laser cut acrylic from vendor cut at a non-right angle - is this common?

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rdur
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Joined: Sun Oct 02, 2016 5:11 pm

laser cut acrylic from vendor cut at a non-right angle - is this common?

Post by rdur »

I'm new to laser cutting services. I am restoring an older piece of industrial equipment and needed some parts laser cut for the restoration, so I hired a local plastics company to cut the parts. When I received them, the cuts were all made about 4 or 5 degrees off-square - that's a huge amount and caused every cut to be slanted and skewed. The angle rendered the parts unusable.

The job was straightforward - circular shapes cut from a 12x12 inch area on a 1/2 inch acrylic sheet and they charged me $130 for it. I realize that's pretty thick acrylic, but needed the parts to be cut at 90 degrees because some rotate at high speed and the weight needs to be balanced and the axle holes in the center need to be at 90 degrees.

This was my first time getting something laser cut, so it occurred to me that this may be the norm, but i feel like I should have heard something like "angle tolerances can vary by 10%" before hiring these people. Could this company not have calibrated its cutter properly?

Should I go back to them and ask them to get it right or get a refund? Does anyone know a reputable service that could get this cut using actual right angles?

Any advice is much appreciated, thank you!
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Wayne
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Joined: Thu Oct 15, 2015 1:55 am

Re: laser cut acrylic from vendor cut at a non-right angle - is this common?

Post by Wayne »

Lasers will always impart an angle on the edge, you can calculate the angle if you know your beam diameter ( say 6mm) and focus length ( say 50mm ). If you think of a right angled triangle, the opposite length is Half the diameter of the beam, the focus length is the adjacent. working out the tangent gives approx 3 degrees, which will be the best case scenario. this presumes the laser is set up perfectly, It can be a lot worse if the mirrors are slightly out, if the beam is entering the focus lens on an angle the output beam angle can be exaggerated and unequal.

Using a longer FC lens such as 100mm will "straighten " the beam out, but correct alignment is paramount.

If you need a 90 degree angle you need to have it milled
rdur
Posts: 2
Joined: Sun Oct 02, 2016 5:11 pm

Re: laser cut acrylic from vendor cut at a non-right angle - is this common?

Post by rdur »

thanks for the reply! very helpful
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