Suitable Bits for Cutting Thick Solid Hardwood

      High speed steel (HSS) outperforms carbide in solid wood because of heat issues. But HSS is getting hard to find. How about a carbide spiral fluted hogger instead? January 3, 2012

Question
We've been using the Onsrud 40-136 high speed steel 2-flute downcut spiral router bits for years. About a year ago they discontinued making that bit due to lack of demand. I found a dealer with 20 or 30 bits left on the shelf and bought them all. Now those are almost gone and I need to find an alternative source for a comparable bit. Carbide is not an alternative for this particular operation. It needs to be HSS. Bit cutting diameter is 3/8". Cutting length can be approximately 1 1/4" to 1 1/2". Shank diameter can be 3/8" or 1/2". Overall length of 2 1/2" to 3" works well, but longer is not out of the question. Any sources out there?

Forum Responses
(CNC Forum)
From contributor C:
You are correct on the HSS, it does seem to be dying because of a quantity issue - HSS has to be made in very large quantities to make any money on it.



From contributor M:
What material requires the use of HSS exclusively? Inquiring minds want to know.


From the original questioner:
It's not a question of material but rather feed rate. We hold our solid wood curved mouldings on the CNC with vac pods. This works well as long as we keep the spindle rpm high and the feed rate low. Go too fast and we can blow the blanks right off the pods. This makes for overheating the bits. HSS holds up to heat better than carbide. As such we get the same number of mouldings cut with carbide and HSS before the bits get dull. Since HSS bits are about 1/3 the price of carbide, it is a logical solution.


From contributor S:
Have you tried single flute carbide bits?


From the original questioner:
No... That's one thing we never tried over the many years we've been doing this. What is the possible advantage? Seems like we would have to slow down even more due to the reduction in cuts per inch.


From contributor W:
Did you find the bits? I agree - HSS for machining solid wood.


From the original questioner:
Yes - one was Ektrom Carlson and the other was Toolmaster. Both are US made bits and located in Rockford, IL. Ekstrom Carlson may be buying the bits from Toolmaster, but I don't know for sure. Or they may be Vortex bits. I'm a bit confused on that point.


From contributor S:
You are correct, I should have written four flute, not single flute. At the same feed speed you can run a four flute tool at half the RPM as two flute, thus reducing the heat.


From the original questioner:
That's a good suggestion and I may give it a try. My concern would be for potential breakage due to the vibration of the wood blanks that are not all that solidly held by the vac pods. Worth a try though.


From contributor D:
Have you tried a 3 flute spiral carbide hogger? Probably the least likely bit to throw a part I can think of. Cut to within 1/16" or so, then run a cleanup pass with a finishing bit.


From the original questioner:
We're cutting 1 1/8" thick hardwoods (oak, maple etc.) in one pass. Do you think the hogger will be up to that without causing any unexpected problems? Or should I expect similar performance to our 2-flute HSS bits, with exception to the edge finish?


From contributor S:
If holding the blank is a problem, the way I would approach that is to make two passes. The first pass would be at 1/2 depth and slightly oversize. It's easy to program that if you can increase the bit diameter from inside the program. Then make the second pass at full depth and actual size.


From contributor D:
I think the hogger will be a sweet surprise for you if you have not used one yet.


From contributor V:
I don't have a suggestion on where to buy them. The other ideas may work, but your use of steel in thick hardwoods is the only solution I have ever seen. I do not think it is the heat that is causing the carbide to wear and burn the material, but that the carbide is just not sharp enough and as a result, generates the heat, which in turn tarnishes and dulls the carbide further.

It will be very interesting to see if carbide can accomplish this. I donít think it can in one pass. I know if I am cutting hardwood with a saw I want a steel blade. Itís night and day. There is almost no resistance to the blade cutting 1 1/2Ē thick maple on a 45 degree angle, and no burns on the lumber either.



From contributor V:
Oh, try the one flute carbide on high RPM and slow feed. If anything works, I think that will be it. Just like a rip saw.


From contributor C:
We [Southeast Tool] have Slow Spiral Ruffers or Hoggers - they will not lift as bad also.


From contributor S:
If you are making dust, then your chip load is incorrect. If it's correct, then you'll see shavings. You should see thin curls of wood after the cuts are made, not dust.


From contributor D:
Um, just to be clear. A 3 flute hogger will go through 1 1/8" oak like a hot knife through butter. A single flute no, and in fact - others can chime in here - even on the cleanup pass it is likely to blow out. Cutting out radius casing right to left, it grabs right at the peak and splinters off a chunk before heading downhill. Very common and very predictable. I think I'm doing pretty much the same thing as the questioner, and when I first discovered hoggers I was freaking out. Way faster, less force on your part, and when sharp, barely a whisper can be heard.


From contributor W:
Same here with the roughing cutters. Ball nose roughers in particular for mouldings. I also outline with them. Never had a complaint. They make fine and coarse roughers.


From contributor I:
We [Vortex] have a two flute compression rougher design, which I'm told works very well for hogging solid wood in one pass. We also have many other rougher designs as well as options for your original HSS tool.

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