Spiral Bits For Routers-Help Needed

[Eric Commarato]

I would like to do some free hand plunge routing to install some dovetail inlays into the top of a table I am working on. I then plan to hand fit the dovetails into the top using a chisel to obtain a close fit, after I clear out most of the material with a router. I know that in the past, regular carbide tipped straight router bits usually grab the wood during the plunge cut operation and can ruin the workpiece. I have never used spiral "upcut or downcut???) bits, but will using these kinds of bits solve the grabbing problem? I know they sell these types of bits Lowes.

Thanks,

Eric

[Tim Sproul]

My guess is that folks are unintentionally climb cutting...hence the 'grabbing' description. The 'grabby' feel can be really striking when routing across the grain.

A spiral bit won't solve issues with accidental climb cutting. Spiral bits can help with surface quality and tear-out, compared to a straight cutter and sometimes feel smoother while cutting but I don't find spiral bits help with 'grabbing' issues.

If the cutter isn't particularlly sharp, that can also lead to 'grabby' feeling when routing.

[pat warner]

I agree with Tim's appraisal but would add:

Steel or carbide faced tool bits are lousy plunge cutters.
You must plunge and travel at least as face as the cut rate to keep these bits from self steering. You may interpret that as jumping.

Solid carbide, straight, shear or spiral, are ground to plunge without travel, like a drill. This type of cutter therefore will not self steer unless you climb cut into at least 1/4" of uncut material. For inside excavational work in tight quarters solid carbide is preferential.

Routers (http://www.patwarner.com)

[glenn bradley]

You probably won't be wanting a very large diameter bit as it will minimize the chisel work at the points of your 'bow-ties'. If that's true, solid carbide downcut bits are not very expensive and would probably give your best result. The downcut shears down across the face of the surface reducing tearout.

[Greg Funk]

Why not make a template rather than freehand routing? You'll have less clean-up and no risk of damaging anything.

Greg