AC synchronous clock

[RichM (Rich Maynard)]

In the process of making a bicycle chain clock for the STEM room at a primary school.

AC synchronous motor, laser-cut MDF gears (not cut at SLMS!)

The AC motor (12v for safety!) spins at a constant 5rpm - well, with UK 50Hz mains, anyway. I had to find a ‘real’ transformer to supply the 12v - so many so-called lighting transformers are in reality electronic-based.

The compound gear chain reduces the speed to 1 revolution per hour. The tooth the bicycle chain is running on has 10 teeth, and there are 10 links between each number on the chain - so one number passes by per hour. This photo shows about 10 past three.

It’s quite pleasing in reality - I should upload some video. The motor spins at a nicely visible speed, and the gear chain gradually slows from there until the final gear is hardly visibly moving at all.

[peter_hellyer (Pete Hellyer)]

@RichM

MDF gears (not cut at SLMS!)

Boo! Hiss!

But also, it looks lovely

[RichM (Rich Maynard)]

Well, we’re not allowed to cut MDF at SLMS! I think I’m going to paint it at some point. Sort of a steam-punk vibe.

[Dermot (Dermot Jones)]

Why is laser MDF not acceptable? @lasertechs?

[tomnewsom]

IIRC, it was because the Atmos filter wouldn’t be able to scrub the formaldehyde thus circulating it around the space.

[Dermot (Dermot Jones)]

So that may no longer apply?

[tomnewsom]

MDF "Forbidden"

MDF and non-laser ply, anything with glue or resin in it will block the filter faster than you can say Makerspace. We did a test, on a project early on and the machine became very dirty, much of the brown discolouration is because of that project. The machine was very sticky inside also. This also increases the risk of breaking the lens from residue on the lens that needs cleaning off. Importantly: The fumes from the MDF go through the filter into the room leaving an acrid smell that I found …

So it also makes a lot of gunk that would have made mincemeat of the Atmos. Our new extract is more robust (and much much cheaper to service!).

I need to talk with the other lasertechs to arrange appointment of new ones, so will bring up the topic then

[RichM (Rich Maynard)]

Any smoke isn’t great for the mirrors. But if the extraction sucks, should be fine!

[unknowndomain (Tommie)]

The mirrors are an issue but less of one, you can probably safely remove this on a trial basis and see how notable the fumes are in the room, sore throats and smell is the warning. Short of doing proper air monitoring.

[lewisss (Mark Johnson)]

@tomnewsom

MDF and non-laser ply, anything with glue or resin in it will block the filter faster than you can say Makerspace. We did a test, on a project early on and the machine became very dirty, much of the brown discolouration is because of that project. The machine was very sticky inside also. This also increases the risk of breaking the lens from residue on the lens that needs cleaning off. Importantly: The fumes from the MDF go through the filter into the room leaving an acrid smell that I fou…

was this laser safe mdf or just normal mdf that was used in this test?