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  #1  
Old 08-24-2022, 04:39 PM
Girraf Girraf is offline
 
Join Date: Dec 2017
Location: Southern Maryland
Posts: 240
Default Source for 100 deg C'sink for Plexiglass/Acrylic

Need a recommendation/vendor for a no flute 100 degree countersink cutter to use on leading edge landing light lenses. I don't think I'm looking for the type with a single hole cutting edge. I'm having trouble sourcing what I need and of the threads I found on this subject, they have broken links to avery tools and sky geek.
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  #2  
Old 08-24-2022, 04:55 PM
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fl-mike fl-mike is offline
 
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Swivel deburring tool and eyeball it.
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Venice, FL

N164WM RV-6A Slider/O-360/FP Sold 4/2022
N184WM (RV-8) Ready for inspection. Titan IOX-370/ CS/G3X
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  #3  
Old 08-24-2022, 05:26 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,988
Default

Quote:
Originally Posted by Girraf View Post
Need a recommendation/vendor for a no flute 100 degree countersink cutter to use on leading edge landing light lenses. I don't think I'm looking for the type with a single hole cutting edge. I'm having trouble sourcing what I need and of the threads I found on this subject, they have broken links to avery tools and sky geek.
A traditional three flute counter sink cutter works great as long as you use low speed and light pressure. The key is that you avoid a lot of friction induced heat. Using a relatively new cutter that is real sharp is also beneficial.
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Scott McDaniels
Hubbard, Oregon
Formerly of Van's Aircraft Engineering Prototype Shop
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  #4  
Old 08-25-2022, 05:04 PM
Girraf Girraf is offline
 
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Location: Southern Maryland
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Quote:
Originally Posted by rvbuilder2002 View Post
A traditional three flute counter sink cutter works great as long as you use low speed and light pressure. The key is that you avoid a lot of friction induced heat. Using a relatively new cutter that is real sharp is also beneficial.
The Authority Hath spoken. I'll give my three flute a chance to show me what it can do. May pick up a fresh one too to better my chances of success.
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  #5  
Old 08-26-2022, 07:20 AM
Southern Pete Southern Pete is offline
 
Join Date: Jul 2015
Location: England
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Or one of these - must be plenty of suppliers in the US
https://www.permagrit.com/large-coun...ree-no-nipple/
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  #6  
Old 08-26-2022, 11:44 PM
No_0ne No_0ne is offline
 
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Location: Martin, Tn
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Quote:
Originally Posted by Southern Pete View Post
Or one of these - must be plenty of suppliers in the US
https://www.permagrit.com/large-coun...ree-no-nipple/
I just went through the same predicament. After searching through the normal channels, I wound up ordering the entire countersink kit directly from PermaGrit in England. Shipping took about a week, the kit contains a number of different sized countersinks as well as a pilotless version, all of which should come in handy when working on the fiberglass parts as well.

https://www.permagrit.com/kt2/
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  #7  
Old 08-27-2022, 11:27 AM
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BillL BillL is offline
 
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Location: Central IL
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Aircraft Tool has single flute 100 deg countersinks, I got two and it was very easy to make clean CS in plexiglass.

https://aircraft-tool.com/shop/searc...id=6391&page=3
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  #8  
Old 08-27-2022, 12:08 PM
Girraf Girraf is offline
 
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Location: Southern Maryland
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Default Success!

I happened to find a new-ish 3 flute #6 countersink cutter among my tools. I cleaned up the backside of each hole and then using a hand deburring tool with light pressure and some boelube got some great looking countersinks!
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  #9  
Old 08-27-2022, 01:07 PM
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DanH DanH is offline
 
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Location: 08A
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Take a hard look using a 10x magnifier. A lot of the time, countersunk plexiglass which looks fine to the naked eye is a mess of stress risers under magnification.

Agree with grinding the CS for final finish. Light touch please.

BTW, I was able to discourage edge cracking on highly bent Lexan by sanding the cut edge, then wiping the edge with a Q-Tip soaked in methylene chloride, aka dichloromethane. Melts away all the potential stress risers, leaves an edge as smooth as the faces. Use only in a well ventilated place.
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  #10  
Old 08-27-2022, 07:15 PM
dcl dcl is offline
 
Join Date: Mar 2012
Location: UK
Posts: 55
Default Permagrit ?

Would a permagrit countersink work ? They are magic on fibreglass

https://www.permagrit.com/kt2/
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