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blade pitch

Started by sabre_tooth, September 14, 2004, 05:36:19 PM

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sabre_tooth

just wondering what everyone would recomend for blade pitch .have 13 hp honda engine runing 1.25 blades.cutting mostly spruce and cadar. thanks in advance

Tom

Typically a 3/4", 7/8" or 1" would be good, with your not noticing much difference in any of them..  The fewer teeth per inch, the less  horses it takes to drive it.  A lot will depend on your sharpening choices.  If you sharpen your own, then you need to match your cam.  

I favor 7/8 for anything, just to keep it simple.


LeeB

Interesting statement Tom. Would the more agressive cut of the 7/8 and 1" pitch equal out the horse power needs? LeeB
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

EZ

Tom,
so why do they make different pitches.
So you are saying that with my mill (16 hp) that I would probally be better off to use 1 inch pitch. I dont know, explain more for me, please.
EZ

Ianab

Now I dont know much about Bandsaws, but from what I know of circle and chain cutters it takes a certain amount of power to drive each cutter or tooth at it's best effiency. If you have more teeth cutting in the wood than you have power for, then you have to slow down the feed and each tooth looses effiency. You have to then slow down even more than you would if you had fewer teeth cutting properly. If you are short of power on a circle mill you can run every 2nd tooth and get better results. Likewise using a skip chain on a chainsaw with an extra long bar will cut better than a full complement chain.
I imagine there are similar things happening with a band saw, and I would expect a larger pitch band to give better results in wide cuts with lower engine power?
Now as to what exactly is the best pitch, angle and set for a certain HP, log size and wood type... NO IDEA  ::)
I am however sure that these are the main factors that makes up the 'which band will cut best' question.

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

Tom

That's how I understand that it works, Ian.

Which pitch is "best" is up for grabs.   Woodmizer started the 7/8 pitch craze when most of the shop bandsaws of any size were 3/4 Pitch.  It has become a defacto standard because of the success Woodmizer has had in the industry.  They were pretty much the reason that 13'2" blades became a standard too.  

Lately, other manufacturers have been changing the length of their blades to compensate for bigger band wheels and wider throats.  Pitch gets changed, band width gets changed and so do other features, such as thickness and tooth rake and set.  A lot ot it is because each manufacturer thinks he has a better mouse trap.  A lot of it is a marketing effort to get the customer to use the manufacturer's blades (and parts).

If it were me and I were trying to do something different than my manufacturer's recommendations, I would start with a thin blade (ie 32 thou.) and a 3/4 or 7/8 pitch with the width being either 1" or 1/14".  Then I would range my experiment upward towards thicker bands,  wider bands and more aggressive tooth configurations.  (You have to consider more than horsepower. Type of wood, width of cut and speed of cutting make a difference too.  The gullet still has to carry the sawdust)  there is a lot of engineering that goes into the design of a tooth.  I don't think a manufacturer can tell you which blade to use.  He can tell you one that will work.  But, you are the only one who knows your application.  That's part of what makes the "Art" part of sawmilling so much fun. :)

Here's a mental picture that might be analagous to the difference in pitch.

A tent that keeps blowing over in the wind gets more tent stakes driven into the ground to hold it.  If you consider each tooth point to be a tent stake, you can imagine the braking power more teeth would provide.

D._Frederick

With my small manual mill with a 7 1/2 hp electric, I have found that the 1 inch pitch works good in the soft woods: fir pine, red cedar wet. For are hard woods: oak, ash, fruit woods, when they are on the dry side, I have better results with a 3/4 inch pitch. The 7/8 pitch is a good all around blade. The HOOK angle makes a big difference on sawing also as does SET.

EZ

So if the 1 inch pitch works better in softwoods, kinda makes me wonder what a 1 1/2 inch pitch would do. Coarse I have never heard of this blade, but I wonder if I would cut off every other set of teeth on one of my bands blades. Call me nuts, I guess so, but I'm always willing to try anything.
EZ

Tom

Most everything good has a point of dimenishing returns, EZ. :D      But, what the heck!  You may never know unless you try :D :D  Something to look for is too much gap might cause a lot of vibration, like when a nail gets a bunch of teeth.

That might be a good use for a blade that has been nailed. :)

If you are cutting widths of 30 inches then you might discoveer something good. :)

leweee

Tom... ever use those monkey blades  ??? if so what pitch & how did they perform ???
just another beaver with a chainsaw &  it's never so bad that it couldn't get worse.

Tom

Nope.  Never have.
Blades I've used are timberwolf, WoodMizer, Simonds Red Streak, Lenox woodmaster C.

Do I still use Timberwolf?  Nope.  tweren't worth the effort.
Would I go back to Wood Mizers?  Yep.
Why red streaks and lenox's"   Because of the shipping and they work. :)

MemphisLogger

I've fooled around with some different pitches. A friend who has a sharpening service has welded some bands for me with 1 and 1 1/4 and 1 1/2" pitches.

I like to use the 1 1/4 and 1 1/2 when I'm flitchsawing a really big log, in which case I open the top and bottom first with a 7/8 (and relieve stress) and then finish the wide cuts with the longer pitch. I also do this when gradesawing big logs.

The longer pitch--less teeth in the cut--definitely improves the performance with my 18hp motor.

The long pitch sucks for sawing narrower material (less than 12") since their not enough teeth in the cut. It tends to saw ragged and even catches, causing the band to slip, stall, kink and/or ride off the back of the wheels.    
Scott Banbury, Urban logger since 2002--Custom Woodworker since 1990. Running a Woodmizer LT-30, a flock of Huskies and a herd of Toy 4x4s Midtown Logging and Lumber Company at www.scottbanbury.com

VA-Sawyer

That sounds about right Scot. The 7/8 pitch is fine enough to allow edge cutting on the mill and still coarse enough to work in w-i-d-e cuts.It is the "best" compromise. Finer pitches will strangle on sawdust on wide cuts, but leave smoother surfaces and allow edging thinner boards without tearout. Coarser pitches would perform better on wide cuts, but cause problems if edging thin boards.
Feed speeds need to be high enough to cause 'cutting' instead of 'scraping'. Each tooth in the wood needs X amount of power to force it through the cut. If you run out of power, you have to slow down the feed. Below a certain point it turns to scraping. The coarser pitch requires less HP for a given width of cut, and allows the faster feed.
Small gullets (fine pitch) can fill with sawdust during wider cuts. This will also cause scraping instead of cutting and require you to slow down the feed.
Maybe this will help on pitch decisions.
VA-Sawyer

EZ

Urbanlogger, thanks for the input. What is your blade speed. Do you think your friend could make me up a 1 1/2 pitch blade. Be more then happy to pay for his effort.
EZ

MemphisLogger

EZ,

I'll call him today and see if he's got any more on hand--if I remember right, the last one he made for me was outta some stock for some big company's resaw that was too short to make one for them.

He doesn't fool around with sharpening anymore since he hasn't/doesn't want to invest in a computer controlled sharpener, but he still welds new ones from coil and rewelds old ones.

The sharpener that he does have is an old semi-automatic Foley-Vollmer which he has offered to let me have for $500--I'm thinking about gettin' it.  ???

EZ, I don't really know what my band speed is--I just go as fast as I can with the 18hp on my Lt-30.  ;)        
Scott Banbury, Urban logger since 2002--Custom Woodworker since 1990. Running a Woodmizer LT-30, a flock of Huskies and a herd of Toy 4x4s Midtown Logging and Lumber Company at www.scottbanbury.com

EZ

Ok, let me know if he has enough to make one blade, 14 ft 6 inches.
Thanks
EZ

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