Mitre saw 'burn' mark

[Munroast]

not in general with a say 3mm from fence/bed length stop as the diagonal deviation is so small it will be around the same or less than the setback off perhaps 0.6mm from blade to tooth edge

and as i said upstream exactly this as my was also my thoughts

"Anyways - getting back to the OP, I wonder if a stop to the right and the blade catching it on the way out is causing these curious burn marks ?"

you did indeed say it before me - my apologies (hate it when people do that to me)

 

[big-all]

you did indeed say it before me - my apologies (hate it when people do that to me)

no apology needed as you have done nothing deliberately misleading or mischievous

 

[GhostIntMachine]

Have the stop on the left hand side !

You only have TWO hands. If you are right handed (as the majority if humans are), the right hand is used to operate the saw. The left hand is used to hold and feed the material, which is generally the longer piece (you are supposed to have a minimum of 12in/300mm separation between your hand and the sawblade). That means the stop block for repeat cuts has to go on the right si de. Believe it or not, for right handed people that is standard practice qnd is what is taught to trade joiners

 

[BelfastGuy82]

Either the blade is not as sharp as it should be, or you are rushing the cut.

In theory it should be a brand new blade, since it's the one that came with the saw, which was new and unused before I started this project.

I don't recall rushing either. Being my first time with a mitre saw, I was being extra cautious about every aspect of what I was doing.

Can sharpness be visually gauged though, other than that which is really obviously blunted...?

Check that the fence is square to the blade, and your timber is held tight to the fence.

It's also possible that any resin in the timber can bind the blade a little to cause scorch marks.

I spent a lot of time setting it up, so everything should be square.

The timber was clamped with the inbuilt clamp, and I'm sure in addition to that I put my hand on it as well.

Whilst I agree with you in general, if the saw was being run without a vacuum it is just as likely that the gullets on the saw blade are becoming (over-)loaded with swarf (saw dust) - in which case making too slow a cut can also cause scorching

Brand new saw; first project. Shouldn't be any dust built up anywhere.

another possibility
if you are using a length stop and you raise the blade with it still turning one or both bits can lift/move and pinch the blade so always stop the blade before lifting or moving the the saw head

No length stop.

Saw blade was allowed to come to a complete stop before lifting.

curious why they are all the same

are you using it as a chop saw or like a radial saw (sliding it across)
and is that make always from the same side of the blade (and is the other side cutting clean)

burn marks are often a sign of a blunt blade, but even a blunt blade should cut that low quality softwood with ease

and have you got a photo of the blade to see what you are cutting with

Radial saw. My recollection (this is from a few months ago) is that I brought the middle of the blade down into the wood, then pushed it forward, slowly, letting it do it's thing.

No idea what the opposite side of the blade is doing because I was shaving millimetres off the workpieces, which had already been cut to inaccurate lengths by the fool at the local lumber yard...

No photo of the blade currently, and no more of this wood to cut. I'll try and update this when I undertake further investigaton in the coming weeks. I have some actual mitres to do for another project.

Not holding timber down will cause that .

It was clamped and held. First mitre saw, was a bit intimidated and extra cautious.

If the tool is hand held, it can move or tilt as you get through the timber and the weight balance changes. This usually happens just as you cut through.

I linked to the tool used in the original post. Is there such a thing as a handheld mitre saw...?

I wonder if he is using a stop to the right of the blade (the stop being something the wood is pushed up against to get a repeatable length) then after the cut when the blade is lifted back up it catches the end of the piece that has just been cut off, this loose bit of wood is trapped between blade and end stop (potentially dangerous)

when the stop is on the left, our hand has that bit held down, and the now loose bit to the right just naturally moves away from the blade


It is bad practice to put the stop to the right of the blade, but many people do it
and on occasions when you have to, then after the cut I hold the saw down until it stops spinnig before gently lifting it back up.

No stop was used.



I measured the distance from the edge of the wood to the bottom point of that really obvious indented burn, and it seems to be roughly 44mm. Don't know if that helps in any way with the diagnosis. The thickness of the wood is about 42mm. Any connection...? Is the maybe the point where all of the teeth that are going to cut have fully entered the wood...?

 

[Harry Bloomfield]

The thickness of the wood is about 42mm. Any connection...? Is the maybe the point where all of the teeth that are going to cut have fully entered the wood...?

The deeper the blade passes into the timber, the hotter it will have become from the friction, the more likely it will be to cause burn marks. That is especially true if the blade is not as sharp as it should be, or the operator pushes it too hard.

 

[GhostIntMachine]

Can sharpness be visually gauged though, other than that which is really obviously blunted...?

Not really, unless the blade is caked in resin. Not a thing in your case - and in any case takes me 2 to 3 months of heavy use to do that to to blades (trade)

No length stop

Which rules out the possibility of the workpiece moving (and in any case you seem to have been holding on to the workpiece and making a dust cut)

Radial saw

So you plunge the blade into the workpiece, then pull the head twowards you? That can sometimes load-up the saw gullets which might pin turn scorch the timber, especially if the plunge was made very alowly. The proper way is to pull the head out, plunge down and push back towards the fence. At least that's what the manufacturers tell us (and what we in turn teach apprentices). Try it and see if it makes a difference

I was shoving millimetres off thevworkpieces, which had already been cut to inaccurate lengths by the fool at the local lumber yard...

In the fool's defence, are you aware that there are often differences in measurements between two tapes? Pull out two or three tapes from different manufacturers side by side and check them along their length. You might be surprised. That could explain a difference. That or he might really just a bit slap dash - which is why he''s labouring in a timber yard and not making stuff in their joinery shop. Either way I'd still rather have timber that I can trim down to fit than timber which is too short - because it is really difficult to stretch wood

I linked to the tool used in the original post. Is there such a thing as a handheld mitre saw...?

Yes there is. We used to use them before electric ones were a thing (from the early 1980s if it matters). The most basic form was a wooden mitre box (you still see plastic ones for cutting plaster coving, the wooden ones have all but disappeared), and there were (and still are) adjustable metal ones - the best known trade quality models are still sold under the Nobex brand. They have their uses and are especially useful for sawing fine metal mouldings and timber/plaster composite mouldings (think picture framing)

 

[robinbanks]

or you are rushing the cut.

Er, I'd have said they're lingering too long..

Show us a picture of the blade. I want to see the tooth condition and whether the teeth have a gummy build up of burnt sap etc

 

[big-all]

i think we really need to see the saw the set up and ideally how you hold the handle whilst cutting or at least the model number please

the uniformity and small area off the burns suggests mechanical intervention rather human intervention where stance and muscle input find any slack or weakness in a general direction but without uniformity

is there any clicking or tight spots when moving the blade before during or after cutting

my thoughts are something like blade guard putting drag or deflection for a split second somthing my dw712 suffered from if the gaurd was loose before i adapted it as the rubber guide wheel would take the wrong path before jumping back to line