[Healeys] Holes in Painted Surface

[warthodson at aol.com]

If I want to drill thru sheet metal I use one of the stepped, cone shaped "unibits". They make much better, rounder holes than standard drill bits in sheet metal. I would buy a new one if I was drilling thru a painted surface. If you have never used one, I suggest  drilling a few test holes in a similar thickness piece of scrap sheet metal, just to get the feel of using it. Also, when drilling it is not always obvious which step is the correct step to stop the drilling. So, I put a clear mark on the step with a felt tip marker before starting to drill. 
Gary Hodson  
 
 
-----Original Message-----
From: Bob Spidell <bspidell at comcast.net>
To: Michael MacLean <rrengineer.mike at att.net>; Healeys Help <healeys at autox.team.net>
Sent: Tue, Apr 12, 2016 8:19 am
Subject: Re: [Healeys] Holes in Painted Surface


    I suspect it would depend on type of material, type of paint,    condition of both, etc. but have always assumed applying some kind    of tape--electrical, masking, etc.--over and under--if the    underneath is painted, too--the area to be drilled is about all you    can do to prevent chipping.  Make sure you use a sharp bit, and a    variable speed drill so you can start slow to drill through the    paint.
    
    Begs the question: do you use a punch to 'prime' the hole--with or    without tape--before drilling?
    
    Bob
    
    
On 4/12/2016 12:29 AM, Michael MacLean      wrote:
    
    
      
        
What's the best          way to drill holes in a painted surface?
        
Mike MacLean
        
      
      
    
    
  
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