How to cut a round hole?

[Axtman]

What is the best way to cut a round speaker hole in playwood without making it look amateurish?

[nosaj]

nail in the center tie a string to it and the other to your jigsaw. Try it on scrap first.

nosaj

[Tom Phillips]

Make sure you have a sharp jigsaw blade and cut slowly. The early Fender baffle speaker holes look like they were cut with a jigsaw. About 1963-64 and earlier.

[Chuck H]

I do it like Tom and just use a jigsaw and cut slow. Here's some tips:

Make the cut with the back of the baffle board up if you can. That is, if it's not attached and glued to the cabinet yet. The cut for a jigsaw blade works on the upstroke so this reduces micro chips on the front. If you have to cut from the front this next trick will help.

Get some two inch masking tape and put it on the surfaces in pieces that can align with your hole drawing. This also reduces micro chips.

Cut as close to your line as practical but never over it. Stay to the inside when in doubt. You can use a barrel sander on your drill to clean things up but if you go over your line you can't put the wood back.

Or can't you? After the cut you can use a little wood dough rubbed into the pores and inclusions at the edge of the cut before a little hand sanding so it doesn't have that pocked and splintered "plywood" look.

Break the cut edge corners with a little hand sanding. Not a lot. You're not going for a bevel but a soft corner looks better than a hard one and the hand sanding evens things out a lot. You'll be tempted to use the barrel sander for this but don't.

How far you take these steps depends on the projects at hand. The last baffle I cut was to add a ten inch speaker to a Champ. I just cut it as close as possible on the line trying not to go over and then did a little hand sanding to soften the corner before repainting with a rattle can of flat black. This was a SF Champ so the baffle was MDF and no wood dough was used. Since this baffle is pretty much hidden by the grill cloth I didn't get real fussy with it. Not that it looked bad but it was less than perfect.

[loudthud]

There is an arm you can get for the more expensive Jig Saws. Locks in place with a thumb screw. A nail acts as a pivot.

[Chuck H]

There is an arm you can get for the more expensive Jig Saws. Locks in place with a thumb screw. A nail acts as a pivot.

I always figured there must be something like this. I just never looked for it. My jigsay is NOT an expensive one so unless I wanted to pony up A LOT it's on the wish list. I've probably only cut about two dozen speaker holes. So that would be less than a hole a year on average so far And as it stands I may never cut another. But if I were going in for a big project or thought I might be doing even a few a year I would absolutely look into this.

EDIT: There's probably a dozen *outube videos on how to improvise a jig that works. Again I never bothered because I was able to do fine without it. And I've done at least six holes in wood that was finished natural. But yeah, with *outube as a resource now I would at least look there for more tips and tricks.

[Greg Robinson]

I like to use a router with circle jig, which is just a stick with holes for different radii that slips over a pin. Here's an example. You certainly don't need to be as fancy as the video. Just use some scrap for backing, take multiple passed to get to full depth. I find it gives better results than a jigsaw and with less effort.

[Chuck H]

I find it gives better results than a jigsaw and with less effort.

This could work.?. I'm skeptical as someone who has used the tools. Routering a hole to a full cut seems like it would take a lot of set up and possibly create a lot of edge burn. Not that it matters if the baffle is painted I guess. But it just seems easier to cut the hole with a jig saw and fine it up a little as long as you don't ham hand it.

I'm on board if you have images, timing and demonstrate results. What works for one person doesn't always work for for everyone I think and I'd like to know more about the process.

EDIT: I have straight cut router bits. I use them for trimming formica laminate to mate with surfaces. I actually can't imagine trying to make a circular THROUGH cutout with them on plywood without a very specific jig. That and the extra time for for making a full cut rather than an edge route has caused surface burn for me in the past. Again, a rundown of the process might help me understand.

[Greg Robinson]

Chuck, if you're having trouble with burning with a router, could be a few causes - dull router bits, dirty/gummed up bits (wood resins), insufficient dust/chip extraction/clearing, or feeding too slow letting heat build up. If you're feeding too slow it might be because you're trying to take too deep a cut (never deeper than the diameter of the bit per pass!), the router is underpowered (smaller diameter bit and more passes to get full depth may be better suited for the router), or you just need to get more confident with the tool.
No extra setup vs what's been described with jigsaw and string above.
We all have our favourite tools that we're most comfortable with.
My comment re: "better results/less effort" was that in my experience you can go straight from router to softening edges and painting, where with a jigsaw I've always needed an extra step smoothing out the cut. Maybe I just need to get better with a jigsaw?

[Mick Bailey]

I've used jigsaws with a radius guide as well as routers. I prefer a router myself, but don't perform the cut in one pass. Many router bits cut inefficiently on the sides and can cause burning. I find a shallow cut to be best using a narrow bit and make 4 or 5 passes with plenty of extraction to keep the cut clear. Plywood varies a lot and even stuff claiming to be void-free can have pockets of abrasive filler in order to maintain that claim.

Jigsaws can have a tendency for the blade to be deflected and seemingly cut to diameter on one side of the board whilst maintaining a tapered cut through the thickness. A lot comes down to blade rigidity, tooth profile and sharpness. I always use a brand-new blade for any critical work. The jigsaw itself should have decent blade guides and no play in the mechanism and it's always worth doing a trial cut and checking the squareness. Some jigsaws have quite flimsy sole plates and even moderate pressure to one side can cant the blade. Once it goes off and begins an angular cut it won't usually correct itself.

[tedmich]

I'm with Mick on this! The jigsaw just deflected too much even with a stout metal guide.
The router works great with a 1/4 in solid carbide down cut bit and several passes. I then use a Whiteside rabbit set to do any front mount speaker inset.

I may try a short flute compression bit at some point, people love them but they're spendy
https://bitsbits.com/product/425-cm250-sf/

[Chuck H]

Jigsaws can have a tendency for the blade to be deflected and seemingly cut to diameter on one side of the board whilst maintaining a tapered cut through the thickness... Once it goes off and begins an angular cut it won't usually correct itself.

Yes. This. True. I don't usually cut really thick material for speaker holes. That Champ I mentioned was the thickest but it was MDF which is really forgiving compared to plywoods. The other baffles I've made were all 5/16" (true measure) marine plywood or 5/16" cabinet grade.(for the wood finish stuff). So nothing real burly to skew the blade much. But it does skew a little. Ergo keep the kerf on the inside of the line and doll it up with the barrel sander. I have noticed more skewing using the jig saw on heavier material though and if I were cutting a speaker hole in something like 1/2" or heavier birch ply (ubiquitous cabinet material) it would be a real concern. My router is a big thing with two handles. I can't imagine a radius rig for a ten inch or even a twelve inch hole so that's probably what confused me.

[tedmich]

I have one of these
https://milescraft.com/product/circleguidekit/
It does circles to 52" but its a bit cumbersome.

and a sturdy DIY version is quite simple.
and Milescraft unit is too small for this

[Helmholtz]

Poor man's method would be to drill many adjacent holes along a somewhat smaller circle, followed by jigsaw and rasp or sander

[35L6]

This should be worth 1000 words