Join Date: Dec 2009
Location: Northern Nevada
Let me first echo the sentiments above by welcoming you to the forum, and by saying that you are doing some excellent work - especially with the limited tools you've described.
As to the router bit snapping, you're luckier than you think. When you consider how fast that bit was spinning, it could have come back and hit your torso, requiring a trip to the hospital to have them dig it out of you.
My first thought is to ask you how far into the router's collet you put the bit shank. The shank of the bit should slip into the collet of the router as far as it can go without the cutting head of the bit actually touching it. I put my bits into the collet until the cutting head touches the collet, then pull it back out about 1/16th of an inch maximum. When you apply pressure on a bit like that, the more of the bit shank you have exposed the more likely the shank will flex. It won't flex much, but it will flex enough. (I'm assuming that you're using router bits with a 1/4 inch shank.)
My second thought was the quality of the bit in question. A cheap bit is just that. You'd be better off getting a better quality bit at Lowe's or HD. They carry some decent quality Freud or Bosch bits that, while they're not top of the line, will perform much better. Also, don't waste your time and money on HSS (Hight Speed Steel) bits - go for carbide tipped bits. They'll stay sharper for a lot longer than a HSS bit will, and will cut a lot cleaner. You'll pay a little bit more for the bit, but you won't be buying 2 or 3 of them to finish a project.
The quality of the bit dovetails (no pun intended) with my next thought. Were you trying to cut the 1/4 inch deep groove in one pass? Smaller routers and cheaper bits can't handle hogging out that much material all at once. It's better to set your bit depth to take out the material in steps - say 1/8th of an inch at a time in your case. Not only is there less material for your bit to try to cut through and less strain put on the router's motor, but when cutting a groove like that, there's nowhere for the sawdust to go. Sawdust build-up can clog the bit and build up even more heat than the spinning bit naturally creates.
Bit failure like what happened to you isn't all that common, but when you put a combination of all of the above factors together, it can happen - as you saw. Now I may be totally wrong here, but unless the bit hit something hard that was embedded in the wood like a screw or nail, I think that a combination of the above may have done it.
My suggestion would be to get a better quality carbide-tipped bit, make sure you put the shank of the bit as deeply into the router's collet as you can without the cutting head actually touching the collet, slow down your feed rate, and cut the groove in a couple of shallower passes. Oh - also, make sure you're feeding the material into the bit from the right direction. If you're feeding it from the wrong direction, you'll know - the work will want to pull away from the fence rather than stay snug against it.
“It’s what you learn after you already know everything that counts.” –Chip Foose-