Drilling into Polyester

[Gene Nelson]

Re: Drilling into PolyesterMany thanks for the detailed insturctions Ron.
I think that I will use my drill press.
Gene
  ----- Original Message ----- 
  From: Ron Overs 
  To: Pianotech List 
  Sent: Monday, November 13, 2006 1:43 PM
  Subject: Re: Drilling into Polyester


  Gene,


  Drilling into polyester is quite straightforward using twist drills. The trick is to have the drill bit very sharp with a lower clearance angle than normal, so that it won't bite into the material too quickly. I generally sharpen all my twist drills with a lower clearance angle than standard. This helps to prevent the drill from pulling itself into the work too quickly, with often disastrous results. As far as speed and feed rate is concerned, I like to have the drill going fairly quickly with a light application pressure. If the drill is razer sharp it will fall through the poly like its cutting butter. I usually cover the area over the hole to be drilled with masking tape before drilling. This helps to prevent any risk of perimeter chip-out. When I'm drilling lids for fitting rubber buffers, I run a couple of strips of wide masking tape on the panel adjacent to where I'm planning to drill, to prevent scratching and scuffing of the surface with the Portaline, which is the drilling attachment I use for holding the drill square to the panel.


  While its easy to drill into polyester with low clearance angle drills, I recommend that you drill or grind away a clearance-diameter of polyester, down to the substrate, so that the mounting screws can't come into contact with the polyester. Preventing the risk of a crack developing. Once you've drilled your minor diameter hole for the mounting screws, you can cut away the polyester to the substrate with a larger drill to ensure that there is good polyester clearance from the outside diameter of the screw. This will prevent any risk of a nasty stress crack running out from the screw hole at some future time. Some caution is required when drilling away the poly to provide clearance, since the larger drill, with no material at the drill centre for control, can allow the drill to tear into the panel unless the feed pressure applied is very light. Another approach might be to drill your hole clearance first, being careful not to drill it too deep, then following it with the minor diameter drill. I generally don't drill the clearance away first, because it increases the risk of drilling the minor diameter hole off line. If you've got some tungsten carbide grinding balls and a die grinder handy, using these can be lot safer way of providing clearance for the screw after drilling the minor diameter hole, without risk of tearing up a piece of polyester.


  Ron O.


    Have a client that wants the 9"x1" hinge installed on the music rack - it originally never had one "
    The piano has a high gloss polyester finish along with some very fancy veneer on the music shelf.
    Drilling into poly makes me a bit nervous - never did it before, expecially in such a visible area of the piano -
    Is there a technique that someone uses to dimple the spot to drill so that the poly will not split, or to prevent the dirll bit from wandering? Accuracy is a must.
    Regards,
    Gene Nelson




-- 
OVERS PIANOS - SYDNEY
     Grand Piano Manufacturers
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