Dear total of our experience explain this

[zombie woods]

A big gap in technology
explain how circle and rip chain tecnology in Australia and New Zeland are so radically different from what we have come to accept in the northern hemespher,
yet work far better in the harder species .

Case in point deliverd a 26 in dia 5 tooth peterson circle blade to a large  local  blade shop to replace a carbide tip
these guys service lots of blades including blades for south america .
they dont even believe its a saw blade .
yet it runs through some of the hardest species known all day long .
with less hp than most portable band mills .
I cant even mill one cut with ANY 1.25 band .
I think we have come to accept  geometry based on steel blades and softer northern henesphere timber from way back .
Anyone experminted with bands with far less teeth , deeper gullets and perhaps more set ?

[tyb525]

I have cut dry black locust with a 7 degree 1.25 blade just fine with a 10hp engine. A little slow but it cut it. I have cut most other hardwoods in the US without a problem. Hearn hardwoods in Pennsylvania I think, have cut some of the biggest exotic hardwood slabs with a bandmill.

Remember, the reason you are able to cut with less hp is because the blade has less teeth. But less teeth means the feed rate is slower so it's a tradeoff.

I'm not sure exactly what you're getting at here.

[isawlogs]

 I was forwarded a study done with bandsaw blades that got me to change my blades on the shop bandsaw, 3 teeth per inche was recomended and it does saw better, much much better.   So yes in certain circumstances less is best. 

[tyb525]

Yes it is, to a point. WM blades are something like 1 tpi, but if you space them much wider than that the cut gets rough.

Still, the rule of thumb is harder woods need finer teeth.

[zombie woods]

TYB cutting some of the tropical species is a whole differern ball game
hard , silica and tention .

A 22 inch dia greenheart log from northern south america basicly uncutable with current thin kerf ban geometery .

[Jay C. White Cloud]

Hey ZW,

I don't get to cut there much any more...but I know what you are saying about milling in North America compared to other places.  There is a huge difference in all kinds of things.  Measuring system used, cut geometry, approach, etc.  The first time I sent a swing blade away to be re-tipped here in the states, they called me and said they wouldn't work on modified or "home made," blades...it wasn't safe.  I should know better than try and cut anything with a blade "like that."  Don't even get me started on ripping chain.

Great post by the way.  Hope others from overseas joins in.

Regards,  jay

[JohnM]

For some reason this thread feels like Jeopardy, ZW has the answers we have the questions. ;) ;D

(no offense intended just sayin  )

JM

[giant splinter]

Thin kerf bandsaw blades can be designed and produced to cut anything (ANYTHING). One of the most efficient ways to cut steel on a small scale is by using a thin kerf bandsaw and there are many versions of hand held thin kerf hand held bandsaws like the Milwaukee line that will get right through 5"X5"  steel bar stock all day long. There is no reason to think that any North American thin kerf band mill or band saw blade manufacturer could not engineer and produce a blade that would cut any classification of wood or most any other material type if the demand was present.

[zombie woods]

Nope John
the question mark at the end of my post was for me .

Giant splinter the demand is present ,
seems the solution may be something other than tweaking current variables
perhaps trying something out of the box
as our brothers down under oviously did .
blade speed , wider swaged style  carbide tips spaced much  further apart ?

[drobertson]

Not sure if I understand the whole issue, but the saw shop, in my opinion should've repaired the blade.  I understand sometimes when working for folks that are searching for a solution to a problem suggestions are available, but if someone knows what they want, and it works for them, then by all rights they should get what they are paying. I have always wondered how my lt 40 would cut some of the exotics. It does seem like there are wmz mills all over the world, many in the jungles doing mission work.  As far as cutting hard material, I have often wondered if a thicker band blade with a slower band speed would get the job done.

[Jay C. White Cloud]

The issue isn't if a band mill blade will work, that, as Giant Splinter pointed out is probably achievable.  I see cut stones with a band mill type set up.

It is a matter of speed and efficiency.  Swing blades just really have it over band mills when it comes to tropical hardwoods.  Some chainsaw mills will cut as fast as most band mills in something like a Greenheart log.  ZW post an excellent question about the gap in technology and machines.  Why aren't there as many makes and models of "Swing Blands," as there are band mills, for example.  I would love to learn more about the same questions, ZW asked.

[Ianab]

When you look at how the two blades work they actually attack the wood in a very different way.

The band saw is running across the grain, each tooth has to cut though the wood fibres, and take out a small section, really fine dust.

The swingsaw blade acts more like a little chisel, running along with the grain, and actually peels out a large sliver of wood, especially when you are only making a shallow cut. You can really move on those shallow cuts. Hard tropical woods tend to react well to this "chisel" action, as opposed to the "cutting every fibre". On a deeper cut, or when you get into a large knot it changes to a more cross-grain geometry, and you need to slow down a lot. The sawdust becomes smaller, and the cut "rougher" it has to rip though the cross grain. It still gets though, but you know it's cutting differently, not as effortlessly.

