Drilling Resin

[Capt_Marlinspike]

I was drilling a hole in the toerail to attach a small fitting. I used a 2mm drill for the pilot hole on a slow speed setting. As soon as the drill bit into the material the resin cracked and shattered and lumps fell off! I think the place I was drilling was all resin and no mat. The boat is 25 years old.
Any suggestions as to how I should go about trying to drill this?

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[VicS]

With a hand drill.

<hr width=100% size=1><font color=purple>Ne te confundant illegitimi.</font color=purple>

 

[sailorman]

perhaps the angle that the "bit" is sparpened may be accute u almost req a negative angle to get a "slower" cut.
its also possible that a faster speed with "light" pressure on starting would work

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[Sparrow]

A new sharp drill will bite into the material quickly and pull the drill bit in causing shattering of the gel coat. An old/used drill bit that is not as sharp will not pull in and will allow you to control the pressure and “feed” into the work.

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[oldharry]

High speed drilling in any plastic can cause sufficient heat to melt the resin which then binds on the drill bit. The drag is easily enough to break both the drill and the plastic.

GRP also has a particular problem that the drilling debris does not easily ride up the drill fluting and clogs it up solid very rapidly. The drill cutting edge continues to cut into the GRP and create more debris which then jams the drill in the hole with terminal results both for the bit and the surrounding GRP!

Use the lowest possible drill speed, and frequently lift the drill out of the hole to clear it. Make sure the flutes are clear before contuing to drill. This may be necessary every few seconds, and you will soon learn to tell when the bit is clogging up again! This also helps prevent overheating of the material. Let the drill do the work, and dont force it into the material.

Howver you say that the GRP shattered as soon as the drill bit into it even at low speed? This suggests the drill is pulling itself into the material too quickly, so that even lower speed is required - and perhaps a slightly blunter bit. Try a larger size in a hand drill.<P ID="edit"><FONT SIZE=-1>Edited by oldharry on 22/01/2004 12:33 (server time).</FONT></P>

 

[richardandtracy]

Sounds to me as if one of the newer style brad point wood bits would help. These usually have tangs on the outer edges to cut the wood fibres. It may cut resin more cleanly than the usual 118 degree metal style bit.

Rigards

Richard.


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