Mortise through 3" hard wood?

[Gary R Katz]

I'm trying to cut 3" deep mortises through Oregon White Oak, an exceptionally hard wood. This wood's Janka rating (I don't know what a Janka rating is) is 1660, compared to red oak at 1320. The lumber came from a large tree in our yard and I'm rather attached to it. I'm (trying to) build a variation on Mr. Barnsley's Hayrake table and the 3" thick legs have 2" X 7/8" through mortises for the lower stretchers. I've drilled out most of the waste and I'm having trouble getting the mortises parallel and square. I've tried using a mortiser but it can only shave small amounts of this hard wood. I also tried an up cut bit on my router table but that wasn't yielding accurate cuts. The primary challenge is the 3" thickness of the piece. I have to cut part way through one face, then flip the piece and finish on the other face. I can finish it off with chisels but it's a long, slow process and I don't seem to keep the sides parallel. I'm sure there are at least a dozen good ways to do this, so whatever help you can offer to turn some of this tree into our dining room table would be greatly appreciated.

[Bob Lang]

You're stuck working from both sides, but assuming there are shoulders on the tenon you only need to be perfect on the exit hole. You can taper the mortise slightly in the direction of the tenon to make trial fits easier. A good rasp or float will be extremely helpful; work from the outer face to avoid blowing anything out on the pretty side. At that length and thickness you will have tremendous strength in the finished joint even if it gets sloppy. Make a practice joint in scrap to see what you can get away with.

Bob Lang

[glenn bradley]

If the bulk of the hole is there I would probably go with a wide chisel keeping my Worksharp on the bench and touching up as I go. For a powered solution, a template with a reference "fence" or two to position the hole and route from each side. Whiteside makes extra long spiral bits for the Mortise Pal (http://mortisepal.com/storefront.html). I have the Mortise Pal but, find other uses for the extra long bits as well; your case in point ;-). You could use the 1/2" and add a bearing or use a template collar.

[Prashun Patel]

As a last resort, you can always rip the legs in half, cut the mortises as dado's and glue back the legs. If you glue it well, it can end up darn near invisible.

[Greg Hines, MD]

I would make a template, and then use a plunge router with a collar to guide the bit, and a long straight or spiral bit to hog out most of it. Then chisel the corners square, if it matters or leave them with a radius.

[Loren Woirhaye]

This is a way to do it:
http://woodworker.com/radial-saw-mortising-attach-mssu-889-372.asp

[Prashun Patel]

Gary,
Also, if you're having trouble lining up your router on both sides properly, then I've seen this done several times with a saddle-style jig that has templates on both sides of the piece that are locked in place by an adjoining saddle and keeps them perfectly lined up, so you don't have to move the jig when you flip.

I also second the idea of establishing square shoulders with a plunge router then chiselling the rest.

You can also get 1/4" more depth from your plunge router by removing the jig after initial routing, and switching to a pattern routing bit (top guided bearing). The bit will ride in the established mortise shoulder and clear some more depth for you.

[Gary R Katz]

Bob, thanks for reminding me it's only going to show on the pretty side. I've been able to get close to clean parallel sides with a lot of chisel work but tapering the mortise would be a good way to focus on the finish side having the tight joint.

[Gary R Katz]

I might just invest into a long bit since i have other mortises besides these 4 leg pieces. A long bit would get me started with straight parallel sides.

[Gary R Katz]

Wow, never thought of that idea! I'll keep it as a last resort, definitely.

[Jeff Duncan]

Might be a long shot, but a couple postings on several WW sites indicating your looking for someone with a large mortiser you could borrow time on could be an option? There's a lot of old beasts out there that I'm thinking would likely handle 3" depth of cut....it's just finding one locally that'd be the trick;)

good luck,
JeffD

[Mel Fulks]

As good as the mortisers are ,the chisels are expensive and it's easy to ruin them on real hard wood so you could end up with a surprisingly high bill. If you decide to sub them look for someone with a chain mortiser. I think for just that one piece of furniture I would use drill press to make straight round holes ...then chisel the rest. I know that doesn't sound traditional but in a way it is. Amateurs and even tradesmen working slightly out of their regular sphere have done that on old work.

[Mark Wooden]

See if you can find someone with a lock mortiser

[Guy Belleman]

Lots of good ideas. I would probably be too impatient, just drilling out the waste and hand chiseling out the mortise, many days before any new tool or attachment arrived. Did 10 in a day through 4" and 5" oak several years ago. Looked great, of course, my sharpening skills gotten increasing better, and my hands were sore/tired, but satisfying work.

[jack forsberg]

if you were closer i do it for you in minutes. My Stenner cuts though mortises 6" deep from one side with a single finger.


http://www.youtube.com/watch?v=Wiq3wfS9Ulw

[John TenEyck]

Gary,
Also, if you're having trouble lining up your router on both sides properly, then I've seen this done several times with a saddle-style jig that has templates on both sides of the piece that are locked in place by an adjoining saddle and keeps them perfectly lined up, so you don't have to move the jig when you flip.

.

This. Then leave the radii in the corners and round over the edges of the tenons to match. It will make a miserable job most any other way pretty easy.

John

[Gary R Katz]

I'm not having much luck responding to each entry, but wow, what a wealth of ideas. I could quit the project and spend a few months trying each one only because you guys got my curiosity activated...Naugh, I don't think I'll do that. I almost built a saddle jig before I tried the other methods and I might go back to that idea.

[Mel Fulks]

Gary,you will find this is a great think tank ,don't worry about thanking us . Just let us know if any of these ideas actually work....and we'll try them.

