Crown guard

[ankledeep]

just been reading the thread on resawing in the hand tools section . and saw woodblokes comment


woodbloke
Post subject: Re: ResawingPosted: Jul 06, 2012 7:11am

Mr. Very Sharp


Joined: Apr 13, 2006 8:53pm
Posts: 11578
Location: Salisbury, UK
Teckel wrote:
I usually just run them on the rip saw. It will cut around 4" then flip it over.
If the board is wider than that I finish off bit to be cut with the bandsaw, then run through the thicknesser

I've done this on a table saw in the past and it's not best practice, as you have to remove the crown guard to do it. The so called technique of 'deep ripping' is illegal in any commercial and professional 'shop for that reason - Rob

_________________
The Blokeblog

NOW...I'll bow to his greater experience in these things simply because doubtless he has been "at it " a hell of a lot longer than me, BUT what I want to know, having looked at this particular aspect of things with a somewhat jaundiced eye for a while now, is just WHAT a crown guard does, what are its duties so to speak. I'm not talking industrial machines with whopping cast iron thingies bolted here there and every where like some robot wars leviathan....but yer ordinary common or garden (or is that garage) variety

I mean, is it to stop things flying if it all goes horribly wrong...cant be...them plasticky things wouldnt stop an arthritic slug, let alone a piece of meteoric timber and any way thats what your riving knife is for...stopping timber going meteoric in the first place. Granted i have had timber start to lift when deep ripping...BUT that is what springy thingies are for.. uhm....they do have a name, but age and poverty mean i forget...so springy thingies is what I call em...Uhm...I have just been informed by a very smug looking swmbo that they are Shaw guards....hmmmmmmmmmm
OR ...is it to stop you slicing digits off? well erm...do you think that pathetic red bit of Airfix is going to do that? Indeed it would have to be something special to stop you sliding your thumbs under if you were THAT careless....besides...thats what push sticks etc are for...sacrificial digits......
OR is it to stop you nutting the blade when you faint with surprise when SWMBO brings you a cuppa for one? Well I suppose it might just achieve that, though I have my doubts
OR is it just a convenient place to stick a (very inefficient) dust extract to

Lets face it most table saws of the ";light trade" variety, seem to be designed for maximum inefficiency, that over reaching riving knife with its attached bit of plastic or tin which requires the arms of an orangutan coupled with the dexterity of a gynecologist to remove and replace is a pain in the butt.

so what...exactly is "that ""thing"" for?

I took mine off....reground the riving knife so it is about 3mm below the blade top and replaced it with a floating jobbie...connected via an old hoover wand to the dust extract no obstructions anywhere around the saw table...cos it descends from the roof.



Dust extract is great as the saw is extracted over head through the guard with a hplv shop vac (exiled out side in a box cos of its racket) and under the saw with a hvlp chip extract fitted with .2 micron filter cartridge in side (atm) SOME odd saw dust CHIPPINGS still escape at times because of their relatively high momentum, but all the dangerous fine stuf goes up that wand...and I know it works,,,I can cut Iroko...without a dust mask (though i DO generally still wear one) without ending up hopping round the workshop sneezing.

SO....I repeat...what EXACTLY is that pathetic bit of plastic supposed to do (apart from getting in the way

 

[tool613]

SO....I repeat...what EXACTLY is that pathetic bit of plastic supposed to do (apart from getting in the way

I think it is to mimic a real crown guard in the cheapest of ways to meet regulation. And what a real crown guard is to do is
one; keep your hand from ever being over top of the blade(and the reason you think its in your way)
two ;keep swarf from hitting your face
three ;reminding you your hands are to close

One only has to ask if i remove the wood suddenly where are my hands?



jack
English machines

 

[baldpate]

SO....I repeat...what EXACTLY is that pathetic bit of plastic supposed to do (apart from getting in the way

Talk about co-incidence! - your question is one I was on the point of asking myself, because I'm in the process of trying to retro-add safety features (riving knife, blade guard, hold-downs etc) to a small, home-made 'table saw'. Thinking about the design of a blade guard, I realised I needed to start by knowing what exactly it's FOR.

So far I've come up with:
- discourasge you, in a moment of absent-mindedness, from placing a body part on top of the blade.
- stop sawdust & chips being thrown in your face.
- help stop/slow lift-off, if the riving knife doesn't prevent kickback.
- serve as dust extraction hood.

Anything else?

