I have an old horizontal boring machine that came with a brad point bit. It
works fine for drilling holes for dowels or to drill holes for a mortise.
What I'd like to try is to drill a slot for a mortise rather than
overlapping holes. I'm wondering if there is a better choice that a brad
point drill. I've tried using the brad point, but the slot comes out
sloppier than it should. For a router I'd get an upcut spiral bit or
something like that, but I'm not sure if there is a similar choice for a
drill at 1700RPM. Someone mentioned something like a four-fluted metal bit
to me once, but I'm out of my element here. Any suggestions on the best bit
to use for cutting a slot rather than just overlapping holes?
You're talking about a four-fluted end mill, which is just a
router bit designed for cutting metal. It'll deliver four
(shallow) cuts per revolution as opposed to two (deeper) cuts
from your up-cut router bit. The end mill has less chip-clearing
capacity than the more agressively cutting router bit. End mills
are available inexpensively from Grizzly (http://www.grizzly.com)
and Enco (http://www.use-enco.com ).
I've had best results routing mortises. I built a jig to provide
support for the router on both sides of the workpiece, fences on
both sides and stops at the end to control size. I used a plunge
base and took advantage of the plunge stops to cut deep mortises
in controlled stages.
To clean up the result from the boring machine you might try
using /lipped/ brad point bits. Lee Valley has some excellent
bits (http://www.leevalley.com/wood/page.asp?pageB352) but I
don't know if they'd be suitable for use in your machine.
<gloat> These days I clamp the workpiece in a CNC router and let
it do a better job than I could ever do with my old PC </gloat>
Precise Cut in Colorado sells a 1/8" router bit with 1-1/2" long
flutes that looks like might work well for small (deep) mortises.
On Fri, 05 Mar 2004 06:22:46 GMT, "Larry C in Auburn, WA"
you don't say if your machine uses threaded shank bits or not. if it
uses plain shank bits any machine shop supply will have them, and
there are always lots on ebay. if they are threaded shank you're gonna
have to look a bit harder...
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