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I want to create long - about 12" or longer and about 1.5" or greater in diameter - holes in some logs.

I found a lot of info online about how to create short holes that are wide, but not long holes that are wide.

What options there are for me to create long tunnels in logs.

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  • I’m voting to close this question because it's a shopping question that can be answered with a simple web search.
    – FreeMan
    Sep 27 at 17:40
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    @FreeMan IMO a shopping question is more like "which 12-inch 1.5-inch diameter auger bit should I buy?" The question at hand is more about different types of tools and what's appropriate for the job; it's not about specific products.
    – Caleb
    Sep 27 at 19:21
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    Could you give us a better idea of exactly what you're doing, and what the holes are for? There are also many relevant details we need to know, including what drill you hope/intend to use here — just so you know right now, this could be literally impossible even in a middling-hard wood with many drills because they lack the required torque (many cordless drills bog down drilling dog holes in thick oak benchtops for example, and this is significantly more taxing than that). As important or more is the species you're working with and whether the wood is fresh or seasoned. [contd]
    – Graphus
    Sep 27 at 22:08
  • Holes of 2" in green pine & the majority of softwoods should be fairly easy, but there's a massive difference if you're looking to do them in seasoned logs of mesquite or osage orange O_O
    – Graphus
    Sep 27 at 22:10
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    @Caleb that's why it takes 3-5 votes to close. "what option there are for me to buy" flags "shopping" to me. I can see your point, too, that "I don't even know what to look for", but even a search for "drill bit 2 inch" turns up options for Forstner, auger, hole saw, even bulb planting bits.
    – FreeMan
    Sep 28 at 11:21
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Please advise as to what options there are for me to buy as tools to create long tunnels in logs.

You need a long drill bit in whatever diameter you want. You can buy auger bits that are 1 1/2" in diameter and more than 12" long, so that's an option. However, auger bits are essentially long metal spirals, and they tend to be a) expensive and b) easy to break. So a better option might be a shorter, cheaper auger bit and an auger extension. The extension is just a straight rod with an appropriate connector at the end, and it effectively adds length to the shaft of the bit rather than the spiral section. A long auger bit can easily cost $50 and is likely to break; a short auger might cost more in the $10 neighborhood, with an extension costing $10 or $20.

The down side to using an extension rather than a long auger is that without the long spiral section, you may need to clear the chips from the hole more often. In practice, that just means pulling the bit out of the hole and re-inserting from time to time.

You can also use other types of bits, of course. A spade bit with an extension would also work. Spade bits tend to be cheap, but also slow.

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  • Heck, you could use a Forstner bit, with extension, though those tend to be pricey.
    – FreeMan
    Sep 28 at 11:22
  • Cheap spade bits do get rather hot, even scorching the wood, especially if you try to make them not slow. And they make clearing the chips harder than an auger. That's not to say don't use them - I would but I've got a selection already - just to consider how you'll set the job up
    – Chris H
    Oct 5 at 14:00
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Take a look at what wooden shipbuilders do for long (longer than 12 inches) holes in timbers that have to be somewhat accurate. An example would be a tunnel for a prop shaft.

You don't say if you need to make through-holes, or auger to a specific depth. Modify these instructions to suit for that.

The key is to drill the hole more than once. Use a long, thinner bit, like 1/4inch or so, and setup plumbs or other references (such as lines along the length of the piece) to keep things true. Drill a pilot hole all the way through (or to the correct depth). It may help to have an assistant watching you to make sure you are true in multiple axes.

You will have to clear the chips often, and you may have to switch to using an extension at some point. Stop often and make sure you are running true.

If the pilot hole ends up in the right position at the other end (or depth), then you have a hole that one or more auger bits in increasing size will just follow. Some boat builders grind the threads off the point of the auger bit (if your auger has one) so the auger literally just falls into the pilot hole instead of trying to pull itself in. Clear chips often.

These bits come in very long lengths, or can be used with extensions. Since you will be clearing chips by hand very often there is no use using bits with flutes along the entire length. What we want is a carefully drilled pilot hole that you then auger out to specific diameter by following the pilot hole.

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    I can see an auger following a narrow pilot hole because the point will follow the hole, but you seem to be suggesting using successively larger bits to widen the hole. What guides the bit once the hole is larger than the auger's point?
    – Caleb
    Sep 28 at 16:52
  • The auger is going to follow the hole if you start it right. It won't start making its own path, and any wallowing out is a function of how true you run things. They've been building ships like this for centuries. You always start with a smaller hole and then follow it up with the finished size. So, at least two attempts. Maybe it is unnecessary to go up more than one size, but it would not necessarily be an insurmountable problem to do so.
    – jdv
    Sep 28 at 17:03
  • Possibly highly relevant: how frequently are shipwrights drilling such holes into end grain, and do they follow the same procedure if/when they do?
    – Graphus
    Sep 28 at 17:43
  • Probably not a lot of reason for shipwrights to auger out through an entire timber. More likely they are augering out holes through multiple attached piece of timber, some of which might be through near end grain, depending on the orientation of the members. Still, any craft that relies on timber framing will have tools and techniques closest to what the OP wants to do.
    – jdv
    Sep 30 at 13:21

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