/Fire/ the Laser.

Mar 28, 2010 17:09

I've just come in from the workshop after putting my fist through the plexiglass on the laser. It was already broken but still ( Read more... )

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sci May 13 2010, 22:29:27 UTC
Couldn't you replace the window with something else? Like polycarbonate? I'm sure that was a lot less when I last got some.

What exactly is it about the unit that's routinely causing the misalignment?

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jencen May 14 2010, 18:32:27 UTC
the laser window is a special IR blocking acrylic. the window you saw at CF is actually supposed to be brown o.o

The alignment system is a wonderful thing.
It uses 3 screws and 2 bolts
the bolts create fulcrum (bendy point o.o) and the screws adjust the pressure against a floating plate that's held on by these 2 bolts
There are many issues with this system.
1) imagine a square. the 3 adjustment screws are in the top left, top right and bottom right and the pivot point bolts are in between those. you now have something that is very difficult to position because you can't make it point up to the right, because there's no screw there to push the bottom of the mirror up
2) while the 2nd mirror is a nich chunky bit of aluminium the 3rd mirror, the one that needs aligning more often, is made out of mild steel plate. it has a nice bend in it from the alignment system.
3) nothing has any form of anti slip. no nylock nuts, no split ring washers or corregated washers. so it all falls apart rather quickly

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sci May 14 2010, 19:05:15 UTC
If you're only doing small items for the moment, why not block out the window as a whole with a bit of plywood and fit a much smaller specialised window just over the bit you're using? Just as an interim cost-saving measure?

And just so I understand it right, the alignment is an issue on the beam guide mirrors themselves?
It sounds like it's time to make some custom modifications to the thing.
I'm surprised at the choice of both aluminium and mild steel. While one will bend, the other will surely wear a lot faster. I would have expected hardened steel or bronze pads for rounded-end set-screws to press against.
In the interim, maybe some Threadlock TL22? It's listed as for holding set-screws and anti-vibration applications.

I know where you're coming from. I'm still making modifications to my lathe to overcome some very bad cheap&Chinese design choices. An extra hole, a bolt and some shims can make all the difference in the world! As can a drop of Threadlock on a badly tapped hole.

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sci May 14 2010, 19:10:10 UTC
btw, do you have a visible alignment laser in the machine yet? IIRC, a mirrored flap that can move into the main beam path (when the laser's off) and send a bog-standard red dot out through the system.

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jencen May 14 2010, 21:31:58 UTC
no i don't have a red dot yet. finding room for the semisilver mirror.

Hopefully i'll be changing the machine in the next month so won't have these problems.

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