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  #1  
Old 07-11-2011, 08:02 PM
pwhaley6347 pwhaley6347 is offline
 
Join Date: Sep 2005
Location: Chico CA
Posts: 32
Default Star cracks around canopy hole

I have a problem with one of my holes (1/8) in my canopy. It has very small cracks all the way around it. The longest one is about 1/2". Anyone have an idea how to repair this problem. Thanks in advance.

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  #2  
Old 07-11-2011, 09:11 PM
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cjensen cjensen is offline
 
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My first thought was to get some Weld-on and use the dropper to wick it in to the cracks...
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  #3  
Old 07-12-2011, 05:10 AM
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apkp777 apkp777 is offline
 
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Chad's suggestion looks like a good one. You may also want to look into and possibly try Ethylene dichloride. I am not sure where you get that stuff. Perhaps a nail salon or pet store (fish tank repair). There are lot's of cracked canopies out there. Someone must have found a fix for this.
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  #4  
Old 07-12-2011, 05:14 AM
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Rick6a Rick6a is offline
 
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If I determined the fractures emanating from around that hole are relatively shallow surface defects, and based upon your photo it *appears* to my eye they may be, using Micromesh or similar, I'd likely blend em away.
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  #5  
Old 07-12-2011, 06:35 AM
terrykohler terrykohler is offline
 
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Posts: 1,009
Default Fix the problem before putting the bandaid on

Looks like a lot of chatter marks in the hole. First, make sure the hole isn't undersize. If the screw touches anywhere in the cylinder, you need to enlarge. Next, take a chamfer bit in your fingers or in a hand brace and gently turn it to smooth out the chamfer. You might also use an intermediate drill size for one turn to break the corner between the chamfer and the hole. Look closely. You may want to fix other holes before they start to show cracks. Any sharp corner or stress riser can be A problem in acrylics.
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  #6  
Old 07-12-2011, 06:45 AM
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mv031161 mv031161 is offline
 
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what you have is the typical result of using a drill bit not designed for plexiglass grabing to much material as it cuts through creating micro cracks and stressed points. it appears by your picture that the cracks are coming from the results of the tapered tool and not as much from the hole itself therefore giving you the appearance of surface cracks and not all the way across.

Chapter 9 of AC43.13-1A has the approved procedures as to how to deal with repairs. you may need to use the Surface or Plug patch procedure. good luck..make sure you use a Plexiglass designed drill bit or some of the pointers given by builders in this forum
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Last edited by mv031161 : 07-12-2011 at 07:02 AM.
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  #7  
Old 07-12-2011, 12:32 PM
rv6ehguy rv6ehguy is offline
 
Join Date: Jan 2007
Location: Toronto, Ontario
Posts: 193
Default Leave it alone

Leave it alone and don't atempt to repair this problem. These are stress fractures and may or may not grow beyond what you have here. I guarantee if you add any kind of liquid, chemical or glue to these fractures you are inviting them to grow into a crack. These fractures are micro in nature and many of them are not even on the surface. With the exception of water, all thin viscosity liguids and glues will be drawn into the fractures via capillary action and in most case expand in the fracture, making the problem even worse. I pesonally would not attempt to fix this problem until you have an actual crack. At that time, I would stop drill the crack and then introduce with a sryinge, an acrylic/plexi glue such as "Rez-n-Bond" 'Hope this helps.
John Van Lieshout
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  #8  
Old 07-12-2011, 08:02 PM
pwhaley6347 pwhaley6347 is offline
 
Join Date: Sep 2005
Location: Chico CA
Posts: 32
Default Thanks for the input

I appreciate all the input on this issue. I also consulted with Vans and this is what their reply was...

"Those look like they were maybe caused by the countersink chattering in the hole. Or possibly the pressure of the cleco was enough to cause some stress cracks - this happens if a fastener exerts too much clamping pressure on the plastic. I don't think there's any way to fix it, but it doesn't look like they go all the way through the plastic, so I doubt they will spread further."

I think I will go with RV6ehguy suggestion and leave it alone.

Thanks again.
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  #9  
Old 07-12-2011, 10:59 PM
vickruis vickruis is offline
 
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Location: Breda, The Netherlands
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I would consider using a drop of chloroform, you can buy this in a pharmacy. Chloroform is used to glue plexiglass, and it has extremely high viscosity, so you can probably fill in the cracks and prevent further tearing.

BTW, I glued my canopy completely, but had a stress crack aroud the infamous 'ears'. Yep, cut them off!
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  #10  
Old 07-13-2011, 09:44 AM
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Av8torTom Av8torTom is offline
 
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Location: Yardley, PA
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Default Chloroform

I second the chloroform idea. We used to use it to "weld" plexiglass parts together. The joints were often stronger than the material itself.

I would first try and reproduce your cracks in a scrap piece and give it a try.
In my opinion, chloroform is very LOW viscosity and will wick into those cracks via capillary action and weld everything nice and tight.
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