[Silas Smith]

if you were closer i do it for you in minutes. My Stenner cuts though mortises 6" deep from one side with a single finger.


http://www.youtube.com/watch?v=Wiq3wfS9Ulw

I'm taking my ball and going home now.

Seriously, I've never seen a Stenner in action before, absolutely awesome!

[Gary R Katz]

Thanks Mel, I'll let you know how it works out, maybe even post a pic. Thanks everyone for the great ideas, I learned a lot of new things.

[Shawn Pixley]

I did similar through mortises a couple of years ago on slightly harder wood. Eight through mortises and eight standard mortises. I used my table top mortiser for the entry and exit as deep as it could go. I did spend some time sharpening and polishing the bit/hollow chisel. I also has to stop and let it cool during the process. I then used sharp chisels to remove the rest and clean them up. There was a full day on the mortiser (with a fair amount of time waiting for the bit to cool). There was the better part of the second day cleaning and tuning with chisels. My sharpening improved as a result.

[Jim Matthews]

If they're through mortises, why not use a jigsaw with a good blade and an exit guide?

Start with a through hole large enough to pass the blade with some clearance.
Tack a batten to the outside edge of the mortise, on both shoulder sides.

On the opposite face, tack a batten that traps the "shoe" of your jigsaw so it can't twist.

You can also shave the shoulders with a blade if your jigsaw has a zero oscillation setting.
(Teeth facing the shoulder, the saw moved laterally along the shoulder wall.)

I use the Bosch line of blades (http://www.boschtools.com/Products/Accessories/Pages/BoschAccessoryDetail.aspx?pid=T344DP#specs), and they cut oak well.
I used them this way to cut a single mortise in Angelim Pedra which has a Janka rating of 3040.

I suspect that you're having alignment problems as the opposing faces aren't precisely parallel.

If you use the batten guide method, you're only referencing off one face, and guiding the blade at the exit.

[Chris Friesen]

I've had good luck with a drill press and a Forstner bit. Drill at each end initially, then at intervals in between, then go back and remove the waste centering the bit on the waste bits if there isn't enough wood left for a full "bite". Finish up by drilling every 1/8" or so and you'll have a decent mortise. If you like you can do a final cleanup with a chisel or float.

[Mark Bolton]

Oddly we are working on a large trestle table for a customer at the moment which has deep mortises (3. 5") in white oak.

We use the DP w/2 1/4" forstner to punch out three holes getting rid of most of it then a template with fences under, clamped, and router with straight bit for the cleanup. If your parts were good and square you could get clear through 3" this way if you had a big enough router.

https://picasaweb.google.com/lh/photo/gUeXXAAw8McYG0dyfbZO-cQYLULDmhn_WM8ntUxqICA?feat=directlink

https://picasaweb.google.com/lh/photo/Lqhq0nSN-dVCbh1tn2mIu8QYLULDmhn_WM8ntUxqICA?feat=directlink

[Danny Thompson]

A mortise float will work aggressively, is easier to control than a chisel, and reduces the risk of gouging the mortise wall. What I used on a similar project: http://www.lie-nielsen.com/joinery-floats/mortise-floats/

[Michael Peet]

You can drill out most of it and clear the remainder with a chisel. Clamp a guide block right on the line. Of course the guide block must be square to the surface. Start with the cross grain ends first to prevent splitting.

274774

Mike

[Brett Robson]

I'd use a router to cut half of the mortise depth, then drill a 1/2" hole through the bottom of the mortise, flip the piece over and stick a bearing-guided flush trim bit through the hole and route out the other half. Square up the corners with a chisel and you're done.

[lowell holmes]

Great solution! I wish I had thought of it.

[Gary R Katz]

I've never seen floats before but they look like they might allow for more control than a chisel. I like that idea.

[Gary R Katz]

Hey Shawn, your post reminded me to check my chisel bits and yes, they need to be sharpened. I keep forgetting to check my tools for sharpness and with this hard oak I'm going to have to keep up on this. Sharpening should help since I could only shave a small amount at a time.

[Gary R Katz]

Yeah, I definitely like the look of that mortise, very nice. I'm going to use a guide block and chisel, starting with the ends, for sure. Thanks for posting the pic.

[lowell holmes]

I have two floats.
I received the second float yesterday. My original float which I've had for a year or two is 1" wide and about 8 or 10" long.
The new one is 1/2"wide, about 5" long.
They are good products.

[Michael Peet]

Yeah, I definitely like the look of that mortise, very nice. I'm going to use a guide block and chisel, starting with the ends, for sure. Thanks for posting the pic.

It helps to remove as much as you can with the drill first, like this:

275054

Also, knifing the lines before you begin chiseling will help assure a clean perimeter, particularly on the end grain edges. You can drop a chisel right in the knife line and give it a gentle tap. You can do this all along the line to establish the edge.

Good luck!

Mike

[Gary R Katz]

I was out of town for a week and finally got back into the shop. The time off gave me a chance to read this thread several times, take notes, then do a lot of thinking. When I got back to the shop I spent a lot of time sharpening chisels and mortise chisels. I hogged out most of the waste on the drill press, then used the mortiser to approach the edges. After that I used my chisels to clean up right to the edges, along with small rasps to hit the high spots. Funny how sharpening everything makes a LOT of difference. I've never made as nice mortises as this, reading the comments and studying the pics you guys listed in the thread really helped to rethink what I was doing. I took some photos but was unable to download because of compatibility problems with my new computer, Windows 8 and an old Photoshop program. UGH!
Thanks to everyone for all the comments, they kept my mind busy all week long.