Cutting openings in the middle of edge-glued solid panels

[hugov]

Hi,

Over the weekend I was working on some cabinets and I needed to cut some medium-sized rectangular openings (e.g. ~100x200mm) in some solid wood panels that I had edge glued together. The wood is north American ash, so fairly hard. I tried cutting a little inside the line with a (guided) jigsaw, and tried plunging with a router (again guided against a straight beam, taking about 5mm per pass using a spiral up-cut 1/4" bit).

Neither gave great results; the jigsaw blade veered off vertical and actually cut over the line on the underside, despite running it along a guide rail on the top side (using a Bosch FSN SA adapter), I think the blade was trying to follow the grain. The router also veered/pulled, especially cross grain, slightly flexing the plastic guide rail adapter resulting in a lightly rippled rather than straight cut.

What am I doing wrong? Any tips for better ways of doing these types of cuts? I am more or less a complete beginner but have used both methods successfully in engineered sheet materials (ply, MDF) and for larger openings the plunge saw (finishing up the corners with a pull saw).

Thanks,
Hugo

 

[Cabinetman]

I think you’re doing fine with the router, it’s just the plastic fence that needs dumping, replace it with a piece of wood and 2 G cramps or better still make a template from 4 pieces of plywood and then just square the corners with a chisel. Ian

 

[Spectric]

I can understand the issues using the jig saw, they are hopeless on thicker stock as the blade cannot hold the 90° and gives an angled cut. The router should give a perfect cut providing you have a decent cutter and although direction is normally important, you are in effect cutting a goove so should not be an issue.

Personally taking 5mm cuts seems a lot, I always take many lighter cuts because it is easier to control the router and use only a small cutter, 8mm is fine because you only want to remove minimal material. I would also use a heavy 1/2 inch router and not a 1/4 one as they have the power which again helps with control.

 

[hugov]

Thanks Spectric and Cabinetman,

I think you’re doing fine with the router, it’s just the plastic fence that needs dumping, replace it with a piece of wood and 2 G cramps or better still make a template from 4 pieces of plywood and then just square the corners with a chisel. Ian

To be clear, only the adapter was plastic, a Makita one, running along a Festool rail. So the rail shouldn't have flexed. I reckon this approach is still superior to running along a wooden fence, since the wooden fence only counteracts forces in one direction (pushing into the fence), whereas the guiderail counteracts both pushing and pulling forces.

I did consider making a template but was lazy . I might have to add something along the lines of this jig to the todo list.

I'll also try taking shallower passes next time. My 1/2" router is fixed in a router table, and I don't think it's worth unmounting it (and re-aligning everything when re-installed), but I was using a cordless 1/4" router, I'll try my cheapie Katsu mains one next time (fits in the same Makita plunge base).

 

[novocaine]

buy a multi tool.

cut out waste 2-4mm from the line. neaten up with router and template. for nice rectangle holes I usually superglue and masking take 4 bits of straight wood to the wood and use a back bearing follower bit.

 

[cowtown_eric]

if you are using a jig saw, a lot depends on the quality of your jigsaw, and the blade. -if the jig saw guides are worn, and you try and force it, the blade will indeed take the weakest path, and the cut will deviate. I often use hacksaw blades in my makita jigsaws and try to practice patience. years ago I had a cheap jig saw that wouldn't cut straight for love nor money.

Nowadays, I use my oscillating saw quite a bit, using a taped on guide to keep the blade perpindicular and so it doesn't go skating off into the surface. (rock the blade a tad to allow the sawdust to clear, otherwise it just binds and burns, overheaating and destroying the blade. ) if it ain't perpendicular, you'll likely find it hard to get your cut out piece out!


You can also do the same quite easily with a japanese saw, perhaps cutting of the tip so that you can start a cut.

Eric

 

[TRITON]

A jigsaw is for cutting curves, it is not a rip tool by any means. The blade, no matter how sharp or supported is too thin and will follow the grain. Yes you can take it for rip, but very very slowly, and with no pressure. It has its place but kind of defeats the point of using a powertool, would be just as quick with a piercing saw.

To demonstrate this while at college we has a festool supplier in trying to sell us their range and even brought some wood samples to show off the new blade support on their jigsaw,it was pretty much a piece of burr.
Cut wonderful curves till i took over and went to rip a piece of ash and no surprise the blade wandered undercutting massively. I think the rep was peeved at me, and I felt somewhat evil but many of the students were swayed by his chat and were new to the game and i didnt want them to be misled.

 

[Dee J]

To be clear, only the adapter was plastic, a Makita one, running along a Festool rail. So the rail shouldn't have flexed. I reckon this approach is still superior to running along a wooden fence, since the wooden fence only counteracts forces in one direction (pushing into the fence), whereas the guiderail counteracts both pushing and pulling forces.

If you're using a guide rail with a router.. I'd always prefer that the direction of cut is chosen to push the router into the fence/guide rail. And it's not like using a track saw with a 'guide' rail where sideways forces are relatively small - a router converts a lot of its cutting force perpendicular to the line of the cut and the rail or fence is a brace against this. A solid timber fence or a wide offcut of panel material with a factory edge are good options. Hth

 

[hugov]

I ended up cutting the undercut bits off from the biggest opening and glueing on some new lengths on since I wasn't happy with it. The mitred corners aren't perfect since I was in a bit of a rush, but much better than how it was. Glueing freshly planed lengths like this resulted in perfect inside edges, not that it really matters (it's an opening for a kitchen extractor, the piece is the bottom of a 1200mm kitchen upper cabinet that goes over the bench and hob) but it annoyed me

[It's the outer frame in the picture, the bit in the middle is unrelated but I wanted to finish it at the same time I had the tin of polyurethane open]