Dado blade - why not...

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wizer":2cablfku said:
I think the vast majority of us groaned when we say the title, I'm surprised it was niki who started it, I'm sure he's been around the block with this a few times. In fact, something tells me niki and scrit specifically fell out over this, but that might be another brain fart.

Still, it's all very civil so far. Maybe it's good to bring it out once in a while. If only to divert from other upsets...

I wasnt here for the last round of dado madness but in general its difficult to see why anyone should fall out over differences of opinion like this - if you think its safe to use then use it, if you dont, dont - pas de problemo ne cest pas
 
Being quite new to the forum, this is the first dado debate i have seen and im quite interested in the subject. I know what a dado is but have never actually used one (or seen one in the flesh for that matter) as i came to furniture making since its ban, and therefore it wasnt covered at college.

I can understand why some people hate them from a safety front but my question is... is it any more dangerous than using the standard blade on the TS with the riving knife and therefore crown guard removed for say separating lid and box?

Luke
 
They are not necessarily more dangerous Luke, it's just they can do a hell of a lot more damage to you if anything goes wrong.

Roy.
 
L Harding":21tkw6yp said:
Being quite new to the forum, this is the first dado debate i have seen and im quite interested in the subject. I know what a dado is but have never actually used one (or seen one in the flesh for that matter) as i came to furniture making since its ban, and therefore it wasnt covered at college.

I can understand why some people hate them from a safety front but my question is... is it any more dangerous than using the standard blade on the TS with the riving knife and therefore crown guard removed for say separating lid and box?

Luke

with the exception of the issue of the arbour nut unscrewing probably not - but then i'm of the school that believes the safety guards are there for a reason and doesnt taken them off for anything. If i cant do it with the guards on i find a way with different kit

(box wise for example i rout a line all round with a 1/8 straight cutter on the table then cut through with a flushcut saw )
 
L Harding":3lvqojue said:
is it any more dangerous than using the standard blade on the TS with the riving knife and therefore crown guard removed for say separating lid and box?

This is the million dollar question that causes upset, everyone has their opinion. In MY opinion, the difference is rather small. I'm not qualified to answer fully. Someone will be along to tell us exactly what the problem is. All I know is that one of the main issues argued is to do with the stopping\breaking time.

Obviously, unless you are using a dado for through cuts (which is pointless), you need to remove traditional guards because they are fixed to the riving knife.
 
big soft moose":1dddbs0g said:
speed wise I would think that its quicker the change a router cutter than to change the blade and remoive the riving knife etc , but each to his own

You are right, Pete... But, on the other hand, a dado blade can usually complete a cut in one single pass where as, with a router cutter, you might have to cut a groove in several passes, raising the blade by a few mm each time. :wink:

If you were looking to do a lot of grooving or rebating like this then, I guess it would also pay to have separate saws set up for ripping and dado-ing... :roll:

Luke, any cutter or blade used without any guarding is potentially dangerous. The only way I can think of where a dado blade might be more lethal is because of the increased kerf - think of how the teeth on your average saw blade become 'invisible' once it starts spinning... :shock: I've used a dado blade in a radial arm saw before and you get the same effect. In that situation though, because of the increased forces, I think they may be more likely to 'snatch' when you hit a knot?
 
hi


but then i'm of the school that believes the safety guards are there for a reason and doesnt taken them off for anything. If i cant do it with the guards on i find a way with different kit


very well said BIG SOFT MOOSE i could not have put that better , i've said it before, remember guys the pinkies only grow once. But don't start me on that subject of guards , or we will be here all knight .

I used dado head / wobble saw for yrs and yrs when we didn't have things like brakes etc we never had accidents back then , if you feel safe using it ok , if it frightens you then don't use one , if you have to remove a guard to use one , or modify your machine in any way , simbles , your nuts .hc
 
Must say (in the nicest possible way - and just to register a view rather than engage in any argument) that i struggle when ideology rather than situation specific practicalities kicks into issues like this - whether the ideology is one of personal freedom, or of big brother knows best.

Rules almost by definition deliver less than optimum results for the majority of situations as the price of preventing extreme happenings in relatively rare specific cases.

I'm no expert, but it seems to me that the problem the legislation is getting at is not so much potentially dangerous practices (what isn't in woodwork - anybody dropped a sharp chisel edge down on their thigh lately?), but the fact that in the work environment employees can be forced as a result of the boss/employee relationship and the power hiring and firing confers to work in situations and with set-ups that truly are dangerous.

It seems to me that there's no piece of wood or metal cutting machinery that doesn't present serious risks if mishandled. There's very little a dado head is going to do you in use that a tenoning head on a spindle moulder isn't, or a legal slotting cutter or a saw blade for that matter.

It's likewise perfectly possible to create a high risk of badly injuring yourself on a guarded saw, or using a badly fitted blade or cutter of safe design on a safe machine - while on the other hand you can avoid most of the risk of an unguarded blade capable of being dangerously installed while cutting a dado IF you adopt appropriate methods.

The problem in both cases (spindle moulder cutters and dado heads) that led to legislation was surely that both left open a high likelihood of accidents if misused or badly set up - but was no doubt partly happenstance too in that somebody in power found themselves needing to be seen to act.

