Table Saw Blade Problems

[Clark Harbaugh]

I just ran a few test cuts on a recently sharpened 24t thin kerf Freud. The bottom 1/4" or so shows a bunch of radial saw marks, however the top part of the piece looks fine. I just went back through the saw setup, and the blade is parallel to the miter slots and the fence. Any ideas why this is happening? Hopefully the pic shows what I'm trying to explain.


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[Tim Janssen]

It looks like those marks are being made by the back of the blade. That might be a clue to the problem. Is the fence parallel to the blade?
Worth checking. Could also be that the wood is twisting as it is being cut.

Tim

Just read your post again and you stated that the fence is parallel to the blade.

[Paul F Franklin]

Try slowing your feed rate down. If that improves it, your blade may be deflecting.

[Clark Harbaugh]

I agree it looks like the back of the blade. Maybe I'll check again on the alignment.

[andy bessette]

I would try a better blade. Why thin kerf?

[Lee Schierer]

I agree it looks like the back of the blade. Maybe I'll check again on the alignment.

I was going to suggest checking the alignment of the blade to the miter slot and then the fence to the miter slot. Those marks are typical for an alignment problem.

[glenn bradley]

As others have said, feed path deviation. If it is consistent on all cuts I would look to alignment. Since it is happening out of true (lower portion of material effected but not the higher portion of the field) I would confirm the two faces being used as your reference surfaces (the side facing the table and the side facing the fence) are true to 90 degrees. The fence also needs to be reliably perpendicular to the table as well as aligned with the blade. If it happens on some material and not on others I would lean toward wood movement during the cut.

[Clark Harbaugh]

Looks like it is a blade problem. Not sure why I didn't think about this yesterday, but just swapped in my old combo blade. No tooth marks on the bottom. Guess it is deflection/vibration. I never had that issue before having it sharpened. Guess I need to find a different source. Oh well, excuse to go buy a better blade!

[Doug Garson]

Maybe contact your blade sharpening service and explain your problem rather than right them off without giving them the chance to make it right. You could have the one blade in a thousand they mess up.

[Evan Stewart]

I had a similar situation with a thin kerf blade awhile ago. My theory was that the blade had warped slightly after milling a decent amount of hard maple that was binding the blade due to internal board stress. After double checking alignment of the fence the problem persisted but after switching to a regular kerf blade everything was fine. Since then I haven't put a thin kerf blade on my TS unless I'm making final dimension cuts.

[Lee Schierer]

If you need a smooth cutting rip blade take a look at the Freud Glue Line rip blade. It is a full kerf blade that cuts as well or better than a 24 tooth thin kerf on my Craftsman 1-1/2 Hp saw.

[Rich Engelhardt]

take a look at the Freud Glue Line rip blade.+1 to that.
I did away with all thin kerf blades on my contractor saw and went over to full kerf.
I seldom, if ever, cut anything thicker than 1" so I really don't notice a lack of power - - matter of fact - - the added inertia of the heavier full kerf blade seems to help it go through 3/4" wood easier.

[Clark Harbaugh]

So, I put on a full kerf glue line rip from Freud. I now have radial.marks in both directions (indicating both front and back of blade) and consistently the full height. I had to step away, as I found myself in the proverbial 'forest for the trees' situation. Busted out the dial indicator to double check. The blade is <.001 with the back of the blade ever so slightly (maybe .0005) away from the right miter. Don't think I'm going to improve that. I did notice that the face on my fence is wavy, so possibly that is my problem. To be on the safe side, I'm going to build a new face to test with. Never really like the plastic face on the Shop Fox. Otherwise, I'm out of guesses.

[Peter Christensen]

It's a long shot but here is another possibility. The bearings may be starting to go. You have the dial indictor so take the blade off and put the indicator tip on the end of the shaft and try to move it from side to side with a board or pry bar. After that put it on the side of the shaft and see if it moves when force is applied. If there is no detectible play then your issue is alignment based and if there is you need new bearings.

[Rich Engelhardt]

So, I put on a full kerf glue line rip from Freud. I now have radial.marks in both directions (indicating both front and back of blade) and consistently the full height.OK - that's not altogether bad news.
When you changed the blade, you also changed the problem.
I suggest returning to the original blade, retest it to make sure only one set of marks is there, then make another change and test it again.

[Clark Harbaugh]

I appreciate everyone's input on this. It's one of the most frustrating issues I've had to work through in the shop in a long time. The strange thing is that I've had this saw for about 8 years and never had an issue. My rips have always been glue ready. My next step is a flat fence face, but I can't see how that would be the route cause of my problems. Otherwise, I would have been having these issues all along with the original Shop Fox HDPE faces. Granted, I need the flat face (shame on me for never noticing mine wasn't), but it's not like the HDPE has suddenly moved with the weather.

Rich, I've tried swapping blades around. On the original 24T blade, I still only get marks on the lower portion of the piece and only from the back side of the blade. Also, went back to the piece I cut with the old 50T combo (that I noted earlier as not having the marks) and noticed it actually had similar marks to the 24T, just not as pronounced. So, I've basically been trying to make small changes then run through all 3 blades and at different feed rates to try and narrow down. It's not the blade to table alignment, so if it is alignment related it has to be on the fence.

The bearings is an interesting thought. I put the dial indicator on the end of the shaft and pried with a 3' length of 2x2. It deflects about .02" with a lot of force, but the deflection doesn't appear to be in the arbor bearings. I get the same deflection when prying under the arm that carries the arbor.

[Clark Harbaugh]

SOLVED! It was indeed the crappy plastic fence face. I fought with it for a while longer this morning to try and shim it out in places to hopefully get it as 'flat' as possible, but in the end I made a quick trip to the big blue store and bought a cheap $9 melamine shelf and cut it to size. It aint pretty, but it works. I'll make it pretty later. The important thing is I'm back to getting a glue ready cut with the 24T thin kerf. My assumption is that when I was setting up the fence with the old face, the waviness prevented me from getting accurate measurements. The new one lets me dial it in exactly parallel. The strange thing is the brand new 30T glue line rip still leaves saw marks. Not happy with that blade at all. Oh well, I guess I can use it for rough cuts.

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[Tim Janssen]

Glad you found the problem!

Tim

[Rich Engelhardt]

Yep - glad you found the problem, but, I'm sorry to hear you aren't happy w/the Glue Line Rip blade.

[Pat Barry]

It looks like those marks are being made by the back of the blade. That might be a clue to the problem. Is the fence parallel to the blade?
Worth checking. Could also be that the wood is twisting as it is being cut.

Tim

Just read your post again and you stated that the fence is parallel to the blade.
I'm a bit stumped about how the back of the blade could be making these marks although that is what the picture says. I think I would raise the blade and recheck before doing anything else. The marks should become more vertical. I suspect the material is not registering fully to the fence after the blade and the piece is vibrating.

[Rick Alexander]

Could it be fence flex? What sort of fence is on the saw? That would align fine but flex in use.

[Clark Harbaugh]

Shop Fox Classic (Bies knock off).


Could it be fence flex? What sort of fence is on the saw? That would align fine but flex in use.

[Andrew Pitonyak]

Step 1: try a different blade.

If you have an alignment problem, I expect it to be visible with more than one blade, especially when you are talking about a newly sharpened blade.