Bosch Miter Saw Problem

[Mark Gibney]

I set up a chop saw station in my shop a few months back, and I bought a new Bosch 12" chop saw specially for this. I wanted accuracy and repeatability, so I got a simple saw with no sliding.

Big problem - every cut I make with this saw goes awry at the very last. The photos will show what I'm trying to say - as the blade is about 1/4" from exiting the cut it veers to my left, leaving my piece with a ragged surface at that corner.

This happens no matter how I make the cut - slow and deliberate, or fast. I am always conscious of holding the trigger handle correctly and bringing it down vertically without pushing left or right. I've done my share of finish carpentry on sites over the years where it pays to be right the first time, so I don't think this is due to my bad technique. I am using the blade that came with the saw - if this is the problem why would it only happen at the very last part of the cut?

I'd like to hear any insights, opinions or similar experiences any of you had.

To be honest, I don't like this saw - it kicks a lot when I pull the trigger, and it's loud. I might pull out my Makita slider (LS 1013) and set it up in place of the Bosch. But I'm scratching my head over this. I have to cut everything oversized and trim them to length with my sled on the tablesaw.325840325841

The first photo shows the ragged corner, the second one shows the size of the gap created.

[Myk Rian]

Unplug it and grab the blade or arbor. Push and pull on it to see if it moves. The arbor might be moving in the motor, indicating bearing problems..

[Prashun Patel]

Dumb questions alert:

1 - Are you clamping your piece?
2 - Are you using a blade for a miter saw? I've heard that using a table saw blade in a miter saw can cause the piece to lift or move. Seems like miter saws want to have less aggressively raked blades. That's hearsay tho; I've only read - not experienced - this.

I would use a 1/2" clamped to the deck of the miters saw, and see if your cut still wanders. That will tell you if it's the holding or the travel.

[Eric Schmid]

The only time I've seen cuts like this is when the material gets sucked into the blade at the end of the cut. Have you tried clamping the piece?

It could be that the blade is causing the problem, but I would clamp it first to see if the result is the same.

You might want to check for blade and arbor runout as well. The blade behaves differently buried in wood than with wood on one side. At the end of a cut there isn't much wood left to "hold" the blade in the cut. The thin kerf blades that ship with the saw can deflect a lot. Also, the washers that hold the blade in place have to run true or the blade wobbles. If you see wobble in the blade regardless of which blade, check these or have Bosch send you a new set.

[Mark Gibney]

Prashun and Eric - I haven't clamped the wood, I've held it steady with my left hand, as normal. I'll try clamping it to see.

I'll check it for runout - a machinist friend of mine suggested this too. The blade is the blade is came with, factory installed. Probably too aggressive as Prashun suggested. Might try changing it out.

I wonder if the hinge on the saw body is poorly machined and at this low point it pushes the blade leftwards?

Anyone have a make and model of chop saw they really like?

[Andrew Hughes]

Check the guard to see if it's hanging up on something at the end of the cut.If your saw has the retractable guard during the cut.

[Kent Adams]

Prashun and Eric - I haven't clamped the wood, I've held it steady with my left hand, as normal. I'll try clamping it to see.

I'll check it for runout - a machinist friend of mine suggested this too. The blade is the blade is came with, factory installed. Probably too aggressive as Prashun suggested. Might try changing it out.

I wonder if the hinge on the saw body is poorly machined and at this low point it pushes the blade leftwards?

Anyone have a make and model of chop saw they really like?

I'm really curious as to what is going on like you. As far as a MS I like, my Bosch compound slider was good for me, but sold it and bought a Kapex but I wouldn't go to that extreme. Bosch are typically very good so this has to be some sort of QA issue on this particular saw.

[Mark Gibney]

Bosch typically make a good tool, or at least have a good reputation. I'll have to strip this saw down and look it over, and maybe as Andrew says, the guard is the culprit. I'll let you all know after the weekend if I find anything. Have a good one!

[peter gagliardi]

Are you letting the trigger go at the end of the cut? A lot of poorly engineered saws "torque" sideways when the trigger is released and the blade brake kicks in.

[John TenEyck]

I have a Bosch 12 inch MS and it cuts shockingly well with the 60 tooth factory blade, better actually than the 96 tooth Freud blade I tried on it. The saw didn't cut square in either plane until I tuned it but it has been great ever since. The problem you are having might be due to blade or arbor runout, as mentioned. The Freud blade gives cuts very much like your first photo. I would try a different blade. If it doesn't go away then it's time to check the arbor.

John

[Martin Wasner]

Have you tried a different blade? The factory supplied blades are typically less than stellar, but I'd think the cut would be less than satisfactory all the way through, not just at the end.

[Justin Ludwig]

Are you letting the trigger go at the end of the cut? A lot of poorly engineered saws "torque" sideways when the trigger is released and the blade brake kicks in.
+1. I have to release the trigger of my Dewalt when below the finished cut or above. A cheap blade could have a little more run-out on the release of the trigger.

[john lawson]

Your fence is misaligned to the blade. I have a 10" Bosch slider and I went through this for awhile before I finally got it. You will have to go through several steps using a square that is actually square to fix it.

First lay the square against the fence and check the blade to it. Chance are it's going to show some gap. Adjust it until the gap is gone by loosening the allen screws hold the fence. Just keep at it until you see results.

Mine was really off because I cut a piece of wood and did not hold it tight enough and it grabbed the wood and jammed it against the fence, bending the fence. I did not realize what had happened immediately. I kind of had to go through what you are doing now to realize what I had done. Mine was bent badly enough I finally took it off, layed it on a concrete floor and beat the heck out it until I had it fairly straight (I know, you should not do that to aluminium, but it was no good the way it was). After that it was close enough to be able to adjust it on the saw. Yours may not be that bad.

Good luck, it's a great saw.

[Mark Wooden]

I think your saw is "heeling" which means the arm may be rising/falling square to the table and fence, but the blade isn't square to the fence. (Or vice versa).Telltale sign is tearout on one side of the cut.
Also, once cut through, move your stock away from the blade before bringing the saw back up so it can't hit the cut face.

[Roy Turbett]

Your fence is misaligned to the blade. I have a 10" Bosch slider and I went through this for awhile before I finally got it. You will have to go through several steps using a square that is actually square to fix it.

First lay the square against the fence and check the blade to it. Chance are it's going to show some gap. Adjust it until the gap is gone by loosening the allen screws hold the fence. Just keep at it until you see results.



+1 I had the same problem with a 12" and a 10" Bosch slider. Followed alignment procedure in manual and fixed the problem. You can calculate the error using the "5 cut method". There are several youtube videos on the subject. Also, shine a flashlight behind a square and the blade to check the vertical alignment.

[Travis Porter]

I had a similar issue with thin kerf blades. I switched to a full kerf Forest chop master and problem went away.

[Marty Schlosser]

I'm with Travis on this one. However, before investing in a more expensive blade, you may see if you could borrow a friend's blade first and try it out. It could very well be that it's heeling or set up poorly, so if a stiffer blank blade doesn't resolve the problem, go the other route.


I had a similar issue with thin kerf blades. I switched to a full kerf Forest chop master and problem went away.

[johnny means]

The fact that the issue only arises in the last bit of the cut is a sure sign of movement at the end of the cut. A bad arbor or blade would show throughout the cut. Assuming the OP isn't just using sloppy technique, this looks like a fence alignment issue. One way to tell would be to do some test cuts where the board doesn't dozen the hero in the fence, but does dozen the kerf. If the issue doesn't reappear, you're probably looking at a fence alignment issue.