Blade thickness

[ncsawyer]

With a two week old baby in the house, I haven't had much forum time lately or much mill time.  But I did manage to slip out to the mill Monday and saw three logs.  One was a big red oak that yielded almost 500 board feet and two hickory logs. 

The two hickory logs were terrible to cut.  I ended up using a brand new blade a piece on them (not surprising for hickory), but even with a brand new blade, I was getting some waves and dips, even on the very first pass with the new blade.  I run 4 degree blades that are 0.055 inch thick and usually have pretty good success when sawing hickory or pecan.   They typically cut good and straight, but dull fairly quickly in those two species. 

I asked a friend of mine (who is a very experienced sawyer who owned a LT40 super for years) about cutting hickory and he told me that I needed be using a thinner blade, something like a 0.042.  He said that since thinner blades take less HP to pull through the log, they don't generate as much heat.  Since they don't generate as much heat, they are easier to keep cool and easier to keep sharp, and it is easier to keep the blade speed up in hard wood, or wide cuts. 

After all that, my question has to do with blade thickness.  My thought process was that thicker is always better (assuming you have HP to spare), if I can tolerate the reduced flex life of the thicker bands, or are there other advantages to thinner blades that I am overlooking? 

[Kbeitz]

I would think the thicker blade with the right set and tension would be better.

[4x4American]

And now we have a curveball...no idea! 

[bandmiller2]

With some species and some individual logs nothing seems to work well, I wish I knew all the answers, try different things but always with a sharp tooth and even set. Frank C.

[dgdrls]

NC do you debark or have a de-barker??
What mill are you running??

I'll qualify that I live in circle blade, swing-mill land, I did however start with a band-mill but am far from expert.  However, these questions really interest me.

So FWIW,

If all things are equal (set, tooth spacing, hook)  than yes a thinner band would use less HP as it simply is removing less material.

I would think a thinner band has a tendency to heat more due to less structural (metal) thickness thus requiring less energy in total to heat it, so if all is equal with the two bands in the cut is it actually a proportional energy gain (heat) when going to an 055 V 042,  good question indeed.

IMHO and as @Kbeitz indicated, on those harder species the 055's are the way to go 

Do 042 have more benefits?  perhaps, but if you have big enough band wheels to carry 055's with good service life than I don't think they do


Best
D

[drobertson]

I've ran both, .042 & .045 bands, there are applications that warrent the thicker, bottom line in my view is any blade that's  lost its edge will produce some wavy lumber,  if the cost is the same then .045' s I just dont have the faith for running .055' s with the 19" wheels, several folks do, .042's have fit the bill for me,

[Magicman]

I have never used .042 or .050, but tried .055's once and it will not happen again.  .045's for me.

[Andries]

Tried these yesterday and they worked out great.

[Andries]

. . . but I'm working with 27" cuts in frozen cedar, not anything as as tough as hickory.

[MartyParsons]

Hello,
   Thickness of the blade is referred as beam strength.  Thin blade has more flex life and Thick blade has less flex life.
Thin blade will flex more often than a thick blade. Thick blade will fail ( break) before a thin blade or less flex life. Larger band wheels will increase the thicker blades flex life cycle.
If you have employees or making every cut count in time and quality you consider thicker blades. If you have hp which also pertains to production you may also choose thicker blades. Cost per bd/ft will increase using thicker blades.
Using thinner blades may reduce quality in some cases. Band saw mills less than 10 hp would have no performance gains running a thicker blade because of min. hp.

.045 thick is my blade of choice from hp range 15 - 47hp. Most band mills over 50 hp would benefit using a thick blade like .055.

Run time on a blade recommended @ 500 bd/ft to 800 bd/ft before it should be sharpened. Sharpening should grind the gullet to remove the stress cracks to increase flex life.
If you sharpen only the tooth you will have more blade breakage in the gullet of the blade. 

Hope this helps. 

There is some info I skipped over.

Marty

[Bluejay27]

The beam strength of the 0.055" blades is actually about 50% more than 0.045" blades (1.22^2), but you only require 22% more cutting force. This means you can run a higher feed rate and take a thicker chip, which takes less hp/volume and helps remove heat from the blade more effectively.

Cutting too slow can actually cause issues since you're making heat without removing it.

And running a wider band improves beam strength proportionally (1.5" is 120% of 1.25", although in reality it is more like 125% because the gullet takes up 1/4"), while increasing band friction proportionally. So for less pitchy woods, it likely pays off to go wider, and pitchy woods can still benefit when lube is used. It's just a matter of having the horsepower and keeping the feed rate up, since band friction is always working to heat the blade.

For the record, my brother and I only run 1.5" bands, but 0.045" currently on 28hp and 42hp LT40s,  and 0.055" on a 55hp LT70. The LT70 saws far faster than horsepower alone would allow, even with all the mills now using HP guides. The 0.055" blades can also handle nails much better and stay sharp 2-3 times as long in part from the higher feed rate, although blade length also plays a role.

So long story short, I'd run the thickest blade that gives you acceptable flex life and widest too as long as you have the horsepower, but it does require that you stay on the feed hard enough (especially sacrificing flex life) and not try to force a dull blade. And some logs are just a pain regardless.

