Cabinet saw blade rubbing zero clearance insert...help!

[Dustin Smith]

Ok guys, this issue is going to make me pull my hair out.

I bought a used Jet Xacta Saw Deluxe last fall, and one of the first things I did for it was make a zero clearance insert out of MDF. The saw came with a Ridgid 60T which I have been using since day one. The blade has since worked fine with the ZCI until last night. Last night I bought my first dado set, a Freud Super Dado, and installed it (stacked to 23/32") to play around with it. Afterwards, I removed the dado stack and reinstalled the 60T blade.

When I put the ZCI back on the saw, I noticed it felt like it was rubbing against the teeth on the back of the blade. I thought maybe the angle of the blade changed during my blade swap process, but I checked it with a digital "Angle Cube" and it was perfect 90.0° to the table. I fully lowered the blade, turned on the saw, and slowly raised the blade up through the ZCI. It made an audible screeching sound, and when I turned the saw off the blade quickly stopped spinning due to the friction of rubbing against the ZCI.

I checked my blade-to-miter slot alignment. The blade was perfectly parallel to the miter slot, as it was before I played with the dado set (I used a dial indicator).

I checked my 60T blade runout, and it is 0.004". I understand this is acceptable for a saw blade.

What am I doing wrong? Why is my blade suddenly rubbing against the ZCI? Will this happen every time I change blades?

Thanks
Dustin

[Mark Godlesky]

Is the insert in exactly the same position? If it's not a snug fit maybe it moved side to side a few thou. If you have leveling screws maybe one got turned a bit so the groove is now tilted with respect to the blade. Are the surfaces the insert sits on clear of sawdust? Just a few things I thought of.

[david brum]

You might also check for crumbs of sawdust between the blade and arbor flange.

[Myk Rian]

Is the insert in exactly the same position?
That would be my guess also.

[Carl Civitella]

Perhaps the MDF took on some moisture and swelled a bit. Carl

[Ellen Lewis]

I too had this happen with a Woodworker II blade and my ZCI. It turned out that the blade was slightly out of round. The only way I could tell was when I put it down on a flat surface and looked VERY carefully. Just another thing to check...

[Matt Day]

Mine seem to develop some slop over time as well. I've never tried MDF (I need about 3/8" thick for my ZCI's) and have used hardwood which expands and contracts slightly, along with all the other things mentioned above that can cause a bit of rubbing. In fact some new ZCI's are on my to do list this weekend!

[Lance Norris]

I fully lowered the blade, turned on the saw, and slowly raised the blade up through the ZCI. It made an audible screeching sound, and when I turned the saw off the blade quickly stopped spinning due to the friction of rubbing against the ZCI.

Dustin, when you raised the blade up through the ZCI again, why didnt it cut the slot slightly wider to fit? That doesnt make sense to me... ?

[johnny means]

This is a none issue. It'll do this until wear and tear develops a little more slop in the ZCI. ZCIs work best when they still rub a little.

[Steve LaFara]

I have had the same thing happen and found that the easiest solution is to lossen the arbor nut and spin the blade an 1/8th of a turn, re tighten the nut and test. Repeat until the rubbing is gone. No blade is perfectly flat and benifit from indexing to the arbor. Once you have in the right spot, take a Sharpie and mark the blade and arbor so you can put it back in the same place next time you use the dado set. Other option is to take a small flat file to the ZCI and remove just a little material where the blade touches. Does not take much.

[Andrew Pitonyak]

Dustin, when you raised the blade up through the ZCI again, why didnt it cut the slot slightly wider to fit? That doesnt make sense to me... ?
I assume that the blade deflects ever so slightly as it is coming through (just a guess). I also guess that this is more of a problem with thin kerf blades than a thicker blade...

[glenn bradley]

I change blades several times per session out in the shop. Any and all small deviations of position have long since been met between my blades and their associated ZCIs. If you have had this insert in the same spot since the original cut then, I am with others that say this is normal. You may have a bit u=of crud between the insert and the sidewall or and other minor deviation that would occur when regularly changing blades/ZCIs. No worries but I would remove it and clean out around the edges to see if that helps.