![]() ![]() This allows for adequate clearance for thermal and moisture expansion and contraction. First, the bolt hole diameter should be at least 2 times the diameter of the bolt. According to Cyro Industries (Evonik): When drilling holes to support sheet by point fastening, there are two rules that apply. This can also happen in a window where something impacts against it - and Boom, there's a crack in your sheet. Why? The expansion and contraction of the plexiglass will put stress on the hole. Second - make sure the hole is BIGGER than the screw or bolt. First - make sure you use a Plexiglas drill bit (the head is reshaped to a 60 degree angle and carves through - metal bits punch out the backside of the plexi and cause chipping). Now a lot of cracks come from the HOLE that was drilled. BTW, the same goes with polycarbonate (Lexan) - it is also "notch sensitive" (like glass too) and WILL break at the chip. Trust me on this - it makes ALL the difference in the impact resistance of the final piece. ![]() That's OK - just sand down the chips with 80-100 grit sandpaper. When you DIY, you might have some chips from your cutting. When you get plexiglass from a "real" dealer (not HD or Lowes) they have the equipment to cut sheet correctly. Most cracks propagate from holes or from edges that have not been smoothed after cutting. However, that said, you "could" do that by using another glue such as WeldOn #16 or better, WeldOn #40 and a small piece of CAST plexiglass sheet (not extruded).ĥ. I don't know FAA regs, but I doubt slapping on a strip over the hole will pass inspection. It may or may not be "stretched" or "pre-shrunk" acrylic. It's chemical resistant and the regular #4 glue won't work. Normally, the plexiglass acrylic used in plane windows and windshields is different than the plexiglass used in displays and windows. Airplanes, gliders, and other aerospace cracking. If there is vibration (like a camper window) it will open up again - but the crack will not get longer.Ĥ. The water thin adhesives such as WeldOn #4 will "wick" into the crack by capillary action, and probably spill out around the crack (wipe off with Kleenex quickly). ![]() This is tricky AND you may have some success if this is a display case, window, or other stationary object. Not because I wanted to, but I was getting grief from my wife about having a plastics company and I really had no excuses left - 8 years was a solid test of my fix.ģ. I finally replaced the top last summer in 2008. I had a patio table top that cracked in 2000 when the wind blew over the table and the umbrella pole jammed the hole. The hole drilled at the end of the crack will STOP the crack from propagating any further.Depending on the severity of the crack, this might be all you need. (otherwise, you really DO nee d those bits for NEW holes).Ģ. You don't need the special Plexiglas drill bit for this one since the Plexiglas is already cracked. Teeny will be defined as the smallest drill bit you have laying around. You do this by drilling a teeny hole at the end of the crack. hey, it's the Plastic Genius, there must be a solution to this! Well, there is and here's the basic idea.ġ. ![]()
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