Sunday, January 8, 2012

A Ceramic Spatula Handle Repair

Pictured below is a ceramic spatula handle in obvious need of repair, but there'll be a little more to this than just closing up the broken out end.

There's a fallacy in the way this handle receives the spatula's shank. The shank should have been secured at the ferrule, so that upward forces on the shank would be taken at the ferrule surrounding the lower end of the handle. Instead, that 'bulb' inside the handle at the upper end of the shank transmits upward forces directly to the brittle, unreinforced tip of the handle. We see in the photo the result of that.

Two things need to be done to effect a sound repair to this:

a) The shank needs to be immobilized within the hollow handle against sideways forces.

b) A tiny roll pin needs to be installed through the shank right at the face of the ferrule. That will correct the fallacy in the utensil's construction.

I had epoxy in mind at first for immobilizing the shank within the handle, but thought better of it. I ended up taking advantage of the long nozzle on a tube of clear silicone sealant to simultaneously stuff the handle with sealant, and provide an adhesive base for the two broken out ceramic bits. Here it is done and clamped up and with a couple of O-rings rolled onto the tip as rubber bands.

I'll set this aside in a safe place for a couple of weeks at least; there's a lot of silicone sealant inside that handle to cure. I need to be sure that it's solidified before I resume working on this.

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SUNDAY, MARCH 25, 2012

Installing the Roll Pin

This is going to be a bit tricky. The shank is stainless steel, and stainless steel is very tough stuff to drill -- I'll need to use a cobalt drill.

The hole has to located such that the pin through it will be right up hard by the ferrule. I don't trust myself to locate a centre punch mark accurately enough, so I've made a drill guide from a piece of mild steel flat, like so.

I drilled through the flat 1/16" diameter very near its end, then ground the end until I'd just opened up the side of the hole at the end of the flat. I've clamped that to the spatula's shank, and the arrangement should give me the outcome I'm after here. We'll see.

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You win some, you lose some.

I swore when I began this blog that I wouldn't try to conceal my failures, so I have to confess that that didn't quite work out as planned. The hole ended up a little away from the face of the ferrule, not right up against it. I installed a roll pin anyway, and wrapped some fine steel wire around to take up the space between the ferrule and the pin, like so.

What I'll do now is encapsulate that affair in J-B Weld, and if that turns out ok I should have more-or-less the effect I was after -- upward forces on the shank will be taken at the ferrule, not up inside the tip of the handle.

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Here's my crude encapsulation form set up.

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That arrangement very nearly went south on me a bit later as I was filling it -- it slipped on me. I managed to keep it together and fill it and set it safely aside. J-B Weld is a very slow curing epoxy, so I had to leave it over night. Here's the outcome.

I'm expecting that beer can aluminum to peel away fairly easily. We'll see.

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As expected, the form peeled away easily. Here's what I've got.

Some trimming and filing is in order. It won't win any industrial design awards, but it'll serve the purpose.

Here it is trimmed and filed.

Not my best ever work. I should have thought to mask the shank, and not filled up the form so much. But the epoxy's adhesion to the the clean stainless steel is quite good; this should be a sound, if somewhat unattractive, repair.

I'll apply some CA adhesive around the ferrule so it can wick in and seal that interface, and also to the seams of the adhered porcelain bits at the tip of the handle. Then it'll be well and truly done, and I can get it out of here.

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