Auger bit stops boring.

[Jeff Cord]

I' drilling some 3/4" dog holes in my new bench and am having problems.

I have an old hand-me-down brace and bit from my grandfather that still seems to turn in circles.
I then added a new Irwin 3/4" auger bit.
Did a quick sharpen on the bit and started drilling holes.
Starts drilling just fine. The threaded tip pulls the bit in, I get a clean start.
Then I get about 1/2" to 1" through the top and it just stops drilling.
I turn and turn but make no progress.

My bench top is 4" thick made from doug-fir glued together so I'm drilling through the side of the boards (not into end-grain).

HELP!

thanks,
jeff

[george wilson]

You must have a clearance angle on the bottom edge of the bit,or it will not bite into the wood. Other than the bit getting too dull,which seems unlikely after sharpening,I can't tell what else might be wrong. You didn't round off the bottom edge of the bit did you?

[mike holden]

Do you get a 1/2 inch or so each time you pull the bit out and start over?
Or do you get 1/2 inch down and it just stops?
Does cleaning out the chips and starting again make any progress?
Are you leaning over the bit and applying downward pressure? (the tip wont do all the work)
Mike

[Jeff Cord]

George, I'll check to be sure I have a clearance on the bottom edge.

Mike, I get 1/2" down and it just stops.
Clearing the hole of any chips makes no difference.
I'm leaning on it almost as hard as I can.

Thanks.
Jeff

[Jim Koepke]

It is possible the bit has been sharpened incorrectly in the past. If the spurs were sharpened on the outside, the clearance becomes less than the outside of the flutes and the bit will jam.

Also, the lips should have the clearance angle from the factory and the underside of these should not be altered. That is how the clearance angle gets lost.

There is a little bit on sharpening in an earlier post of mine:

http://www.sawmillcreek.org/showthread.php?t=131238

It may help.

jim

[Ross Canant]

Auger bits come with fine threads for dry hardwoods, and with coarse threads for green and softwoods. Most of the new ones sold these days are coarse threaded for putting up gates and doing decks, not the fine threads you need for hardwood and cabinetmaking. You are stripping the lead screw out of the wood because the bit can't cut hardwood fast enough. The lead screw does the work of pulling the bit through the wood. Find a good set of Russell Jennings pattern bits on eBay. Make sure they are the model 100 fine thread. The model 101 is the coarse thread.

[John McClanahan]

My guess is that Ross has it figured out.

John

[Ross Canant]

I see this a lot in timber framing with old boring machines. There is no down pressure in a boring machine, the lead screw has to work. Most of the old bits for boring machines are designed to work green wood.

[Jim Koepke]

George, I'll check to be sure I have a clearance on the bottom edge.

Mike, I get 1/2" down and it just stops.
Clearing the hole of any chips makes no difference.
I'm leaning on it almost as hard as I can.

Thanks.
Jeff

With the line about "leaning on it almost as hard as I can" it made me think that even if the lead screw had started to spin in place, there may be something else causing the stalling.

It might be helpful if Jeff could post pictures or let us know if his bit will get though a 4 inch piece of soft wood.

Another note, Zahid, thank you, has put Bob Smalser's "The Incredibly Versatile Sweep Brace" and my "A Bit About Augers" threads in the lead Neanderthal wisdom/FAQs post in section #10 Misc Tools.

jim

[David Weaver]

What is the orientation of the wood?

I've had trouble in the past when drilling out totes going into the face of quartersawn woods.

Try taking a dry board and running the bit through the face of the board and see if it cuts. If it cuts that well, but not into what looks like the face of a quartersawn board, then part of it is just the orientation of what you're drilling, and the other part the geometry of the edge on the bit if the elephant ears and lead screw are fine.

[Gary Herrmann]

Also agree with Ross. I haven't drilled through 4" with an auger and a brace but I have drilled through 2" using both RJ and Irwin bits.

I picked up a bunch in cheap lots on the bay. A number of them had been sharpened badly.