 

[MattMoore]

I run a commercial workshop, and I have deep ripped timber on a number of occasions. quite what is illegal about it I don't know. my riving knife is set millimetres below the height of the saw blade so I can pass material over without it being a problem. my dust extraction is attached to the side of the saw on a counter balanced head so this is as close as possible to the material(when you do the second cut the saw dust really kicks up so having extraction is essential)

Sent from my Desire HD using Tapatalk 2

 

[woodbloke]

I run a commercial workshop, and I have deep ripped timber on a number of occasions. quite what is illegal about it I don't know. my riving knife is set millimetres below the height of the saw blade so I can pass material over without it being a problem. my dust extraction is attached to the side of the saw on a counter balanced head so this is as close as possible to the material(when you do the second cut the saw dust really kicks up so having extraction is essential)

Sent from my Desire HD using Tapatalk 2

You have to use an unguarded blade, it's that simple and in a commercial 'shop that is illegal...end of story. What we choose to do in our own 'shops at home is an entirely different kettle of worms, but in a 'commercial 'shop, the regs state that saw blades must be guarded - Rob

 

[sw_edge]

Rob, Matmoore is saying the blade is guarded....just not by a crown guard attached to the top of the riving knife as can be found with most cheap table saws like my TS-200.
First thing I did with mine when I got it was rig a new floating cantilevered crown guard so I could deep rip/cross cut.

 

[Cheshirechappie]

The sole reason that regulations have developed concerning woodworking (and other) machinery in a workplace is because of accidents. It used to be a statutory obligation on the Factory Inspectorate (now part of the Health and Safety Executive) to record accidents resulting in personal injuries in workplaces, and to recommend measures to reduce the chances of reoccurrence. Anybody who has read any woodworking related history will know that machine operators rarely survived a career with all their fingers intact, a situation that arose partly through inadequate guarding of moving parts. Bear in mind that large establisments may employ tens of people, under pressure of time or on piecework, in noisy and bustling surroundings. Momentary inattention could be fatal - and sometimes was. The regulations surrounding guarding came about to reduce, or if possible eliminate, such accidents.

Others have explained what a crown-guard does. It's there to make your activity safer, because others in the past (and not just one or two) suffered injury for the lack of it.

In your own workshop at home, you can do pretty much as you choose - the remit of the HSE does not cover people's activities in their own homes. If you have other people using your machinery, you may be on less solid ground - you have a duty of care to others. In a workplace, you may 'get away' with things if you are the sole user of the workshop, but if anybody else uses the machine for any purpose, you must abide by the safty regs or face prosecution if something goes amiss.

Many years of accumulated experience would suggest that a table saw or circular rip saw has the potential to cause a lot of damage very quickly if things go wrong; you can lose control of an operation very suddenly. It makes a lot of sense to reduce the chances of that happening, and to remain in control, by not using the machine beyond it's limits, and taking sensible steps with guarding and guides.

Much the same applies to any machine; though the regulations may be slightly different in other fields than woodworking, the basic principles are the same, and for the same purpose - to reduce or eliminate personal injuries, especially in the workplace.

 

[Lord Kitchener]

Just to add to the sensible stuff above, a crown guard bolted to the riving knife, with the whole set up adjusted so the guard is only just above the material being cut, will help prevent the wood lifting, the guard obstructs it.

Another reason is that if you lose your footing, or get heavily distracted, or faint of have a hreart attck or stroke you are quite likely to put your hand out to prevent yourself from falling as a reflex action. A guard will stop your hand hitting the blade in these circumstances. They are not there for when one is paying careful attention.

 

[woodbloke]

The sole reason that regulations have developed concerning woodworking (and other) machinery in a workplace is because of accidents. It used to be a statutory obligation on the Factory Inspectorate (now part of the Health and Safety Executive) to record accidents resulting in personal injuries in workplaces, and to recommend measures to reduce the chances of reoccurrence. Anybody who has read any woodworking related history will know that machine operators rarely survived a career with all their fingers intact, a situation that arose partly through inadequate guarding of moving parts. Bear in mind that large establisments may employ tens of people, under pressure of time or on piecework, in noisy and bustling surroundings. Momentary inattention could be fatal - and sometimes was. The regulations surrounding guarding came about to reduce, or if possible eliminate, such accidents.

Others have explained what a crown-guard does. It's there to make your activity safer, because others in the past (and not just one or two) suffered injury for the lack of it.

In your own workshop at home, you can do pretty much as you choose - the remit of the HSE does not cover people's activities in their own homes. If you have other people using your machinery, you may be on less solid ground - you have a duty of care to others. In a workplace, you may 'get away' with things if you are the sole user of the workshop, but if anybody else uses the machine for any purpose, you must abide by the safty regs or face prosecution if something goes amiss.

Many years of accumulated experience would suggest that a table saw or circular rip saw has the potential to cause a lot of damage very quickly if things go wrong; you can lose control of an operation very suddenly. It makes a lot of sense to reduce the chances of that happening, and to remain in control, by not using the machine beyond it's limits, and taking sensible steps with guarding and guides.

Much the same applies to any machine; though the regulations may be slightly different in other fields than woodworking, the basic principles are the same, and for the same purpose - to reduce or eliminate personal injuries, especially in the workplace.

