Godd Ol' Government Side-step (RE: Riving Knives)

[FoggyTown]

Further to the thread on riving knives and specifically the sub-thread of stacked dado head cutters therein, I went directly to the HSE woodworking section in England with the following question:

Dear Sir,

I am not sure where to go with this question and I am hoping, since it is related to your field, you may be able to assist by pointing me in the right direction. It involves the use of stacked dado head cutters on table saws in the private sector.

I have been told that these accessories are not allowed, mainly due to some EU regulations regarding the blade spin-down time and how it is increased beyond regulations by the heavy dado cutter sets. But I also heard on one of the woodworking programmes on the telly (David somebody) that as long as the arbor on the TS was long enough to accomodate the cutters then they could be used. I also know that the sets are sold in the UK (see

other sources) so I am interested to know the official position on using these sets. Are there on-line regulations I can go to?

Now I don't think that was a particularly complicated statement of the issues. Here is the very prompt reply I received in return:

there are two considerations here. The first is braking. Woodworking machines now have to be fitted with brakes to stop them in under 10 seconds. For details go the link for Woodworking Info. Sheet 38 below.

Secondly, if you are fitting moulding cutters into a circular saw the tool has to be of the limited cutter projection type. See the link for WIS37 also below.

I hope this helps

Regards Brian

can't tell. Did he answer my question? Does that mean that if you have brakes which stop a cutter-loaded arbor in 10m seconds that the cutters can be used? Is a dado cutter considered to be a moulding cutter?

I LOVE governments! I think from now on I'll just stack 3 or 4 regulat TS blades side-by-side and make my own cutter.

FoggyTown

[Upscale]

Sounds like an answer to me although not as definitive as one might want. If you consider the limited cutter projection type to the limited projection type of cutter on a router bit, then you've got an answer and it's "yes" a dado setup is allowed as long as the dado can't easily cut your finger off. Yup, it sure could take a big chunk out of your hand or a finger, but all things being equal, one shouldn't be able to have an entire finger lopped off, at least not all at once.

As to dados with limited projection cutters, don't know that I've actually seen one, but they shouldn't be too difficult to manufacture if they aren't already available.

[Upscale]

Sounds like an answer to me although not as definitive as one might want. If you consider the limited cutter projection type to the limited projection type of cutter on a router bit, then you've got an answer and it's "yes" a dado setup is allowed as long as the dado can't easily cut your finger off. Yup, it sure could take a big chunk out of your hand or a finger, but all things being equal, one shouldn't be able to have an entire finger lopped off, at least not all at once.

As to dados with limited projection cutters, don't know that I've actually seen one, but they shouldn't be too difficult to manufacture if they aren't already available.

[dpb]

and other sources) so I am interested to know the official position on

Did he answer your question? Did you read the publications he directed you to?

From the latter...

"Are there any machining operations where it is not possible to use limited cutter projection tooling?

The use of limited cutter projection tooling should always be the first option considered as part of the tool selection procedure. Other types of tooling should only be used where the desired profile cannot be achieved with the use of limited cutter projection tooling. Grooving will generally be the only operation where limited cutter projection tooling cannot be used, eg a grooving saw might have to be fitted instead."

I would consider in US parlance a dado to be a "grooving cut" and, therefore, permitted by the above paragraph.

[dpb]

...

It strikes me that

10 s is quite a long time for anything other than the tendency to reach near the blade for making an adjustment, etc. It certainly won't have much bearing even on reaching for a cutoff, etc., as that typically will be well withing that time span if done as the common reflex-type action of long experience...

Just the thought that was generated by reading the response...

ymmv, etc., ...

--

[Leon]

Yes 10 seconds does seem to be quite a long time, even with a stacked dado set. That said however, in the commercial and or industrial setting the bigger RAS's can spin up to 30 seconds with a single blade after being turned off. Then again, ;~) since this pertains to any woodworking machine, I have a very common sized 12" disk sander that spins for 60 seconds after being turned off. I suspect that it would need a brake.

[Doug Miller]

I was thinking the same thing when I read that. Just checked -- my TS spins down to a dead stop in 14 seconds *without* brakes, so it's hard for me to see much point in a brake that can't achieve any better than 10 sec.

