Router Bit type for Mortise Jig?

[Peter Pedisich]

Hi,

I'm looking for a router bit to use for making deep mortises for a storm/screen door - loose tenon construction.

I'm not sure if I should go with a solid carbide spiral upcut (Holbren - Whiteside, RU5200) , or a HSS spiral upcut (Leigh-Valley - Onsrud), or a carbide tipped straight bit such as the PRC-508 on Pat Warners site?:confused:

The door will be 1-1/8" to 1-1/4" thick pine or spanish cedar, and I got some good advice to go with 1/2" wide mortises versus the 3/8" I was thinking of doing. I'd like to mortise 2" deep, or 2.5" if possible. Meaning 4-5" loose tenons.
So where a 4" stile meets a 4" rail, I'll have a 1/2" wide x 2" long x 2.5" deep mortise. And the bottom rail will be 8", and I'll put two on that one.
Does this sound OK?

I really appreciate any advice!

Pete

[Greg Hines, MD]

I would definitely use a solid carbide spiral bit, and 1/2" would be a good size. That is how I made a work table for my shop, except that I used integral tenons instead of loose ones.

Doc

[mreza Salav]

solid carbide spiral (up-cut) is the way to go. Make sure you do it in multiple passes. I'd recommend doing it with a plunge router (instead of a router table), however I find the depth you are looking for (2.5") challenging with some plunge routers.

[glenn bradley]

Another vote for solid carbide spiral upcut. I don't think you need to pay for the chip breaker style Whiteside that you list. I just use a standard two flute Whiteside spiral. Be sure to get one long enough to keep a safe amount of shaft in the collet and still reach your depth. This will be a challenge for your 2-1/2". The 1/2" Whiteside is 3" overall if I recall. Chopping the last 1/2" or so with a chisel is not a big deal. Stay safe.

[Brian Gumpper]

Glenn,

The RU5200 is not the chip breaker style, that would be RU5200CB.

[Cliff Rohrabacher]

I use the Whiteside 3/8" stagger tooth cutter.
It's long enough to cut deep for through mortises. It leaves a good surface for gluing and I have not experienced any teat out.

[Peter Pedisich]

Thanks for the input guys, maybe I should reconsider the mortise depth.
Maybe 2" in each piece is sufficient.

[Ralph Barhorst]

I always buy endmills from ebay for this application. Take a look at this item on ebay as an example 370085028845. This particular endmill is HSS, not carbide. It is a 1/2" and will fit in your router. Make sure you get a "2 flute" endmill. The price of these endmills is much lower than "router bits".

When you search ebay, try the search with "endmill" (no space) and then again with "end mill" (added space) to make sure that you see all of the available end mills.

You should also check out 370083899160. This endmill has a 1/2" shank with a 3/4" cutter. I have one and it is great for routing 3/4" holes in your workbench.

[pat warner]

There are other choices (http://patwarner.com/router_morticing.html). Tho you've well defined your needs, straight, on-shear, spiral, HSS and other cutters can also do well here.

[Peter Pedisich]

I always buy endmills from ebay for this application. Take a look at this item on ebay as an example 370085028845. This particular endmill is HSS, not carbide. It is a 1/2" and will fit in your router. Make sure you get a "2 flute" endmill. The price of these endmills is much lower than "router bits".

Ralph, In your experience, do the HSS hold an edge long enough? Say for 25-30 mortices in softwood?

Pete

[Ralph Barhorst]

Pete,

Yeh. They seem to work pretty well for short runs. However, I have found that many of the carbide endmills are usually available at a low cost on ebay. If you can't find a carbide endmill then the HSS ones will work.

[Peter Quinn]

You say you were given 'good advice' to make 1/2" thick mortises in 1 1/8" stock? Not sure that leaves enough wood out side the cheeks. Maybe? In any event a 3/8" tenon is more than sufficient to make that door.

I like Onsrud solid carbide spiral carbide upcut bits for mortises. They make them in lengths long enough to do 2 3/4" deep mortises, problem is that gets a bit hairy with a plunge router, a jig, and a spiral carbide bit, so be careful and hold on tight. For a 3/8" mortise you will need a 3/8" collet to reach that depth and a bit with a 3/8" shank. I have a few HSS bits, I don't like HSS for mortises. It lasts well in hard and soft wood for profile cutters, but for plunging the heat created is going to kill HSS too quick for my taste.

I've had real good results with Freud spirals too, but I don't know that they have one to make that depth? Can't go wrong with Whiteside either.

[Jerry Thompson]

Ralph;
I assume that endmills can handle router RPM's?

[Aaron Beaver]

Ralph;
I assume that endmills can handle router RPM's?

Also Ralph, is there any issue when chip clearing when you need to go deeper than the 1 5/16" cutting length?

[Charles Lent]

I always use an up cut carbide bit for this, like others have said, but they left out a description of the proper technique for making mortises with a router. It's best to make many full depth plunge cuts to clear out most of the material in the mortise, followed by a back and forth clearing cut, favoring the left side going away from you and then the right side on the return stroke. This will minimize the router's desire to pull sideways and minimize heavy cutting, which tends to create a mis-positioned mortise.

Charley

[Ron Bontz]

Plunge cuts work well for me on closed mortises. I prefer upcut spiral cutters as well, but I am curious. Isn't 1/3 the material thickness the generally accepted thickness for mortises / tenons?:confused:

[Peter Pedisich]

Plunge cuts work well for me on closed mortises. I prefer upcut spiral cutters as well, but I am curious. Isn't 1/3 the material thickness the generally accepted thickness for mortises / tenons?:confused:

Ron,

That's what I thought, but I've seen different articles with conflicting info.
I'm going to make some test mortises in both 3/8" and 1/2" wide in 1-1/8" stock, and see which breaks sooner!
I'm new to mortising with a router.

Pete