Auger Bits Not Advancing

[J_SAMa]

Sharpened up some old auger bits for use with brace only to discover that they all have one same problem: the bits will stop to advance after about 2 cm into the wood unless I put a LOT of pressure on it. It feels as if the lead screw threads just cease to "bite" into the wood. I then "sharpened" the threads with a small saw file but that didn't seem to change anything. It appears as if no one else on the internet is having the same problem (I'm probably not putting the right search terms in...). I would buy new but they are all round shafted, don't work with hand braces and the square chuck of yesteryear.
The cutting parts of the bits appear fine. Checked and made sure that there is relief on the underside of the cutting edge.
Any idea what might be going on? I'm clueless

Thank you,
Sam

 

[Racers]

What wood are you drilling into?

You get coarse and fine lead screws so it might be you are using the wrong one.

Pete

 

[Sheffield Tony]

Augur bits don't do too well into end grain, and some of mine do as you describe. In most cases it was down to them having been badly sharpened so that there was not enough relief angle behind the cutting edge, so the edge doesn't cut in without more pressure than the lead screw can provide without stripping the thread.

I got a few new old stock German made ones from Dieter Schmidt which are better, or there are always the Clico ones if you feel affluent - other than that it is down to second hand, an augur file, and dump the ones you can't make good.

 

[Richard T]

What Pete says.

It's always about trying to find middle ground between the coarseness of the thread and the diameter of the bit. If it is wood that is difficult to bore a large hole into, dry Ash for eg. you'll get nowhere with a coarse thread as the wood is too strong to rip the thread and it is too wide a hole to cut and you'll bend the bit before making any progress .... you need a finer thread. A soft wood will rip the thread of a finer bit if the hole is too wide and you'll need coarser.

No wonder there are so many old wood bits about.

 

[Bod]

The sides are parallel, all the way up, and clean?
If the side cutter have been wrongly sharpened on the outside at some time, this will wreck them.
Clean out the lead screw, with valve grinding paste in a bit of hard wood, rather than take a file to them.
In my experience, don't expect much from old rusty bits, they've had a hard time! Shiny well looked after ones, can be still as good as new.

Bod

 

[Cheshirechappie]

As said above - auger bits seem to be a bit choosey about the wood they will and won't cut. Drilling some 1/2" holes in wettish softwood recently, 9 out 10 holes went without a problem, but on the tenth the bit went in about 10 mm and then just spun. Withdrawing it and clearing the compacted wood from the thread normally solved the problem, but the odd one just wouldn't have it without quite a lot of pressure. Once the bit did decide to bite, all was well. So, maybe you've hit a hard bit, or a knot, or a soft squidgy bit that gums the threads, or something.

With hardwoods, I find that about 5/8" (16mm) is about the practical limit using a standard 10" sweep brace. I can just about manage 3/4" (20mm) with a sharp bit in dry beech, but I'm working hard, and possibly using enough force to damage something - there's more force than control. A longish t-handle might be a wise idea rather than the brace for bigger holes in hardwoods.

 

[J_SAMa]

What wood are you drilling into?

You get coarse and fine lead screws so it might be you are using the wrong one.

Pete

In pine, will have to try hardwood sometime. Not sure if it's fine or coarse...

 

[J_SAMa]

As said above - auger bits seem to be a bit choosey about the wood they will and won't cut. Drilling some 1/2" holes in wettish softwood recently, 9 out 10 holes went without a problem, but on the tenth the bit went in about 10 mm and then just spun. Withdrawing it and clearing the compacted wood from the thread normally solved the problem, but the odd one just wouldn't have it without quite a lot of pressure. Once the bit did decide to bite, all was well. So, maybe you've hit a hard bit, or a knot, or a soft squidgy bit that gums the threads, or something.

With hardwoods, I find that about 5/8" (16mm) is about the practical limit using a standard 10" sweep brace. I can just about manage 3/4" (20mm) with a sharp bit in dry beech, but I'm working hard, and possibly using enough force to damage something - there's more force than control. A longish t-handle might be a wise idea rather than the brace for bigger holes in hardwoods.

Well 9 out of 10 for me WON'T go farther than 2 cm :x. I was mainly testing the 3/4" bit since I found it easiest to sharpen. The smaller ones (1/4" to 1/2") were just as bad. Cleaning the hole didn't make it any easier.
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How much relief angle is enough? Mine's got about 5 degrees. Should I try to raise that?

