Hi. Thanks for the reply. Yes, the first bit was a solid carbide "upcutting" spiral bit - brand new. However, it was an inexpensive one from China or something (I don't know). The second was a Grizzly plywood bit.
The bit just sort of "burned" off at the point they were contacting the plywood.
This was just baltic birch from HD - nothing special.
So, after making 4 drawers (the sides and the drawer bottoms) I went through 2 bits.
I did think about getting a "slot cutter" for in the future. I would think the 3/16" would be perfect for the plywood as to the thickness. Although I will have to "sneak" that home hidden from the wife because I already went to Lowes to get replacement 1/4" bits for those that broke - they have a pretty complete line of router bits at my local Lowes - amazingly so - much better than HD. She already asked, "What did you buy at Lowes that was so expensive?"