Router Bit for Dados/Rabbits

[slopjock78]

I just recently obtained a lightly used OF1400, and would like to start using it for some dado work.  My question is which type of router bit is best for creating dados?  up spiral, down spiral, straight cut??  Does material (solid wood, ply, MDF, etc) make a difference on what type of bit to use?  Does doing a rabbit vs a dado require a different bit?

up to this point i have only created dados with my table saw, so I want to make sure i am using the right bit for the job.

also, another question on technique:  do you use an undersized bit, and make multiple passes, or use the correct sized bit and make one pass?

thanks for any help

 

[Neal W]

I have used a straight bit.  (The dust collection on the OF1400 will help significantly with this task as well)

For me, I have found it better to make multiple passes:  1st pass a 1/4" depth, do 1/4" on the next to final depth.

The size of bit is more dependent on the width of the dado.  If you want a 3/4" wide dado, use a 3/4" wide bit.  Trying to do a 3/4" dado with a 1/2" bit is going to be frustrating.

There are some bits which are made for nominally sized plywood if your dado's accept plywood.

Do you need a different bit for a rabbet?  Not necessarily, but you may wish to.  A rabbetting bit usually has a guide bearing on it to track the edge of the wood.  You can use a straight bit for this, but you may find it more time consuming for the setup. 

The guide rail and OF1400 is a great combination for doing Dados in larger pieces like cabinet panels and such. 

 

[Sparktrician]

Another thing to consider is the purpose of the rabbet.  If it's for a sliding partition, you might want a looser fit, but for permanent joinery, a snug fit is better.  Select your bit and size based on purpose and material.  As Neal W mentioned, there are bits that are sized specifically for under-sized plywood.  Nominal 3/4" (19mm) is often 18mm in reality, so a 23/32" bit would be appropriate for a snug fit.  Nominal 1/2" is often 12mm mandating a 31/64" bit.  1/4" nominal would get a 7/32" bit.  You get the picture. 

 

[grbmds]

I've used straight bits for dados and, with superior OF1400 dust collection, almost no dust will escape.

Definitely should make multiple passes for deeper dadoes, especially if you are making 1/4" dadoes (with a 1/4" bit). I learned the hard way when making dados on drawer sides for a 1/4" bottom insert. Too deep means that you could break the bit or the shaft on a 1/4" bit. I should have known better but was trying to save time.

I love using the router for dadoes. I think the result is much better than with the table saw.

 

[Greg M]

I went the opposite way.  I've used a router for dados and finally bought an 8" dado for my table saw.  Used it for the first time today and I'm not going back to using a router for dados.

 

[slopjock78]

Greg,

i dont have a problem with dado's on a table saw.  I have a very nice ridge carbide stack that is very nice.  However, i have a set a shelves i'm making this weekend for a volunteer group, which i'm making out of plywood.  I would like to make the dados on the full sheet of ply before ripping to width, so i know the dado's are matched perfectly

 

[Greg M]

Greg,

i dont have a problem with dado's on a table saw.  I have a very nice ridge carbide stack that is very nice.  However, i have a set a shelves i'm making this weekend for a volunteer group, which i'm making out of plywood.  I would like to make the dados on the full sheet of ply before ripping to width, so i know the dado's are matched perfectly

Wouldn't that still be easier on the table saw?  I might be missing something but rip first and then dado should give perfectly matched results.

 

[grbmds]

I went the opposite way.  I've used a router for dados and finally bought an 8" dado for my table saw.  Used it for the first time today and I'm not going back to using a router for dados.

We all use the methods we feel most comfortable with. I've never liked dado sets and was really happy with the dust-free router dadoes I made a couple of months ago. The bottoms of the dados were completely smooth and flat and the depth was perfectly on the mark with what I wanted. For me, the only dado that I would do on a table saw would be in a piece so small it wouldn't be practical to do with a router. That's just me, though. I realize there are just as many or more who use dado blades.