 

[J_SAMa]

The sides are parallel, all the way up, and clean?
If the side cutter have been wrongly sharpened on the outside at some time, this will wreck them.
Clean out the lead screw, with valve grinding paste in a bit of hard wood, rather than take a file to them.
In my experience, don't expect much from old rusty bits, they've had a hard time! Shiny well looked after ones, can be still as good as new.

Bod

The outer rim's had all the surface rust scrubbed off but the "shaft" is hard to get at so haven't bothered. I should mention that it's a Jennings pattern. Have a very similar Irwin pattern one, will try it some time.

 

[Graham Orm]

What are you driving them with? They are designed to go slow, if you have them in a cordless drill they won't work unless you go as slow as possible.

 

[tool-me-up]

I would buy new but they are all round shafted, don't work with hand braces and the square chuck of yesteryear.

Sam

I carry hex shanked if those are any good to you. You can also get SDS fittings now aswell as SDS drills are usually slow and have a high torque output, I would assume it to be better than a cordless or similar.

 

[MIGNAL]

They should go through Pine at an alarming rate! As stated previously, they aren't very good on end grain. Hopeless. I found a decent solution for end grain though.

 

[bugbear]

The sides are parallel, all the way up, and clean?
If the side cutter have been wrongly sharpened on the outside at some time, this will wreck them.
Clean out the lead screw, with valve grinding paste in a bit of hard wood, rather than take a file to them.
In my experience, don't expect much from old rusty bits, they've had a hard time! Shiny well looked after ones, can be still as good as new.

Bod

The outer rim's had all the surface rust scrubbed off but the "shaft" is hard to get at so haven't bothered. I should mention that it's a Jennings pattern. Have a very similar Irwin pattern one, will try it some time.

Can you do us a good, "macro" photo of the auger end including the lead and cutting area?
Someone might spot seomthing.

BugBear

 

[Cowboy _Builder]

They should go through Pine at an alarming rate! As stated previously, they aren't very good on end grain. Hopeless. I found a decent solution for end grain though.

Please enlighten us with your solution .

 

[MIGNAL]

Well, I don't know if he is drilling through end grain. But FWIW.
Brad point bits do OK in end grain. Not many people have brad point bits that are over 10 mm's though. I drill a pilot hole (say 5 mm's) with a brad point. I then follow with a reshaped spade bit (any cheap old thing will do, an old blunt one is perfect). Grind it to a V point - so the whole end is just like a large letter 'V'. It will follow the pilot hole and cuts a pretty clean hole, fast. I've also used it to good effect after drilling with a shell auger. I even put an extension on the spade bit and drilled through 12" of end grain. Commonly known as making a wooden flute. Of course if you want a flat bottomed hole in end grain you will need to find another solution!

 

[AndyT]

While on the topic of end grain, here's some more info - perhaps helping to show why there used to be such a wide variety of bits. These styles were all good for end grain:

If you want an auger style bit, for larger holes, choose a solid auger bit. (The two on the right have had their taper shank cut off by a previous owner.)

For the smaller sizes, shell bits are common and robust, but if you only want a blind hole, they can be a bit annoying and leave a central core behind (like a long thin plug cutter)

For a superior design which pulls the core out, there was the nose bit - I expect that many of these would have been worn away by repeated sharpening and turned into shell bits.

All well worth finding and using.

 

[Sheffield Tony]

What about the gimlet style of bit ? I ask because I saw recently a "flute maker's gimlet", which surely must be intended to bore into end grain.

See here:
http://www.fine-tools.com/bohr2.htm

For new augurs, gimlets, and an augur file for 10 euro !

 

[J_SAMa]

What are you driving them with? They are designed to go slow, if you have them in a cordless drill they won't work unless you go as slow as possible.

Bog standard 10" brace

 

[AndyT]

Tony thanks for the tip on gimlet bits. I have a few small ones which look similar so I have just tried them out. They do seem to work better in end grain than side grain.

Dieter Schmid looks an excellent source - new old stock is always tempting. And there I was thinking I didn't need any more drill bits!

 

[Sheffield Tony]

Dieter Schmid looks an excellent source - new old stock is always tempting. And there I was thinking I didn't need any more drill bits!

Sorry :lol: