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CPO over cracked plexi?

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Xiaou2:


 Firstly,  drilling backwards is a myth.   Ive always drilled forwards with plexi..  tried drilling in reverse once - and that cracked the plexi.

 From the pic, it looks as if there are no clamps on the panel.   You will neen to clamp the plexi really well so that it will not move at all.  Any vibration can cause
the crack.

 Place some carboard or simular material between the clamp and plexi so it wont marr.   Clamp tight.. but not so tight it will crack.

 The key to keeping the plexi from cracking is: Fastest speed, slowest downward pressure. 

 With a high speed drill,  use at full speed.. and press downward so slow, that it may take something like 15seconds to create a small hole.  The speed will create heat, which will melt the plexi.  The teeth will remove the melted plexi. 

 Pressing down too fast,  and the plexi will not be melted enough.  A tooth may catch too deeply and make a crack.

 In reverse, the melted plexi will not always be removed, can cause a problem as it cools and hardens near the edges.  Can cause the the drill to skip and vibrate a crack.   

  Use a 'drill guide'  if you do not have a drill press.  They are about 30$.  Harbor freight might be cheaper.   These will keep the drill perfectly straight while you are drilling.  Any wobble or change in the position can cause a jump and crack. 

 

Bones:


--- Quote from: Ken Layton on November 21, 2005, 01:22:06 am ---Ummmm..... the purpose of the plexi is to put over the control panel overlay to protect the overlay. You never put a control panel overlay on top of a plexi.

--- End quote ---
Yeah, what is the purpose of this thread/question? I am pretty lost here.

coasternuts:

The purpose was to see if I can use my artwork over my cracked plexi.

According to Ken, no.  Never over artwork.  So I think Ken is not a fan of how Kelsey did his panel, http://www.oscarcontrols.com/sinistar.  I believe it is done this way so there are no screws/bolts showing on the panel and the controls are accessible under the artwork.

I'm still planning on doing it this way.  Maybe I'll regret it.  I can always build another.  ::)

In response to Xiaou2, actually I finished the control panel by drilling in reverse and going slow.  I cracked it going forward.  You are right about the vibration causing the cracking however.  That is how it cracked.  Going too fast and forcing it with a larger drill bit.  It grabbed(probably because of your explanation), pulled, and cracked!

I'm working on it today, so if I can't find the plexi glue, I'll drill me another one.



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