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Monday, May 29, 2017

Forged Chandelier: The Frame

Over the last few months, it has been incredibly difficult to get any time in the shop. Rather, to find any time anywhere to be productive making things. Throughout the weeks since I last posted anything, I have been working on designing and forging a chandelier. The ultimate design will have the piece detailed below hang from chain (which I will also make) and hold a collection of lights that cascade around the rim.

First off, the tools and techniques here are all period to the shop I am working out of, as I am here as a public demonstrator and educator to the 1850s era. To begin with, I forged the outer pieces of the rim. These ultimately determine the size of the chandelier, so I figured it would be best to do this before the cross piece in the centre.

Via hack saw, I cut the four pieces. Originally, I was going to have a solid rim with the ends lap welded together, then forged into round. This quickly turned into something else when I tried to figure out how to get the internals worked out.

To give it a little more flair and character, I added some swept corners to each of the ends. I intended them to be sharp corners, but I decided I liked the curves better (and were less work...). For the sake of repetition, as there are eight of them, I used the pair of double calipers I forged a while back. Half the fun of making things is using the tools you made to make them.

To that half inch mark, I drew out little tenons on each end of the four bars. These are what became the bent down points.

Which look like this. There are a lot of parts of this build that I was not able, for one reason or another, to document. To forge in these points, I held the tenons down over the face of the anvil and hammered them to a right angle with the long edge of the pieces. Then, clamping the lot in a post vice, upset the material back into the bar to get something resembling a corner on the far side. If I were to make it a sharp angle, I would have continued forging this way until the two lines came together, but I wanted the rounded corner on the inside and outside of the bend.

Considering the variation in the process, the result was remarkably uniform. Symmetry, I have come to realise, is my mortal enemy.

Next up is to make them round. No mysteries here. I just hammered them over the horn until I was satisfied.

Having them all bend slightly more than the 90 degrees of the arc they were cut to fit in results in a lobed sort of shape, which I liked more than a straight circle. It just seems a little more interesting.

Part II is to build the internal frame. At first I thought about some weird skewed thing that would not have any intersections, then having two layers where one side passes over the others, but in the end I decided to try out slitting and drifting each of the bars to pass through one another. It is a technique that I learned requires a bit of practise to get right.

This is the general layout of the bars, and where each of the intersections is, one of the bars will pass through the other. Blacksmiths are, as far as I have been able to reason, the only people who can put a 1" hole in a 1" bar and still have it all stay together.

This is where I wasn't able to take any photos again... But, to explain the process, I measured a distance from one end of each bar that was less than half, then marked it on all of them. Having a uniform distance here is critical to it working right. The distance off of the bar's centre determines how large the square in the middle is. The closer to centre, the smaller the square.

To actually make the holes, I took a chisel and slitted it to roughly the skewed length of the bar that passes through it. Then, I forged a drift with the tip that tapers only in one direction. This way, as it is hammered through the slit, it widens the hole in the right directions. It's really just a wedge that turns into a square at the end. Having the slit be wider than the width of the drift helps with not stretching out the cheeks of the hole you are making.

With all that out of the way, I set it out again to determine the next move. Attaching the outer rim to the cross went through a few design changes as well. Before I actually started any of this, I thought about using wedges to hold the outside pieces on to tenons sort of like in Japanese woodwork joinery, but I gave up on that almost immediately.

Instead, I decided to make regular tenons and forge them down like rivets. To make these, I used a guillotine tool for the shoulders, then followed it up with a hot rasp (after this picture was taken) to make it all square and aligned.

Making the square holes for the tenons to fit into was actually the easiest part of this ordeal. Because they were all slightly different, I made a tapered punch/drift that I eased into the size of the tenons. Because of that, it all fit together only one way, but that's fine.

Getting the thing to assemble was tricky. Once the first three rim pieces were on, the entire thing became more rigid, and since the sector length at the end of the tenons is a fair bit longer than it is at the shoulders, working that last piece into place took a bit of patience. This too also helped lock the inside frame into place. Due to the nature of its construction, the four bars can slide closer and farther apart until they are constrained in some way. Having the outside pieces there prevented it from moving about.

And there we have it! This bit is done for now, all eight rivets in place. Heating it in the forge was precarious at best, because the thing is large and awkward. I had to clamp it all in the post vice to hammer down the rivet heads, and even then the ones that were not yet affixed tended to fall off without any help getting them back on again.

Next time, I will forge the chain and hanging assembly, and maybe also just finish it with the wiring. Who knows? I guess we'll have to learn together.

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