Disaster please stop using the Dremel as a saw...

I didn't think a nibbler was the best tool for curves, thanks for confirming it. Decided to use a jigsaw in the end and it worked perfectly.

richms, Stuey,
It was a Draper nibbler I was thinking of buying, but decided it would be a waste of money.

 

I've handled those as well - they're not really nibblers, they function more like shears and only do well in cutting short and straight cuts.

 

Done with a dremel; NEVER AGAIN

 

With a dremel? because that is some seriously awesome dremelling!

 

Ouch! hehe, I bet it took a while!!!! <=D

 

Just tried cutting the circle for a 120mm fan out of the centre of a piece of perspex using a jigsaw. Had a bit of a giggle cutting it, as heat caused by the blade's friction left melted perspex trailing behind the cut, which then just fused the cut back together. Went round the circle three times before deciding to cut straight through the centre, which sort of shattered the centre out.

So apart from forking out for an expensive 120mm hole saw, anyone got a better method? I don't own a dremel.

 

You don't need a bi-metal holesaw for plexi. A cheapass one should work fine.

 

variable speed pendulum jigsaw, set slow with pendulum on + right blade its piece of cake..

 

Dremels are useless for most case cutting jobs, a jigsaw thats variable speed (and maybe pendulum) is far more use in serious mods..

in 20 odd years of modding (started in early 1988 on an Atari ST 520!) i've needed a dremel less than 5 times..

 

I've got a cheapass set, doesn't go up to 120mm though.

So what's the difference between a pendulum jigsaw and a regular jigsaw?

 

My point was that if you need to buy a holesaw just to cut plexi, it's not going to cost a lot. Discount store crap that wouldn't last 10 seconds cutting metal should work fine.

 

the blade is move backwards after its cutting stroke helps remove the chafe, then when ready to cut again its back in place (rufflyhow it works)

 

A pendulum jigsaw can do this (image is clickable):


Although I doubt this is a accurate depiction of the movement of the blade.. but you get the idea.

 

I'll look out for a cheap 120mm bit.

 

Hmm, is a "pendulum" jigsaw the same as an orbital jigsaw? Jigsaws are typically marketed in the US with the later phrase.

I wouldn't bother looking for a cheap 120mm holesaw. You'd still need an arbor and a pilot bit. It might just be better to buy a variable radius circle cutter, or a different type of Dremel cutting tool.

 

How well do holesaws work on plexi then? I would assume it suffers the same problems as a helger saw or wrongly set up jigsaw, as the blade is in constant moving contact with the plastic it'd all fuse together in one giant mess...?

 

I have the exact same problem using a bandsaw.
I just went round once, then 'popped' the hole out by gently bending the plexy and stressing the cut. After some wiggling, it'll come out. After that, you need some aftercare with a knife to remove all the debris, which screws up the "roundness" of the curve.
I don't think there will be anything that even approaches the quality/budget ratio of a holesaw in this case. Go with that option

 

I've got a bandsaw, but it's impossible to cut a hole out of the centre without first cutting in from the edge.

 

simple, just drill a hole in the part that needs removal, detach the sawblade, insert sawblade through hole, re-attach the sawblade with soon-to-be-cut part now in place, saw away like a happy modder

When finished, just reverse the procedure.

 

well "orbital seems strange word butt (? you americanos don't always get the lingo right !

cheap large holesaws kits are cheap & inc arbor usually. But useless for anything harder than soft butter (but probably do plexi fine . Only ever used quality holesaws, but would say worth a try!

ok always worth reingforcing plexi esp in centre as the arbor can side cut the hole. but not such a problem with plexi as metal ( holesaw beds into cut sooner. but i'd always use some mdf (cheap!) as backing/support on anything below steel.


Just remembered the hole saw (AKA stueys variable radius circle cutter) i bought last month from local diy/houehold/garden supercentre - cost £2.85 (5 bucks). its fully adjustable & has two arms and you adjust cutters to suit. I need to cut 150mm (6" hole) in ceiling then wood floor above - fully expect it to die but hopefully afer job done.. that would cut acrylic well! A cheapo brand called blackspur. can post pics later. A150mm quality holesaw just way to expensive to fit a cooker hood.