I Drilled a Hole and chipped the Gelcoat!!!

[Richard10002]

The hole is for a bolt holding a bimini bracket, and I'm thinking that the sealant I'm going to use to waterproof the joint/s will fill the chipped gelcoat around the hole, (about a quarter inch V shaped chip, down to the fibreglass underneath).

However, I'm beginning to think that I should use gelcoat in the chip, then let it set, then fit and seal the bracket.

1) Will I get away with sealant, (Sikaflex 291), or should I get the gel out.

2) How do you avoid chipping the gelcoat when drilling a hole, (I used progressively larger drill bits, (3mm, 3.5mm, 4mm, 5mm, 6mm), the chipping occured with th 6mm bit.... should I have found a 5.5mm bit? and so on....

Cheers

Richard

 

[Swagman]

Suspect the sealant will do the job.

I always use masking tape when drilling gelcoat - with progressively larger bits just like you.

JOHN

 

[ostria]

I believe that sikaflex 291 will do the trick, but i would do the proper job: use gelcoat in the chip...

 

[fluffc]

[ QUOTE ]
(I used progressively larger drill bits, (3mm, 3.5mm, 4mm, 5mm, 6mm), the chipping occured with th 6mm bit.... should I have found a 5.5mm bit? and so on....


[/ QUOTE ]

That'll be why it chipped.

You only need a pilot hole, then a decent sized sharp bit of the correct final size.

By stepping up in such small increments, you are probably not letting the drill cut down through the hole properly.

 

[Aja]

Can you use sealant and a washer on top with the bolt going through both?

If not I would put a wee dab of gelcoat filler on and let it set.

Donald

When drilling through gelcoat try placing some tape (insulating or masking) over the hole you are going to drill.

 

[aitchw]

Chipping usually occurs when you either use too much pressure on the drill or when the drill is allowed to go out of true and catches the gelcoat with the side flutes on the drill. Very high drill speed can also be a problem.

I guess the gentle approach is best.

As far as the chip is concerned I am sure the Sikaflex will seal it effectively but you will know it's there. Why not just fill with gel and be done with it. It won't take that long in the grand scheme of things.

 

[ms1]

fluff is right pilot hole plus nice sharp drill.
Gel/sealant wont make any diff just depends on your "threshold for perfection"

 

[VicS]

[ QUOTE ]
fluff is right pilot hole plus nice sharp drill

[/ QUOTE ] I agree too.
If the bracket covers all the chipped area no point in repairing the gelcoat.

 

[Adaero]

The pilot hole should be just slightly larger than the "web" of the finished size drill. (The web is the area at the drill point where you get a small flat before it goes into the cutting edge. This area, because it has no cutting edge tends to push the material aside rather than cut hence the reason for the pilot drill). For a finished drill size of 6mm a 2 or 2.5mm pilot should be fine.

 

[tobble]

How about drilling a pilot hole, going through half way from each side? I guess that's not possible in many places tho. def gel coat it, it's so easy with plastic padding 2 pac stuff, 5 min job.

And use sharp tools for EVERYTHING (except for hitting nails maybe)

 

[Richard10002]

I guess I knew the answer really.... sealant will do, but gelcoat for a proper job..... so I've put a blob of gelcoat in the chip and smoothed it off with a scraper.

I definitely feel better having done it.... not sure why I asked really <g>

Thanks to all for the input

Richard

 

[pheonix]

[ QUOTE ]
[ QUOTE ]
(I used progressively larger drill bits, (3mm, 3.5mm, 4mm, 5mm, 6mm), the chipping occured with th 6mm bit.... should I have found a 5.5mm bit? and so on....


[/ QUOTE ]

That'll be why it chipped.

You only need a pilot hole, then a decent sized sharp bit of the correct final size.

By stepping up in such small increments, you are probably not letting the drill cut down through the hole properly.

[/ QUOTE ]

i'll second this stepping up in smaller increments has a tendancy to cause the drill to shudder as the cutting surfaces dig into the shoulder of the hole which is far steeper than the angle of cut of the bit.
start with small pilot hole mearley to guide the point of the full hole sized bit.
that 's my twopeneth
/forums/images/graemlins/smirk.gif

 

[Stork_III]

I always use pilot hole then countersunk bit to cut away top gelcoat to diameter larger than final hole for fitting, then final drill size. Since using this no chipped gelcoat.