Drilling big holes with auger bits . . .

[Jessica Pierce-LaRose]

I decided to drill a couple of 1" holes in the maple I made my saw sharpening jig out of, to aid in clamping it to a surface using f-style clamps rather than trying to finangle c-clamps around some of the pieces.

I grabbed the 16/16 bit from the Irwin auger bit set I picked up from the classifieds here a little while ago. I don't think I've used the larger bits in this set yet.

Man, I wasn't prepared for the arm power this took - the hole drilled was nice, but took almost more arm power than I could muster. I gave the bit a go in some scrap 2x6 SPF (framing lumber type stuff) and that was okay - obviously maple is quite a bit harder.

The bit was lightly sharpened before use; it cuts well, the spurs do their job, and the lead screw is functioning. Did a great job in the SPF as well.

So I've narrowed down my problem to a few potentials, I was wondering if anyone could add their input:

1) I just need to bulk up. I don't have the best upper body strength. (This is probably pretty likely)

2) I need a wider sweep brace for large holes. I've got a 6", 8" and 10" brace. Maybe a 12" brace (or larger) would make this more feasible.

3) How the bit is sharpened - I lightly sharpened the bit - it's sharp now - but whoever sharpened the bit in the many years before me changed the cutting angle, almost giving it a "secondary bevel". The cutting angle is now effectively steeper. I don't know if this can be remedied, or if it's normal, but it seems to me the lower the cutting angle, the easier it would be to "push" the bit through the wood.

4) The pitch of the leadscrew is too steep - it seems like the bit is trying to take too big of a "bite" as it turns - when testing the bit in pine again to make sure each side was taking off a reasonably equal cut (it appears to be) I noticed that the thickness of the shavings being pulled up by the bit where quite thick. Perhaps I'd be better served by searching out a Jennings-pattern bit for these larger sized holes?

I like using a brace when I can - I seem to be less likely to screw things up with one, and honestly, I don't drill holes that often...

So any opinions? Should I be looking at the bit, the brace, or the operator? I think my next step is tomorrow (I got to get to bed!) is to compare the Irwin bit with the Jennings bit I have in a hard wood (I've got a 3/4" Jennings bit, so I'm hoping it's close enough to give me an idea of the performance.) Otherwise, I guess I hit the weights or dig out the holesaws or fortstner bits next time I need to drill a big hole in hardwood. . .

[Pedro Reyes]

Pretty big hole on pretty hard stuff. I would guess a larger sweep (based solely on physics) would provide the most punch. This is assuming the bit is not dull, but if it cut clean and effortlessly on softer stuff, then I am guessing it is not.

/p

[Bill Houghton]

Irwin bits are generally optimized for softwoods; Jennings bits for hardwoods. And, yes, a 10" sweep brace is perhaps a little small for a bit that size. 14" maybe best, but they're not common; 12" is more common.

[ray hampton]

I am not knocking brace & bits but for a hole like this a post drill would be better if you can take the wood to the drill

[Joel Goodman]

+1 on the larger brace, I have a 12" and a 14" isn't a mistake. Archimedes said something like "give me a big enough lever and I could move the world."

[Jack Curtis]

Irwin bits are generally optimized for softwoods; Jennings bits for hardwoods....

I've had better results in most woods with Jennings bits, to the point I sold all the Irwins; but most of this drilling was in harder woods, didn't even think that might be the reason. Thanks, Bill.

Jack

[Erik Manchester]

What Bill said +1.

Getting a set of Jennings bits makes a big difference in drilling in hard woods, and the sharpness of the bit helps as well.

[Eric Brown]

First, make sure the spurs are sharpened only on the inside edge.
A little wax on the bit also helps.
A larger sweep brace definately would help.
A double-handle Tee type would be even better.

However, your real problem is the screw on the end. It has a coarse pitch which determines the rate.
The Irwins and most other solid center type bits are optimized for soft woods.

The common Russell Jennings Number 100 set has a fine double pitch screw which is better for hardwoods.
Unfortunately the Russell Jennings bit fails to hold in very hard woods. (Like maple).

There are other bits that can handle maple, but they are less common.
The single twist bits can do it but they usually only have one spur and leave a rougher hole.
Brad point drill bits in the drill press work very well.

Eric

[Mike Olson]

try pre-drilling a pilot hole with an egg beater just like you would before putting a screw into Maple. The Lead screw on the auger should still get enough bite and it should be easier to drill.
First time I used a 14 on Maple it was tough going and it split the wood. The only reason I could think of for the split was the lead screw. I pre-drilled the next piece and it was a bit easier and no split. " i wouldn't say it was EASY, just easier"

[Jim Koepke]

Pretty good advice above.

The one on drilling a small pilot hole for the lead screw is good. Put a little wax on the lead screw when you wax the sides of the auger.

Some free weights might help bulk up your arms for turning your brace. A 12" brace could also help.

The angle of the cutting edge is not going to have as much effect as how much it is being made to cut by the feed rate determined by the lead screw.

I have pretty good upper body strength and can muscle a 1" bit through most soft woods with an 8" sweep. I will use a 10" for hardwoods and the 12" when I am tired. The smaller sweep makes for faster turning.

