I would like to know the kerf thickness/loss of an 8 wide inch band mill , a baker resaw and a 22 inch round disk blade.
It sounds simple but I cannot find the data.
Jim, generally circular saws have a kerf of 1/8" on small saws, and up to somewhere around 1/4" on big saws. A wide band mill blade is probably about the same. Resaws, and narrows bandsaws, are usually a little less than 1/8" kerf.
Well, let us see if my math is correct.
A baker resaw should be around 0.110 - 0.125
A swedge tooth saw 8"-14"shoumd be around 3/16"
Now the round saw disk blade could be as thin as 1/8" or as thick as 3/8" depending on what the application is.
This might be a good place to jump in. :-\
I tried figuring this thing out the other day.
My bandmill blades are .045 thick.
My set is .025.
So...... Do I add the .045+.025left set+.025right set, and come up with .095 kerf?
my bands should be the same as chucks and 1/8 '' is 0.125''. the circle blades that most use are changeable tooth. most of those are3/8''
kerf loss lets me cut more boards for customers than i used to be able to make. for every 3 cuts with a 3/8'' kerf is another1'' board plus 1/8'' kerf. why the question? pc
A small band will take out about 1/8th of an inch. A large band takes out about 1/4th of an inch. A good circle blade will take out about 3/8th of an inch.
What is important is not the kerf but the time spent sawing and the finished product. While a large band or circle blade will take out more kerf it will saw alot faster. Can a board saved after 5 or 6 cuts (on one face) be worth the time spent making the boards. So do you want to saw 2 mbdft a day or do you want to saw 2 mbdft an hour? Also with a large band you can cut larger dia logs. Now if you have a few logs and recovery of product is important then a small band is a better deal. Another thing is power source and supply. Then one key thing is blade care. Can you afford to put in blade sharpening for the choice of blade or is it local. Circle blades are easy so long as you do not need to have it hammered.
Here the sawdust from a circle mill is easier to sell then the sawdust from a band mill.
Chuck, I think you are correct. We run WM .055" bands, and we set the kerf at .110 in Accuset2. That was the number I was given for 10° bands, the 4° might take a little bit bigger bite, but I don't change the kerf setting.
HEY arkie,
the bandsaw i cut with is manual and it cuts faster than the pto powered belsaw circle mill i used to have. the tractor we turned the belsaw used 5 x the fuel that the 20 hp honda on my bandmill. those figures you gave must have been relative to what speed the blade turned on the circle saw. i gained customers who want to get as much from their tree as possible. most of them wow about how little loss there is with this bandsaw. i really doubt that the pay from the sawdust off a circle mill will pay as much as an extra board every 3 cuts. my $.02 worth pc
You have to compare white oak to white oak. Just because you compare a well designed unit to a inefficient one does not make one better then the other. On a 12 inch Dia log I can pull just as many boards with a circle mill as you can with a band. I can do it for half the cost. So how would your customers act when you hand them a bill for twice as much as mine and only a few more boards? Do not get me wrong. I saw with small bands as well. It is just that you can not always compare walnut to white oak and have a fair comparison. You have to look at many many other considerations in a choice of mills. Each has it's place but none cover everything. If you just choose by kerf alone you are missing some very important things. You can have more mill then needed or not enough power to do the work. Some times you can waste wood, other times you can waste time.
If you get in to 0.001 thickness on lumber and kerf you will waste more time then lumber. Sometimes you have to remember there is a reason it is called "rough green lumber". If you think that if you save 0.015" per board that you will save trees and produce alot of extra lumber I am afraid that you will not be spending much extra cash. Because most of the time you have to make 19 cuts on a face of a log to gain a board and most logs do not have that many cuts.
An extra board every 3 cuts?
It's more like every 4 boards 1/8 vs 3/8. A lot depends on what size were sawing, when I'm sawing 1" for customers with a value of .60 a bf my sawing is almost free for them vs a circle saw. The downside is they have to offbear, the upside is they don't have to haul thier logs to and from a mill, they get all of thier lumber and slabs. Steve
5 years ago they could come to our circle mill and buy any thing they wanted, other then grade lumber, for .35 cents a board foot and that was our logs. I don't know what the prices are now, I am sure they are a bit higher.
I don't know how you figure such a gain. Your .60 price and their logs is set much because of the time it takes to do the sawing (I know the other factors), our .35 price and our logs was set because of the ease of production and volume. That's what ARKANSAWYER is trying to relate. Time is money. Sometimes, time wins over yield.
