the crown guard fitted, which is also far from ideal). Although for cutting joinery, wood is generally pretty straight grained and particularly if the depth of cut is not great (and even more so if the remaining section of wood is substantial) then the wood isn't going to move a great deal so the risk of kick back, even without an RK fitted, is pretty low. NB I am not recommending this practice

If you look at the likes of Felder and Altendorf, their more expensive saws dispense with this altogether and replace it with a (very substantially built) overhead supported guard. That in itself should tell you what the optimal solution is if you buy the best engineered kit. No one seems to be arguing that a flimsy overhead guard is an acceptable guarding solution, but properly built this would appear to be regarded by most as the best solution.

 

[blackrodd]

The guarding mentioned as a preference by some members are for different saw benches.The ripsaw, Wadkin for instance, https://www.google.co.uk/search?q=wadki ... rWYHn_o%3D
These have far heavier duty over guard mainly because the riving knife mounting wouldn't be man enough for the
potential kickback hazard.
As these saw benches were designed to cut and convert really thick timber, 6", 8", or 9" with a 5 or more HP motor
driving the blade, imagine a 9" railway sleeper coming back at you!
I've used these for years in the sawmill with an assistant at the back with a large mallet and wedge, waiting for my nod, or shake of the head as to weather I can hold it 6" past the riving knife while he whacks the wedge in to relieve the pinching, or I pull out of cut and start sawing again.
A band re saw would be too dangerous for this job as the feed would easily drive the blade off the wheels!
As width is not an issue on the ripsaw, the guarding is off to the right side as seen in the link above.

The running or dimension saw will usually only cut 3" and not so hazardous situations as above, are usual, the guarding on these is usually on the riving knife which is set just below the blade tip and can be left in place for non through cuts, as in housing joins, tenons, also cutterblocks, etc
This also caters for the larger 8x4, or10x5 sheet cuts as the guarding is on the riving knife.
The Felder and Altendorf models mentioned I think you'll find are guarded in that style simply because of the need for the removal of the very fine and worst dust hazard experienced by cutting man made boards, mdf etc,Again it's a multi use machine and has the benefit of a sliding bed
I know the pipe affixed to the guard is only about 30mm to suck the dust away but a 100mm extractor pipe would be rather a menace to fix and keep in place etc.
I personally can't see any advantage in a ceiling mounted saw guard in the usual workshop situation, Fixing in a strong and very sturdy way, ducking and dodging the thing hanging down whilst the saw bench is stowed away and also then trying to line up the guard and bench and the blade.
Still, What would I know, I'm just a fully trained professional!
Regards Rodders

 

[PAC1]

For all those that cannot see the advantage of riving knife or crown guard read this http://www.hse.gov.uk/pubns/wis16.pdf
It may be said to be aimed at professionals rather than amatures but it is really about saving digits and avoiding pieces of wood heading towards you far faster than you can react
A cross cut sledge is not a valid excuse for ditching the crown guard. Adapt your sledge to work with your crown guard.
The crown guard needs to be rigidly fixed whether to the riving knife or beam or ceiling.

 

[Woodmonkey]

The running or dimension saw will usually only cut 3" and not so hazardous situations as above, are usual, the guarding on these is usually on the riving knife which is set just below the blade tip and can be left in place for non through cuts, as in housing joins, tenons....

Many saws, mine included, the riving knife can't go low enough to achieve this so the only way is to take it off. Even if it did go low enough, you would still need to remove the guard, hence why people would rather have the overhead style guard

 

[No skills]

I will be making a beam mounted guard for my saw (one day) as like Dennis I'm not keen on large routers/router bits and would prefer to do certain cuts on the table saw. Luckly the riving knife on my saw can be adjusted for height so no need to remove it and fire pieces of wood through the garage door or me.

Funny I'm fine with smaller router bits and other much more dangerous tools and practices, not sure how I'd go with a spindle moulder - either love it or dung myself I spose.

I wonder if unistrut could be used to construct the basis of the ceiling mounted guard??

