Flush trim bit question

Once in awhile i get tearout or bearing scars while flush trimming the top or back.

Currently using a 3/8th 9mm diameter bit. Will a larger diameter flush trim bit help with less tear out and bearing scar. For example a larger 1/2 inch or 3/4 inch diameter bit?

In my limited experience those are two separate issues. A larger bearing or moving the router more quickly may help prevent scarring, but a larger bearing probably won't help so much with tearout and moving quickly will likely make tearout worse. To avoid tearout, avoid moving the router in the direction a tearout chip will go (start from that direction and move in), move at a moderately slow but steady pace, and perhaps consider a spiral down-cut bit.

I belive the larger the cutter the more tearout you will get not less. A spiral bit will give you less tearout. With a spiral downcut being the one that should give you the least. You should only get scaring from the bearing if it is not functioning properly.

I use a 1/2" bit but I start with a larger bearing and run the router in the climb cut direction. I then change to the 1/2" bearing and only have a small amount to remove, again a climb cut. It is harder to control the router when climb cutting but much less chance of tearout. I use a nylon coated bearing to reduce marking the sides.
https://www.whitesiderouterbits.com/collections/ball-bearings/products/b3s

As an alternative, don't forget that a simple well sharpened thumb plane will take care of trimming back those back and top over hangs in a jiffy with less danger of a tear out. I'm not against power tools and use them all the time, but this is an area where I like to get up close and personal with my uke. I love seeing the curls come off and the skritch-skritch sound. There is a danger with this method though in that you can gouge your sides by mistake which is not a good thing. Not good at all. I also put 2 or 3 coats of a 1 pound shellac cut on the edges before I cut. Makes things much more forgiving and less stress. Also it is much quieter. Very meditative. Try it.

Got it thank you. Yeah im using the stewmac routing method to prevent tear outs.

Didnt know they made nylon bearings, will look into that.

Yes i also shellac before routing , and i also used mini plane to flush trim before i bought a laminate trimmer. Maybe ill go back to old school and just do it by hand again.

Maybe it could be my bit. I was using a bosch brand bit with almost flawless trimming. I bought this new cmt brand one same size , and it really tore the top and bearing scars on the first use.. Easy fix is to router it out for binding .