A good number of years ago, I ran through an analysis of running a thin kerf band over the heavier circle saw. I factored in the extra wood that you are supposed to save against the time it took to get those savings. Back then, you had to average $600/Mbf log run to break even. That's pretty hard to do.
I always figured guys that make a living cutting logs day in and day out would have taken the time to figure out what makes the best set up and the most money. I never saw too many guys tear out their circle mills and replace them with thin kerf mills. I did see a few that went to the wide band. Most common was to use a circle mill for primary breakdown and a wide band as a resaw. Most just geared up to saw faster, which lowers costs.
Hardwoods are always sawn plump. If you're sawing 1" boards, then you are selling construction lumber. We sell that type of low grade for 35-50¢, our logs.
If you're sawing grade lumber, then you will need at least 5 cuts to make up for that one 4/4 board. But, if you're sawing different thicknesses, you may not even have 5 cuts in a log, let alone in one plane. I often saw 4/4 and 8/4 in the same run.
Just kind of averaging what I can sell it for around here, I sell a lot of WO trailer decking , fencing etc for . 75 to .85 , nice red oak for 1.25 , edging boards go for flooring for .50 Steve
The board you save by using a thin kerf bandmill in hardwoods is gonna be the lowest grade board in the log. Educated customers don't really want to pay me to saw those last few low grade boards out of a oak log...they have no use for anything much below 1C. Even though they don't know hardwood grades they know junk when they see it.
Not mentioned is how a thin kerf bandmill can make money when sawing walnut. Walnut has it's own rules and is sold a bit different than other hardwoods. Top grade is normally sold as FAS-1F...a board that is FAS on one side and 1C on the reverse. The walnut mills picked up on it a long time go and have either a band headrig or some kind of bandsaw running behind the circle mill. There not really interested in the extra board, but want the higher grade that an extra 1/2" of wood can give them. Higher grade on a few boards makes a big difference...4 years ago when I was sawing walnut, FAS-1F paid $2.00 and 1C paid a dollar and it didn't bother me a bit to take another cut when that swirl showed up on a face.
The slickest mill I ever saw had two Corley circle mills plus a Brewco grade re-saw. Gave em all kind of options. Normally they would send walnut cant's off the Corley to the Brewco. The Brewco, I think ran 2" bands and had a merry-go-round. They could keep the band in the wood maybe 90% of the time. It still wasn't as fast as the circle mills but it would leave something like an LT-70 in the dust. And all the time it was saving that little bit of walnut that added up to big dollars at the end of the day.
When I saw I'm sawing boards, not making sawdust from the outside. If I have a 20" log I'll get more good grade boards with a thin kerf saw. This just makes sence. Last week I was sawing nice cedar boards that sold at Menards for $12 each, getting 2 extra boards out of each log way more than paid for my sawing at 5 to 8 logs a hour. For the life of me I can't figure out why anyone wants to discount the overrun that comes with a thin kerf saw, I guess if your just sawing pallet wood out of real low priced logs it wouldn't matter much. Steve
Eventually, you saw pallet wood in each log. You just have to wail away at it long enough.
My cost/Mbf of lumber for sawing is probably less than $200/Mbf. I've always used the formula that profit = lumber value - log costs - mfg costs. When comparing 2 operations, I always consider log costs to be equal. Breakeven is always lumber value - mfg costs.
If your costs are $300/Mbf, then you have to get $100/Mbf more for your log run to make up for the increased cost of manufacturing. In my marketplace, it can't be done.
We had a mill that tried to use 2 Woodmizers feeding a Baker resaw. They were sawing high grade cherry when cherry markets were good. They had a fire, and never rebuilt. Their production was too low to sustain the operation.
For your niche, thin kerf works fine. Just realize that it doesn't work in every situation.
I went from circle to band and have certaainly noticed the increase in lumber yield. The theory that small logs only have(say)5 cuts in them and may not yield an extra board seems to ignore the fact that by advancing an extra 1/4 inch each for every board, there is definitely wood going missing. If in fact you do get the same number of boards,the first and /or last ones will have to have more wane on them, because youve used up more inches to get there.
I never cease to be surprised at the difference in sawdust volume from a bandmill. Not only am I making less than 1/3 the sawdust, but it must pack tighter because I can go SOO much longer without having to deal with it. Of course it is nicely spread out over a hundred square feet or so instead of in a heap under the blade with a circle setup.
