Cutting circles on a router, how many passes?

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ol_london

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I’m not experienced with a router, I only have a Makita cordless 1/4. Recently I had to cut a circle 30cm diameter out of 25mm oak and it took around 10 passes. Obviously this is not ideal so I am thinking I need more power. I’m considering the Triton 1/2 inch plunge router, but does anyone know how many passes I could expect to cut that circle (hardwood 25mm thick) in with a machine like that?
 
I agree. It is not about power here.
The shallower your passes are, the better the results will be and you will have more control.

I made this hoop recently out of 18mm MDF for my son's mobile,it was done in probably 5 passes on each, inner and outer circle (about 30cm outer dia and rounded over on four sharp edges.
But it was done on a router table with an improvised jig.
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Probably quicker to do a couple of extra passes than push it to its limits anyway.
 
Thanks. If I’m looking at 10 passes either way I may as well stick with my cordless router then.
 
10 doesn't sound excessive at all to me. I would say the first few passes should be very shallow, so there is minimal tearout. Also I'd run a hoover over the circle after every pass.
 
I do quite a bit of circle cutting and target 3mm per pass like the others. But I always wonder what bit to use: you'd perhaps have thought that a small bit would be able to cut deeper, because there's less material to obliterate, but going below ~10mm doesn't seem to help much. What do others do? Do spiral bits help?
 
What do others do? Do spiral bits help?
I don’t cut a lot of circles but do use a router for dados and trenching. I think it probably depends on your dust collection. My OF1010 with a 10mm spiral upcutter is pretty good at 5-6mm depth in most materials but the dust collection is pulling almost all of that out of the top which means I never really need to clean the cut out. That makes it easier for the bit (and router).

I think the general rule of thumb is that you want the cutter to eject the waste in the direction of the dust/chip collection so a spiral upcutter is helpful for deeper cuts if you have good collection pulling it away. The downside of deeper cuts is bigger chips. I have a cyclone to help keep it all moving
 
So a more powerful router does not allow a deeper cut.
Would each pass be quicker with a more powerful router?
If not then what, if anything, is the advantage of a more powerful device?
Asking from a position of total ignorance of powered routers - I have only recently advanced as far as a Stanley 71 hand tool.
 
More power means you can use much larger bits 1/2" shank compared to a small 1/4" also you are less likely to overwork the the motor. In most cases More power should mean that you can work faster as you will be removing the material quicker.
You could put a 1/4" in a router table but i believe most would opt for a larger 1/2".
 
as smakie says, an upcut will clear the chips faster, but at the expense of tearout on the top of the wood. A downcut gives you the cleanest on the top (i.e. nearest the router), but compresses the chips down, making it difficult to clear. Good extraction + upcut spiral = most chips removed while you work. An upcut bit will also leave the bottom of the wood (furthest from the router) with the least tearout. There are also compound bits that do downcuts at one end and of the bit and upcuts at the other. If you match those to the right thickness of wood, you can get pretty near perfect cuts with almost no tearout. I use these with a CNC for cutting plywood for instance with great results even on fretwork.

That doesn't equate to cutting your hole faster! I don't very often cut holes, but I've cut a lot of worktops of various types and would have had to charge a lot more if I'd had to do 20 passes!

A big (i.e. 1/2 inch with a decent motor) router and a SHARP bit will cut through a LOT more than 2mm a pass with nice clean results. There's a reason why you see worktop cutters in multi-packs though, they last for only a few cut outs or mitres before they start to blunt.
 
All helpful advice, thank you. I suspect that you worktop guys are using templates, correct, which allow you cut most of the waste and use the router for a clean finish? For my part I'm generally using a piece of ply screwed to the router base with a pin in the workpiece in the centre of the circle; and sometimes I'm cutting circles (circular table tops), sometimes holes, and sometimes rings. Of course with circles you can jigsaw off most of the waste and finish with router, as long as you can anchor the workpiece ....
 
Cutting a circle then yes you have little option as you want to support the centre. Ive done it a few times where the pin is in a oard behind.
 
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