Thanks CC, an excellent summation - Rob

 

[JakeS]

Another reason is that if you lose your footing, or get heavily distracted, or faint of have a hreart attck or stroke you are quite likely to put your hand out to prevent yourself from falling as a reflex action. A guard will stop your hand hitting the blade in these circumstances. They are not there for when one is paying careful attention.

This may be the case with your saw, but I doubt very much the ABS guard on mine would do more than buy me an extra fraction of a second to move my hand or other body part while the saw chewed through it. I'm not convinced it would be long enough...

 

[Lord Kitchener]

Another reason is that if you lose your footing, or get heavily distracted, or faint of have a hreart attck or stroke you are quite likely to put your hand out to prevent yourself from falling as a reflex action. A guard will stop your hand hitting the blade in these circumstances. They are not there for when one is paying careful attention.

This may be the case with your saw, but I doubt very much the ABS guard on mine would do more than buy me an extra fraction of a second to move my hand or other body part while the saw chewed through it. I'm not convinced it would be long enough...

Have you considered making one out of plywood etc, large enough so that it will hit the table of the saw before the blade will penetrate it?

 

[Steve Maskery]

Mine is polycarbonate and mounted on a boom from the far right corner of my saw. It is articulated so that it rises as the wood enters, stays level as the cut proceeds then drops from the front down as the wood exits. The only way I can cut my fingers is if I deliberately put my fingers under the guard and move it up out of the way. If I did fall on it it would withstand even my weight, I think.

I think my guard is better than anything that comes with a consumer TS and as good as those on most industrial machines.

S

 

[JakeS]

Have you considered making one out of plywood etc, large enough so that it will hit the table of the saw before the blade will penetrate it?

It is in fact on my list of things to do (following the pattern Steve outlines in his table saw safety DVD, in fact - speak of the devil!), along with shortening/replacing the riving knife to do "non-separating cuts".

All the same, I figure it's worth mentioning; lots of people will leave the plasticky thing that came with their saw in place. I'd hope nobody would rely on their crown guard being stiff enough to lean on, of course!

 

[ankledeep]

Another reason is that if you lose your footing, or get heavily distracted, or faint of have a hreart attck or stroke you are quite likely to put your hand out to prevent yourself from falling as a reflex action. A guard will stop your hand hitting the blade in these circumstances. They are not there for when one is paying careful attention.

This may be the case with your saw, but I doubt very much the ABS guard on mine would do more than buy me an extra fraction of a second to move my hand or other body part while the saw chewed through it. I'm not convinced it would be long enough...

Which is why I altered mine (along with regaining the facility to deep rip) I would suggest that the arrangement I have is safer than the plasticky thing stuck to most "light trade " saws, extracts far better and fulfils all the other requirements for a crown guard.

Steve M...yes I like your design of guard very much, and I am atm looking at how I can articulate my type and yet retain the suspension from above, which has the advantage that There is nothing "at the side of the table", where it would interfere with cutting 8x 4 sheets(something I have a need for quite regularly.

The bristle strip on the bottom of the guard was added because i cut 3mm GRP sheets, having the bristles there means a good seal to the sheet AND it sweeps up all the odd bits that would other wise escape to itch itch itch

 

[Steve Maskery]

Andrew
Is there a reason why you can't just make your boom longer than mine?
If you end up mounting it from the ceiling, I'd be very interested indeed in seeing a pic of it.
Steve

 

[ankledeep]

Andrew
Is there a reason why you can't just make your boom longer than mine?
If you end up mounting it from the ceiling, I'd be very interested indeed in seeing a pic of it.
Steve

Steve...if you look in the photo thats with the OP you can see the vac sweeper wand (the silver thing) descending from the roof with my (real 'orrible) first go at the guard hanging from it. I can take more detailed pics if you like ...

 

[Steve Maskery]

Ah, got you. Hmm, that doesn't get you a very good pivot point, does it?
S

 

[ankledeep]

Ah, got you. Hmm, that doesn't get you a very good pivot point, does it?
S

quite right Steve, so I'm going to have to make a suitable (fairly) air tight pivot point at the end where the hood fits the pipe, similar I suppose to those you find on vac sweeper brushes. :?: It works as it is, very efficiently, with little or no dust escaping, however it is open to the criticism that it is locked up in position, at a depth determined by the thickness of timber, (in much the same way as a standard crown guard) and thus does not offer the best available protection (though it has to be said i have NO intention on playing "lets see how close i can get my fingers to the blade"), although that photo seems to show my hands close to the blade it is misleading as its taken directly from the side, my hands are actually a good 6 inches to the side of the blade. So what i want to do is pivot the actual hood on the pipe...thinking cap has been on for about 3 weeks over this (hammer)