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I am trying to make a gallows for Halloween. I found this on wikihow (picture here) which shows using something like a 2x4 as a brace for the 4x4 which is attached to the 4x4 and floor. I found this question, here, that describes something similar to what I am trying to accomplish. My concern is the floor is only about 1" thick so not sure this joint would work.

I would like to re-use the gallows again, so using nails is probably not my best option. I was looking into using an insert nut (similar to what I see used on beds). I also thought about using a Kreg Jig, but the conern of the floor only being 1" thick was a concern again.

So, what would be the best approach, in this case, especially the joint between the 2x4 and floor?

Thanks

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  • 1" plywood is thick by plywood standards so fixing to it isn't so much of a problem, it's common to screw things to 3/4" and even 1/2" ply. Which leads on to a rule of thumb when it comes to screws, you usually want to screw the thinner piece to the thicker piece. So you'd generally screw through the plywood into any of the 2x material that makes up the rest of the structure. – Graphus Sep 28 '17 at 20:24
  • @Graphus that makes sense, but given the 2x4 is cut in an angle isn't the material thinner? I am afraid it would be weak given the screw would go through the plywood and into the 2x4. – lordhog Sep 28 '17 at 23:39
  • Screwing through the ply into the wood should allow the screw to penetrate into the second piece a full 1" or slightly more, which you won't get doing the reverse (and the hold in plywood isn't so good as in solid wood as well). You do have to be careful not to screw directly into end grain on solid wood as standard screws don't hold well in end grain, but across the angle of a 45° support like this you are getting decent side grain for the screw to grip. If you do go this route place the screws towards the fat side of the mitred end, this should allow the use of a screw over 2" long. – Graphus Sep 29 '17 at 6:02
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For something that could be disassembled and reassembled each year, I would give strong consideration to carriage bolts.

A single carriage bolt could serve for both braces where they meet the upright. An oversized washer underneath would mitigate any possibility of pulling through the plywood, although I'd be inclined to think a regular-sized washer would be plenty. You'll need to judge based on how solid the plywood is.

This would require drilling holes at 45-degrees to the surface, which can be a little tricky. You would want to counterbore the holes in the 2 x 4 to accommodate the head of the carriage bolt.

You would want to position the carriage bolts well away from the "sharp" edges of the mitered ends to reduce the risk of tearing out. I'd say centering them 2/3 of the way in would be a good first notion.

If you oriented the 2 x 4 brace the "wide" way rather than the "tall" way, you might consider using two smaller carriage bolts at each end side-by-side.

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    @lordhog Not that I know of. Drilling the clearance hole for the bolt would be fairly straightforward, just start it straight-in (perpendicular) a short ways (1/4" maybe) and then tilt the drill up to the 45-degree angle. The short starter hole will hold the bit from wandering off. The counterbore for the head would be a lot trickier. I suppose I would use a chisel to carefully remove enough material for the head to seat in. If you weren't too particular, the head will crush in a spot for itself as you tighten it, although that's not likely to be pretty. – scanny Sep 29 '17 at 0:30
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    @lordhog A production approach with a full shop would probably be to clamp it to a 45-degree block on the drill press and go at it with a Forstner bit. That would produce a clean flat-bottomed hole and give you a starter center for the clearance hole. But I understand being limited by available tools. You might consider just using deck screws. You could get a few seasons out of those if you were careful and they come in inconspicuous colors. – scanny Sep 29 '17 at 0:32
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If you go to your local big box home center, they have metal brackets with which you can attach 2x4s and 4x4s in almost any configuration you can imagine. I used some of them several years ago to attach 4x4 legs for a balcony to the stage floor. This removes the need to screw at a 45 degree angle or to try to get access from underneath (and screw into end grain). You should be able to find them over near the construction grade dimensional lumber.

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  • Thanks for the suggestion. I think I may try this out, along with @scanny, suggestion on some dummy material to see what works best. I don't have a lot wood working tools, so I am limited. I just have the standard 3/8" drill, starter miter saw, and worm saw. – lordhog Sep 28 '17 at 23:47
  • You should be able to do this with just your drill. – CharlieHorse Sep 29 '17 at 14:18

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