Friday, July 1, 2011

Lengthening a Sign Holder's Stakes

From the, "What were they thinking?" department comes this item. Pictured below is the staked base of a sign holder, along with some bits I'll be putting to use to improve it.

Those stakes are only six inches long from the crossbar on down. That doesn't strike me as long enough to securely hold up much of anything, especially a cantilevered load as will be the case with this sign holder.

The stakes are a bit of an odd diameter -- 9/32". The best nearest thing I have for lengthening material is that length of 8mm diameter rod salvaged from a laser printer. The two 1/4"-20 coupling nuts will serve as joining sleeves. (It would be nice if there were an easy way to do this 'seamlessly', without introducing the bulges that the joining sleeves will create, but that's really not on.) While I'm at it, I'll put pointy ends on the lengthened stakes; stakes are supposed to have pointy ends on them, surely.

I'll start with making two pointy-ended extensions from that length of 8mm rod.

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And here they are. Those will give stakes that are seven inches longer. That should be more like it.

(The camera angle really distorts things. Those rods are exactly the same length.)

Next up is the two joining sleeves. I'll bore through the coupling nuts 9/32" all the way, then 8mm half way and they should do the job nicely.

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Here's everything ready for initial assembly.

While I was at the coupling nuts, I chamfered their ends somewhat. I evened up and squared off and chamfered the ends of the original stakes.

What I have in mind now is to glue this up with CA adhesive. Once that has cured sufficiently, I'll drill through at four places for interference-fit steel pins and I'll have this thing together for good.

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Slight Problem

My 8mm bores turned out a bit oversize, so there was too much clearance for CA adhesive to work effectively. (Although I'm on record as having said that CA adhesive can be made to 'build' and be of some use as a filler, and that's true, for successful adhesion the parts to be adhered together must be very close-fitting.) I had to use five-minute epoxy to glue the 8mm diameter rods in their bores. I suspect the bores turned out oversize because of a little quirk in common mass-produced coupling nuts, and the way I went about the job. See this post for more on that.

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Interference Fit Pins

I happen to have a supply of 5/8" long hard steel dowel pins that should do nicely for this, but may be a bit problematic to install.

The pins are 0.092" in diameter, (That's just shy of 3/32".) The nearest smaller drill size that I have is No. 43 (0.089" diameter). That's a difference of 0.003", and that's a lot for parts this small to start with. (A difference of 0.001" would be what's wanted.) So, I'll be pushing my luck here, but let's see how it goes.

And here it is pinned. A qualified success -- not a complete botch, but certainly not something I'm proud of.

Note the mushrooming and folding over. A proper job would not exhibit any of that. Also, a couple of pins didn't quite make it all the way through so, as I said, I'm not at all proud of this outcome. Anyway, it'll have to do. I'll trim off the excess lengths and it will serve for what's needed.

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That went fine, and CA adhesive performed admirably as a filler for the spots where the pins didn't go far enough through and left little recesses. Here's a close-up shot of two filled and sanded spots.

The adhesive has outstanding characteristics for use as a filler for tiny flaws. Just apply it where needed as needed. Surface tension effects allow it 'build' somewhat even in its wet, runny state. Leave it alone for awhile and it'll harden. Repeat if need be. (It's humid around here today and that has helped it to cure quickly just sitting on a surface.) Once hardened, it sands and 'feathers' beautifully. I doubt there'll be even a trace of those flaws to 'telegraph' through paint.

So, the sign holder now has 13" long stakes that should anchor the thing reliably.

There are two other pieces to this sign holder, and all three pieces need a new paint job. I'll update this post as I make progress, and photograph the finished complete item.

[And the next time I do an interference fit, I'll think it through more carefully and get it right.]

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Addendum -- Paint Job Done and an Installation Tool Made

The CA adhesive worked perfectly as a filler to conceal the flaws in my joining sleeves; there's no evidence of the pins' installation whatsoever.

And I've made an installation tool for it from a piece of hardwood.

Now I can hammer on it without directly hammering on it.

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