Now the waiting begins… laser cutting a case – Part 3 of 3

As mentioned previously my Ponoko order arrived.

So people tend not to show off their screw ups.  The purpose of my building this site was to share with friends, family, and the internet at large what exactly it takes to create a coffee roaster controller.  The money, the heartaches, and well…. the good… the bad… and the ugly.

Unfortunately, today I give you… the ugly.

The Ugly

You don’t usually get to see what goes wrong with laser cutting jobs but considering how many times the curves overlapped each other I’m surprised it isn’t worse.

Surprised it isn't worse!

Most of what’s wrong with the job is obviously what happened on the bottom where the acrylic came in contact with whatever Ponoko cuts on top of.  It seems that some sections obviously burned and melted/cratered portions of the acrylic.

Some areas are brittle.

In a few places the plastic is brittle but only from the bottom side but that last one looked ok on top but there wasn’t enough to count on it not breaking later.  In some areas pieces burned back into one another!

Some areas burned back into one another

Many of the bad spots would not be an issue for a small one off project that gets covered with some sort of screw or bolt.  Others that appear on the surface would be a huge deal.  A few places I apparently removed too much line near a curve and didn’t fill in the straight line so I need to dremel off some stray plastic.

Oops! Apparently I deleted too many straight lines!

Outside of the too many circles and that stray plastic I did not make the spacing correct on the hole that keeps the fan and heat potentiometers from spinning even though I measured it with a micrometer.  It was VERY close but still off by a small bit.

Close... no cigar

I could totally fix it with the dremel for now but will fix it properly for the next run.  Also it appears that I calculated a reduction in the length of the inner bottom plate wrong.

Sometimes you forget you already subtracted the length off the total.

I had taken the outside measurements and subtracted the thickness of the acrylic twice when I had subtracted the rear once already and then subtracted the front and rear later.  Finally I calculated it into a measurement adding it back twice instead of the one extra time.  As a result it is too short front to back.

For these parts I will be testing the process of infilling the engravings for the test to see how they come out for very narrow and wider text.  I will also (when the tools arrive) test the drilling and countersinking with a few various plastic bits before trying them out on the final plastic pieces.

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