Drilling a Hole the Length of a Log

People have actually succeeded at drilling holes in logs the long way. Here, they explain how to do it. December 27, 2006

I am a rustic furniture maker and I have a request to make a lamp from a log that is 6' - 7' long. The log will be 2-1/2" to 4" in diameter. Because it is a log, it is irregular and not perfectly cylindrical. While I thought of cutting the log lengthwise, making a channel cut, then gluing it back together, I have two issues that I cannot resolve with that process. 1) I want to avoid or minimize the glue joint, and 2) because the log is irregular and may have a few branches still on it, I am not sure I can properly re-join the two halves. I appreciate your assistance in finding a solution.

Forum Responses
(Cabinetmaking Forum)
From contributor F:
Look into remodel drill bits that electricians use. I am pretty sure I have seen some three footers. If you are careful, you will make the ends meet!

From contributor A:
Here's a slick trick for you. Take a speedbore and jamb it in the end of a piece of steel pipe (1/4" ID should fit pretty good). The other consideration is how to keep the bit parallel to the log. I would clamp the log to a workbench and fabricate a U shaped guide at least a foot long to hold the pipe in a straight line in both planes.

From contributor C:
I would do it exactly as you described - by ripping and cutting a channel to guide the drill bit - or I wouldn't do it at all.

From contributor H:
Does the log still have its bark on it? If not, cut a groove the length of the log, bury the wire, insert piece of same wood back into slot and drawknife it off to match surrounding surface. Do this on the back side of the lamp.

From contributor P:
If you can weld, or know a welder, weld a twist drill, not a spade bit, onto a rod or piece of pipe long enough to drill the distance. Twist drills are easier to guide in a straight line than a spade bit for long cuts. Of course, the drill needs to be a slightly larger diameter than the rod, and you will need to clear the shavings often or you won't be able to withdraw the drill. My father in law, a welder, did this about 10 years ago for an electric line through a solid wood porch post. The remodel bits mentioned by contributor F come in lengths up to 6 ft, but they have very flexible shafts, meant for drilling long curved holes or around objects, etc. They are very hard to drill straight holes with. They are also very expensive. But if you're good at feeling which way the bit is drilling, you can get them to meet in the middle.

From contributor K:
My band saw has a kerf of 3/32 of an inch. I would saw the post any way you wanted to snap the line. It would glue back together when you were ready. Twenty bucks and it is back in the pickup and headed to the shop. The talking would take longer than the milling.

From contributor B:
Boat builders do things like this. You need a drill bit at least just over 1/2 the length of the log so you can meet in the middle. Auger-type bits work best, as they wander the least. Use a drill with a level built in, or strap one onto it (we have a cheap 3/8" DeWalt drill that has a level). Clamp or secure the log to a table. Verify the level of the table is the same as the level reading on the drill. So now you know that if you keep the drill bubble level, your hole will stay level across the table and through the log.

Now take a long straight stick, longer than the log, and tack it on top of the log down the center. It may help to mill or add on a little flag to the top of the stick at each end, as it's easier to see (think of it like the sight of a gun). Mark a point on each end of the log where the holes should start; the marks should be the same distance off the table (i.e., on the same horizontal plane); and perpendicular to the stick you tacked on top (i.e., on the same vertical plane).

Now start drilling. Go slow. Sight down the drill and drill bit so that it stays lined up with the stick. Keep watching the bubble so the bit stays level. Frequently back up, and make sure the shavings are cleared. If the shavings don't clear the hole, the bit has a greater tendency to wander. Drill just over half the depth. Switch sides and do the same until you meet the other hole.

This method works amazingly well. Also, if you want a 1/2" diameter hole, it's best to drill say a 3/8" hole, then chase it with a 1/2"; this will take care of any offset that exists at the center where the 3/8" holes meet.

From contributor B:
Contributor P is right about drill bits. You want a ship auger bit. You may need to buy the bit and an extension.

From contributor S:
The long remodel bits are available from the box stores. Look for Greenlee brand electrical tools. I use them all the time to run cabling, etc. I can drill through wall studs without it coming through the wall. 2x4 is 3.5". They have a flexible shaft true enough. But the twist type drill end is about 3-4" long and has a screw type guide on the end to pull the bit through. They come in three foot lengths. They also have 3" extensions for them. I have run two extensions to go from an attic to a wall outlet. The ceilings were 12'. As for your log, I don't know how many curves are in it.

From contributor J:
I would suggest avoiding cutting the log, because as soon as you do, the internal stresses will be released and each half will distort, making it very difficult to glue them back together.

From contributor L:
We do this all of the time, except our logs are typically 2' in diameter and are over 15' long. We usually have to drill these monsters to accept electrical outlets if they are used as a post or to accept ceiling fans and lights if they are used as a vega. Nonetheless, having tried many methods, the way that worked best for us was to purchase a ship auger bit. We took the bit to a machine shop where they attached it to a length of cold-roll steel. The same type of steel that is used by the oil companies to drill into the earth. Total cost was under $100 and it took a day to get it back. Drilling the hole is rather straightforward. The difficulty lies in chip extraction, so we drilled a small hole perpendicular to the length of the post and every so often, we would extract the bit and then blow compressed air into the side hole, blowing out the chips. It helps to have a shop vac attached to the top as well. Using this method, I can drill a hole in one of these larger logs and wire it in about 3 hours.

from the original questioner:
Thank you all for the input. I guess I'll go the drill route. This is going to take me a while to get set up for the task (finishing current projects, selecting the log(s), getting the drill), but I think that I will be at it in the next three weeks or so. All the input has also provided confidence that there is a way and that others have preceded me. I guess that is the power of forums.

From Professor Gene Wengert, Sawing and Drying Forum forum technical advisor:
Check to see if there is a log cabin manufacturer nearby. They often drill such holes and could maybe do it for you cheaper than you could do it yourself.