How to use a router
from fine woodworking they discuss on how to use a router...In the video segement Rabbets and Dadoes they instruct not to take the whole depth in one pass...why not?...And what is the rule of thumb of how much material one can take away with a certain router bit size..
click on the following link and then click on Rabbets and Dadoes segment:
Re: How to use a router
[quote=tonyc56;51651]they instruct not to take the whole depth in one pass...why not?[/quote]
Because working the edge of a board, you're prone to get significant tear out the more material you try to remove in a single pass. Depending on the grain of the wood you're working with, it may require three to five passes to get full depth/width. Similarly with a dado, the deeper/wider the cut, the less material you want to remove in a single pass. You want the bit to cut the wood, not tear it out. You also want a margin of safety while working with the tool and if you bury the cutter into a board, you won't have the control over the tool that you should, as well as overtaxing the tool.
[quote=tonyc56;51651]And what is the rule of thumb of how much material one can take away with a certain router bit size.[/quote]
The larger the bit, the less you should cut per pass. The exact amount will depend on the material, quality of the cutter and tool, and your own comfort zone. You should NEVER force a cutter through the material, that's only asking for trouble. Another reason for making a second pass is that the cutter will compress the material slightly on the initial pass. The second pass cleans up the cut for more precise fits, regardless of changing the depth settings on the tool.
Re: How to use a router
[quote=jkirk;51708]sprucey's got it,
with hardwoods you have to make multiple passes, one of three things will happen, you chip out the wood, burn the wood or burn up the bit[/quote]
Actually there's at least a fourth, if not [U][I]the[/I][/U] most important, reason and that is breaking the cutter. This, of course, applies to all materials, not just hard woods, but the harder the material the more the chances increase. This is part of the reason to use 1/2" shanked cutters as much as possible, they're less likely to break under stress.
The cutter shank goes a long way towards dampening vibration and chatter, affecting the quality of cut. Half inch shanks are much stronger than quarter inch shanks as well. Unless you've got small detail cutters that are no more than 2 to 3 times the diameter of the shank, go with 1/2" shanks for a smoother cut and margin of safety. On top of that, buy the most expensive, carbide tipped cutters you can afford, there is a HUGE difference in cut quality, cutter life, and strain on the router while making the cut, all of which increase safety as well as user satisfaction and enjoyment.:cool: