milling the ultra hard tropicals

[zombie woods]

I was asking for opinions on blades for cutting ipe , green heart and the like with thin kerf band mills a while back .
tryed many blades ,sets ,rake angles in the mean time .
My conclusion FWIW
As for milling 20 inch + green heart logs you just aint doing it efficently with 1.25 thin kerf blades,
down in South America they use minium  3 in bands under high tension .
As for ipe , mora etc .
the best setup buck per board foot is 1.25 wide 1.1 tpi .055 woodmizer 4 degre with 18 to .022 side set and the key seems to be running no less than 2700 psi blade tension with enough fluid to keep blade from getting hot and loosing some tension ,
the water mix with vegetable oil and dish soap does seem to help .
going through and tightening up my old drag style sharpner (bushings etc ) made a difference .
and a protractor for guageing accurate rake angle is a must
less than 4 degree seems to break blades prematurely .
The Lenox .055 c sharp on the woodmizer 4 degree cam worked well also .
bi metal , carbide , stelite no great advantage to my surprise .
So my conclusion 4 dregree .055 carbon steel ,lots of tension ,lube and a trip to the sharpener at first signs of devation .
FWIW so far
ZW

[JustinW_NZ]

Thanks for giving the feedback, interesting to hear!

Cheers
Justin

[drobertson]

Thanks for the note zombie, as a machinist, and sawyer, I have always thought it would be nice to know the hardness of woods, cutting speeds as it relates to band speed is a constant with what I know from normal setups, but cutting edge geometry can be adjusted to suit most needs.  I think a variable speed that controls rpm's would help when it comes to "hard wood"  it only makes sense, machining is machining regardless of material, slower cutting speeds is always used for tougher, harder steels, so why not on wood?  cutting speed of any material is a factor that relates to the hardness, toughness of any material, it regulates the proper rmp's and feed rate, of a given cutting tool,  I can only imagine that your tropical hardwoods bring a chalange when you are dealing with set rpm's and variable hardnesses, 

[zombie woods]

Thats a thought drobertson
I have often wondered if any one has put a phase invertor on the 3 phase woodmizer it would have varible speed with good low speed tork . you could custon mill I beams  .
with the diesel mills has any one used a hand throtle along with tach
to controll blade speed a bit ? the power curve on a diesel would allow plenty tork at some what lower rpm's .
Also in the fwiw department I found that the low voltage variable speed set up on the WM has verry poor tork at low feed rate which makes for a erratic cut in the hard stuff , looked into changing the pulley's but no room would have to build a new bracket etc , and it would slow down the head return as well .
ZW

[drobertson]

No doubt there are obsticales with sawing and speeds,   my saw runs at one speed, the cuts are only contolled by the the feed through the log,  I know that on some of the harder dried out oaks a slower rpm and correct blade would have been an asset.  Much like cutting steel, roughing or finishing the rpm's don't vary with 3 phs motors, the cutters just plow. No brains at the cutting edge, just hp. Petro supplied engines have a different factor, so as rpm's change so should the feed rate.  Unless the torque value can remain constant there will be variances in the cutter path.