[pineywoods]

I agree, thicker is better except for blade life..Here's some experience from going the other way.. I was given a bunch of used blades. All .035 1.25 7/8 woodmizer. All had been sharpend down to about an inch in width. Ran them past my sharpener and setter (25 thou set) and started using them on my WM LT40. Conclusions...With 25 hp, it is real easy to push these blades pass their limits, resulting in waves, climbs and dives. Anything on the mill that's the least bit out of spec shows up quickly..Sap buildup on the blade is especially critical. One thing that amazed me was how suddenly things went down hill once the critical point was reached. I know that woodmizer recommends a complete alignment using a freshly sharpened or even new blade, and I agree, but if you can saw hardwood lumber with one of these antique blades, you're good to go with a decent blade..
Testing done a 98 WM LT40 manual, 8000+ hrs 25 hp kawasaki power, goodyear B57 band wheel belts.

[ncsawyer]

NC do you debark or have a de-barker??
What mill are you running??

I run a Woodmizer LT40 with the 36HP Diesel with the Debarker.

I have never used .042 or .050, but tried .055's once and it will not happen again.  .045's for me.

MM I remember reading somewhere else on the forum that you were not a big fan of the 0.55's.  Is it simply due to the flex life, or are there some other performance deficiencies?

Hello,
   Thickness of the blade is referred as beam strength.  Thin blade has more flex life and Thick blade has less flex life.
Thin blade will flex more often than a thick blade. Thick blade will fail ( break) before a thin blade or less flex life. Larger band wheels will increase the thicker blades flex life cycle.
If you have employees or making every cut count in time and quality you consider thicker blades. If you have hp which also pertains to production you may also choose thicker blades. Cost per bd/ft will increase using thicker blades.
Using thinner blades may reduce quality in some cases. Band saw mills less than 10 hp would have no performance gains running a thicker blade because of min. hp.

.045 thick is my blade of choice from hp range 15 - 47hp. Most band mills over 50 hp would benefit using a thick blade like .055.

Run time on a blade recommended @ 500 bd/ft to 800 bd/ft before it should be sharpened. Sharpening should grind the gullet to remove the stress cracks to increase flex life.
If you sharpen only the tooth you will have more blade breakage in the gullet of the blade. 

Hope this helps. 

There is some info I skipped over.

Marty

As usual, great information!  I am glad you brought up the cost issue.  I did some cost analysis on my operation.  Keep in mind that I just saw part-time (I have a full-time job) and its mostly on the weekends and mostly mobile.  I only provide the sawing service, and don't sell lumber.  I run 0.055's all year and looked at my blade cost.  My blade costs account for just less than 13% of my gross revenue.  So it costs me $130 in blades costs to generate $1,000 in revenue.  The blade cost would have been little lower but I bought a lot of new $30 blades last year, building up to a 70 blade rotation.  Overall, though, I am happy with the 13% blade cost.  Fuel accounted for another 2% (that Yanmar just sips it!).  So my variable mill costs are about 15%. 

Has anyone else done a similar analysis of their business?  It would be interesting to see what others blade and fuel costs are. 

[Magicman]

MM I remember reading somewhere else on the forum that you were not a big fan of the 0.55's.  Is it simply due to the flex life, or are there some other performance deficiencies?

This happened while sawing our late FF member wwsjr's logs.  Hookpilot, logs2lumber, and I all experienced short blade life, but this was our first experience with .055 blades.  Chances are that it was our fault, and we were probably sawing too slowly.  No matter because we broke all ten of them.  I am satisfied with .045's and am content to stick with them.

That experience did show me the value of 7° Turbo's and I am converting to them as my 10° blades are rejected.

[terrifictimbersllc]

Has anyone else done a similar analysis of their business?  It would be interesting to see what others blade and fuel costs are.

The wonder of Quickbooks. Averaged over almost 10 yrs in business:

Diesel fuel cost for Sawmill:  2.3% of gross revenue from bandsawing with this mill (2001 42Hp LT40 super)

Adjusted blade/sharpener costs:  3.9% as above.  DOES NOT count my time spent sharpening blades.  Includes net or projected net cost of owning sharpener/setters after their actual or projected resale.

Surprising result, if I subtract from above blade costs the amount received for blades hitting metal my blades are essentially paid for and blade/sharpener cost drops from 3.9% to 1% of gross revenue.  So I essentially am able to run a blade until it hits metal and the customer buys it. Again this analysis DOES NOT count my labor spent resharpening blades and carefully inspecting and recovering some of the metal damaged blades (maybe a third of them).  I do wear out many blades till they break, but the explanation seems to be that I save roughly the same number that hit  metal and were paid for by the customer.

[ncsawyer]

Terrifictimbers,

Thanks for sharing!  Its interesting to see other people's operations.  It looks like our fuel costs are very similar. 

[YellowHammer]

I am in the same boat as MM, with my LT40 band wheels, the .055 bands just fail too quickly due to flex life, and the increase in speed is not worth the cost.  The only exception I use are the 7° Turbos in 055, they will saw through the hardest hickory and such, at speed, but have a relatively sort life.  Everything else I use .045's.