[Swingman]

I'm supposed to be gearing up this morning to cut a _bunch_ (approximately

200 LF), of dadoes/grooves in stiles and rails, starting when I get this last cup of coffee down, and overcome the other distraction of having the laptop out in the shop (ostensibly to make it easier to check dimensions, but really to keep you guys straight) :)

First thing I do after getting the width on this 3/4" dado stack dialed in is time how long it takes for spin down.

My bet is that it's less than 10 seconds, but we'll see.

I'll let y'all know. :)

[dpb]

It's pretty clear reading these publications they're aimed at the commercial, large equipment of major milling facilities and manufacturers, not the home shop or small cabinet shop, primarily.

As (Swingman, maybe?, I forget) just noted, some large RAS and others may take quite some time to spin down. They also specifically talk of spindle shapers, etc., and many of those make take some time to w/ a large panel raiser, etc.

I'm sure my RAS takes quite a bit over 10s and it's only a 14, the PM66 probably takes close to that if not longer although I don't know that I've timed it.

Again, it could be of some advantage in a really high production commercial environment and for really large stuff like the 1" or greater diameter spindle shapers, moulders, etc.

[Doug Miller]

Definitely, the bigger saws take much longer to spin down. All mine (TS, RAS, and CMS) are 10". One of our local lumberyards has, I think, a 16" RAS that seems to spin for about a week after it's shut off.

Sure, but if you're going to put a brake on a machine, put a *brake* on it. I mean, really! Ten seconds??

[dpb]

Doug Miller wrote: ...

I suspect the problem is the regulations have to deal with the reality of retrofits to existing equipment and initial cost. One of the issues contributing to the problems Sawstop ran into w/ licensing their technology to manufacturers rather than manufacturing them themselves as another example...

[Swingman]

Well ... I would lose that bet.

Average of ten times, for this TS, _with this particular configuration_, was

10.6 seconds.

Longest: 11.2, fastest: 9.3.

Admittedly unscientific, not something on which to bet your money, but for today's temperature/humidity/sock color, a shade _over_ ten seconds for certain.

Now, back to doing actual woodwork ...

[Andy Dingley]

This isn't strictly true. If you're a purely domestic user and also using a pre-98 machine, you can dodge it. The rules apply to "commercial" outfits (with a very much broader scope than I have time to type) and also to new machinery supplied post '98. Some of these issues (notably the spindle moulder head rules) also apply to old machinery supplied after '98.

Another issue is that carefully designed brakes (i.e. not sudden lockup from a crude DC injection brake) can brake within the appropriate time, with a heavy dado set, and without applying the levels of decceleration that can cause problems for a simple blade locking mechanism.

This is always good advice. Although it's easy to buy dado sets in the UK (and hard to buy new saws that can mount them!) I haven't seen new- ish tooling that wasn't of a suitable design for sale in several years. Remember this is quite old legislation we're talking about - nearly 10 years since most of it came into effect and even the legacy permissions expired nearly 5 years back.

the guideline documents.

He pointed you to two good resources that do.

Yes. You don't even need brakes.

_If_ you can stop in the time limit, you're OK. Doesn't matter whether you have deliberate brakes, or just a sluggish belt drive and bearings.

You _may_ need a complicated piece of kit to achieve this, for a heavy piece of tooling. Heavy tooling shouldn't be stopped that quickly if it's only held in place by a left-handed nut. Trying to do so would be even more dangerous than a slower rundown time. Even though PUWER doesn't explicitly state so, there's still a general provision that unsafe equipment must not be used! Badly thought-out brakes would certainly count as such (incidentally, I used to design braking systems for huge metal-bashing presses. I stopped doing so owing to the liability issues, when I felt that the portion of the design I had control over wasn't adequate to ensure a safe overall machine).

Yes (in this context).

That doesn't work too well, and it's no better (PUWER wise) than using the right tools.

[dpb]

...

And, although it may be addressed in other regulations/places, all the words I saw in the two referenced documents were "should" not "shall".

That's a major difference...

--

[Leon]

Darn Swingman, surely it did not take you 1 hour and 20 minutes to dial in that dado. ;~)

[Frank Campbell]

snip

My guess is the 10 seconds is so the machine has stopped after one person has used it and before a second person gets to it in a production shop employing several workers.

[Dave Gordon]

I think the rule applies irrespective of whatever blade is fitted.

wis38 says "...if there is a risk of contact with the blade as it runs down"

Don't touch the blade when you turn the saw off, until the blade has stopped. In any case, surely the risk is less than before you turn it off.