I need to drill a 0.5" hole for a big bolt going through 4x8 beam (used in swing). Now I only have the hand drill and no drill press tool (which could be nice). I only need to make 2 holes and they must be straight from one end to the other.

What are some tricks to drill a straight hole through 8" of wood? I am thinking about putting my drill sideway and slowly move in with a piece of lumber below to support while drilling. But then I don't really have a 8" long drill bit so I need to drill on both side. Even 1/4" off would be a big issue.

Please let me know any suggestion.

3 Answers 3


If you are drilling a hole through 3 pieces, and you do not want to purchase a 12" "twist" (metal bit) bit to do the job, which would be the way to do it.

drill bit

If you choose to use the shorter version, there is a way to do that too. Main thing is, is to use a twist bit since it is full round so to speak and once it starts in a direction, it usually will not redirect or change it's angle of drilling. It will take a few steps to accomplish the job.

First drill the hole all the way in as far as it will possibly go, hopefully a good distance into the second piece. If possible re-chuck the drill bit into the drill so it is barely in the chuck to maximize the drill depth, after you do the initial fist bore to get that "last little bit of depth".

Remove the first piece you drilled through. Using the hole that is started in the second piece, and re-chucking the drill bit in properly continue drilling using the hole that was started in the second piece as a guide. If that does not get you all the way through, use the same method mentioned earlier to get the rest of the way through.

If the holes are needed to go through the 7 1/4" height of the beam, you would be wise to get the long drill bit. If not take the chance and line the holes from either side the best you can, drill them in as deep as possible from each side and hammer the livin' crap outta them. They might make through... I have been that fortunate doing it that way too. It does blow out the wood a little bit on one side. That is the trade off, if it works....

  • I was searching and found the "Bosch 1/2-in x 12-in SDS-Plus Drill Bit" for like $19 which is not bad. Is that the one? I am not sure what is the twist metal bit for?
    – HP.
    Jul 18, 2016 at 3:40
  • SDS bits are usually for concrete, not suitable for wood. Twist bits are usually for drilling metal, here is a link. lowes.com/pd/DEWALT-1-2-In-x-12-In-Black-Oxide-Twist-Drill-Bit/…
    – Jack
    Jul 18, 2016 at 4:00

You could try clamping something rigid and relatively straight (like a T-square or 1x4) to the beam and then using that to ensure it's perpendicular. Then measure your holes and drill with, say, your knuckles making contact on the rigid surface

If I were you, I'd just buy a longer bit tho. Sounds like a waste, but when you need the right tool, you need the right tool. And it makes life easier. Your regular bit may not penetrate enough to connect the holes (I've had that one happen).

  • 1
    Dunno where you are, but there are places like Princess Auto and Harbor Freight that sell cheap (and crappy) drill bits like this that would be perfect for a single use. Jul 18, 2016 at 0:24
  • So I am thinking of getting this set from Harbor Freight harborfreight.com/… and then use 2x4 as my guide. Basically I found temporarily attach the 2x4 into the 4x8 using L bracket. That would give me 90 degree angle so I can use as a guide. Thought?
    – HP.
    Jul 18, 2016 at 3:45
  • Good plan. Even the L bracket alone (unattached, even) would give a good 90 degree guide. Jul 18, 2016 at 13:19

There are a number of tricks, ranging from placing a mirror next to the hole so you can see more easily whether you are really drilling perpendicularly to the board's surface to using a small square to check this to using a small jig with a guide bushing to hold the nit at the right angle.

However, this does not sound like an application where perfect alignment is required. I'd probably just use the Mk. 1 Eyeball.


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