Setting succcessive routing depths for "profile" bits

[bent]

My router has a depth stop and integral back-off wheel so that I can set the final depth and lock it, and then back off the router for a small first cut, and the steps on the adjustment wheel allow 1/8" incremental cuts. I do use this when not confused. It is obviously necessary with larger bits of understandable geometry, and I have broke a 1/4" Dia. straight bit at a depth of 5/8", just trying to get a good estimate of the depth I had set in a test piece, after a short distance. Forget about it with a smaller bit, or a larger I guess.

I just did a bunch of 1/4" roundover, and also 1/4" rogee at the edge of some 5/8" mdf. I did it all at the final depth, no increments. These are small bits, 1/4", so think I just got away with it. I was prepared for it to let go at any time, but I had already started. I was using the companies best Ti-C bit set. But I do not know the teachings when it comes to these kind of profile bits. What is the rule. Is there any difference from other bits? To be honest the question is a little premature because me ain't even considered what type of bits need only one pass because of the actual profile generated, if necessarily possible. If I don't find out I may be in for a rough ride.

[Patriarch]

"bent" wrote in news:1165090541 [e-mail]:

's an instructor at one of the well respected colleges in SoCal, and has this really indepth website on all things router. Spend a cold evening at the computer reading Pat's stuff, and you'll be a lot further ahead with the practical, doable side of routing.

And most of the stuff he sells is first rate, too.

Patriarch

[JeffB]

If you are only talking about the depth setting on your router, then several types of bits that produce beaded profiles, or joints - including dovetails - cannot be routed in successive passes at increasing depth settings. If you are talking about mounting the router in a table (or possibly using a guide fence), then you have more options for making a larger cut using multiple passes.

When multiple passes are necessary depends on the amount of wood being removed, the type of wood being worked, the size of the router bit and router, and how good a cut surface you want. All decorative routed edges and routed joints benefit when the last, or finish, pass through the router removes only a small amount of material. This produces a smoother surface, better fitting joints, less sanding, etc.

Router bits that produces joints such as -

?dept=1062or any bit where any part of the cutting profile toward to bottom of the bit (away from the router) is a larger diameter than a part of the profile nearer the top of the bit - ?dept=1040cannot have the router depth setting altered in successive passes. However, when the router is mounted in a table, you can make successive passes using different fence settings.

Dovetail sockets are routed to size in one pass, but a preliminary cut using a straight bit that is smaller that the dovetail socket profile can be helpful. This technique also works with T-slot bits, although here multiple passes can be used if you need to deepen or widen the cut slot.