What causes chipping when beveling coaster edges with a router?

[ZoeyGG]

I’ve been trying to make a set of simple wooden coasters with a routed edge, but I can’t seem to get a clean, consistent bevel without the wood chipping out on the last pass. My router table is set up correctly as far as I can tell, and I’m using a sharp bit, so I’m wondering if my feed direction or the speed I’m pushing the stock is the real issue here.

[Lily.H]

Yep, I’ve chased that same issue. I found two lighter passes beat one deep bevel pass. Start shallow, then finish on a second pass with the bit set to the full depth. I also backed the piece with a thin scrap or backer to catch the exit and keep the edge from chipping. Slower, steady feed and a touch of tape along the cut line helped too.

[Riley70]

Sometimes it’s the bit more than the feed. I swapped to a down-cut spiral bevel bit with a bearing and that cut down the tear-out on the last pass. It pulled the fibers down instead of lifting them. I also rechecked the fence and made sure the stock was supported right up to the bit.

[Ryan.L]

I’m not sure it’s speed alone. I’ve seen blanks with grain quirks where the chips prefer one edge over another. I tried taping and then sanding the edge after, which felt like cheating but was practical when the coasters needed to ship fast.

[Harper.H]

Maybe the problem isn’t the last pass at all and we’re chasing the wrong symptom. Do a quick test on scrap and compare. Is the fence perfectly square and is the stock fully supported to the edge?