HSS OK for spiral upcut bit?

[Gator95]

If I'm not making huge numbers of mortices, is high speed steel ok for the bit cutting edge, or do I really need a solid carbide bit?

Just trying to figure out if the extra $$$ for solid carbide is really necessary for a weekend woodworder.

[Santa Clarita Len]

If I'm not making huge numbers of mortices, is high speed steel ok for the bit cutting edge, or do I really need a solid carbide bit?

Just trying to figure out if the extra $$$ for solid carbide is really necessary for a weekend woodworder.

I would use only carbide, it is a much better investment and it will last much longer.

[Tom Slick]

HSS is ok but carbide lasts much longer. HSS is actually sharper initially but when it starts to become dull it dulls faster then carbide.
HSS will cut steel and aluminum, it certainly will handle wood.

[cabinetman]

I would rather use a straight (mortising) carbide tipped bit, than a solid carbide or HSS.
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[drumpriest]

At 1/4" I use HSS for my spiral bits, it's less likely to break than the solid carbide, but doesn't last as long. That being said, I get a lot of wear out of each one. For 1/2" you may as well go with solid carbide. I prefer the spiral for mortising, as it's smoother, and you can plunge as seen in my mortising video.

http://www.bt3central.com/showthread.php?t=27419

With a straight mortising bit you cannot plunge down the depth, you must move once you have reached the depth of the mortising tips.

[cabinetman]

At 1/4" I use HSS for my spiral bits, it's less likely to break than the solid carbide, but doesn't last as long. That being said, I get a lot of wear out of each one. For 1/2" you may as well go with solid carbide. I prefer the spiral for mortising, as it's smoother, and you can plunge as seen in my mortising video.

http://www.bt3central.com/showthread.php?t=27419

With a straight mortising bit you cannot plunge down the depth, you must move once you have reached the depth of the mortising tips.

I used straight mortising bits before there were spiral bits (at least that I knew of). If a 1/4" bit is used to mortise a 3/4" hole, the bottom of the mortise is unimportant, and the bit would have to be moved around. Never had a problem with chips clearing, or getting in the way. Being that most spiral bits are solid carbide, I have better luck with carbide tipped bits, both staying sharp, breaking less, and being resharpened.
.

[Holbren]

What a timeley thread. I just ordered some HSS spiral upcut bits to sell because I do think there is a market for lower cost options for those that only have a few mortises to make or whatever they would be used for.

As mentioned, long term carbide is a better investment. If you find yourself buying any straight bits, look at the plunging versions. Could be a dual purpose bit.