Arch

I wanted to make a small arch. Cheap, because it is for a cheap project and I don’t know how I’m going to make it but bent laminations seem like the way to go. So, off to Home Depot to get some doug fir 2x8s. Strike 1, no KD (kiln dried) 2x8s. But they have KD 2x6s. And they all suck. Next pallet over, pond dried 8′ 2x6s, I pulled apart the stack to find some without 100 knots per foot AND no wain. Take them to the check out and get change back from $10. Take them home and try to slice them up so I can bend them. Complete and utter failure. Me + bandsaw couldn’t cut the mustard. Then the planer would chew them up and spit out pieces. What I managed to salvage just broke when I tried to bend it. Plan A does the Hindenburg.

Plan B is to chop a bunch of pieces and glue them together. Biscuits will be used in hopes I won’t get a fallen arch. A bit of TurboCAD gets me a cut list and the chop saw makes the pieces. Since the arch isn’t circular (it is a flat topped oval), I’m forced to take extra care to keep track of what is connected to what.

My Porter-Cable biscuit joiner works a treat on the funky angles. I put two biscuits low so I can slice off the crowns without exposing the biscuits (and weight on the top of the arch will pull on the biscuits and not try to open the joint). Here it is with just biscuits; dogs are keeping the legs together and there is a weight on the top.

How to clamp this thing for gluing? What I did was glue each half separately. I took a couple of 2×2 and notched them to hold the ends of the arch half, clamped those between bench dogs and used a F clamp to bear down on the arch. By moving the dogs and adjusting the height of the F clamp, I was able to get a good squeeze.

But, before the final glue up, I did some preliminary shaping: a #3 to remove the bulk of the crown at the join and files to sorta round it. The batten clamped to the bench worked really well.
This shaping is pretty tedious, slow, and tedious but at least I get to listen to tunes and don’t have to wear a hazard suit and hum along to a screaming sander (which I don’t have anyway).

To glue the two halves (one of which has the top plate), I did bigger version of gluing each half. It was dryer than I expected but still not very so I put it in the attic for a month or so (it gets screaming hot up there) while I did some other stuff (like put a skylight in the shop). The moisture meter says about 1-3% over the fir that has been in shop for multiple years so hopefully it won’t pretzel on me. Then an ungodly amount of filing, eyeballing, drawing lines, filing, etc. After that, into the hazard suit and have at it with the 80 grit paper. This construction lumber really is garbage – the early and late woods come off at very different rates so it pretty much impossible to get any kind of a flat surface.

And a load test. You would think I’d do something nutso like this before all that shaping but noooooooo. It does flex a bit, I’d tie the legs together if it was a chair part, but it’s not and will do just fine for the < 30# load limit I’m going to put on it.

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2 Responses to Arch

  1. Vern says:

    Hi, I noticed your arch table. You will probably enjoy this you tube link that shows a guy making an arch table using steam and its out of one piece of wood. enjoy

  2. Zander K says:

    Thanks for the link, that is an awesome bench – I love the shape and the fact that he makes from a log. Steam bending is something I’d like to work up to.

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