Jim Becker - no European dado sets

[Jules Dominguez]

Jim, I was interested in your comment that dado sets aren't used in Europe. I know there are usually several different ways to make any cut, but wondered why that is so?

[Steve Schoene]

Here are a few things I've heard over the years.

To European regulators dado sets are not considered safe.

Part of this may be related to blade brakes. A dado set is heavy, and can spin off if the arbor stops too quickly.

Of course, it is also related to the sliding table system which is close to the blade and would call for some serious adjustments to accomodate the dado set.

Others may have more definitive answers, I throw these out for comment not as "truth."

[Jim Becker]

What Steve said...

[Steve Schoene]

By the way, spinning off a dado blade is not just a theoretical idea. I have seen the marks in a shop where, for some reason, the Unisaw motor was equiped with an electronic brake. After that, the approved drill required having a 2 foot long 2x4 to jam into the dado blades after the motor stopped. Really.

[Ian Barley]

All tools sold into in workplaces in European Union countries have to carry a "CE" mark - kind of like a mandatory UL system.

The CE mark carries various requirements. One of these is that all blades capable of being touched by an operator must come to rest within 10 seconds of power down. This is usually achieved with DC braking where a DC current is injected into the AC motor which causes it to stop rapidly. As has been said, with a heavy dado set this could result in the blade set spinning off.

There is also a maximum allowable length to the blade spindle, designed to preclude the use of dado sets. This is basically because statistics show that a dado cut is more likely to result in an injury than a through cut where the full benefit of riving knife and guard is available.

Most dados will be cut with a router or shaper depending on the position of the cut in relation to the material edge etc.

[Dev Emch]

I have heard this as well and I believe the SMC contributors. But in pragmatic terms, this is poppy cock rubish.

Often, dados need to be cut into the cabinet sides to accept tops and bottoms, etc. In some very limited cases, you can use a shaper to do this. But the greatest issue with the shaper is that for most cabinet dados, the cutting edge is 90 degrees out of wack. Let me explain.

My hofmann shaper has a killer sliding table on it. It could in theory cut extremely nice dados very quickly. But in order to do this, the cutting tool has to be a vertically oriented router bit. Now I need to find a unique HSK 80 collet spindle which Hofmann does not make. I can use a cutter head such as my Leitz adjustable groover to cut dados around the primeter space of a panel, but not across the deep dimensions. This operation would involve the use of the standard fence and not the sliding table.

Another issue that comes up with the use of a sliding table along with a collet spindle or a router for that matter is dado width. Many times, I need to laminate exotic resawn veneers to a baltic birch substrate. This leaves me with substrates of unqiue thickness dimensions and often no two similar jobs are the same. I may have resawn the XYZ job a few thousandths more or less then the current job. So this makes the use of a single router bit unreasonable. Do I need to make a custom router bit for every job I do so that I can live with a single pass and have all my dados fit nice and tight? Remember that often you have to batch cut many panels. So running things with one pass and resetting for a second pass is more opportunity for error and it eats more precious time.

So if I go to the table saw and use an adjustable dado, I can accomplish all this in short order. What is amusing about the braking argument is that some of us have actually run adjustable shaper groovers ON THE TABLE SAW! That is one advantage of using the larger, heavy iron table saws. Also, all shapers have to follow the same rules for spindle shut down. They dont have any issues here.

And how does one explain the Hofmann Prisim. This is a new shaper which will never be available in the USA. This shaper can tilt its spindle from -5 degrees BELOW the table deck to + 45 degrees from vertical in the other direction as well. Talk about a contortion artist!

At any rate, this shaper can and does function as a table saw when its spindle is horizontal. I can install a series of saw blades, dado blades or groovers or stair railing cutters on this machine. The point here is that I can run the equivalent of a dado blade in the form of an adjustable groover which actually produces a nicer result anyway. But, once again, you have issues with the fence. The shaper fence does not provide you with the very large ripping capacities you normally get with a table saw, thus, you cannot cut deep center dado grooves on larger panels.

So that brings us right back to square one. The table saw should have its spindle redesigned to accomadate shaper cutters. I can do it because I have machined a unique nut and mini spindle spacer to hold my Leitz groover. THIS IS DEFINITELY ONE OF THOSE ITEMS WHERE ONE SAYS: KIDDIES, DONT TRY THIS AT HOME. WE LIKE TO THINK OF OURSELVES AS TRAINED PROFESSIONALS. In otherwords, if something happens, I cannot sue myself.

The euro rules do indeed make things harder to accomplish sometimes. Maybe that is why the Festool stuff has all that interworking guide hardware that works with routers and saws and jig saws, etc. It does seem to fill a nitche hole that the rules over there have created.

[Ian Barley]

Dev - While your insight into the subject is fascinating - the fact remains that the reasons stated are the reasons why dado sets are not implemented on table saws which are going to carry the CE mark, which is a requirement for any commercial shop in Europe. That was the question that Jules asked.

[Dev Emch]

Ian, as I stated, I understand this. The standards in Germany esp. are brutal to meet. I know as I have been involved in getting CE approvals out of Braunswich, Germany for storage infrastructure.

My point however is clear. There are a few simple design changes that can be made to alter how table saws work. In the end, a table saw is nothing more than a horizontal shaper with a fixed spindle. If the shapers can do it so can the table saws. After all, I have never had a dado fly apart on my martin. And the northfield and oliver large table saws not only have mechanical brakes, some also have DC injection brakes. The new northfield #4 has a full bore DC injection brake available.

My point? Have you ever seen the Dado option for one of these saws? Grusome is a world that comes to mind. I can swing a 4 inch wide dado blade up to 14 inches in diameter! These saws can chew up lumber like a beaver recovering from a hunger strike.

And how about some of the timber framers. Some of these guys are using Northfield X-36 Radial Arm Saws called Unipoints. Some of them have been lifted to support 20 inch blade flasks. Others are using 7.5 HP direct drive motors to swing the same dado sets mentioned above. And these are equipped with the warner DC injection brake.

No braking issues here. So I still wonder why folks hide behind this argument. Unless you have a 150,000 dollar CNC gantry router, this issue can cost you some serious money unless your just doing it for a hobby!

[Ian Barley]

Dev

Nobody is hiding behind anything as far as I can see. You are correct that all these things are physically possible. So is juggling chainsaws whilst riding a unicycle. Possible, legal and wise are different standards of measurement.

The European system is different to the American one. There are many reasons why it is different many of which relate to differences in a political and social outlook from the two continents. I have no axe on which is better or worse and in which respects. I was simply trying to answer a reasonably asked question with a reasonably comprehensive answer.