Deep dado cuts.

[Hans Hauge]

I have a big beam of white oak I need to cut 2 1/2” deep by 1 1/16” wide dadoes in. I could get started with a track saw and clear out the bulk of the waste that way. I’ve found router bits online with that cutting depth. How do you feel about that much cutter poking out the bottom of your 3 1/4HP router? I’d need to max out the cutting depth so I suppose a template bushing won’t work. I can’t find a top bearing bit that’s long enough. I’d probably have to clamp a guide for the router to ride against. Is this crazy? Is there a better way?

[Kevin Jenness]

That's a very large overhang in a confined space with a powerful hand-guided machine - you have already identified the downside potential. It would be safer to finish the outlining cuts with a handsaw and clean out the waste with a chisel. You might consider using a larger (10") circular saw and making multiple cuts.

[Rich Engelhardt]

Is there a better way?Chain morticer maybe?
New ones are really expensive. Used ones are pretty reasonable.

[Robert Engel]

Multiple cuts with track saw, remove bulk then you can use router to clean up bottom.

But, if this is some type of timber framing, a chisel and a rasp will clean it up well enough.

[Bill Dufour]

Radial arm saw.
Bill D

[Rich Engelhardt]

Looks like the chain mortisor is too wide.
Pity - everyone needs some odd-ball tool that got limited use & a lot of "WOW" factor ;).

Radial Arm Saw could work if it fits & you can find one.

[Edward Weber]

If you saw first then use a long router bit its not bad, 2/1/2" isn't that long with a guide bearing bit to keep you where you need to be.
Even drilling out the bulk with an auger bit saves lots of effort as has been done for centuries
I would probably use my mortiser
What ever works for you

[Kevin Jenness]

It probably would be safe enough to run a 2 1/2" d.o.c. router bit with fences clamped to the beam on both sides of the router, taking several passes to achieve the full depth after cutting out an 11/16" x 2 1/2" groove with overlapping tracksaw cuts. A rule of thumb I have seen is to limit the bit length to 4x the diameter. Going over that calls for light cuts to limit bit deflection.

It would be faster to just do the whole groove with a circular saw that will cut the full depth.

[Warren Lake]

not enough info

[Justin Rapp]

circular saw. Most 7 1/4 saws can cut a max of 2 1/2 inches. Get a flat cut blade and built a fence you can clamp. You will just have to make a pass, move the fence, make another pass, repeat. It will be time consuming but should be safe and effective.

[Edward Weber]

I should amend my post, is this a stopped dado or just a through dado accross the width of the beam.

[johnny means]

A straight bit and a collar in a plunge router. You'd just oversize the pattern to account for the collar. Quarter inch deep passes will get it done cleanly in no time.

[Mark Hennebury]

Need more information!

[Michael Schuch]

I agree with making the initial cuts with your track saw then cleaning up the bottom with a router bit or chisel. If you cut the two sides with the track saw and the dado is cross grain then you should be able to pop out the vast majority of the center piece with a chisel and a couple hits with a mallet.

I would use my radial arm saw for through dados but I wouldn't really expect anyone to run out and buy a RAS for a single cut.

I would not try to take all that wood out with just a router bit. That would put a ton of torque on your routers lower bearing. If you do decide to go with only using a router I would definitely make many shallow cuts instead of one or a few big cuts. There is nothing wrong with using a couple scrap boards on each side of the cuts to act as guides for the router.

[Scott T Smith]

I also concur with the direction to start with a track saw and finish with a router.

Here is a tip for you.... a 1/2" end mill is available in lengths up to 4" and works great on wood. I've used one with a track router to edge joint large slabs for Roubo style work benches.

Here is a link to the one that I use in my router.

https://www.travers.com/product/niagara-n52167-finishing-end-mill-08-052-167

[Hans Hauge]

Sounds like, tracksaw, chisel, router. Thanks all.

[Tom Bussey]

I agree with Scott. but one can use the shank of the end mill as a rub coller I use end mills from MCS to cut stuff like you are asking. End mills have a longer shank than router bits. There are some router bits that have a solid piolet so it is not a new concept. Carbide is pricier but steel can tend to me more whippy in a long length. but the yours is not really that deep. I would rough the groove out and finish it to size and use the end mill to finish the sides and just a light cut on the bottom to flatten the groove