this post was submitted on 09 Jan 2024
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This is an abrasive disk, rotating at 1500 rpm. When I shine my flashlight at it, it carries the glow with it, approximately halfway around the disk. What am I seeing happen here?

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[–] Brokkr@lemmy.world 145 points 5 months ago (2 children)

I'm guessing it's an aluminum oxide abrasive? The abrasive is flourescing due to the little bit of uv coming out of the LEDs.

You might find this interesting, if you are grinding iron or steel then the grinding surface may not flouresce due to the iron bonding with the aluminum oxide.

[–] troyunrau@lemmy.ca 35 points 5 months ago (1 children)

This seems like a perfectly reasonable answer. OP! You could probably test this by changing the type of light you're using. Try a red laser pointer as a control, and a black light wand (the sort they use to detect counterfiet bills), and see what happens.

[–] Wogi@lemmy.world 39 points 5 months ago* (last edited 5 months ago) (1 children)

Sadly I have neither of these things available on hand to test that theory but I can at least confirm that the abrasive wheel is a ceramic alumina.

Actually NVM, I found a laser pointer and it has no effect, though it is admittedly quite dim.

[–] troyunrau@lemmy.ca 87 points 5 months ago (2 children)

Complete tangent, but alumina, aka aluminum oxide, is usually considered the second hardest naturally occurring material. When it is found in nature, it is given the mineral name corundum and is clear. But if there are some impurities in it, you can get colours. Red corundum is called Ruby, and blue is called Sapphire. In the beauty industry, the same material (mixed with magnetite) is called emery, and lends its name to emery board, and is used in nail files. In the tech industry, it's used to make the extremely scratch resistant coating on most modern phone screens (basically nothing but diamond will scratch it).

You have subscribed to alumina facts. I'm sorry, the cat facts guy was busy.

[–] Wogi@lemmy.world 42 points 5 months ago (1 children)

We also use emery paper to smooth out rough surface finishes on machined parts. None of my tools but some of the tools the other guys have in the shop use little Ruby beads as reference surfaces. Our wire EDM also uses Ruby for some critical parts.

You've been subscribed to machine facts, strap in it's a bumpy ride

[–] troyunrau@lemmy.ca 21 points 5 months ago (1 children)
[–] Wogi@lemmy.world 20 points 5 months ago (1 children)

Fun fact, machinists do not have friends. Only mortal and natural enemies.

[–] troyunrau@lemmy.ca 16 points 5 months ago (1 children)
[–] Wogi@lemmy.world 11 points 5 months ago (1 children)

Well. SOMEONE'S gotta pick up day shifts mess!

[–] troyunrau@lemmy.ca 5 points 5 months ago (1 children)

Is there a machining community active somewhere on lemmy (yet)? I only dabble, but I like to sneak peaks at real folks fucking up, err, showing off their projects.

[–] Wogi@lemmy.world 8 points 5 months ago* (last edited 5 months ago) (1 children)

https://sh.itjust.works/c/machinist

Not super active but we got shit to do

Ok that's a lie but like we gotta LOOK like we got shit to do

[–] CommunityLinkFixer@lemmings.world 2 points 5 months ago (1 children)

Hi there! Looks like you linked to a Lemmy community using a URL instead of its name, which doesn't work well for people on different instances. Try fixing it like this: !machinist@sh.itjust.works

[–] thantik@lemmy.world 3 points 5 months ago

Works fine for me on a different instance. Maybe other instances should get their shit together instead?

[–] Mango@lemmy.world 6 points 5 months ago

Yo this is fascinating!

[–] 9point6@lemmy.world 2 points 5 months ago* (last edited 5 months ago)

I saw "iron", "aluminium" and "oxide" and I briefly assumed you were trolling until I looked again to check which one was the oxide.