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drill bits for plexiglass

for the canopy you need a no 30 and 27 plexiglass drill bit.

the no 30 can be ordered through Spruce. But I can not find a no 27. Is the diameter very critical?
 
Not sure on the diameter question on the RV-12, but for the -8 I drilled the holes oversized a bit so the canopy can "float" (expand/contract) relative to the fasteners. No cracks in 300 hours.

For the drill bits ... file the "shoulders" off a standard bit and you now have a plexi-bit.

Only drill the plexi when it is plenty warm.
 
for the canopy you need a no 30 and 27 plexiglass drill bit.

the no 30 can be ordered through Spruce. But I can not find a no 27. Is the diameter very critical?
I think I ended up needing 3 different plexiglass bits for the 12 and got them from McMasters.
 
Instead of using progressively larger drill bits to enlarge the pilot holes, I took the recommendation in Section 5 and used reamers. And as mentioned earlier, I oversized the holes slightly to avoid any potential binding. I called Van’s Support on this, and they recommended the reamer approach over drilling.
 

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FWIW, I cracked up a landing light lens (multiple times) with a plastics bit that I think came from McMaster but may have been another source. On the other side, and on the replacement lens, I did the old 'run a regular bit against some concrete' trick and successfully finished the job.

I'm not sure what the heck I'm going to to when it comes to the canopy, but I'm only a couple weeks away from that point so I appreciate the food for thought!
 
On the front side of the cutting edge of your drill bit, use sharpening stone and make the front of the cutting edge flat. In other words remove the rake from the cutting edge of the drill bit. This will make it so you have to push on the drill bit and the bit won’t suck itself into the hole and cracking the plastic. The flat on the cutting edge should be substantial. Be sure to practice on scraps and check the hole size after drilling. Practice until you are comfortable drilling holes in plastic.
 
I'm not sure what the heck I'm going to to when it comes to the canopy, but I'm only a couple weeks away from that point so I appreciate the food for thought!

Follow the direction in Section 5 and Van’s Support and use progressively larger reamers.
 
If you are looking for a #27 plexi drill bit for #6 screws, stop looking. Use a 3/16” plexi drill bit instead. Before you do that, countersink the holes in the plexiglass, using whatever hole size you used for the original drilling (#40 or #30), so you can use your piloted countersink - then drill out to 3/16 using your 3/16 plexi drill bit. Enlarging the holes allows the plexi to “float” a bit - helps prevent cracks in the future. On all of mine I’ve squirted a bit of clear silicone in the hole before installing the screw. Provides a sort of rubber bumper between the screw and the edge of the hole in the plexiglass.

If you are looking for a #27 plexi drill bit for 1/8” pulled rivets, stop looking. Use a 5/16” plexi drill bit instead - easily found. Gives plenty of flex room for the expanding/contracting plexiglass.

In all cases, make sure you smooth all edges, including the holes you made, to the point that they look like they are polished before final assembly.
 
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Follow the direction in Section 5 and Van’s Support and use progressively larger reamers.

Yeah, "follow section 5" is always the best advice and that's what I intend to do. After several operations in the fuse kit that involve enlarging holes I have realized that a reamer is almost always the best option for the task, regardless of the material.
 
I'm about to start my RV-12 canopy and have a couple questions for those that used reamers to drill your canopies:

1) Do standard straight reamers work fine on plexiglass? If so, any tips on how to use them (i.e., speed, pressure, etc)?

2) Can I use a #27 reamer directly in a #30 hole in plexiglass? The KAI have you drill #30 pilot holes first and then upsize to #27. That's a larger jump in size than what you would use in aluminum, but wondering if it works OK with plexiglass. If not, I'll buy a #28 or #29 reamer to progressively upsize the holes.
 
I used #28 and #26 reamers in a cordless screwdriver with a drill chuck. I went slightly over sized with the #26 just for a little more clearance with the screws.
 
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