So I'm not sure if the idea would transfer directly between the two blade technologies

[Jeff]

The circle blade technology with 5 teeth is no different than with 40. You need a certain amount of horsepower per tooth, that is why the swingblade mills require less horsepower, and they are no where near as fast of feed as a commercial circle mill running big horses and plenty of teeth.

[zombie woods]

Jeff , we where resawing ebony cants that we squared with a frick mill over in west africa years back long before I knew of swing blade mills
the resaw was a big three phase wadkins with a 24 in convential carbide blade with power feed
we had to constantly  flood the kerf with water just to grind through .
yet the swing saws cut it wiht ease .

[Tree Feller]

DanG, I guess us North Americans will just have to struggle along chewing our way through logs with inferior band blades on outdated mills. What a pity. 

[hackberry jake]

I like the swing blades mainly because of portability and log capacity. I would love to have one. The width is a pretty big issue in my book though. The big swing blades can cut 10". That makes it hard to cut 2x12s. And sure their feed rates are higher but as mentioned they sometimes have to make two passes on deep cuts. On a 10" wide cut in oak I don't know if the time would be much different between a band and a swinger. A lot of the swingers are limited to 4,6, and 8". A bandmill will zing through narrow cuts like that and waste less wood. Swingers have lower blade maintence costs as well. I think everybody should have one of each  8)

[zombie woods]

Good explanation Ianab
Apparently there is a demand if wm saw the need to develop a stelite tiped blade .
but from my own experience the wm .055. 4 degree hook blade actually does a better job at less than  half the price ,
stiffer blade and you can keep lightly sharpen right down to the cobb or until it breaks .

[zombie woods]

Hey Tree feller bought a good competive american made chainsaw lately ?

[Tree Feller]

Hey Tree feller bought a good competive american made chainsaw lately ?

No, I'm happy with my Stihl. BTW, you misspelled "competitive."   ;)

[54Dutchman]

I think everybody is coming to the right (same) conclusion:
gullect size=amount of cut material that a tooth can cut on a pass(when the gullet is full the tooth will not cut)
tooth size(width&spacing)= horsepower to cut(more material removed per tooth)
This would give:
circle saw blade with its bigger kerf and larger gullet requires lots of horsepower to acheive it's cut rate.
band saw blade with its small kerf and gullet size requires less horsepower to acheive it's cut rate.
I do not believe on a thin kerf band blade you could get a large enough gullet and acheive the tooth stablity required to cut faster.
Ianab is correct also smaller chips more cuting, larger chips less cutting.

[Ianab]

Just to illustrate the difference, here is some "sawdust" from the re-sawing I did yesterday. This is DRY hardwood (walnut).



VERY different to what a band mill will spit out, you can almost see how it could be made by hand with a small chisel or rabbet plane. A band saw would be more comparable to a hand rip saw, as far as the tooth action is concerned.

Not saying which technology is best, as there are things that a band does that a swingblade can't, like cut a 24" wide board and takes out a thinner kerf... Just showing how they work in a different way, at the level where the tooth meets the wood. The hand tool analogy is to help visualise what is happening as we saw. With either sawmill the cutters are going through the wood at ~75 mph, and you can't really see what they are doing inside the log anyway. But if you visualise a hand tool attacking the wood the same way, you can actually see how the cutting action works.

Who knows, if people understand this better some bright spark may come up with a new idea that dose work better.  ??? :P

Ian

[zombie woods]

Dutchman speed is not even a concern , personaly I would be happy to just get through with moderate devation .

FWIW the harmonics comeing  through the mill suggest way to many teeth in the cut ,
imho.
I had hoped someone has tryed running a blade with 1/3 or 1/2 of the teeth ground down , guess I will give it a try .

[zombie woods]

Ianab
whats the largest dia ft swing style blades have seen .
could tou run one on a frick type mill ?

[Ianab]

Usually a 10" cut is as big as they go, although Turbo-saw have a 12" cut model now. I think the blade dynamics get a bit weird when you try swinging a bigger blade than that into the horizontal. Or at least it would need to be much thicker, and then you loose too much kerf.

The other factor is the a swingmill cuts with the outer rim of the blade, while a conventional circle mill making a shallow cut does so near the hub. This affects the angle the cutters are meeting the wood. Cutting near the rim means the longer strips being cut, and less power needed. Cutting near the hub means a more cross grain cutting action, and smaller chips being produced.

I have wondered how a larger circle mill would function if the smaller cants where cut at the rim of the saw? Probably impractical to have the carriage adjust the height as well as sideways, but for a resaw operation I think it might cut more efficiently?

Ian

[JohnM]

Ian, wide angle lens on that camera or a ruler made for measuring bowed cants? ;) :D