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?
Horizontal Boring Machine Drill Bit?
Mar 05, 2004
2 Replies
Larry...
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
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and Enco
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'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
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but I don't know if they'd be suitable for use in your machine.
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
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.
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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