Drill bits/ Saw blades for fiberglass applications-gctid345668

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I will be installing a Lewmar size 10 Ocean hatch (http://www.lewmar.com/products.asp?id=8018&lid=25098) in my hardtop (Discovery 246).

Will I need special cutting tools [diamond/carbide drill bit for pilot hole and long (> 2" because the headliner is about 2" below hardtop) diamond/carbide jig saw blade?

Thanks.

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I use carbide blades in my circular saw on wood projects and on fiberglass. I will use all of my wood working tools on fiberglass. The big issue with me is keeping the fiberglass dust out of my lungs and as much as practical off my skin.

[richardson Seasoned Member Find all posts View Profile Close richardson]

Standard metal working twist drill bits and saw blades will do the job. Since you have 2" between top and bottom you may not be able to cut both in one operation. If you have "monkey fur" or fabric on the underside; it will have to be cut out first.

[706jim Seasoned Member Find all posts View Profile Close 706jim]

Ordinary drill bits and saw blades will work for the relatively small amount of cutting you have to do to install a hatch. You can expect the drills to be somewhat dulled and the blades to be worn out when you're done.

You might consider running a shop vac to try and control the dust and chips.

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I have a Bosch jigsaw and their blades for plastics work well on fiberglass.

[Aqua_Therapy Frequent Contributor Find all posts View Profile Close Aqua_Therapy]

Run the drill bits at the highest speed your drill is capable of to reduce chipping.

[JimMc Guru Find all posts View Profile Close JimMc]

Start drilling holes by running the bit backwards to penetrate the gell coat then finish in the normal rotation.

I have also used a Rotozip with success.

[driz Seasoned Member Find all posts View Profile Close driz]

If I was going for a nice clean long cut I would use the Skillsaw and a Masonary or steel cutting disk instead of a blade. Either is only about $4 and won't even generate much dust at all. I wouldn't think you would even need to have a metal blade guard on the saw to use them cutting glass and it will leave a nice even cut with no ragged edges like you would have with a demo or any wood blade will. Still you should wear a mask no matter what you cut it with. It might even cut the rat hair evenly right along with it if you had someone holding a piece of some sort of wooden backer against the area you are cutting. I can't say I have ever done that so try it in an out of the way spot or scrap piece first. Another thing that will cut nicely is a 4 or 4.5" grinder with a cutoff wheel on it. Those work well in close spaces, handle easily and cut just like a skill saw with a similar blade. The nice thing about either of those blades is that if you bump yourself or your helper all it's going to do is leave a bit of a burn rather than flying meat and blood. Lastly the standard grinding wheel works well for shaping and deburring. Even the humble Dremel has uses doing the finer work in places.

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Driz is right about the grinder. It works. He is also right about the hazard. You are often working in an awkward position and sometimes cannot position yourself out of the kickback area. These tools will kick back and perhaps more so with the larger blade of a circular saw.

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Put painter's tape on all cut lines and holes to be drilled. Chamfer all holes before putting screws into them.

My favorite tool for working on fiberglass is this: http://www.harborfreight.com/12-volt...ool-67707.html

It produces very little dust, has no danger of cutting you, doesn't produce chip-out, etc etc. You don't need to tape the cut with this tool.

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SwampNut wrote:
Put painter's tape on all cut lines and holes to be drilled. Chamfer all holes before putting screws into them.

My favorite tool for working on fiberglass is this: http://www.harborfreight.com/12-volt...ool-67707.html

It produces very little dust, has no danger of cutting you, doesn't produce chip-out, etc etc. You don't need to tape the cut with this tool.

Can this oscillating saw round corners?

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I used a laminate trim router with 1/4" straight bit.I lowered the bit 1/4" each pass and did the job freehand.You need a steady hand because the router can drift on first couple passes and as you go deeper it can break the bit at 20 000 rpm so wear goggles and have someone hold vacuum next to baseplate.

Hope this helps.:tinhat

[706jim Seasoned Member Find all posts View Profile Close 706jim]

wallinlitwa wrote:
Can this oscillating saw round corners?

That's about the one thing they can't do. However, they would easily match up with a round hole made by a holesaw.

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Can this oscillating saw round corners?

Depends on how pretty and round you want it. I've cut a corner with multiple bevels that worked great for a hatch, because the cuts were going to be covered. It wasn't pretty, but a functional rounded-corner hole.

But their real brilliance is for drilling a square hole. Like for panel switches.

[driz Seasoned Member Find all posts View Profile Close driz]

A simple round 1" stone on a dremel tool will cope in and finish any rough spots quite well. No serious dust with those either . They grind slow but do a very nice clean job without messing up your work. They drill quite well too. If you don't have one you should since they come in oh so handy in all those places where the grinders and other tools don't fit. Stick a 1" wire wheel on a dremel and it will clean hard to reach electrical terminals like nothing I have ever found, rust in tiny creases too. Sorry, I drifted O/T.....my bad:arr