[kindanewbie]

This might sound crazy. But, yesterday I made some cuts with my miter saw which i havent used in a while. After the cuts, I noticed little black specs. My assumption was rat poop that got chopped by the saw/motor. Maybe not logical but that was m first thought. Thinking back I dont remember if i saw any full, obviously identifiable rat poop or did I just think I did?

In any case I cleaned up, brought the saw outside and blew it off with an air compressor. All clean.

Just made some cuts and black specs all over again. ( threw the dust bag away yesterday so the sawdust just went on my workbench behind the saw) These saws arent that complicated. There arent crevices all over. So, I assume I am wrong about the rats but what in the world is creating black specs in my cuts? All I cut were two cuts of 1/4 ply as a test cut and then 6 or 7 cuts of sycamore. No black markings anywhere in any of the wood.

Any thoughts?

 

[kindanewbie]

Pic

 

[rogerh]

If you try to brush it off with your fingers, does it smudge into the wood, instead of moving off the wood. If it does, it could be carbon dust from the motor brushes, that are disintegrating.

 

[John Smith_inFL]

not rats or mice.
I would think bugs, lizards, frogs, etc. I'm in Central Florida and see them all the time but I can never catch the critter with his pants down.

 

[Horseapple Man]

Sweep some of the black stuff onto paper or cardboard and try smearing it like Roger said.

If it smears, its probably poop. If it crumbles apart, it could be dry poop.

Just a quick question though... Did you or anyone else use the saw to cut black plastic?

I cut high density polyethylene sometimes. It makes a lot of black stuff like that. I blow off the saw afterwards, as I don't want it mixing in with my wood sawdust because I'm probably going to end up composting it.

 

[Wingedwheel]

Could it be black plastic from the blade clearance insert? Perhaps the stop screw moved a little or the blade developed a slight wobble letting it cut into the insert? Just a thought.

 

[Tony B]

Some of you guys really know your stuff.
Makes me proud to be a member.

 

[kiwi_outdoors]

Maybe Dry Wood Borer in the wood above your work areas - or in the ceiling - we had some of these eat thru the drywall ceiling in our master bedroom! Little black feces - like poppyseeds.

 

[FrankC]

Can't help, cause I don't know you know what!

 

[kindanewbie]

Sweep some of the black stuff onto paper or cardboard and try smearing it like Roger said.

If it smears, its probably poop. If it crumbles apart, it could be dry poop.

Just a quick question though... Did you or anyone else use the saw to cut black plastic?

I cut high density polyethylene sometimes. It makes a lot of black stuff like that. I blow off the saw afterwards, as I don't want it mixing in with my wood sawdust because I'm probably going to end up composting it.

No black plastic that I can remember. I havent used the saw in a while so not sure what I cut last. If not wood, likely white pvc though.

The weird thing is, I cant figure out where its coming from as I cleaned it all out with compressed air and the blade only touches the wood.

That leads me to believe it is carbon, as rogerh mentioned.
It did disintegerate when smeared but didnt leave any kind of streak like I expected.

But the saw was cleaned so it must be coming from the motor area.

 

[rogerh]

No black plastic that I can remember. I havent used the saw in a while so not sure what I cut last. If not wood, likely white pvc though.

The weird thing is, I cant figure out where its coming from as I cleaned it all out with compressed air and the blade only touches the wood.

That leads me to believe it is carbon, as rogerh mentioned.
It did disintegerate when smeared but didnt leave any kind of streak like I expected.

But the saw was cleaned so it must be coming from the motor area.

Most saws have vents around the brushes, can you see if the brushes are arcing, while the saw is running?

 

[kindanewbie]

Most saws have vents around the brushes, can you see if the brushes are arcing, while the saw is running?

I do see some arcing but not a whole lot. It is set back from the vent about 5 or 6 inches so tough to see how big it is. For example on my table saw the arcing is much closer to the vent and very easy to see.

Is a little arcing was normal? Or are both my table saw and miter saw on their way out? The table saw was smoking a few weeks ago as I cut a bunch of black locust (posted about it here somewhere). But its still running.

 

[rogerh]

I do see some arcing but not a whole lot. It is set back from the vent about 5 or 6 inches so tough to see how big it is. For example on my table saw the arcing is much closer to the vent and very easy to see.

Is a little arcing was normal? Or are both my table saw and miter saw on their way out? The table saw was smoking a few weeks ago as I cut a bunch of black locust (posted about it here somewhere). But its still running.

A little arcing is normal. To see if the arcing of your mitersaw is your problem, just temporally tap up those vents. See if the rat poop stops or if the tap catches any black stuff.

 

[Horseapple Man]

Plastic dust seal on the blade shaft bearing?

 

[DrRobert]

I hope those darn wood elves have not found your shop! They sneak in the middle of the night and do all kinds of mischief - jointer fence mysteriously no longer 90°, miter saw not cutting square even though the last board was perfect, one of 5 boards bows overnight, your favorite pencil goes missing, never to be found again……

My guess is something is coming apart or flaking off. Check under the insert. What brand of saw?

 

[kindanewbie]

I hope those darn wood elves have not found your shop! They sneak in the middle of the night and do all kinds of mischief - jointer fence mysteriously no longer 90°, miter saw not cutting square even though the last board was perfect, one of 5 boards bows overnight, your favorite pencil goes missing, never to be found again……

My guess is something is coming apart or flaking off. Check under the insert. What brand of saw?

Are you not leaving them cookies?

 

[Bob Bengal]

From the photos I don't know what it is but doesn't look like poop to me. Maybe clean the area, then run the saw without cutting anything, see what happens.

 

[kindanewbie]

Ok, so I used masking tape to cover both the vent and the part the bag attaches to for catching the sawdust.
The vent tape was clean. The other tape had the black spots.
So, it cant be rat poop. The stuff is still coming out. And when you look down that chute, where the bag attaches to, its a wide open spot with only the saw blade visible. Theres nothing there. No plastic. Nothing at all. And when the blade goes down below the platform at then end of the cut, there is no obstruction either.
Its an older (20 years) Ryobi

 

[kindanewbie]

From the photos I don't know what it is but doesn't look like poop to me. Maybe clean the area, then run the saw without cutting anything, see what happens.

My initial thought was from rats and that it was chopped up by the blade. The more I think about it, the sillier that sounds. But i was cleaning out a couple of spots the last week or two making some room and did see some rat poop (including the spot where I had the miter saw previously), so it was on my mind.

 

[DrRobert]

Which kind you think is best?