Trouble is that it's a moving target. Accidents usually occur as a result of unthinking errors rather than deliberate risk taking, and one of the problems of creating 'safer' circumstances is that we tend to just reduce our vigilance accordingly to restore the level of perceived risk we feel comfortable with. (or just below that at which we feel the need to bother our buttocks to respond)

The result is that the tightening of the screws that the safety lobby goes for as a result of this (e.g. speeding) just ends up creating an exponentially increasing overlay of impracticality, restriction, direct cost, and vested interests in return for an ever reducing benefit for a few loons, and probably a nett disadvantage (even in terms of accident reduction) for the majority.

I don't know what the accident statistics are in the US where dado heads have long been the norm, but they surely can't be that bad or they would have long since been canned there too.

For what it's worth woodworking is inherently dangerous, but the reality for those machining wood every day is that the effects of sub par performance by dust systems (or of rushing to get work through as a result of not being very well paid) are probably far more likely to bring them to a sticky end than a dado head....


ian :) ?
 
I have managed without the dado and I think it a classic example of what you never had you haven't missed.

My Shepparch T/S came with a form of dado cutting blade, but I never actually set it up before the saw was returned to suppliers.
 
As far as I am aware Dados have never been banned. When braked saws became compulsory it became apparent that a Dado set could come loose very easily due to the inertia when the brake was applied. To get around this they they restricted the length of the arbour making it impossible to fit a Dado set. All it really needs is a keyed arbour as used on a horizontal milling machine where cutters much wider than a Dado set are used as standard.

John
 
Personally I don't understand this 10 second braking rule, one second of contact with a blade is enough to do considerable damage.

I think a 10 second rule is really a ploy for economics when doing repetitious work on a machine, it avoids longer waiting times when wanting to put a new piece on to the table?
 
Paul.J":qg803ou1 said:
We used to use groovers at work upto 1/2" wide which were unguarded,and even put slithers of card in to make them wobble to get that little bit of extra width.
I still use my dado set on my home table saw and find them quicker to set up than the router.
If used correctly i just can't see a problem with them.

I still have 'wobble-saw and washers' for my Coronet Major. Can't recall when I last used it. This saw is a 'table saw' because its guard and knife are fixed to each other. So to use the saw for grooving etc. meant the guard had to come off. So, if I used the wobble-saw, well I was sort of.... careful? Simple as that!

When I bought my first router, it was obvious which method to use for grooving.

John
:)
 
The 10s rule is there because most tablesaw accidents occur not whilst actually cutting, but when retrieving the workpiece immediately after it has been cut, whilst the blade is slowing down. By shortening this time there is less risk of injury.
S
 
I'm so sorry, I didn't have any intention to make any "thunder storm" around this subject...

I don't care if one is using dado blade or not. I just asked why it is prohibited and what is the official reason of the HSE for prohibiting the use of dado blades on table saws...

The reason that I'm asking is that, many times I'm asked (on American forums) why they are prohibited....

I believe that the HSE knows the reason and it's written somewhere just that the access to the HSE material is very limited.

I was reading somewhere, that dado blades up to 1/2" width where legal but than they prohibited...

Somebody told me that since they imposed the "Blade must stop within 10 seconds" low - they prohibited the use of all the dado blades on table saws because of the danger that the Arbor nut will open....

So, if you don't have a direct answer to my question, please don't "Add fuel to the fire"....

Devonwoody
The "10 seconds" law came after the HSE discovered that many accidents happened during the blade run-down...people just pushed the fingers too early.
So, for all those "un-patient" guys (like me) they "invented" the "10 seconds" law.

Regards
niki
 
The main reason for the braking regs is that if the motor isn't running, there isn't the obvious 'danger' signal of the sound of the motor.

I don't think that dado heads are expressly prohibited per se, but they are widely regarded as failing the obvious safety principle that you should use the safest method to achieve a given end.

Non-limiter dado heads would be unlawful to use in a workplace and dado heads with limiters are not widely available at all. US style heads do not have limiters, so if you did get bitten, you would stand a very good chance of getting dragged in and having your fingers/hand very badly mangled.

As an amateur you can take whatever risks you like, including that one - it depends whether you think it is worth it. Usually this calculation involves not actually thinking about the possible consequences because it will never happen to me.

The argument that US would have banned them if they were dangerous is false. US health and safety regulation is very slack indeed, and their industrial accident record is far worse; they are decades behind us on this kind of thing.
 
Steve Maskery":3cni4ksm said:
The 10s rule is there because most tablesaw accidents occur not whilst actually cutting, but when retrieving the workpiece immediately after it has been cut, whilst the blade is slowing down. By shortening this time there is less risk of injury.
S

Your comments are valid, but if the blade took 60 seconds to come to a stop and there were 100 operations made on the saw in one day that would amount to 6000 seconds = 100 minutes or only around 17 minutes lost at 10 second stop time.

So perhaps time is also a factor.
 
From my reading dado heads are not prohibited but there is a maximum blade width permitted of 15/16 mill.

Roy.
 
devonwoody":2mxh7xt3 said:
Personally I don't understand this 10 second braking rule, one second of contact with a blade is enough to do considerable damage.

I think you will find the 10 second rule applies to all of the workshop machines, it is to protect the users from machine that without a brake will run on for a long time, with very little noise. On a well set-up machine this can be several minutes. This can lead to cutters being touched while they are still moving and the momentum of the machine will still remove bits of the unfortunate users, not good.
Having fitted brakes to machines you introduce problems with the de-acceleration undoing fixings and extra locking pins are then needed. A dado head is much heavier than a single blade so this problem then appears on the saw that did not need a locking pin when fitted with the original blade.

Guarding is also a problem but this can be overcome with an overhead guard on its own support arm.
 
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