First lesson of ANY type of shop is: clean your tools!!!

As a side project, I’ve been working to miniaturize and create in acrylic a cam and gear box I ran across in a book on automata and mechanical movements.
Cam box in wood

Tabs in the original plans accounted for the actual thickness of the acrylic (.220″); tab-depth was adjusted accordingly to ensure none of the tabs extended past the edge of the joining sides. The first prototype was cut from paper-backed display board. Not an ideal material for prototyping: the laser cut cleanly through the top layer of paper but not the bottom. Additional attempts were made using slower speed, higher power, and/or multiple passes — however, the foam core tended to melt anywhere from 1/16″ to 1/8″ into the pieces, raising concerns that they would not give me a true sense of fit, due to compromised structural integrity.

Foam board prototype

for the press-fit exercise, I modified plans for the bottom support beams to make them fully inter-lockable.
Mod sketch

Comparison of original and press-fit SVGs
SVGs
Three attempts were made to cut the press-fit box: two in plywood, and one in masonite. Plywood attempts failed to cut completely through the wood. Pretty, but useless.
plywood try

The Masonite trial was my first experience with Flaming Things In The Laser Cutter.
Ooo, crap!

Root cause — a previous student had used a plywood with high sap or glue content. Thorough cleaning of lens and mirror eliminated the charring, but no luck with full-depth cutting (1/8″ masonite, so well within tolerances of the Epilog). Inspection of the machine suggests that a full maintenance cleaning and calibration is due.

While I do not have a box to show, I did learn this week that the word “kerf” comes from the Old English cyrf, a cutting, and has been used to designate the amount of material lost during cutting since pre-industrial times. Early sawmills used large cutting blades with kerfs exceeding 6 inches. Spontaneous explosions due to a saturation of airborne sawdust was common.

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3 Responses to First lesson of ANY type of shop is: clean your tools!!!

  1. garret says:

    According to some, MDF is supposed to be good for laser cutting. Do a Google on the subject.

  2. aimante says:

    “When MDF is cut a large quantity of dust particles are released into the air…. It is a good practice to seal the exposed edges to limit the emissions from the binders contained in this material.”

    Have to tell you, this experience has been a rapid education in MSDSs, moderately distressing physiological reactions to dust, sound and/or the laser pulsations, and now safety equipment. Not that I won’t *try* MDF. I’ve long held that this vessel should be well-used before I pass this veil.

  3. garret says:

    Sorry – WP didn’t pass this on to me via email (as I’d asked). Just saw it.

    I think airbrushing is the most hideous of deaths. All professional airbrushers I knew back in NYC died horrible deaths.

    Dust is bleedin’ dangerous in enclosed spaces. Problem is, most dust masks are really poorly designed. The standard N95 jobs are so thick that unfiltered air spews and sucks around the edges. I’ve had good luck with another type, though I don’t know how effective they are against construction dust:

    http://www.groupweston.com/qmask_info.asp

    At least you can BREATHE through them. That’s something.

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