 

[n0legs]

I wonder if unistrut could be used to construct the basis of the ceiling mounted guard??

I've used that stuff so many times for so many applications, it would be my first choice for such a task.

 

[DennisCA]

Speaking of rigid, this is the setup on mine, though it's an old picture with my shop not yet complete, the saw faces the opposite direction now and I have removed the wood mitre fence with the factory aluminum one which is much longer. As you can see here, the mount point is out to the left. But the setup is rigid and sturdy, in fact it's far more sturdy than any riving knife mounted solution, that hood once the levers are locked, easily holds up and supports long boards when you get to the end of a cut. I've ripped boards as long as 4 meters.

This is the proper way a classic dimensioning saw is put together and any proper modern saw for that matter. And yes, fully trained professionals have told me this in person, while decrying the riving knife mounted solution as a finger chopper, because it so often gets removed.

I might just keep it and get a shorter aluminum extrusion as a mitre fence and reduce the footprint that way...

 

[Jacob]

Speaking of rigid, this is the setup on mine, though it's an old picture with my shop not yet complete, the saw faces the opposite direction now and I have removed the wood mitre fence with the factory aluminum one which is much longer. As you can see here, the mount point is out to the left. But the setup is rigid and sturdy, in fact it's far more sturdy than any riving knife mounted solution, that hood once the levers are locked, easily holds up and supports long boards when you get to the end of a cut. I've ripped boards as long as 4 meters.

This is the proper way a classic dimensioning saw is put together and any proper modern saw for that matter. And yes, fully trained professionals have told me this in person, while decrying the riving knife mounted solution as a finger chopper, because it so often gets removed.

I might just keep it and get a shorter aluminum extrusion as a mitre fence and reduce the footprint that way...

I see your problem - the room is too small for the saw. The guarding looks excellent however. Maybe you should think of a smaller saw with riving-knife/crown-guard? Or a bigger room?

The riving knife is for smaller saws say max 12" dia as blackrodd explains above. It most certainly is not a "finger chopper", even if removed, if push sticks are used. Even without push sticks it offers a good deal of protection. It is simple, reliable and safe.
Whereas an inadequately fitted top guard most definitely is a finger chopper - as Steve Maskery demonstrated some months ago in another thread.

PS if you are worried about the risks ensuing from taking a guard off (whatever the design) then don't take it off.

 

[DennisCA]

It's not too small and I won't downgrade.

 

[nev]

The OP was a request for info on ceiling mounted guards, not a request for a debate on alternatives.

Jacob, when you offer advice and it is rejected as off topic by the OP, please refrain from banging on about it post after post and ultimately hijacking the thread. If it bothers / interests you that much please by all means start a fresh thread. ( and please don't be pedantic and reply to this, any reasonable person can see that the OP is not interested in the advice you have offered.)

Now back to the original question, ceiling mounted guard ideas anyone?

 

[Steve Maskery]

Dennis
I see your problem. I also think that anything you build down from the ceiling will have to be at least as solid. I will be interested to see where you go with this.

Jacob, you will be delighted to know that my damaged fingernail has just about grown out! I'm rather more diligent about making sure it is adjusted correctly after that little episode.

 

[Sporky McGuffin]

In terms of mounting something reasonably rigidly to a ceiling, there's a solution that already exists - my last job was at an audio-visual integrator, and we mounted projectors up to 50kg and flat panel screens way over that from ceilings via 52mm diameter steel columns. There are lots of different plates, brackets and clamps to enable the columns to be mounted to pretty much any ceiling that'll take the load, and a 52mm steel tube is pretty stiff. Combine some of this with some Unistrut and the world is your mollusc of choice.

Mostly I specced stuff from www.unicol.com but there are lots of alternatives.

 

[paulrockliffe]

I'd be concerned that a projector mount isn't designed to take a bending moment; the mount is unlikely to be stiff enough with a side load on it. I reckon you need the welder out and a bracing solution that spans two or three ceiling joists for it to have sufficient stability to stop a large kickback.