Thread: Cutting a curve in a thick slab ...

How thick is it?

55mm (2 inches) for most of it.

Make a bow saw from an broken bandsaw blade.

saber saw / reciprocating saw - you would have to be very careful and there would be cleanup required.

make a template and use a router.
this would be slow and take a lot of passes.
flip it over and work from the other side with a flush trim bit when you run out of depth of cut.

The router idea appeals to me (basically because I have a router already!) I've never routed with a template before. Thanks for that blackhole.

I assume I just make a template out of ply, then use a template with a guide bushing on my router to run it against.

What type of bit would I use for this?

Thanks,
Af.

2" thick?

With careful alignment marks you might be able to trim 1" deep with a router from both sides, but 1" is a LOT of router bit protruding in a hand-held and I'm thinking you'll have problems getting the template to line up neatly on the second side, so you'll end up with a "step" which'll need hand-finishing to remove anyway. (It's all do-able, but there are potential problems.)

Personally, I think I'd make a pair of templates & clamp them to top & bottom, then use a bow-saw to make rip-cuts down to the templates at 1/2" or so spacings. The templates are just so you can easily see where to stop cutting, helping to keep the ends of the cuts square to the surface - trying to accurately pencil the same curve on both sides isn't easy and IMHO it's a mongrel to see a pencil line on the bottom...

Then I'd use a long blade in a jigsaw to "join the dots," cross-cutting between each finger. As each section breaks away, there's less chance of the blade binding and breaking.

You'd still need to hand-finish, but somehow I don't think you're likely to find any method which'll avoid that.

Why is it too big for bandsaw? Afterall, you are only trimming one end. Move the bandsaw outside and support the slab in rollers or something like it. Just need someone else to help to ensure it passes through the bandsaw evenly, ie doesn't rotate.

Good point re. bandsaw. Problem is I don't have one!

I'll give the "finger" and jigsaw option a go later this week and see what happens. I can always try the template/router option after that if it doesn't work.

Shame you're not a bit closer, my jigsaw will handle that thickness no worries.

I have a 2" long router bit with a ball bearing follower on it. If I was going to use it on something like this though, I would be using it to tidy up after I had cut nearly to the line with another method - like the bow saw and jigsaw segment thing.

Peter

I think you could make your way around that curve with a handsaw cutting out triangles then get to it with a rasp. Another way is to drill close holes through, say 6mm that follow the curve then have another go with your jigsaw then get to it with a rasp.

hi afroboy, i cut 2" slabs everyday with a jigsaw and long blade, i cut 3" slabs with a reciprocating saw.
no need for fancy templates, routers, etc, etc.
i have 3 festool routers but using the jigsaw is much easier and faster.
just visit your local tool store and i'm sure you will find a longer blade for the jigsaw.
i also set the jigsaw base plate at 22.5, 33, and 45 degree angles when cutting, to create artificial "natural" edges.
the blades work perfectly.
no need to reinvent the wheel here, use the tools you already have.

good luck, justin.

I'd be ripping a number of cuts down to near the chalk line about 1 every 15-20mm using a circular saw. Then using the jig saw to cut the curve. As the ripped areas are cut by the jig saw, they can be knocked off and the open space will allow for more freedom in the blade movement around the curve. This is what I have done on thick curves in the past.

RayM

I would go with a long jigsaw blade as you already have a jigsaw. Nice looking Elm.