What is the best rotary tool bit for kayak plastic?

What is everyone's favorite rotary tool bit for cutting out kayak plastic? I'm talking here specifically about plunge-cutting circles for flush-mount rod holders and that kind of thing.

Does a "general purpose" bit work fine? (Like this: http://a.co/0oSw0eA)

Are there advantages to using a larger rotary tool like the kind they use for drywall or will a smaller "Dremel" hobby-sized tool work fine?

What is everyone's favorite rotary tool bit for cutting out kayak plastic? I'm talking here specifically about plunge-cutting circles for flush-mount rod holders and that kind of thing.

Does a "general purpose" bit work fine? (Like this: http://a.co/0oSw0eA)

Are there advantages to using a larger rotary tool like the kind they use for drywall or will a smaller "Dremel" hobby-sized tool work fine?

I would use a hole saw with a pilot bit. A router can get away from you if you are not carful.


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Yeah I wouldn't use my router. When I said "a larger rotary tool" meant something like a Rotozip; like what they commonly use to plunge-cut drywall.

A spade bit works fine for drilling big holes in kayaks, like in the 1" - 1.5" range.

Unfortunately my cut-outs aren't round; they're oval.

I haven't had much luck with my dremel or that drywall bit on kayaks other than cleaning up edges. I've used regular spade-bits with good success for the smaller holes and hole-saws for those a bit larger. Just use a regular drill / driver and drill a pilot hole to keep the bit from walking.

On my Hobie, that general purpose bit is what I've used with good results.  Run it at low speed or you'll melt as much plastic as you cut.

If it's a larger hole and I have room to use it, a Dremel tungsten cut-off wheel is faster to do the initial cutting, then switch to the rotary bit to finish to the marked outline.  You have to run the wheel slowly, too.

The RPM on drywall tools may be too high for plastics.

Thanks for the feedback, guys. I'll let you know how it shakes out for me.

Low speed is the most important thing. Plastic is easy enough to cut through, but if you try to go too fast you'll melt it and make a mess.

I use this style cutter in various sizes.



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Yeah I wouldn't use my router. When I said "a larger rotary tool" meant something like a Rotozip; like what they commonly use to plunge-cut drywall.

Oof. Those are real easy to wander off course. DAMHIK

Yeah I wouldn't use my router. When I said "a larger rotary tool" meant something like a Rotozip; like what they commonly use to plunge-cut drywall.

Oof. Those are real easy to wander off course. DAMHIK

For what it's worth everyone, the reason I brought up the Rotozip is because that's what I saw used in several videos. So I was just asking if anyone had used those.

I am partial to air tools with sharp carbide grinding/cutting bits.  With good hand and variable air control, I can plunge, trim, widen out and shape pretty much any hole in a kayak with ease. 

If you don't have or have access to an air compressor and air tools, then I would guess the RotoZip would work.  Just make sure you have good hand control, as I am not familiar with the speed control on the RotoZip. 

Also, I am always willing to make holes in friends kayaks if you need a hand. 

Hopefully this will help someone in the future.

This is what I landed on, and it worked great. I got a Dremel brand multi-purpose cutting bit (similar to the link above). I used that with my hobby-sized rotary tool (B&W Wizard).



It was a little hard to control, but if you practice for a few seconds and use two hands it's not that bad. I was happy with the results:



Notes:

• My rotary tool is multi-speed so I experimented. I actually found I got better results at higher RPMs.
• The bit I bought seemed to "chip off" hair-sized pieces and so I had no issues with melting at any speed, because the kayak material was never in contact with the bit for more than a split second. I have had issues with kayak plastic (and plexiglass, etc.) melting using cut-off wheels and similar, but this was different. So I think it has to do with the type of bit/wheel/etc. more than the RPMs.
• I could see that a Rotozip or similar tool would be useful for this type of thing but the Dremel-type rotary tool cut through the plastic like butter, so you don't really need any more power.
• The bit seemed to cut better in one direction than the other, which makes sense if you look at it, but required that I change my hand position and lighting several times, which was inconvenient.

Glad to hear it worked well.  I used the same bit but kept getting melted plastic boogers ahead of the bit... must have been cheaper plastic.

Looks good!

Yeah I wouldn't use my router. When I said "a larger rotary tool" meant something like a Rotozip; like what they commonly use to plunge-cut drywall.

Oof. Those are real easy to wander off course. DAMHIK

For what it's worth everyone, the reason I brought up the Rotozip is because that's what I saw used in several videos. So I was just asking if anyone had used those.

If you have used them before and know how to control them, it would work. But if someone refers to such a tool as "one of those" I figure they either don't have one or they haven't used it much yet. Practice on other material, like a slab of plastic from TAP, before attempting live fire would be my advice.


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