Boring holes for 2” mortises in hardwood

[wvwoodworker]

Hey guys - I'm building a timber frame with some pretty large format timbers (up to 8"x12" cross section). Many are white oak since that is plentiful around here and I have access to a lot of it locally. I'm doing a lot of 2" thick tenons and mortises and the old Swan boring machine that I picked up at an estate auction last year is kicking my butt in the white oak. I have a sharp 2" auger in it and it is really hard to turn the handles, and I'm not a small guy. Clearly I am pushing the design limits of the machine. I can see the frame of the boring machine torquing to the right and left as I bore. I sheared through the original pin pretty quickly, and the other day I just sheared through a replacement 7/32" hardened roll pin. I've had my eyes peeled for a 2" auger bit with a less aggressive lead screw pitch but no luck so far. The machine works fine for 1.5" holes in oak, or 2" in softer wood. Bores pretty straight no matter what.

My question is, would other boring machines perform better than the Swan in this application or would it be about the same? I'm hesitant to buy a chain mortiser. I'm not a professional so it's hard to justify the layout, and there aren't a lot of other timber framers in the area to resell to if I did go down that path.

[beenthere]

Welcome to the Forestry Forum. 

[Don P]

You're a manlier man than me  :D. My borer did about 2 holes in oak when she asked if there wasn't something electric. I ordered a chain mortiser that night. It will resell if you're done at the end of the job.

[Ljohnsaw]

You're correct on needing a less aggressive lead screw.  Turns out I have two 2" bits.  I'm doing soft woods.  My "hardwood bit" just won't go in the soft wood, it strips out on quite often.  I had a couple 16" timbers I needed to through bore.  Drilling 8" from both sides made it doable but once you pass 5", it becomes a real workout!  I did save on a gym membership for the past few years ;)

Search around on the FF.  Someone made a drill press for boring using a slow drill.

[wvwoodworker]

Thanks for the advice everybody. I'll redouble my efforts to find a bit with a hardwood lead screw. I think I may have found one on eBay, we'll see when it gets here... I did see the drill press pictures in my earlier research. It's a nice idea but I don't believe that it's possible to find 2" auger bits that are made for a drill, the biggest I've seen is 1.5".

[Ljohnsaw]

Forstner bits work great if you have a slow and powerful drill.  I haven't tried them on my boring machine - need to give them a shot this summer.  You just need to back out often so you don't get stuck.  The only problem is the shanks are a little short.  Drilling a 2" hole, the drill chuck will fit down that and give you more depth.  Or, get/make an extension for the bit.

[Don P]

Take a look at saw tooth edged multi spur bits rather than smooth rimmed forstners if going the electric drill press route. Same caution, if the chips overtop the bit, you'll wish they hadn't.

That may be the last ones we did by hand.


 

[Tom King]

I use the magnetic base of my magnetic drill press to clamp it to a 3/4" steel plate.  That steel plate is clamped to the beam.  This particular drill press is adjustable a bit after the magnet is engaged, so once you get past the 100 pound weight, it's easy to position where you want it, and cuts a perfectly pretty hole with a Forstner bit very quickly.

[DonW]

You're not considering not boring? There's always hammer and chisel.

But an axe is faster.

 

[Hilltop366]

I used a drill press with sawtooth bit, it was either that or handheld drill at the time. It drilled good but did not always have enough vertical travel so I would drill as far as it could then lower the bit in the chuck and finish. I would also use a smaller bit in the corners first, I'm thinking it was 9/16" but anything from ½" to 1" would do, this made it much easier to chisel out the corners after.



 

The drill press head sits on the pipe with the head facing to the right, Also made a height adjustable clamp to hold in place but found I did not use it much as the weight of the drill was usually enough. The clamp was handy at time when there was a knot or when overlapping holes which is easier to do with a sawtooth or forstner bit.

[Brad_bb]

White oak is a bear with a hand boring machine, as you've found out.  I'd prefer a chain mortiser.  Easiest on the wallet will be the Makita.  You can resell at the end of the project.  They hold value pretty well.  If you're determined to do it by hand, as you're aware, a fine thread top boring bit that is sharp, and understand how to sharpen it and what NOT to touch with the file.  I don't remember the gear ratio of the sawn, but you want want one that is Greater than 1 and the higher numerically the better (gear on the drilling shaft # of teeth/#of teeth on the cranking gear).  It's like putting your bike in 1st gear to go up a hill rather than 6th gear.  The length of the handles could also make a difference, but they are probably all fairly similar from one boring machine to the next.  I prefer a millers falls or a boss double eagle boring machine over the others.  A milwaukee hole hawg drill and a good short boring or Forster bit would be easier and faster, but still make you sore at the end of the day.