I run a circle mill with a 9/32" kerf. Years ago I sat down and figured out that any lumber worth less than $.50 / bf was produced more efficiently on my mill than on a thin kerf band. If an entire log averages over that then a thin kerf band makes a little more sense. In this market there aren't that many logs that are sawing out at well over $.50 / bf for the entire log. When I do find those logs I sell them to other mills that are setup with band resaws. They all use a circle headrig for squaring up the logs and then kick the cant down to the resaw.
There are alot of niche markets where a thin kerf band makes sense. One is someone getting into the business who knows nothing about sawing. A friend down the road bought a 00 Frick to setup as a hobby / part-time business for he and his teenage son. I have finally talked him into selling it and buying a thin kerf band. I am afraid of him getting hurt or killed with a handset circle mill when he has zero sawmill experience.
depends a lot on the set and the saw doctor but typically 3.5mm , 2.0mm and 4.0mm in that order (more if 22" circ is cross cut
my time isnt worth much guys so speed doesnt always figure into the equation. i do some jobs that no one would take on board footage for a customer when things are slack. pc
Quote from: Jeff on May 31, 2010, 10:54:40 AM
An extra board every 3 cuts?
most people who bring me stuff to cut 1'' want it 7/8 or 3/4 so yes every 3 cuts on a 3/8 circle mill makes 1 extra board. pc
No idea where you guys are getting 3/8ths kerf other then to try and stretch your point.
I've been collecting Kerfs for years. Have a whole barn full of them, but no market. They don't cost anything, I get them for the asking and they would be a good product to base a retail on, but, like I said, no market.
I've tried to push a few stretched points too. All that ever got me was funny looks, so I keep them under wraps too. Someday, mark my words, I'm going to be a rich man. :P
Yeah, I don't know many if any circular saws that have a 3/8 kerf, My 24" Mobil D has half that at 3/16 or so, I've got a 54" that I'd say isn't more than a 1/4.
Quote from: Tom on May 31, 2010, 10:24:03 PM
I've been collecting Kerfs for years. Have a whole barn full of them, but no market. They don't cost anything, I get them for the asking and they would be a good product to base a retail on, but, like I said, no market.
I've tried to push a few stretched points too. All that ever got me was funny looks, so I keep them under wraps too. Someday, mark my words, I'm going to be a rich man. :P
My kerfs are always stuck in the log and as soon as I try to get them out they turn to dust ???
My kerfs are always stuck in the log and as soon as I try to get them out they turn to dust ???
[/quote]
Now thats funny, I don't care who you are!!
KTF
Quote from: Tom on May 31, 2010, 10:24:03 PM
... Someday, mark my words, I'm going to be a rich man. :P
Tom,
I'd think that unmarked, perhaps even unused, words would be worth more than those that had been used and marked... :D
Herb
not sure what the big blades have for a kerf. i have several of them but have never ran the blades thru logs.
i know at one time a couple years ago i could go over to the sawmill a circular rig, and purchase timbers of any diminsion for 25 cents a bdft. it costs me the same to buy logs from loggers.
i could not understand how they could afford to buy logs at that mill for 18 and 20 cents a bdft and sell product for 25-36 cents a bd ft.
i often thought about just buying a load of cants from them to saw on my mill. heck they already found all the metal in them for me. ;D
Around here, 52 inch and 54 inch circ blades all take 3/8 teeth. ive owned one and measured others.It must be one thin blade that takes a 1/4 inch tooth.Although I havent measured an MD lately(has anyone?) Im pretty sure the local MD mills take a 1/4 inch kerf.Guess you can get thinner blades for them too?
clgr
I was the head sawyer in commercial circle mills all of my working life prior to 2006, and never even saw a 3/8s kerf tooth let alone ran one. We ran almost exclusively 56" saws and the standard bits were 9/32s. One sharpening and they become less then a quarter inch.
Couple of good articles in Sawmill & Woodlot mag this week, along the lines of this kerf discussion....Opening face, and grade sawing. 8)
Your first cut, going into the log, kerf is irrelevant no matter what it is.
But, that last kerf. Now, that's where it might get to be important. :)
That's right, its all relevant to the application and circumstance. That's what Arky, Ron and myself are trying to say. One answer is not always the answer. It always depends on the question.
i see what the guys are saying on kerf loss though. circle mill will eat up more wood than a band mill. but i would like to have a circle mill just so i could say i have ran one before.
