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  #1  
Old 01-26-2014, 09:14 PM
petersb petersb is offline
 
Join Date: Mar 2008
Location: Toronto
Posts: 328
Default Need to open up canopy rivet holes without removing plexi.

My canopy recently cracked " The Polar Vortex Got Me". I have removed the trim strip covering the center bow to check damage to the plexi.

The original holes where drilled as per plan 5/32 , IMHO, in retrospect, way too small. So I plan on doing a temporary repair using "Plastifix" on the crack but still need to open the existing holes to a more reasonable size, thinking around 1/4 inch.

The problem, how to drill the existing 5/32 holes to 1/4 with the plexi still attached to the frame. If I use a 1/4 plexi drill it will hit the frame before exiting the plexi, also, if I was able to get it through the plexi I would be unable to debure the exit point.

A unibit would not work as it would open up the 1/8 rivet hole in the frame.

Thoughts please.

Peter
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Last edited by petersb : 01-27-2014 at 07:58 AM.
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Old 01-26-2014, 10:02 PM
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Mike S Mike S is offline
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
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Default Couple of thoughts..............

I wonder if a heated rod would do the trick????

Melt the hole, not drill it.

Another idea would be a piloted reamer.........no idea if it would be safe on the plexi.
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  #3  
Old 01-26-2014, 10:21 PM
petersb petersb is offline
 
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Default

Quote:
Originally Posted by Mike S View Post
I wonder if a heated rod would do the trick????

Melt the hole, not drill it.

Another idea would be a piloted reamer.........no idea if it would be safe on the plexi.
Yes, I was thinking about melting it. I did read in other threads that melting a hole might cause stress fractures.

Of course the plan is to replace the canopy this summer, so possible stress points might not be a problem in the short term.
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Old 01-27-2014, 02:17 AM
crashley crashley is offline
 
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Location: hazelwood north vic
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Default

hi I believe a melted hole will have less stress risers than a drilled hole if you want to drill it you could grind a pilot point of 1/8 onto a 5/16 drill and grind the cutting edge of the 5/16 part flat like an end mill
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Old 01-27-2014, 07:02 AM
petersb petersb is offline
 
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Quote:
Originally Posted by crashley View Post
hi I believe a melted hole will have less stress risers than a drilled hole if you want to drill it you could grind a pilot point of 1/8 onto a 5/16 drill and grind the cutting edge of the 5/16 part flat like an end mill
Good thought, I read that a forstner wood bit works well, requires using lubricant. The lubricant they suggest is water and baking powder. Water alone will cause rust on metal, the baking powder will stop the rusting.
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  #6  
Old 01-27-2014, 10:04 AM
terrykohler terrykohler is offline
 
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Default If You Melt It In Place, You May Be Trading One Problem for Another?

Just thinking...
The melted plexi isn't going to vaporize. Will it flow into the threaded hole? If so, then re-tapping might fix that problem. On the other hand, if it somehow results in an uneven surface on either side of the plexi, that won't necessarily be good as far clamping that surface goes.
I'd also be a little nervous about any kind of square end bit being used to re-cut the hole. You might try cutting a piece from a small diameter, round chain saw file and chucking that in your drill or die grinder. Just a thought.
Terry, CFI
RV9A N323TP
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  #7  
Old 01-31-2014, 02:07 AM
hayabusa hayabusa is offline
 
Join Date: Feb 2011
Location: Brisbane, Australia
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Default

Have you guys ever heard of a One-shot drill?
Usually used on carbon fibre composite panels, it is essentially a tapered lead straight flute reamer for your drill, with a cutting tip to start the hole.

http://www.mohawkeu.com/products.html
Look under the heading "one shot drill"
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