I also did not feel a need for a log splitter because swinging an axe or maul is fun. My wife insisted because she doesn't want me to wear myself down.

Splitting fire wood by hand does a lot to build upper body strength.

jtk

[Jessica Pierce-LaRose]

Thanks for the advice, folks.

It's good to know that I don't need to worry too awful much about the angle of the cutting edge.

One of these days I'll pick up a larger brace. Normally I would drill a hole like this with my small drill press, but this was one of those weird places where I was adding a hole after the fact, and there wasn't a convenient way to easily and safely mount it on the press. Would love a post drill like Ray mentions (well, in addition to a nice, larger electric drill press) - drove out to see one "fully restored" at a shop, and whoever "restored" it painted many surfaces that shouldn't be painted - I guess it would have been fine if I never wanted to adjust the table . . .

The lead screw pilot hole helps a lot, as does wax. Drilling some 3/4" holes with one of the couple of Jennings bits I have kicking around and the Irwin bit confirms that the Jennings (when the screw holds - the pilot hole helped) does better with the slower feed rate in these harder woods.

At some point I guess I'd like to pick up a set of Jennings bits as well - should I look for the 100 or 101? The couple of loose Jennings bits I have are the double threaded. I believe the 100 has the double thread, an the 101 the single, but are the pitches of the threads similar, or are the single-threaded Jennings similar in pitch to the courser Irwins?

[Joshua Clark]

A 1in. hole in hard maple is a tough job for a 10 in brace in the hands of a normal person. I'd go with a larger brace, personally.

That's not likely the problem though. You said that the former owner put a secondary bevel on the cutters- that could be a big problem. The cutters need to be sharpened to a single-bevel chisel edge. The the face of the cutter (the side that contacts the wood first) has to be flat and should never be sharpened. Doing so puts a knife edge on the cutter. This prevents it from cutting easily as the screw pulls the bit into the wood. You'll find many bits improperly sharpened like this. Unfortunately, the cutters are so small that it's almost impossible to correct this without seriously reducing the size of the cutters.

The cutters also need to be the same size otherwise you'll only be using one cutter. You should see two distinct shavings leaving the auger head, one from each cutter. If you don't then one cutter is doing all the work.

The whole issue of Jennings are for hardwood, Irwins are for softwood is completely untrue, but it's been posted and re-posted so much on the Internet that most folks think it's a fact. The Jennings pattern bits work exceptionally well on most seasoned hardwoods. They are designed to bore clean and fast. The Irwin bits are a more general purpose bit and will work well in all woods, hard, soft, green, or wet. They bore much slower than Jennings bits, but they do the job well and most importantly, won't loose their grip. In especially hard woods Irwins are he best choice.

It all comes down to the lead screws- Irwin pattern bits generally speaking have a coarse lead screw with a single start or thread. These coarse threads give a better "grip" to the screw, but the thread pitch is fairly flat thus the bit cuts slow. Most Jennings pattern bits have a fine lead screw with two starts, or threads, which results in a more aggressive pitch so the bit pulls much faster (up to 70% my test have shown) per revolution. This makes the Jennings bits bore faster but the fine threads are prone to clogging and loosing their grip in very hard woods.

I have to keep saying "generally" above because Jennings made bits with both coarse and fine lead screws (though the coarse ones are very scarce). Irwin also made bits with lead screws of varying pitches, though all single-threaded.

The solution, of course, is to have a couple of sets of bits- some Irwins, some Jennings, maybe some Ford pattern for really rough stuff. Don't forget center bits! Oh, and if you want to get into the really weird stuff like boring holes in end grain or on steep angles, look for some Whitehouse or Cook patent bits. Oh, don't forget Forstners either- the real Forstners with square shanks. :)

-Josh

[Jessica Pierce-LaRose]

Josh- the poor sharpening job I mentioned was more of a "secondary" bevel, than a knife edge - the back side was sharpened steeper, but the "front" side - the face facing the wood when drilling, that's been left alone. So the cutting angle is steep, but the cutting edge still hits.

Some practice work in pine does show me that both cutters are hitting the wood at pretty much the same time, and I'm getting two shavings.

Now I'm confused then if something else is going on with my bits though , because it seems like it's trying to pull up a much thicker shaving than a comparable Jennings bits . . .

[Tom Vanzant]

Joshua,
A coarse lead thread will do that. If the thread pitch is .010", you'll get a .010" shaving, .020" will get you a .020" shaving, etc. That's why a coarse pitch in a really hard wood will result in a tear-out of the lead screw. The bit simply chokes on too large a mouthfull.

[Joshua Clark]

Now I'm confused then if something else is going on with my bits though , because it seems like it's trying to pull up a much thicker shaving than a comparable Jennings bits . . .

Can you post a picture of the lead screw? It should be pretty easy to tell what sort of pitch it has and whether it's too agressive for very hard wood.

You mentioned you were boring in maple- are you using hard (aka sugar or rock maple), or a soft maple like silver, red/swamp, big leaf or other maple? There's a huge difference between hard maple and soft.

-Josh