deep mortises in ipe

[Igor Petrenko]

I am trying to make outdoor bench and have problems with 2.5x3/4 mortises that are 2-3" deep. What is the best way to dig them up? Routing is not an option, no way to make it go that deep and it's getting kind of scary with long router bit.
Wood is too dense for mortising machine - it's just not going in and chisel's sharp corners just bend.
Drill press and bench chisel work but it takes an hour with 1 resharpening per earch mortise...

[John Shuk]

On such a strong wood, must the tenons be so long? Perhaps you can reduce the depth until it is more workable.

[Jamie Buxton]

I've done 3"-deep mortises in other species with a plunger router. My router doesn't have a 3" stroke, so it took two router bits -- one long and one short. I used a template guide and a shop-built template. The reassuring thing about using the guide is that you can take the router out of the cut, change the bit, re-insert the router with a long bit sticking out the front, and restart the router without fear that it is going to catch something. Ipe is tough, but it should be do-able with this technique.

One more thing.. If you need 3/4" mortises, don't use a 3/4" bit. Use a half-inch. This will assure you can put it in and out without colliding with the sides. And it is way less expensive than buying a long 3/4" bit.

[Kent A Bathurst]

..........Drill press and bench chisel work but it takes an hour with 1 resharpening per earch mortise...

Hog it out with DP - then use DP in small increments (1/8"??) to clean up the sides of the mortises to "almost done". Assume you are using Forstner bit. Use bench chisel to finish sides. Leave the corners of the mortises round, and use a chisel to chop the corners of the tenons at 45* (small amount wasted out is all that is needed to get them to fit - only one or two whacks are needed - if it splits with the grain, not dead plumb, no big deal - doesn't matter). You won't have a dead-nuts perfect fit at the corners, but you don't need them to be dead nuts - the ends and faces of the cheek cuts will provide more than enough contact/gluing surface.

IMO - you are overdriving your headlights for outdoor stuff. Actually, same applies for indoor work as well, but for those I go for the dead-nuts because I have the tools to do it (HC mortiser, etc), and it is easy to use chisels + planes to clean up the mortises/tenons on that material.

This past weekend, I made a coffee-table-type-thingy-with-lower-shelf for outdoor use for friends - from washed-up-on-the-shoreline wood they had collected - all beat to hell, which was what they wanted. "I just want it to look rustic" were the instructions from his SWMBO, and rustic she got - but I had to use M+T for joints - couldn't help myself :D. Some was regular pressure treated, and some was creosote (Holy Smoke and Smell, Batman!!). He has a pretty good benchtop DP, a good CMS, a few Stanley chisels (they were a gift from me and they left my house sharp-sharp) and a general-purpose-Ace-Hardware-Stanley-handsaw for the tenons. M+T for the legs-to-battens and for the legs-to-stretchers. No glue (couldn't imagine anything that would adhere to creosote) - used SS screws instead. Did the M+T as described above. Can O' Corn.

[Igor Petrenko]

...Leave the corners of the mortises round, and use a chisel to chop the corners of the tenons ...
Thank you! I think this will cut the time in half.

[Peter Quinn]

I am trying to make outdoor bench and have problems with 2.5x3/4 mortises that are 2-3" deep. What is the best way to dig them up? Routing is not an option, no way to make it go that deep and it's getting kind of scary with long router bit.
Wood is too dense for mortising machine - it's just not going in and chisel's sharp corners just bend.
Drill press and bench chisel work but it takes an hour with 1 resharpening per earch mortise...

The only things I can think of that need tenons that long are barn timbers and doors where the entire weight of the thing hangs in the horizontal plane off a few stout connections. I'd agree with other assessments, a 3/4"X3" mortise in IPE is big time over kill, and that's not the species to fight with. You can safely cut way back on those tenons and save your self some headaches.

You can hit those depths with a few bits from Onsrud, I've done 2 3/4" with a plunge router in softer species like mahogany, and it does get scary at those depths, and takes a lot of light passes. The only machine I know of that will do it with ease is a bridgeport milling machine, and IPE mills like metal, so that may be appropriate! Make sure to look for carbide tips if you go with the drill press idea, cause IPE eats HSS pretty quick.