Router burning

[transatlantic]

I've just made a circle cutting jig for my Katsu trim router, but I'm having issues with burning. I'm only taking 5mm passes with a relatively new Trend 5mm double flute straight bit, yet it's scorching both the jig and the workpiece.

I did notice that there is very little dust being thrown out s(stays in the wells) so I'm wondering if an up cut spiral bit would be worth the investment?

https://www.wealdentool.com/acatalog/On ... e_229.html

And if so, what diameter would you recommened I go for? I obvisouly want it to be thin for cutting circles, but also robust enough to last. I'm thinking 5mm? (T4U5000)

 

[MattRoberts]

You'll definitely get a better cut with a spiral. The twin flute bits are predominantly for edge trimming - they don't actually have a cutting edge in the centre of the bit, so aren't good for plunge cuts or deep cuts where the bit is completely enclosed.

A lot depends on the material you're cutting too - if it's a soft wood or mdf, you're much more likely to get heat build up.

I'd always recommend a 5mm and 10mm spiral up cut bit. They can be pricey, but worth the investment

 

[transatlantic]

It's plywood (the hardwood stuff from Wickes)

5mm and 20mm?

Also - I just noticed the 5mm only has a spiral length of 19mm. I think I best go with the 6.35mm to give me 25mm cutting length as the material is 18mm thick?

 

[MattRoberts]

Sorry! I meant 5mm and 10mm.

You also don't need to cut full depth with the bit. You can go down about 5mm, use a jigsaw to cut in between the lines and then use a flush trim from the other side to clean it up. Way less stress on the bit, but you still get the neat edges

 

[custard]

I'm having issues with burning. I'm only taking 5mm passes with a relatively new Trend 5mm double flute straight bit, yet it's scorching both the jig and the workpiece.

I did notice that there is very little dust being thrown out s(stays in the wells) so I'm wondering if an up cut spiral bit would be worth the investment?

When the waste isn't being cleared that's often one of the causes of scorching (along with blunt cutters and a feed rate that's too slow), as Matt said it's also a sign that you're taking too deep a cut. Try 2 or 3mm at a time with multiple passes. Too long scorching though and the bit overheats and goes blunt, if you've got one of those credit card sized 600 grit diamond stones you can touch up the cutting edges on single or double flute straight bits.

Again as Matt says, make sure the straight bit has a bottom cut, some do, some don't.

Yes, a solid carbide spiral upcut bit knocks spots off a straight cutter for this application. 5mm or 6mm would be favourite in a 1/4" collet.

 

[Racers]

You need one of these, I have one and I have done stupid amounts of work with it and it still wont blunt

https://www.ebay.co.uk/itm/1-4-6-35mm-C ... SwtXBavQ5H

Pete

 

[transatlantic]

You need one of these, I have one and I have done stupid amounts of work with it and it still wont blunt

https://www.ebay.co.uk/itm/1-4-6-35mm-C ... SwtXBavQ5H

Pete

In wood? (ply/mdf) ... also - is it an up cut spiral?

... bah out of stock ... although they do have the 2 and 4 flute versions?

 

[Racers]

The one I have is a two flute up cut spiral.

https://www.ebay.co.uk/itm/1-4-6-35mm-S ... SwmmxW4We-

I use it for everything wood mdf ply.

Pete

 

[transatlantic]

Right - I've ordered one. Thanks for the heads up

 

[sunnybob]

Burning on the wood, see above. But if youre burning the jig, then it sounds like a seized bearing.

 

[transatlantic]

The one I have is a two flute up cut spiral.

https://www.ebay.co.uk/itm/1-4-6-35mm-S ... SwmmxW4We-

I use it for everything wood mdf ply.

Pete

This arrived today! I've not used it, but I can't believe how sharp it is :shock:

 

[Racers]

Excellent! let us know how you get on.

Pete

 

[sploo]

The one I have is a two flute up cut spiral.

https://www.ebay.co.uk/itm/1-4-6-35mm-S ... SwmmxW4We-

I use it for everything wood mdf ply.

Pete

That's the bit I use on my CNC machine. 1/4" deep cuts at 2" per second feed rate is fine in MDF. Highly recommended.

Wickes ply these days is total carp though. Likely to get lots of chipout and tearing.

 

[transatlantic]

The one I have is a two flute up cut spiral.

https://www.ebay.co.uk/itm/1-4-6-35mm-S ... SwmmxW4We-

I use it for everything wood mdf ply.

Pete

That's the bit I use on my CNC machine. 1/4" deep cuts at 2" per second feed rate is fine in MDF. Highly recommended.

Wickes ply these days is total carp though. Likely to get lots of chipout and tearing.

Yeah - it's doesn't need to look good fortunately