[Steve Dallas]

I' drilling some 3/4" dog holes in my new bench and am having problems.

I have an old hand-me-down brace and bit from my grandfather that still seems to turn in circles.
I then added a new Irwin 3/4" auger bit.
Did a quick sharpen on the bit and started drilling holes.
Starts drilling just fine. The threaded tip pulls the bit in, I get a clean start.
Then I get about 1/2" to 1" through the top and it just stops drilling.
I turn and turn but make no progress.

My bench top is 4" thick made from doug-fir glued together so I'm drilling through the side of the boards (not into end-grain).

HELP!

thanks,
jeff

Occam's razor would suggest that the problem is most likely with the lead screw as others have mentioned.

[David Keller NC]

Jeff - the comments on this thread are the probable cause (stripped out lead screw hole), but there's one more thing to check. The outside diameter of the cutting flutes at the business end must be at least the same as, and preferably slightly larger than, the outside diameter of the flutes on the shaft. If not, and the flutes are bigger than the cutting flanges, then the bit will stall against the side walls of the hole and guarantee stripping out the lead screw's hole.

I had to take back an Irwin bit that was poorly manufactured that had this flaw, and many of the antique ones have been compromised by an inexperienced sharpner honing the outside of the cutting flutes (and therefore reducing the effective cutting circle diameter).

[Jeff Cord]

Here is the bench.
152016
I now realize I'm drilling down a glueline which may be a problem.

Here is the auger.
152015

Jeff

[mike holden]

Jeff,
Coming down the glue line should not be an issue, I could argue that it is an advantage, but a very very small one.
I think that the bit has been "sharpened" on the outer circumference causing the bit to jam as has been suggested.
Can you drill with any other size bits? - in a piece of scrap/cutoff - If so, then we can rule out the brace and your technique.
You may just have to replace the bit.
Mike

[Jeff Cord]

Mike, I just tried to bore a hole with an ancient Irwin bit that I have (has a 6 on the side).
Not sure what the 6 refers to but it works just fine. It continued as long as I wanted to.
Probably the fact it's very old is the reason it works.
I then tried my new 3/4" bit and same story: It went about 1/2" and stopped.

What number bit would I be looking for to be a 3/4"

Jeff

[Jim Koepke]

The numbers designate 16ths of an inch.

A 6 is 3/8 and a 3/4 will be a 12.

jim

[Jim Koepke]

Jeff,

I tried to send you a PM, but your message box is full.

jim

[Jack Wilson]

Is it possible that there are any bolts going thru the bench top and you have landed on one?

[David Myers]

Jeff,

I'm in the process of boring the holes for my bench as well. I have a new Jennings bit and an older Irwin one. I had a similar problem as you describe then made a small change in technique. First, I stood on a stepstool so that I could get my chest over the brace, then I took advantage of the ratcheting mechanism and pushed the brace only thru an arc of about 1/4 to 1/3 of a circle. I think that when I was making full sweeps I was not applying enough pressure on the far end of the sweep causing the cutting edges to stop digging in and the lead screw to ream out its hole.

The other thing I've done is to liberally wax the bits.

Good luck.

[Ross Canant]

The bit pictured has a very course lead screw which tries to pull the bit rapidly through the wood. With the hard maple, it can't take that deep of a cut, so the lead screw strips. The same thing will happen if the cutting edges are dull and skate instead of cutting. You really don't have to lean on a brace that hard when everything is right. I'll say again, borning machines have zero down pressure and they have worked for 150 years. Check this picture of bits designed for hard woods. Look at the lead screw and how fine it is by comparison.
http://www.tias.com/stores/gea/origpics/t26566f.jpg

http://www.myoldtools.com/boringpic.jpg

[Rick Rutten]

Ross I like that mallet in the picture. Is that just on piece of log?

Thanks,
Rick

PS: I tried to post this earlier but it got lost. Sorry if it double posts.

[Ross Canant]

Just a piece of hornbeam with the end cut down with a draw knife.