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 ?
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.
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. :)
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.
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 .
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
For some reason this thread feels like Jeopardy, ZW has the answers we have the questions. ;) ;D
(no offense intended just sayin :))
JM
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.
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 ?
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.
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.
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
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.
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 .
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.
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)
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 .
Hey Tree feller bought a good competive american made chainsaw lately ?
Quote from: zombie woods on February 06, 2013, 03:27:59 PM
Hey Tree feller bought a good competive american made chainsaw lately ?
No, I'm happy with my Stihl. BTW, you misspelled "competitive." ;)
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.
Just to illustrate the difference, here is some "sawdust" from the re-sawing I did yesterday. This is DRY hardwood (walnut).
(https://forestryforum.com/gallery/albums/userpics/10460/IMG_5023.JPG)
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
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 .
Ianab
whats the largest dia ft swing style blades have seen .
could tou run one on a frick type mill ?
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
Ian, wide angle lens on that camera or a ruler made for measuring bowed cants? ;) :D
If you space your teeth out too far on a band mill or chainsaw mill, they don't work too well in narrower cuts. They grab too hard and try to throw the work piece. I have been thinking about a new style saw that cuts say 9' material. It would be a band about 2" thick under considerable tension and would cut through the log perpendicular instead of parrallel. Log diameter wouldn't be an issue and as Ian said it would cut long slivers of wood out. Maybe too long and bog up the whole works. It would have to have extreme gullet size and tooth spacing. Impracticle? Probably so. Fun to think about though.
QuoteI 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 .
WZ, I'll do it if you will. I just have to find a pattern to make it work. I have a Left, Right and No Set tooth configuration. Now I just have to figure out which teeth to take out and in what pattern.
Jake,
We do hope to own both mill again. We sold the 250 mm (8") Peterson, and now are looking at a 180° swing blade giving us a 500 mm (~20") width of cut. It is made by EZ Forestry, (http://ezforestry.com/sawmill_products.html). Because of cost most folks go with a band mill, I did, and still own my Oscar 760 mm (30".) They two saws with an assortment of chainsaw mills and hewing blades are more than enough to do commercial sawing for timber frames and specialty milling.
Quote from: zombie woods on February 06, 2013, 04:24:50 PM
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 .
With a properly adjusted band mill, you really shouldn't feel too many harmonics. If the blade is vibrating, it means the tension is wrong.
Based on your thinking, why do metal cutting blades have much more teeth than wood blades? Metal is certainly very hard and dense.
The circle mill that had trouble cutting compared to the swing mill, was it set up correctly, did it have enough power, was it sharp with correctly set teeth? Way too many variables to say the swing mill was definitely better.
Now I have nothing against swing mills, I think they are really great for a wide range of things. But I don't understand the vendetta you have for American band mills and circle mills.
We had a member on here who owned a tropical hardwood business, he had several crews cutting the stuff on bandmills.
Like Ianab has said, the way a swingmill cuts is different from a bandmill and circle mill. It's the same as ripping with a chainsaw. Ripping with the grain makes long shavings but a rougher cut, and ripping into the end grain makes a smoother cut bit makes fine sawust.
No vendetta I am operateing a woodmizer for 20+ years .
I would inot trade it for a swing mill for the for what I primarily mill .
my original quiery is how can a blade concept so radically different develop in one reigon with reletivity little acceptance the North America /South America.
and could this general concept be somehow be transfered to improve our thin kerf band mill blades for milling the ultra hard South American timbers .
As i said current thin kerf band mill blades cant hack it
Any one that thinks otherwise send me a 158 inch blade I will pay retail + s&h and give it a go .
Trust me the South American market could be massive .
I read were Guyana is the worlds biggest importer of stil chain saws for example .
This thread has given me some good insight and avenues to persue so far .
Nothing ventured nothing gained .
ZW
I see what you were getting at Zombie woods, its funny to think of a "saw doctor" looking at one of the saw blade patterns and laughing at it :D :D
being in NZ you mostly see swing mills running those "funny blades" out and about.
And yes, those 5 tipped saw blades just chisel stuff really well as Ianb points out.
They act very consistant on the more annoying timbers out there in my view.
Cheers
Justin
I am following your thinking on this subject Zombie Woods and at the same time I am thinking to myself:
"We have some of the greatest engineers and Saw Blade manufacturers in the world right here in North America as well as many overseas blade manufacturers and in todays world wide markets with UPS and FedEx you can manufacture it in one place and send it where ever you want or where there is a demand for your products, so it occurs to me that if there was a worthwhile demand it would be over-run with blade manufacturing companies trying to meet that demand. I noticed that you run a Wood-Mizer mill and I have to ask if you considered taking up this topic with one of the leaders in band mill blade technology, I am sure that they will do everything possible to help you with your specialized interest band mill saw blades for extreme hardwoods and exotic hardwood milling."
I think you can find out where the hardwood sawyers are on this forum and ask them a few blade questions to see what is being used around the world.
I hope this helps shed a little light on your efforts to find the perfect blade ;D
I have tried lots of different blades. One of the worse ones on hardwood was 1 1/8" tooth spacing. A friend of mine cuts mostly pine and it is the only blade he uses. So in that little bit of real world application I don't think your line of thinking will work. I do like the way you are looking at things and maybe that wasn't a large enough tooth spacing for what you are trying to accomplish. The blades that I have found to work the best on the densest hardwoods we have is the WM 4° blade.
along those lines, i had a friend once that brought me a band to sharpen and set, he had hit some steel with it previously. it had several spots around the band missing 4 and 5 teeth continuosly. i sharpened and set what was left of the band and he said while cutting pine that was the blade he always went to... because it cut so well in pine. hardwood he would not even try it with the band.
Maybe try taking out every 4th tooth on a band blade. That would leave less teeth to drag through but not alter the geometry too much. Another approach might be a veriable tooth spacing.
Very interesting & thought provoking discussion here guys!
gus
Alright, I think I have the difference. If you look at a rip blade for a table saw, it has few teeth per inch. If you buy a trim knife for a miter saw, it has a bunch of teeth per inch. It's all about weather it's cross cutting or ripping. I have an old "buzz saw" and it has a bunch of teeth. American circle mills have more teeth because they are usually cross cutting. Southern hemisphere saws have fewer teeth because they are usually ripping. Am I close?
Jake, American circle mills have more teeth because of the size of the blade. They rip just the same. Just a guess here because I don't own or operate one, but I would say the bigger blade is used kinda like a large flywheel, in that it's mass helps keep up the rpm once it starts in the cut and also to wider cuts.