When to use spiral router bits??

[George Bowen]

Kind of basic I'm sure but besides plunge cutting mortises and what not. When should I use spiral router bits?

On MLCS their videos show using them for multiple cuts.

Anyway, I want to make sure I am using the righ tool for the right job.

[Matt Meiser]

I use mine most frequently for drilling shelf pin holes using Norm's jig. Next up would be mortises. Third, well, I can't think of a third thing I've used them for.

[keith ouellette]

one thing you should know, in case you don't, is to make sure you have the correct shear angle for the job. Spirals come in up and down shear angles.

They work good with guided bushings.

Say you have the bit on a router table and you are cutting with the work piece face up You would want an up shear bit so the pull of the cut would be down.

If you are cutting from above the finished side you would want a down shear angle.

Check it out further because i am a lieltt lisdexic and tend to get things backwards some time but I think i told you correct.

[George Bowen]

Thank you for the help. This is great info.

Would it work the same as a 2-3 flute standard bit for rabiting and what not? Or is it a waste of a bit to use it for that.

I plan to only use one for mortising, but thinking (too deeply) through how a spiral bit cuts it seems more efficient. A fluted bit simply gauges the surface, a spiral bit both gauges and slides.

Anyway, I am new to woodworking. I have a good working knowledge but am finially at the point to buy tools for the right job, not getting the job done with just the tools I have....

[Greg Hines, MD]

I use spiral bits for all kinds of tasks, from plowing mortises to jointing in the table. They are also great for drilling holes.

Doc

[Charlie Plesums]

I talked to the bit designer at Woodline. He recommended a straight cut router bit for drilling shelf pin holes, but as soon as I suggested that I might go all the way through a divider with pins on both sides, he instantly and emphatically suggested an up-spiral to keep from tearing out the veneer on the bottom.

Remember that a spiral bit is much more fragile than an straight bit.

[Anthony Whitesell]

I asked a similar question a month or so ago. The only reasoning I got to use spiral versus straight cut. The straight cut are cheap and they can be touched up (sharpened) easier than the spiral and when they are sharpened they don't lose as much in diameter as spirals.

[pat warner]

Short overview at FAQ no.12.

[Chris Padilla]

They also have up/down sprial bits so you get the best of both worlds in one bit but they are pricey suckers. However, they cut so very nicely with no tearout on either face! But, they are PRICEY!!

[Art Mann]

My answer is always. I started using 1/4" and 3/8" spiral upcuts for mortises but found the shearing action cuts smoother and with less effort in just about all applications. The 1/4" ones don't seem to break off as easy as the straight cut ones.

[George Bowen]

Thanks again for the help. I am starting a number of projects and will be mostly doing rabeting, mortises, profiling, etc with the router table.

I have seen tennons made with spiral bits that turned out great (on a horizontal table, not a multi router), which got me thinking to the versatility of the spiral bit.

[Steve knight]

myself for solid wood and not just plunging a straight bit will cut cleaner I have found on my cnc router. most straight bits are not great plungers though.