 

[slopjock78]

Greg,

i dont have a problem with dado's on a table saw.  I have a very nice ridge carbide stack that is very nice.  However, i have a set a shelves i'm making this weekend for a volunteer group, which i'm making out of plywood.  I would like to make the dados on the full sheet of ply before ripping to width, so i know the dado's are matched perfectly

Wouldn't that still be easier on the table saw?  I might be missing something but rip first and then dado should give perfectly matched results.

yes, but the shelves are 7' long and 6' tall.  i dont really want to push a 7' long piece of ply across my table saw.  I know its possible, and can be done safely.  But, with my new router, i thought a good time to get some experience with the 1400

http://festoolownersgroup.com/member-projects/riding-helmet-shelving/

 

[bkharman]

Here is what I did recently.  I used the following:

• OF 1400 router with spiral upcut bit
• a rail (1400 in my case)
• Precision Dogs Parallel Guides
• clamps

I cut out the two sides, made sure they were square to each other and clamped them to the table.  I then set my rail and parallel guides on the inside or outside of where the dado needed to start or finish.  Run the dado.  Move the parallel guides to the next mark and run that.  In my case I was using a 1/2" bit, so I only needed to move it once for each dado... plus I used my KM-1 to make sure it took into account the bit width.  If you dont have a KM-1, you just will need to make sure that your dont route it out too wide.

Normally i would do this on my table saw or in my router table with my Incra fence, but they were setup for another task, so i went topside.

Hope this helps.

cheers.  Bryan.

 

[ear3]

I don't think it's been addressed yet, so I'll just add that while a straight bit will work in most, if not all cases, if you are doing veneered plywood you might consider downcut spiral, as it will minimize tearout along the edges of the dado.  Keep in mind though that non-standard size bits (7/32" vs. 1/4) in up/down cut spiral are a bit harder to source, though they do exist.

I just recently obtained a lightly used OF1400, and would like to start using it for some dado work.  My question is which type of router bit is best for creating dados?  up spiral, down spiral, straight cut??  Does material (solid wood, ply, MDF, etc) make a difference on what type of bit to use?  Does doing a rabbit vs a dado require a different bit?

up to this point i have only created dados with my table saw, so I want to make sure i am using the right bit for the job.

also, another question on technique:  do you use an undersized bit, and make multiple passes, or use the correct sized bit and make one pass?

thanks for any help

 

[Greg M]

Greg,

i dont have a problem with dado's on a table saw.  I have a very nice ridge carbide stack that is very nice.  However, i have a set a shelves i'm making this weekend for a volunteer group, which i'm making out of plywood.  I would like to make the dados on the full sheet of ply before ripping to width, so i know the dado's are matched perfectly

Wouldn't that still be easier on the table saw?  I might be missing something but rip first and then dado should give perfectly matched results.

yes, but the shelves are 7' long and 6' tall.  i dont really want to push a 7' long piece of ply across my table saw.  I know its possible, and can be done safely.  But, with my new router, i thought a good time to get some experience with the 1400

http://festoolownersgroup.com/member-projects/riding-helmet-shelving/

See, I was missing something  [big grin]  That makes sense.

 

[Mr Heavy]

Nanny won't let us have dado sets to play with.  [crying]
It's been covered to death on Usenet over the years but it's basically a consequence of table saws having to be braked and the brakes not being able to cope with the inertia of a stack.

We're (generally) not allowed to have locking switches on routers either, so in a table we have to lash things down with duct tape and cable ties. My Trend / Metabos have a switch that needs sliding AND pushing then duct taping into position against the shearing force of the spring. Apparently this is "safer" than having a push on, push off switch. The legislation doesn't apply to pre-law designs like the Elu, so copies of this - later Trends, Dewalts etc - are exempt.

Festool seem to have got round this O.K.

/rant.

The game's afoot;
Follow your spirit: and upon this charge,
Cry — God for Harry! England and Saint George!

As the bard would have it. (Henry V)

St. George's day today. Hurrah!! Time for all Englishmen to celebrate our "freedom."

 

[Brent Taylor]

As Edward stated there are too many variables to take in account, what type of material,  where the joint is located and is it to be a through cut or not. What works best for solid wood is not necessarily what you would use in MDF.  Up cuts for non-through cut in solids, down cuts for through in the same. Ply and MDF's like straight or shearcut multi-bladed bits, single bladed for plastics. Then there is router speeds and size. Number of cuts and direction of feed and rate. This is what makes woodworking, work.
I have done woodworking for 40 + years professionally , I have currently 9 routers, 4 tables and a large number of bits. I also have 3 table saws and I still have trouble knowing which to use. 

 

[waho6o9]

http://www.infinitytools.com/Solid-Carbide-Spiral-Router-Bits/products/1088/?utm_source=Flash+-+Solid+Carbide&utm_campaign=10%25+Off+spiral+bits&utm_medium=email

This may shed some light on the differences between the up and down spiral bits.