My tumbler works well for some blades and worse for others, and it works really well for removing scale from pieces with complicated gomtry. However, as I alluded to last time, I had several problems with the drum itself.

The first problem was the water tightness. Not only the lid was not properly watertight, but the sides were neither. I have used screws to secure three wooden planks inside to prevent the contents from simply sliding around the inside without tumbling. And the water was seeping around the screws too. I was able to make it watertight in the end, but it was still not ideal. Plus the inner wooden ribs got worn down a lot quicker than I thought they will, they impeded the contents probably a bit too much.

The second problem was the change of the tumbling medium. I found out that fine gravel with water works great for removing scale, fine sand with walnut shells for a nice satin finish, and walnut shells with ferrous oxide for an even nicer satin finish. However, getting all of the coarser medium out of the drum in order to be able to use a finer one has proven to be nigh impossible. I did not run into any quality problems due to this, given the limited amount of time I have used the tumbler so far, but it did worry me enough to actually postpone its use until I find a solution.

The main problem was finding some kind of receptacle with a screw-on lid of the right size. I was crawling the internet occasionally for months, I even recruited my mother to help me, but we found nothing. We found plenty of products of course, but there were not always measurements written near them and thus we could not order them. And when the measurements were written, they were always of the ronk size.

But the week before Christmas I got lucky and during shopping for groceries, I stumbled upon just the thing I needed. I bought six pieces without hesitation. And this week I took a break from making knives and I made six new tumbling drums. That way I can use six different tumbling mediums without having to worry about contamination.

I started by cutting a 38 cm piece of 100 mm plumbing pipe that remained surplus during house renovations. It is a bit discolored on the outside because it lay outdoors in the sun for a few years, but other than that it is completely fine.

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Second, I have marked and cut in half the receptacles.

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The receptacles were a teensy tiny bit too big and did not fit inside the pipe, but that was not a problem since they are made from PET which is thermoplastic. I have carefully heated the edges with my heat gun and they shrunk a little when cooling town. The edges are not very neat, but that is not a problem.

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Copious amounts of adhesive putty helped to seal both the bottom and the top of the receptacle into the pipes. This was actually the hardest work of all, the putty is a bugger to squeeze out of the tube. theoretically it cannot glue PE, PP, and PTFE, but I did glue PVC to PP with it and it held watertight and strong enough so PET to PVC should not be a problem either. Maybe it won’t be the strongest possible bond, but it should be strong for this application. It is strong enough for me to be able to screw the lid on very tight.

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To prevents the contents from sliding and force them to tumble I have decided to try a different approach, one that does not involve breaching the integrity of the pipe. I have cut three pieces of PVC vinyl flooring, also surplus from house renovations. On one side of those pieces, I have made four cuts and inserted the uncut end s into them as depicted.

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Duct tape helped to hold the pieces in place while I rolled them together and inserted them inside the pipe.

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And voilala (or somtin’)! The inside of the drum is not smooth and round anymore, so the contents should be forced to tumble.

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There were some bugs to figure out and correct. The lids were not perfectly watertight, but I was able to cut circular gaskets from some softer leftover PVC vinyl flooring that has solved that problem. I also had to increase the span between the bearings on the axel on which the drum spins, because I am an idiot and I did not measure it correctly and I made the drum too big.

Currently, it is spinning with fine gravel and a few uncleaned broken blades to see how it works. After twelve hours there were no major problems and it did make reasonable progress on removing the scale.

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One problem remains and I have yet to find a good solution to it. During tumbling, some bigger particles of the tumbling medium (a fine stone or a piece of walnut shell) do wander into the thread of the lid and make it difficult to open the drum afterward. I have tried a few things, but so far without success. But as long as the lids do not get stuck completely, it is a minor issue and I am sure I will find a solution eventually.