Below you will see a speed chart ,,,
posted by " curiousgeorge "
"prevent tear out" = cut your parts just a bit longer than they need to be.
Some types of wood just like to blow out "tear out" at the end of the pass.
Oak for just one of many..
You can sometimes stop it with a wood push block then over run the pass into the push block...
You can also over come the blow out sometimes by making small cuts but it can be hard to do with some bits like the dovetails..
" rabit bit rip out"== this is a real hard one to over come.
But by making your stock just a bit wider then rerip the stock to the right size on the table saw..
You can also use a strait bit and leave just a bit of the out side edge in place and then make one more pass to remove the small lip left by the 1st pass.
You can also make a sub fence and put in a chip breaker in the new fence.
see snapshot below for just one type of chip breaker sub fence.
NOTE**** the chip breaker fence works the best for rabbit bit cuts, it gives the bit a place to push the stock into the fence and will help hold the stock in place...the bit is spining counter clock wise and pushing the stock into the fence..and the hole in the fence gives you a chip breaker so to speak...
To make a quick sub fence, take some scrap 3/4" MDF stock ,rip it to the same size as your router table fence,then take it to the band saw/jig saw and cut a hole out the same size as the bit you want to use, then just clamp it to the main fence,( with 1/16" clearence on both sides of the bit and on the top side of the bit, don't forget the bearing and the nut on the shaft.
Originally Posted by RuggerJoe
Working on my first project with my first router, and I have a couple new guy questions. I'm working with a Bosch Colt, and cutting some rabits and dados.
1) Is there a table with what RPMs should be used with a given bit diameter and wood? I know larger bits are supposed to be run slower as well with harder woods.
2) Whats the best way to prevent tear out? At the top of the dado/rabit and at the ends of them? I only have a straight cutter in my set and can't aford to buy more bits right now so spiral cutters are out for the time being.
3) On one rabit I had a large blow out. A 3 inch piece splintered off at the end of the rabit I was cutting across the grain.