Tumble Dryer Alarm Clock

It looks like my tumble dryer has an alarm built in to it that wakes me up about once a year. Last year it was a clacking clanking scraping sound (see here).

This year it's a thump thump-thump sound. (Sort of D in Morse code). OK, it's 1:30am so I don't get up, but try to sleep through it. After a couple of hours the dryer finishes its program and I get some sleep. Five o'clock comes round and I get up and investigate.

I've forgotten how to get the top off properly (just undo the side screws and the top comes off to the front. Don't undo the rear screws like I did. Again). To get the sides off I need to take the front panel off and to do that I need to take the bottom vent off. I forgot that it slides on these clips:

I finally have the top and two sides off and can now look for the D-thump. Turning the drum manually I can just feel a bump now and again. The rear bearings look fine, so I have a look at the rollers. They are fine too. Then I notice the drum has some black marks where something has stuck to the track the rollers run in.

I find that there's a big blob and several smaller blobs, which probably accounts for the D pattern of thumping. I scrape the blobs off with a wooden stick and re-assemble the dryer.

A quick test and the D-thump is gone. I have no idea what the black blobs were. At first I thought it might be material from the rollers, but they look fine, with no obvious missing material. Maybe something fell onto a roller and ended up smeared around the drum?  I have no idea, but the dryer seems well again, which is good.

More Magic Metallised Paper Experiments

I've been trying to make paper that works in the Casio FP-10 printer. See the previous post for attempts one to six:


 https://trochilidae.blogspot.com/2019/12/magic-metal-paper-in-seventies-casio.html

Attempt Seven 

 Spot weld primer.

Anyway, I was watching an episode of Wheeler Dealers and Edd mentioned that you use a conductive spray primer before you spot weld, sometimes. That was interesting as I had been looking for conductive spray paint. A quick google and it appeared that yes, this primer was indeed conductive due to either zinc or copper in the spray. Not only that but it as available at a local auto supply shop.
One trip to the shop later and I had a can of pretty expensive zinc spray paint. It was no problem to then spray a sheet of A4 paper:

When dry the surface is similar to the magic paper, and even shines up a bit if you rub the surface:

Unfortunately, even though I did measure some conductivity when drying, the paint seemed to not be conductive when dry. I did a couple of sheets with varying numbers of layers and ran some test strips through the printer:

As you can see, it's a bit messy and clogged the print head as the final product is quite thick. It also didn't work.

Attempt 6b

I then had an idea about testing the paper. I set up a PSU with 15V on it and attached one wire to the paper then dragged the other wire across the paper. This gave me an idea whether the paper would spark erode or not. The real Casio paper worked fine (as expected), but the only paper from my tests that worked was the 'gilded' aluminium one. Here's some scribbles I made, which are spark eroded. The black you can see is some paint I sprayed under the aluminium, just like the real paper.

Even though this manual test worked, it didn't print in the FP-10.