[drone_pilot]

Page 38-24 of the RV-14 plans tells me to drill the canopy side skins to #27 then shortly after to drill the canopy to #27. My question is what tool do you use to countersink the plexi when it has a #27 hole drilled into it?

Thanks!

Ben
RV-7A completed 12/17
RV-14A to be completed on Tuesday (just don’t know which Tuesday)

 

[TASEsq]

My question is what tool do you use to countersink the plexi when it has a #27 hole drilled into it?

#6 screw countersink cutter.

Countersink Cutter

Countersink Cutter

cleavelandtool.com

Although some people reckon a 100 degree permagrit grinder. In a few tests on a canopy scrap, I’ve found that this leaves a rougher surface and a ‘less nice’ countersink. I don’t think they make one with a #27 pilot.

Countersink 100º No Nipple 11.5mm dia. LC5

Large countersink, 100 degree, NO Nipple. Shaft / arbor 6mm (.24")Overall length 33.5mmGritted length 8mmWidest point 11.5mm(all measurements are approximate)Tungsten carbide abrasive grit countersink. Designed for Lancair aircraft, Motorsport & Leisure craft industry. Countersink:- GRP, Fiber...

permagrit.com

 

[Halleffect]

Although some people reckon a 100 degree permagrit grinder. In a few tests on a canopy scrap, I’ve found that this leaves a rougher surface and a ‘less nice’ countersink. I don’t think they make one with a #27 pilot.

Countersink 100º No Nipple 11.5mm dia. LC5

Large countersink, 100 degree, NO Nipple. Shaft / arbor 6mm (.24")Overall length 33.5mmGritted length 8mmWidest point 11.5mm(all measurements are approximate)Tungsten carbide abrasive grit countersink. Designed for Lancair aircraft, Motorsport & Leisure craft industry. Countersink:- GRP, Fiber...

permagrit.com

The Perma-Grit LC2 bit has a #30 nipple that works great. It is included in their 5-bit kit.

 

[PaulvS]

Page 38-24 of the RV-14 plans tells me to drill the canopy side skins to #27 then shortly after to drill the canopy to #27. My question is what tool do you use to countersink the plexi when it has a #27 hole drilled into it?

Thanks!

Ben
RV-7A completed 12/17
RV-14A to be completed on Tuesday (just don’t know which Tuesday)

If you have a #30 countersink cutter then you can potentially first drill the holes to #30 and countersink them to the correct screwhead diameter and then enlarge the hole from #30 to #27 (use a plexi bit for sure). This is what I did on my 6A canopy and it worked fine, though there may be differences in the -14 parts.

Permagrit is good for use on fiberglass but I wouldn't use it on plexi because the finish is too rough and creates a potential stress riser for cracking.