Saw Burn

[Grahamshed]

Hi again, another newbie question please.

I doesn't seem to matter whether I am using the RAS or a portable circular saw I always seem to get saw burns along the cut. Iam cutting old beech at the moment but I think it happens with soft woods as well.

So what am I doing wrong ?

regards
Graham

 

[Blister]

Using a blunt blade ?

 

[Grahamshed]

The one on the circular saw is a brand new dewalt blade. The RAS one could be blunt though.

 

[Blister]

are you crosscutting or ripping ?

as the number and size of teeth will vary depending on that

 

[Grahamshed]

At the moment I am 'ripping'. I have some 6 inch long, 3 inch wide, 3/4 inch thick pieces of beech which I need to cut in half to 1.5 inches wide.
In absence of a bandsaw I am using the RAS in cross cut fashion to rip down their length. The blade is very fine,probably 80 tooth, little used but maybe 20 years old or more......... think I am answering my own question here....

 

[deserter]

Make sure you keep the wood/saw moving all the time. You can guarantee a burn every time you stop your progress with the blade still turning.

 

[Blister]

At the moment I am 'ripping'. I have some 6 inch long, 3 inch wide, 3/4 inch thick pieces of beech which I need to cut in half to 1.5 inches wide.
In absence of a bandsaw I am using the RAS in cross cut fashion to rip down their length. The blade is very fine,probably 80 tooth, little used but maybe 20 years old or more......... think I am answering my own question here....

think I am answering my own question here.... Yes

Far too many teeth for ripping , suggest a different blade be used ( for ripping ) :wink:

 

[andersonec]

At the moment I am 'ripping'. I have some 6 inch long, 3 inch wide, 3/4 inch thick pieces of beech which I need to cut in half to 1.5 inches wide.
In absence of a bandsaw I am using the RAS in cross cut fashion to rip down their length. The blade is very fine,probably 80 tooth, little used but maybe 20 years old or more......... think I am answering my own question here....

think I am answering my own question here.... Yes

Far too many teeth for ripping , suggest a different blade be used ( for ripping ) :wink:

And is the timber being held by hand? if so try using the clamp which is usually attached to the fence, if it won't reach then clamp a stop block to the fence and hold the timber tight against it, a crosscut blade should be able to do a 6" length without too much problem, a crosscut blade is designed to clear away the sawdust created when doing longer and thicker planks, hence the fewer teeth and the curved gullet.
I think your main problem is trying to do small pieces like that and they are not being held firmly enough, I can guess that you are holding them by hand and unconsciously pushing them against the blade.

Andy

 

[Grahamshed]

And is the timber being held by hand? <snip> I can guess that you are holding them by hand and unconsciously pushing them against the blade.

Andy

In part. I have a stop clamped against the fence 1.5 inches from blade and then using another piece of wood to hold/push the workpiece against the fence.

regards
Graham

 

[Grahamshed]

I am leaning towards a blunt blade ( sounds dangerous ) as the the saw was having a job to crosscut the 3 inch wide pieces of 3/4 inch beech, often stopped and had to be backed out.

Regards
Graham

<edit> Just been down to the shed for a close look at the blade. 10 inch, 120 teeth, and it doesn't 'feel' sharp.

 

[9fingers]

Totally the wrong blade even for cross cutting in my book.
120 teeth would be for thin ply or perhaps laminates.

60teeth for crosscutting and 20 ish for ripping.

Bob

 

[Steve Maskery]

Ripping with a RAS, with any blade, is not a good idea. They are designed for crosscutting. Yes I know the DeWalt manual shows how to swing the head round. It doesn't mean it's a good idea. A RAS uis always tring to lift the workpiece, and for ripping it is very difficult to keep it pressed down.
Not just wrong blade, but wrong machine, I'm afraid.
S

 

[Steve Blackdog]

Following on from the OP, is saw burn (when ripping), even with a band saw generally caused by too many teeth? I was using a fairly fine toothed bandsaw blade on the bandsaw to cut a fine slice off a piece of 2" cherry, thinking it would give a much smoother cut, only to find that the cherry burned very easily and the blade got clogged up with burnt wood. I may have been pushing too hard, but I couldn't stop the burn.

I also found the cherry burnt easily when cutting a plug with a plug cutter. Oddly I haven't found it burning with the router.

Steve

 

[Steve Maskery]

Cherry burns easily, whatever machine you are using.
To understand tooth configuration you have to understand what is happening to the wood fibres.
Ripping produces long curls of fibre, so needs large gullets to carry away the waste. Crosscutting produces much finer waster, so the gullets do not need to be so big, The teeth can therefore be closer together and each take a smaller cut, giving a finer finish. If you try to rip (producing large sawdust) with a fine blade (small gullets) you will get the effect you describe.
S

 

[Steve Blackdog]

Thanks, Steve

 

[Benchwayze]

Graham,

Have your blade sharpened. See what difference there is. BTW, don't scorn HSS blades, if that's what you have. (Old saws sometimes came with them fitted.) These blades will cut well if sharpened properly. It's just that TCT blades hold the edge longer, so they make economic sense, unless you are competent at sharpening HSS blades. Some woods do burn more easily of course, but I never noticed it much with beech.

Best of Luck

 

[Grahamshed]

Thanks guys. I am off to get a new blade, though looking through the lists neg rake blades seem rare and expensive, but needs must

While I am waiting I am going to strip it down and give it a good clean up, it has been neglected for quite a while..... maybe fit a new table as this one is a bit knocked about...... maybe another thread about that.

 

[cutting solutions]

Wow
120 teeth for ripping.
No wonder the blade is burning.
I am even surprised it cut at all.
there arent many 120 teeth blades sold so I would like to know the geometry (there are some thin kerf, square top, neg rake blades.....is it one of them?)

as 9fingers said
with 10" diameter
for ripping 20 ish teeth
crosscutting 48 to 60 teeth
and for fine work the 120 tooth one is probably a bit too fine. 80 teeth would be ok.

Neg rake blades are rare and expensive but are not that essential these days.
RAS used to snatch a bit with older designed blades pos rake blades.
with modern blades it doesnt happen.

not all suppliers charge high prices for blades :wink: