Drilling holes in Gelcoat

Markyboyo · 17 June 2009, 12:37

Whats the secret to getting clean holes drilled in the gelcoat with no damage to the surrounding area. I seem to get variable results!

Mark

Mollers · 17 June 2009, 12:52

Quote:

Originally Posted by Markyboyo

Whats the secret to getting clean holes drilled in the gelcoat with no damage to the surrounding area. I seem to get variable results!

Mark

Two layers of masking tape and a sharp bit. What sort of bit are you using?

chewy · 17 June 2009, 12:59

What Mollers said, it'll stop the bit sliding about.

Markyboyo · 17 June 2009, 13:00

Brand new set of HSS.
do you want to start and finish at a slow speed or keep a constant higher speed throughout?? (referring specifically to drilling holes in boats before the comments start!)

Markyboyo · 17 June 2009, 13:00

Quote:

Originally Posted by chewy

What Mollers said, it'll stop the bit sliding about.

Its not so much when the hole starts but when it comes through the other side...

Mollers · 17 June 2009, 14:26

Quote:

Originally Posted by Markyboyo

Its not so much when the hole starts but when it comes through the other side...

Start on the gelcoat side not the mat side, then it doesn't matter.

Nos4r2 · 17 June 2009, 15:56

Quote:

Originally Posted by Mollers

Two layers of masking tape and a sharp bit. What sort of bit are you using?

I find sellotape works better-a sharp bit isn't quite so critical then.

Downhilldai · 17 June 2009, 20:58

Quote:

Originally Posted by Mollers

Start on the gelcoat side not the mat side, then it doesn't matter.

Too right

But, if for some reason, you have to start on the mat side, then start with a small pilot hole As the drill bit is about to break through the gelcoat, reduce the pressure on the drill and increase the rpm so that it cuts through, nice and cleanly.

Can't believe I've just posted on one of those 'ole drillin' threads.
Look out - gArf will be here soon.

Bigmuz7 · 17 June 2009, 21:45

Quote:

Originally Posted by Downhilldai

Too right

Can't believe I've just posted on one of those 'ole drillin' threads.
Look out - gArf will be here soon.

I know he's a man of many talents .. but .. even he will admit .. we have the suject of hole drilling pretty much in the bag .. unless he has a special substance for preventing cracking in gel coats ofcourse

ribraff · 17 June 2009, 22:17

Put the drill in reverse for a few revs

iandl · 18 June 2009, 07:19

what mollers said works good .....also i have found drilling a small pilot hole then use a wide head countersink bit first before drilling the final hole size.

another one i use is a lathe centre drill ....this gives you a small pilot hole and 60 degree countersink all in one.
I have also found a slightly blunt drill is better.. a nice new hss drill bit will grab and crack/tear surrounding gelcoat ....

regards

Ian

Mollers · 18 June 2009, 08:00

Quote:

Originally Posted by iandl

I have also found a slightly blunt drill is better.. a nice new hss drill bit will grab and crack/tear surrounding gelcoat ....
Ian

Yeah, I wondered whether that would be a good way to go. Never had an issue with munched holes myself.

When the screw, bolt/washer or fitting etc is fitted the hole is covered.

JABS · 18 June 2009, 08:47

There are some drills on the market which are more like a trepanning tool. They have two teeth on the OD which scores the OD of the hole. These are brilliant, if used slowly and carefully.

I think the biggest problem is being impatient. Does it really mtter if it takes three minutes to drill a hole rather than fifteen seconds.

The drills mentioned above are also neat on the inside since the OD breaks through first.

iandl · 18 June 2009, 09:50

Quote:

Originally Posted by Mollers

When the screw, bolt/washer or fitting etc is fitted the hole is covered.

i think weve all done that at some point .......for me the best by far was the countersink .......on another note ....when i removed my console i found myself with a 1/2 thick layer of fibreglass the full size of my console needing removed ....rather than grinding i opted for a heavy duty electric planer ...with dull blades .....brilliant at removing fibreglass and leaves a reasonably flat surface only needing minor surgery after (topcoat).

I

The Garfish · 18 June 2009, 15:13

Quote:

Originally Posted by Downhilldai

Can't believe I've just posted on one of those 'ole drillin' threads.

i av grantid a amnisty too orl ole drillin ribnobburs.

i av cum too reelize dat torkin bollix bowt ole drillin plaiys a impawtunt parrt inn fulfillin de rekwirements rekwired bi de rekwirements ov fulfillin de maslovs tryangul an becumin compleet an appy pirsuns.

wot i avunt grantid a amnisty too iz dem nobburs wot wonder abowt in de fogg cokkin ther eers lyke colly doggs an sniffin forr de smel ov seewead. i tryed it wunce an endid upp crashin innto a meetin ov de calshott WI.

JABS · 18 June 2009, 15:34

What's with Sea Start???

Nos4r2 · 18 June 2009, 16:27

Quote:

Originally Posted by The Garfish

wot i avunt grantid a amnisty too iz dem nobburs wot wonder abowt in de fogg cokkin ther eers lyke colly doggs an sniffin forr de smel ov seewead. i tryed it wunce an endid upp crashin innto a meetin ov de calshott WI.

I knew it wasn't going to work letting you demo that SeaLegs...

Poly · 18 June 2009, 18:18

Quote:

Originally Posted by JABS

What's with Sea Start???

Nos4r2 · 18 June 2009, 20:47

Quote:

Originally Posted by Polwart

gaRfies boat name is the Sea Start number.

Poly · 18 June 2009, 21:56

Quote:

Originally Posted by Nos4r2

gaRfies boat name is the Sea Start number.

, garf must have too much time on his hands, you and JABS must be even sadder for working it out!