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Discussion Starter · #1 ·
Had to get more clearance for my new mids so I thought I'd use a jigsaw to cut what little mdf I had left into 2 rings. I never work with this type of stuff, so keep that in mind.

I drew my circles, cut them pretty close with the jigsaw, but something wasn't right.... it's like the blade was angled as it cut. Angled so that if it was a 5.5" hole I was cutting, it turned out to be say 6" on the other side. How could that happen? Now there's not enough meat to run the screws through.

I have just a tad more mdf, now I need opinions to get this right before I screw up again :blush: I figured 2 hole saws would work easiest, but it doesn't look like there are any cheap 5.5" and 6.5" ones out there :-/

One more question. I've read I should paint and clearcoat these things to make them water proof. Can you get clear in a rattle can?
 

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You just discovered a fabrication truth. You can't cut good circles with a jig saw no matter how hard you try. The blade will bend and that causes the two different sized circles. You need to do it with a router and circle guide to really do it right.

Yeah you can get clear in a can
 

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Sounds like you may have been forcing the blade rather than just letting it do the work. The smaller you try to make a circle the more that can happen.
If you can't round up a router for the next go-around, try starting with a new jigsaw blade and go slow- let the blade do the work, you're just there to guide it.

Also if you don't want to pony up for a router but already have a drill press, you can get an adjustable hole cutter from Harbor Freight or Sears for pretty cheap.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98127
 

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Discussion Starter · #4 ·
Not sure if I can get a router, but I know a friend has a drill press. I'll drop by Sears and/or Harbor Freight. Seems like a more sure fire way to get these cuts right. Then paint and clear and maybe I'll have something kinda nice ;) Thanks guys!
 

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Did you have the guide set at an angle? Sometimes those little screws come loose and you'll be cutting an angle before you know it. If you make sure those are all tight and the guide is level, then take your time and don't force it. Like was mentioned above, that will bend the blade and you'll get some crazy waves.

A router is the best way, but you can do it w/a jigsaw. Probably won't be perfect, but you can make some nice cuts if you watch what you are doing.
 

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i always use a fresh blade before cutting circles and let the blade do it's work instead of forcing it to cut. blades with heavy tooth rake can handle curves alot better,too.
a good jig saw also cuts alot straighter than a cheap jigsaw.
but if you are cutting rings on a regular basis...the circle jig/router is the way to go
 

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how does a dremmel tool hold up in 1/2" MDF? i have one of those 10,000RPM ones and i have a jigsaw which obviously won't work out.
 

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Discussion Starter · #9 ·
This is a friend's jigsaw, and it's a Dewalt. Thought it'd be good, and he's hardly ever used it. He has a few more blades with it....are wood blades usually the ones with more teeth? I think it does have some sort of angle adjustment on it, so I'll check that out again.

I still have a drill press I can use if I can find one of those adjustable hole cutter deals, I'll shop around tomorrow. Thanks everybody :)
 

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Look on ebay/craigslist for a used router.

I found a skil plunge router in great condition for... ready..

15 dollars, SHIPPED

And it works great. Seriously, just take some time and get the right tool for the job, besides, having a router on hand is essential for many tasks related to mdf anyway.
 

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dupe post because i was downloading rescue me and it was taking all my bandwidth :p
 

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i cut all my holes with a jigsaw, the problem is the blade. i have a bosch jigsaw and what i noticed about it that i like the best is the blade, its about twice as thick so when you do your turns it doesnt bend the blade. i havent had that problem since i changed saws. the blades are available at lowes and also work with my $30 craftsman jigsaw. made that saw work completely differently!

my 2 cents
 

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I have only cut a few circles in my day....and I used what I had at the time and place. A roto-zip with its circle jig. Basically a pin with an adjustable length. It actually cut the 3/4" MDF fine. It was not "perfect" but it worked better than I know I would do with the jig saw.....but yeah....my next go around, I will make sure to have a router and proper jig. :)
 

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At bare minimum get a small router.

Any rotozip or dremel ain't gonna cut it....pun intended.;)
 

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that used to happen to me with jigsaws. Look on the bright side, it's like chamfering with a jigsaw :p
Actually I think this midbass 'breathing' chamfer is cool plus for those of us 'suffering' w/ a jigsaw. For midbass size hole should not really be too hard. Now if you are talking tweeter size that could be a pain.
 

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This is a friend's jigsaw, and it's a Dewalt. Thought it'd be good, and he's hardly ever used it. He has a few more blades with it....are wood blades usually the ones with more teeth? :)
Wood blades have the least teeth ...IIRC most will be 6-10 tpi.

>^..^<
 

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Discussion Starter · #18 ·
Well I got a decent router ($100 Skil) and the cuts are better, but not perfect. At least I can mount them now. I wonder if I needed a different bit for the router?

Thanks for all the replies!
 

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using a thinner blade will help with this problem, and also letting the machine do the work and not forcing it. Some of the course blades are almost a half inch deep versus less than a quarter inch for fine cutting blades.
 

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I use a 1/4" spiral bit for cutting circles, a 1/4" straight bit will work too but it'll leave more sawdust in the slot where a spiral bit pulls most of it out for a cleaner next pass.
 
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