Burns marks from router

[Robbo60]

I haven't used a router much and I am getting some scorch marks when putting a round over on some hard wood (Beech I thinK?) I am using a trim router.
It's a new bit so should be sharp.
How do I avoid this? Is speed too high?
TIA

 

[DrPhill]

I am far from expert, but it may be that you are not moving the router fast enough along the workpiece. In my experience the bits tend to get hot, and the longer a bit of timber is exposed to the heat the more likely it is to scorch. You may be moving slowly because you are trying to cut too much off at a time. Try cutting less off and doing more 'passes'.

Of course, there could be a real expert along any minute.....

 

[novocaine]

high tannin woods and woods with lots resin in will burn more easily, I find beech to be especially bad for it. especially across the grain.
The usual fix is to take shallow passes. with a bearing guided bit I'd usually wrap a bit of tape round the bearing for the first cut then take a spring cut with the tape removed.
is there a reason why you are running the cut so deep that you get a lip on the top? I'm assuming it's intentional.

 

[SkinnyB]

RPM too fast, Cut speed too slow, dull bit, too heavy of a cut.

 

[Spectric]

poor quality cutter

 

[clogs]

looking at the cut apart from taking to much in one go it looks like a cheapo cutter set......ask me how I know.....
A decent Whithill/hall cutter would eat it but it'll be around £40 on it's own.....

 

[MikeJhn]

Wealden tools make the best cutters I have used: Wealden Tool Company Limited

 

[sometimewoodworker]

looking at the cut apart from taking to much in one go it looks like a cheapo cutter set......ask me how I know.....
A decent Whithill/hall cutter would eat it but it'll be around £40 on it's own.....

Even the best bit will burn if you are moving it too slowly

 

[Midge]

A few shallow passes, keeping the router moving along the work at a reasonable speed should ensure success. If you’ve got any offcuts to practice on that should help you get a feel for how fast to move the machine if you’re using a handheld router or how quick to move the work if the router is mounted in a table.

 

[kinverkid]

high tannin woods and woods with lots resin in will burn more easily, I find beech to be especially bad for it. especially across the grain.
The usual fix is to take shallow passes. with a bearing guided bit I'd usually wrap a bit of tape round the bearing for the first cut then take a spring cut with the tape removed.
is there a reason why you are running the cut so deep that you get a lip on the top? I'm assuming it's intentional.

I like the idea of the tape. Never thought of that. I agree with shallower passes and move a little faster if possible too.

 

[Robbo60]

high tannin woods and woods with lots resin in will burn more easily, I find beech to be especially bad for it. especially across the grain.
The usual fix is to take shallow passes. with a bearing guided bit I'd usually wrap a bit of tape round the bearing for the first cut then take a spring cut with the tape removed.
is there a reason why you are running the cut so deep that you get a lip on the top? I'm assuming it's intentional.

Hi. That's the profile the bit is designed to cut?

 

[Robbo60]

Thanks everyone. EDASD. I'll give it a go with slower speed, lighter cut, and quicker pass!

 

[novocaine]

Hi. That's the profile the bit is designed to cut?

Most just use the round over though rather than still leaving a sharp arris to deal with.

 

[Phil Pascoe]

^^^^ +1 The arris will usually only get damaged anyway. Set the depth on a bit of scrap first.
You can of course run the mould without the arris and change it afterwards if you change your mind. Doesn't work in reverse, of course.

 

[sometimewoodworker]

A point that many people forget is that there is no need to use the full profile or full depth of a router bit.

 

[Tuna808]

Rate of feed too slow and as already said you can get the desired cut in stages,particularly if you haven't yet got the feel for the router.Do a trial run on a scrap piece first.Make sure your bit is sharp if its not bin it!
A quality router bit will surely help.......having said that even the most experienced woodworker will get the occasional burn when there a laps of concentration.

 

[sometimewoodworker]

Make sure your bit is sharp if its not bin it!

NO. If it’s not sharp use a diamond slip to touch it up, it’s neither rocket science nor difficult.
Unless you’re the kind of user who just bins every tool for a new one when they get blunt.

 

[Tuna808]

No ,but definitely bin the blunt router bits,all be it after they’ve rendered their life expectancy and few 100 m of cutting.