That blade has a teflon coating...

Quoted from a Blade cleaning article:

Charles McCracken, of Freud, Inc. said, "We recently started doing so testing with Simple Green concentrate and have found it to be very effective, too."

McCracken says of Freud Teflon coated blades, "Soap and water usually cleans very well. Kerosene can be used for more stubborn build up around the teeth if necessary."

If scrubbing of a coated blade is needed to loosen residue, household scrubbing pads designed for use with Teflon coated cooking utensils will help prevent marring your blade coating. Make sure to keep cleaning pads used in the woodshop separate so they are not accidentally returned to use around food.

For those slots, I have a stiff nylon scrup brush.

The Laser cuts are anit-vibration slots. The are also supposed to help with expansion and keep the blade true during that. So if they are clogged...

Other things might cause the saw marks- Blade being dull (you said it was sharp), the saw being out of tune (but that would leave burn marks also) or the blade picked up some wobble (out of true).

To check that... You could check it with a dial indicator. If you don't have one, use a miter gauge with an adjustable fence. If you don't have one with an adjustable fence, put a thin piece of wood with the tip lightly against the blade... spin the blade slowly, so the blade pushes it back... Clamp it to to the miter gauge. High spot should still touch the blade. Low spot check with a feeler gauge.

It it had no saw marks before, then the arbor runout was probably at least fair... You can still check that, if you have a dial indicator. Even if you don't check it, you can still push and pull on the arbor to check the arbor bearing. They should spin, but they shouldn't have any play laterally. Make sure the arbor flange is clean. Something caught between the arbor flange and blade will cause runout.

I try to get arbor flange run out less than 0.005" (if my own, less than 0.002") and blades under 0.015"... (if a premium blade 0.005" - 0.007") At 0.001" runout at the arbor, ).001" run-out on the blade would proportionately translate to 0.004" - 0.005" out by the teeth. 0.001" is what Forrest says their blades are.

On the blades... it really depends on the individual blade. Some will have some static warp that will spin out flat. I say that, because I've had some that were .025" out and spun flat and left no marks... Yet I've had some with 0.015" that left saw marks because it spun out further. I usually "Eye" it while it spins down that last couple turns before coming to a stop... Make a cut and look at the cut. Then measure it. I'd rather have my blades "flat" as can be.

If off too much, take to a saw shop or where ever that has saw sharpening and they can re-tension the blade. On a Glue Line Rip TCG, that might run about $15 for a retension and resharpening. I'm not sure on just retensioning. On that Frued blade, if a good shop, it should be even better than new after a resharping and retension. (At least with mine.)

If your arbor is out a little and the blade out a little and the arbor flange is clean... you can bring in all in closer by marking the high spot on the arbor flange, mark the high spot on the blade, mount the blade with the mark 180 from the mark on the arbor.

Others reading this might think this might all sounds anal for work on wood, but the whole idea of a "glue line rip" is to get a straight smooth edge that doesn't need to hit a jointer before the glue up.

EDIT-- Add-in/additional: On some old contractor saws, a bad belt will cause a vibration... that will also cause that.
*** I'm assuming you mean the Freud Lm74R series and not the LM75R series right? (or LCL7M's?

(If you are serious about those and want a recommendation on a better glue joint rip blade...)

 

I looked at the spec's on your saw (Dewalt 745).

You know your saw. It's a bench/work site saw. Only weighs in at 45 pounds. (Over 1250 pounds lighter than mine.) Very portable.

Have it in a stand?
How steady is it and how's the vibration on it?

 

The saw is on a stand, but I do move it about on wheels. However, that has been the same between then (clean cuts) and now (marked cuts).

I will check to see if there is debris between the blade and arbor.

Mike seems to support my view that the clogged laser cuts are probably the culprit. Mike - you say an abrasive pad gets them clean? Do you soak it in something caustic beforehand? Do you use any little tool or something to clean the cuts out?

I'm not sure which of the two types of blade I have. Mine is red. Does that help? Which is preferred?

Any preferred brands for dial indicators in the below 40$ range?

 

Phillip; Mike mentioned the msg. from Freud (a Freudian msg?) re 'Simple Green', I've switched over from oven cleaner due to a LOT of warnings about damaging the carbide, and more certainly, the coatings which they all seem to be using now.

It's not corrosive so a plastic dishpan would work great. Just let it soak in warm water and Simple Green; give it a bit of a brushing...maybe an old tooth brush for any tight spots. I think you'll be pleasantly surprised, and no nasty disposal problems for the cleaner!
Good luck,
-Dan

 

Do you have other blades you use and are they still cutting the same? If the answer to that is yes and yes then it is not the saw.