Best hole saw for GRP?

[Han_solo]

I need to cut a couple of 20mm holes in GRP that I have to cut from the gelcoat side. Is it best to use the standard toothed hole cutters that you'd use on wood or is it better to use the diamond tipped ones to avoid chipping the gelcoat?

Cheers.

 

[Boathook]

I try and use the starret? standard ones that are suitable for metal. They seem to work well and do quite a few cuts.

 

[waynes world]

I have always used standard toothed type, just take it slow to get through the gel coat. Or go a little smaller Dremmel the hole to size.

 

[Mr Googler]

I get on well with a flat wood hole bit

These are good

https://www.screwfix.com/p/bosch-self-cut-speed-flat-wood-drill-bit-set-8-pcs/5393v

 

[Scubadoo]

When I needed to cut a hole of a similar size, I used hole cutter for wood at a slow speed, no issues perfect cut.

 

[rafiki_]

I used a Makita hole cutter fir some 12mm holes. Worked brilliantly

 

[salar]

I use and swear by the diamond-tipped hole saws used for cutting tiles. There is no guide drill but the finish is perfect and no chips.

 

[Han_solo]

Cheers for the replies everyone.

 

[sprocker]

Whichever hole cutter you decide on, drill the pilot hole first then run the hole cutter in reverse until you get through the gelcoat. This method does not chip the gelcoat.

 

[simonfraser]

and make sure you tighten the chuck very well, i lost two in voids recently ...

 

[ArthurDavis]

One can also go for standard Mandrels in order to cut.