When we first got our mill from Canada, they included a new saw with 3/8" teeth. It had fewer teeth in it. They said everyone in Canada used that type of blade. I think it was one they had laying around. I never sawed with it.
Of all the stacks that I built while sawing without a computer, I always used 1/4". Even the computer uses 1/4". Its always worked out right.
I know on my mill that when I use the yard-stick scale to saw with, I have to just split the difference on my last cut.
If I just put the pointer on the 1" mark, that last (bottom) board will be a little thicker. As in 4/4 instead of 1".
This Mighty Might that I have been running is using 3/8" kerk on both saws, add in the flex of the saw and a yard stick rule with jerky hydraulics and you have to allow 1/2" + or -. Now when compairing that to .110 kerf with accurate setworks and the dirence in these to machines is real clear, But as has been stated not all round saws are equel. On the other end of that equation is a thin kerf gang edger where the round saws are pulling .110 kerf. As a rule the more advanced the tecnology used in the design of the sawmill it's self, not the whole operation, the more eficiant it will be, less kerf equels less energy needed and results in higher qualty of cuts, or higher recovery rates, but idealy both. The more you pay for your logs and the more volume that you process the more relevant it all becomes.
Gday
On Circular Headrigs
A 3/8th 9.1mm kerf would be on a 4 to 5 gauge saw plate and thats Heavy gauge to be using and generaly reserved for realy big saws and buck saws that need a stout body or cop abit of abuse ;) Or idiots who dont know how to make a saw to run properly on their Mill ;) :o :D :D so they over compensate buy using a heavy saw ;) most mills run 7/8 gauge saw plates with 9/32 or 6.8mm kerf on the teeth on a 44" to 56" saw works well for anyone who knows what they are doing with a mill and you could go down to a slightly narrower kerf in harwoods but why bother ;)
Regards Chris
(As a rule the more advanced the tecnology used in the design of the sawmill it's self, not the whole operation, the more eficiant it will be)
I'll take my 1960's technology any day of the week, things where built to last, and if they did brake you or a repair man could fix them. Know days if it brakes you throw it away and buy a new one, No more TV repairmen. Keep it simple, keep it running.
(less kerf equels less energy needed and results in higher qualty of cuts, or higher recovery rates, but idealy both.)
Yeah I'd disagree here too, Thicker blades cut more accurate and faster giving you a better product quicker. Costing you less per bft. I'll make more sawdust at the end of the but I'll also make more lumber, even without all the bells, whisltes and bright accuset lights. Used to be craftsmen learn how to do things on a manual machine, then you got to use a computer controled machine. So you understood the principles of machining.
Jason
As wood here in the Amazon is getting rather pricey I ask the question about kerf. Here is what I found after a few days study.
Our 8 inch band mill looses over 50% of the lumber out of a log.
Our old 22" disc mill looses a consistant 50% of the lumber out of chainsaw cut cants. The discount when scaling is 1" . Meaning that if they bring in a 6" x 8" cant we pay for 5" x 7 ".
Our little Baker resaw gains about 5% over what is scaled when we buy. For the Baker we buy the wood in cants 7 feet long and when scaling reduce the size 1/2 inch. The only problem is that we can only get about 1000 bf a day of 1". But with the value of rough cut green 1" flooring lumber now at $1.60 and our wood costs US $0.40 delivered in cants to the mill, the little Baker makes more money than the big band mills or the disc mill. For the cants used in the Baker we only discount 1/2" to the seller.
Jim I'm surprised at the recovery rate from a bandmill, from the point of view the band mill is always hammered as a big winner in kerf over a sawblade, but the figures you are giving are way below the figure I run on my Lucas.
Recently had a little competition here in Aus and achieved almost 70% recovery in a race situation over two days of competition, I always work on recovering more than traditional hardwood mills, but was very pleased I got such a nice amount. Very interesting a band mill runs at a lower recovery when kerf thickness is harped on so much...
i dont understand whatt your saying jim.
who is scaling your logs? what scale? is that recovery of grade or what?
the doyle scale and my band mill always work out to where i get 110% or more than scale of boards or cants. guess i need a little more info on what you are calling recovery. pc
Here are a few more details about how we work here. Most of the marketable woods in the 30 inch dia range have about 4 inches of white sapwood and up to 12 inches of bad heart.
