What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Plexiglass & Fiberglass Bits

Bobo

Member
I?m working on the 14 landing light lens, wingtip lens and fiberglass wingtips. On page 17-09, Step 7 it states ?Match-drill #27 the screw holes in the W-00014 Lens with a plexi-bit.? For the wingtip & wingtip lens, on page 24-03 in various steps it calls for #40, #28 & #27 bits. When starting the build a while back, I bought the only plexiglass bits I could find from ACS which are 1/8, 5/32, 3/16 & 1/4 inch.
Where can I purchase numbered plexi-bits? I?ve looked at ACS, Cleveland, Yard Store, and Brown but can?t find them there. I?ve found some threads discussing the modification of bits for plexiglass & fiberglass but I?m not sure how well I?ll be able to accurately do that so they work well.
Thanks for any help you can provide!
 
If you can get the work in a drill press you can control the feed and a standard drill will do fine. If you are using a hand drill the special plastic bits will help. All plastic likes to grab the bit and pull it into the work, a drill press will prevent this, your arms will probably not react in time and when they do they will jerk the bit out of the plastic making a real mess.

run the RPM at 800 or less for small drills (less than .125), high RPM can generate enough heat to soften the plastic and that makes everything described above all the worse.
 
Plex drill bit

On a very fine grinding wheel take the cutting lead off the drill bit and make so it does not pull itself into the work, but scrapes off the plex.It takes a steady hand and a magnifier light helps.
 
After drilling a test hole in your scrap plexiglass, pull out a 10x magnifier and look close. If there is an issue with your bit or drilling technique, you may find radial cracks not large enough to see with the naked eye. Better to find them on the practice piece. And if it looks good, you won't get dizzy from holding your breath while drilling the real canopy....

All good? Now deburr the hole and look again at 10x. A standard deburring tool generally does a poor job on plexiglass. You'll probably see some chatter and gouging, which serve as stress risers. Instead of a cutting tool, chuck a very fine cone-shaped stone in your slow drill and lightly grind the hole edge to deburr.
 
Instead of a cutting tool, chuck a very fine cone-shaped stone in your slow drill and lightly grind the hole edge to deburr.

I second that. Also, make sure you have the right type and angle of cone-shaped stone when it comes to countersinking the plexi. I got my 100 degree stone from Permagrit and it's perfect for that application. Also danged expensive since shipping was from the U.K. at that time. :eek: (They might be available in the U.S. today.)
 
I second that. Also, make sure you have the right type and angle of cone-shaped stone when it comes to countersinking the plexi. I got my 100 degree stone from Permagrit and it's perfect for that application. Also danged expensive since shipping was from the U.K. at that time. :eek: (They might be available in the U.S. today.)

I just looked at the Permagrit site. Can't see the 100 degree stone.
Could you post the part number or a hoto of the 100 Ddegree stone you used?
 
Thanks again for all the great recommendations, especially the grinding stone for deburring the hole.
Of note, I ended finding a great source for Wire Gauge Size Drill Bits for plastics at https://www.mcmaster.com/#plastic-cutting-drill-bits/=1adc8ly and it?s only 10 minutes from my house! The only downside is they only go up to #31 size. I know there are other parts in the RV-14 plans that I will get to later that call for #33 & #40.
 
Back
Top