[Ljohnsaw]

I use the magnetic base of my magnetic drill press to clamp it to a 3/4" steel plate.  That steel plate is clamped to the beam.  This particular drill press is adjustable a bit after the magnet is engaged, so once you get past the 100 pound weight, it's easy to position where you want it, and cuts a perfectly pretty hole with a Forstner bit very quickly.

I picked up a mag drill last year to fab up a pair of grapple claws for my tractor.  I'll have to try it this summer.  I'm all for getting things to go faster on my cabin!

[Dakota]

Another vote for the Makita chain mortiser.  I bought a new  one, kept it long enough to erect my frame and then sold it on Ebay for more than I paid for it.

[Tom King]

I use the magnetic base of my magnetic drill press to clamp it to a 3/4" steel plate.  That steel plate is clamped to the beam.  This particular drill press is adjustable a bit after the magnet is engaged, so once you get past the 100 pound weight, it's easy to position where you want it, and cuts a perfectly pretty hole with a Forstner bit very quickly.

I picked up a mag drill last year to fab up a pair of grapple claws for my tractor.  I'll have to try it this summer.  I'm all for getting things to go faster on my cabin!

Mine says it gets maximum clamping force from the magnet with 1" plate, but I had the 3/4" plate already and it clamps plenty strong enough for drilling in wood.  Mine is the big Milwaukee.  I forget what the stroke length is, but it's plenty of travel for this.
Once you get it moved, the hole is nothing.  It's a lot easier, and makes a prettier hole than a spade handled drill.  Overlap the holes any kind of way you want to depending on what chisel you want to use.
I use a single old Jorgensen Deep Engagement bar clamp to hold the plate in position.

[Prizl tha Chizl]

 Jim bode tools has a couple two inch bits for sale. You can compare the threading with what you're using. I never did any more than 1 1/2" in hardwood with mine, why do you need the beefier tenons?

This thing here was my transition between boring machine and chain mortiser- the neighbor put it together for a couple hundred bucks (I supplied the hole hawg.) not my invention, I saw it at a workshop I took, but I have thought about seeing if the folks set Bigfoot would want to make them-I don't use it any more for mortises, but it makes drilling peg holes a breeze. 

 The only problem was I had a hard time finding a 2" spiral
bit for it, so I tried modifying my boring machine bit, but again, the threads/cutting ability were an issue, it just kept spinning its wheels and losing its bite, so I settled for a 2" Forstner.

[Tom King]

These aren't cheap, but they're pretty amazing.

FAMAG Bormax 2.0 Forstner Bits

and these come in handy, and are the best bit extensions I've ever used:

Famag Forstner Bit Accessories

[Don P]

Uhh, yeah, a multi spur bit. When did we start calling that a forstner?

[Tom King]

I think they started with Forstner bits, and cut parts of them away  :D.

Plumbing bits would work fine, without a self feed screw, but they only come in odd sizes for holes for pipes.  

The only multi-spur bit I had was for lock mortises, and it was 2-1/8".  I just happened to run across those when I was googling for "2" Forstner bit" when I was replacing some timbers in an old house frame, so I ordered one and the extensions.  I have a cheap set of Forstner bits, but no extention that I trust to use with them.

These cut as clean a hole as a regular Forstner bit, but much faster with better chip clearing.  When I run across another job where I need to drill some other size holes that I don't have the right bit for, I'm ordering another one of those.

[Mainecoast]

Isn't the rule of thumb 1 1/2 tenons in hardwood and 2" in soft wood? 

I was able to chisel out 1 1/2 mortise in less than 5 minutes including layout. Only chisel and hammer. 

Not saying I'd do a whole frame but a friend told me a German timber framers test was that..layout and cut in less than 5 minutes chisel and mallet only, 

[Don P]

Don't make a habit of it, I'm at the far end of that, we only have so many good swats in us  :D

If you wander around grading rules for defects and the NDS notching rules, 1/4 comes up a lot.
1/4 of 6 is 1-1/2.
1/4 of 8 is 2