Router, Stopping burn marks in oak worktop

[Mr Chibs]

Wonder if you guys can advise please.

I’ve been installing a new kitchen and have solid oak worktops.
When testing on some off cuts (new router, old one died) I noticed I’m getting some burn/ scorch marks.

The router bits are new, is there a rule of thumb in minimising these scorch marks? I. E. higher/slower Router speed, very small depth of cut??

I will be tackling an undermounted sink this weekend, so want to get it right.

tia

 

[foxhole]

You can sand off scorch marks.But blunt buts are often cause , what did you pay for the router bits?

 

[Mr Chibs]

Have erbauer, trend and titman ones, might be down to bad technique, had recently read to back off the router speed and Speed up the feeding/movement, so will give it a try.

 

[Deleted member 174758]

1. Cut as near to the line as you can with a circular saw and/jigsaw, say 3 to 4mm off the final cut line. The idea is to minimise the volume of material you are removing with the router. Inexperienced router users tend to overwork the cutter which leads to the cutter getting clogged, overheating and blunting. The more blunt the cutter the hotter it gets and the more likely you are together scorched work

2. Use a larger diameter cutter - I'd suggest at least 1/2in (12.7mm) diameter, although 3/4in (19mm) is a better choice. With bearing-guided cutters the larger the diameter of bearing the better because small bearings not only heat up and scorch more easily, but they wear out faster. A 1/2in shank cutter is a better choice than an 8mm shank one which in turn is better than a 2/4in shank one. The cutter must be sharp and I suggest avoiding cheaper Chinese bits as they can sometimes be blunt out of the box. Good brands at affordable prices include Wealden Tooling and Trend Craftsman (green) ranges. Replaceable tip carbide tooling is sharper than brazed carbide, but is a lot more expensive.

3. Run your cutter at 18,000 to 22,000rpm. Higher speeds are more likely to induce scorching, especially as the cutter gets blunter during use

5. Hook up a vacuum cleaner to the router if possible

6. Feed fast enough - if you feed too slowly and your cut is too deep it is far more likely to scorch

Oak is a fairly tough wood and requires very sharp cutters to deal with it. It blunts tool edges a lot faster than, say, pine

 

[Mr Chibs]

Thanks for that, have routed successfully... kind of.

At the edge near the window, there is a bloody split in the wood. When you prod it, there is a slight void behind it.

Franke’s template That was supplied is not that accurate. I think the aperture could be a good few mm larger.

I used a 12.5mm bit with 30mm guide bush. I have a 19mm diameter bit, and I’m thinking of skimming it again, as I may pass the dodgy split.

To my surprise there is not a scorch mark to be seen, was well chuffed until I saw the split.

The erbauer bit has been excellent at 17,000 rpm taking 3mm passes.
I silicon sprayed the guide bush and lubed the bit with dry oil.

What would you guys do with the split?