Miter Saw adjustment...

[D-train]

Ok, I have had my miter saw for years. I have used it for many projects. I am currently re-casing all of my doors and windows. But I had a problem with my saw cutting bad miters. My saw was cutting 45's with the inner and outer portions of the cuts having gaps. ...ie there is a "pivot point" (identified between the pencil marks in the first photo) I had reset my fence. ...changed my blade, and have check the individual cuts and they are perfect 90's and 45's, even on a 1x6.

So I decided to add an additional fence, so as to bring my work piece away from the (original) fence about an inch. Low and behold, I'm getting almost a dead on miter (second picture) it does appear that the "inner" part of the joint does have a space, but that isn't true, it is butted.

So my question is, what am I missing, that I am not getting a good cut/miter with the piece against the original fence?

Thanks,

Mark

 

[MichaelP]

Are left and right parts of your fence parallel to each other and are in the same plane? You can check it with a straightedge.

 

[D-train]

Yes. Both fences are inline with each other and perpendicular with the blade. They are dead-nut on. When I slide my work piece from one side to the other... The piece doesn't hang-up or catch the edge of the fence. ...yet it is right against it.

 

[PCustoms]

Pic of a straightedge against the face of the cut?

What blade are you using?

 

[scooterbum46]

I have had my miter saw for years. I have used it for many projects

Is it possible that the motor bearings are ever so slightly worn/loose? The blade's first point of contact is in the middle of the piece and the cut spreads both in and out from that point - I can see where a slight wobble in the blade could create issues.

 

[AEAdam]

Step one: Replace the blade

Step two: make sure the blade bolt is clean, surfaces are all clean, I'd hose it all down with WD-40, then put in the new blade and tighten it up correctly. I feel like you are getting wobble and the blade is being supported by the wood in the center of the cut. You should see the exact same thing in a 90 degree cut.

A dull blade could cause that wandering.

Oh, and if this is a sliding miter saw, make sure you get the right blade for that. I put a Diablo blade on my sliding miter that I picked up at Home Depot in a 2 pack and it was a disaster. The slides have teeth that angle in the opposite direction to produce really smooth cuts. The replacement blade for my ancient Bosch slider was like $80.

 

[jar944]

The cuts don't look straight in the pictures. Typically its either flex in the saw during the cut or blade deflection.

 

[LXCam]

Step one: Replace the blade

Step two: make sure the blade bolt is clean, surfaces are all clean, I'd hose it all down with WD-40, then put in the new blade and tighten it up correctly. I feel like you are getting wobble and the blade is being supported by the wood in the center of the cut. You should see the exact same thing in a 90 degree cut.

A dull blade could cause that wandering.

Oh, and if this is a sliding miter saw, make sure you get the right blade for that. I put a Diablo blade on my sliding miter that I picked up at Home Depot in a 2 pack and it was a disaster. The slides have teeth that angle in the opposite direction to produce really smooth cuts. The replacement blade for my ancient Bosch slider was like $80.

My last wood project I picked up a new Diablo blade and my miters went to ****. The blade looked like it tracked straight which a dial indicator confirmed. I switched back to an older blade and my issues went away. The only thing I can imagine happening is the teeth weren’t brazed on correctly, I could have been as simple as a single tooth out of alignment. Anyhow, there went $60 in the trash.

 

[dnschmidt]

If it's not mechanical, meaning wore out parts, then it's buy a Chopmaster II from Forrest of the equivalent from Ridge Carbide. These will cost well over $100 each but they work.

 

[tarbellb]

Step one: Replace the blade

He's already replaced the blade, Mentioned in first paragraph
----------
Are you changing 45s for left vs right cuts or flipping the piece upside down?

If you lay the piece upside down this can have a effect on the cut


Also every slider will deflect some if heavy handed

I would not be using the slide action, rather lock the slide all the way back and just drop the blade

I don't think it's anything to do w the machine or blade but rather the orientation of the wood or flexing it while performing the cut

 

[T45]

How much of this is trying to do fine woodwoorking with contractor grade tool ? This results in things like less stiff blade, with more slop in it. Stiffest, straightest seup is going to be chopsaw with thick kerf blade. Alot of box store blades are thin for use with battery powered saws, sot no the correct spec. Basically all blades were super thin-kerf or table saw blades that have the wrong teeth shapes, etc for the mitre saw. Kind of annoying/inconvenient, for sure.

 

[KnurledNut]

Check your trim. It may be cupped. A bevel cut will have a more pronounced arch but it will show slightly on miters too, especially when mating pieces out of different boards. I ran into this on occasion when I was building houses.

 

[Old tool guy]

Agree with Knurled, it’s the trim. Not sitting consistently flat on the table. Do a sample cut with a good piece of s4s.

 

[PCustoms]

Agree with Knurled, it’s the trim. Not sitting consistently flat on the table. Do a sample cut with a good piece of s4s.

And then put a straightedge on the cut surface...