Do I really need a spiral bit?

Re: Do I really need a spiral bit?

I would say that they are worth the money. For deep cuts, the spiral bits will pull the chips out of the cut, preventing, or at least minimizing clogging. A straight cut will clog up and possibly burn. I use spiral bits for all deep cuts and use a downcut spiral for sensitive materials where chipout is a problem.

Re: Do I really need a spiral bit?

ANother approach is to drill out the majority of the material with a 7/16" drill bit. Drill to full depth. Then using your router setup, take 1/4" deep cuts working your way down to full depth. Clean out the morise between each cut so that chips don't build up or cause problems.

When making cuts that have been pre-drilled like this, use extra caution. The router bit may have a tendency to grab and pull itself along - which is why I take very shallow, incremental cuts.

You may also have a problem finding a 1/2" straight flute router bit with enough flute length to do what you want.

Chris

Re: Do I really need a spiral bit?

There is a middle ground choice. The spiral bit doesn't have to be carbide. I have a HSS 1/2" spiral bit that has cut more than twelve deep mortises just fine. Price is close to a straight 1/2" cutter. Just go slow and take shallow passes; It's the heat buildup that kills the edge.

Re: Do I really need a spiral bit?

Probably not but they are well worth the money. They work quite well. I purchased some oldam at a woodworkers show and they are just as good as the Jesada I have. What really surprised me was some dewalt plunge 3/8 bits that are a hybrid spiral that worked better than the spiral bits and were not very expensive. They had a 1/2 shank and 3/8 cut.

I am a beginner.

Yes, you do

You will be a much happier camper if you get the up spiral bit to mill your mortises. One, HSS (not carbide) won't stay sharp enough long enough to get the job done. Two, a straight bit does not exhaust the waste. This creates a BIG heat problem. Up to and including starting a fire! Been there, done that. Surprised the dickens out of me! If you scorch the cheeks of the mortise glue won't stick. If you even just burnish the cheeks, glue won't stick. Burnishing is the least that will occur with a straight bit. Scorching and burnishing glaze over the wood cells. Moisture from the glue cannot penetrate these cells. If the moisture in the glue cannot soak into the cells, the glue joint fails. Further, the heat build-up will kill the sharp edge of a carbide bit as well. A dull bit makes the router work much harder and get hotter. That will prematurely kill your router as well.

The path of least resistance here is to get the proper bit. It will live to be used again. BTW, another use for a spiral bit is to use it on a router table with a stepped fence for jointing edges. You can joint edges of very squirrelly grained wood that you cannot joint with a conventional jointer.

So you see, there is more involved here than an extra $20 for the bit.