Sawing on the big head rig is difficult to get an efficient yield in addition to the kerf being a problem. Our buyers only buy FAS , no sapwood. We scale Doyle coming in for tax reporting and the chain of custody. When the product is finished we scale by the cubic meter for invoicing.
The loss between the waste wood for the kiln and the export wood for export is discounted as a loss on the income tax.
Our headrigs without question have a ¼ inch plus kery and the 22" disc mill looses a consistant 50% form rectangular chainsaw cut cants. The small resaw gaining with only a ½ inch discount I cannot explain yet.
For working in the tropics the most profitable way is chainsaw cants brought in and resawn. Our longest product for flooring for the Chinese market is 6 ½ feet long down to 2 feet long.
(https://forestryforum.com/gallery/albums/userpics/14293/1920A1wxe%7E0.jpg)
(https://forestryforum.com/gallery/albums/userpics/14293/CANTS_The_Road_Problem_198.jpg)
(https://forestryforum.com/gallery/albums/userpics/14293/Copia_de_Proyecto_Nanay_Copia_de_DSC03763%7E0.JPG)
(https://forestryforum.com/gallery/albums/userpics/14293/Cutting_Bloodwood_004%7E1.jpg)
(https://forestryforum.com/gallery/albums/userpics/14293/Severo_mill_MVC-006F%7E3.JPG)
Is that last shot your operation? I was under the impression that all the wood brought in was by chainsaw cant. But, I see some mighty hefty logs and a big band headrig.
I can see where a band resaw is better than your other headrig. I wonder if it wouldn't make sense to square up one side on the disc saw before sending it to the resaw. That would give you one square side.
Well part of the problem is you are not compairing walnut to white oak. You are using two different measures for two different yelds.
The chain saw cants you are getting from the forest are already free of sap and heart wood. You are just buying wood that you can sell. The loss is saw kerf and drying shrinkage along with final machining of product. A frame saw or a narrow kerf gangsaw would split them up most quick. The Baker resaw is a better deal as it is a bit narrower kerf. But with it you are losing money by production loss. Your cant size might be a problem as well. If you are buying 6x8x7' cants are you producing 6 inch wide flooring? If not what is the final product size?
Case in point. I have a guy who builds cedar furniture. For years he bought 1x6x8' boards to build the stuff he made and he would come in and buy a $100 dollar bills worth each time. One day he was griping about all the waste he had. Seems he rips the boards to 2 1/2" wide and planes down to 3/4 and the shortest board he uses is 18". Seems he has alot of 3/4x3/4 strips and alot of 14" long boards that he could do nothing with. So I looked at his pattern and started making the boards 5 1/4" wide and 9' 4" long. This was great! as he had less waste but he was mad because he was getting less boards for the same $100.00. Even though he could build just as much furniture or more for the money he was getting less boards. So now he is back to buying 1x6x8' boards and griping about the waste.
In the logs you are processing you are not losing the wood due to kerf. In a 30" 8 ft log you have 338 bdft but are throwing out 50 bdft of sapwood and about 60 bdft of heart wood. So that means you discount over 30% away before you ever saw into the log. The chainsaw cants have already left that in the forest. The 8" head saw should just be making cants any way and feeding a gangrip. So if a 30 inch log comes in you should only be paying 228 bdft for it or pay less money per bdft and buy at 338 bdft. You should be able to process 50 mbdft a day with any kind of a good set up.
Can you steam the wood to make the sapwood look like the heart wood like we do cherry and walnut?
Yes those photos are of our operation here. We are switching to 100 % cants asap and buying more thin kerf machines , as we have no waste and a fixed cost for raw material with cants the profit margin is fixed and we are happy at the end of the day.
With the forestry laws pushed on these small countries it is almost impossible to produce legal wood in any other form.
Plus using a skidder in the biggest swamp in the world is not any ones idea of a good day.
I want to get to 40 cubic meters a day (one container) of finished product and I will be quite happy.
Would your recovery rates be any higher if the cants were made more accurate? That shouldn't be hard to do, and it isn't high tech or costly.
Ron:
I have no loss on the chainsaw cants. These guys can cut very well. My problem is the big rigs which I hope to get rid of asap.
Having watched numerous WM thin band mills over the years, it seems any thin kerf advantage goes out the window the first wavy cut... which I notice happened very frequently. Along with blade changes. Thats why I bought a Select 6" double cut. I allow a .125 kerf.