Home built bandsaw mill

SPIKER · Mar 8, 2006

Really nice to see people still building stuff for themselves!

I think you got a great start a few more refinements and you will be sawing up a storm.

might I suggest a water lube system for the blade this may help keep the blade cooler s it don't damage the tires and or over heat it. this is a common item on commercial mills (the water / oiler ) some guys when cutting sappy woods will use a mix of water & pine sol or oil soap. something that will not affect the woods finish later if stained.

a moveable guid is also a great idea waves MAY be a result of no bottom guide, it would be inexcpensive to put on the bottom guides and make the blade straighter as any bend will fatigue it & lessen it's life. slight bend around the guids as is now can cause small cracks pretty fast and will cause it to break sonner than later.

these are just a few things i've picked up since watching seeing and looking at a bunch of them and asking qusetions.

I just wanted to pass em along, but I belive you are 50 steps ahead of me in a 51 step race.

mark M

KYErik · Mar 8, 2006

Yep- I know about stressing the blade from poor guide alignment. I broke a blade last year while cutting the third log /forums/images/graemlins/blush.gif

A close inspection showed many cracks. I have since aligned the guides much better to reduce the stress on the blade, but I'm sure better, movable guides would help. I do use a lube after every cut- I have a spray bottle of half kerosene/half chainsaw bar oil. A dribbling system as you suggested would probably be better.

SPIKER · Mar 9, 2006

ahh way they have them set up is generally using 2.5 gallong gas gans, (plastic ones) and a hole in the bottom with a fitting holding a small hose the hose goes down to the saw IN side, (first part of blade cutting the log) and has either a small square tube holder with a sponge or a cloth type wick, the tube has a small on/off fitting such as a fuel shut off valve which drips onto the sponge to keep it wet. remember one top & bottom if possable, the oil is not good on the wood or the tires, the oil soap or pine sol & water would be better to keep ffom staining wood. some use wipper fluid I read too... not sure on this staining though

looks great though

mark M

Clyde · Mar 9, 2006

Erik - There are many factors that come into play with a bandsaw versus a circular saw. Adjustable blade guides are essential for keeping the blade supported somewhat to try in avoiding the "wave". A water injector or lubricator system is nothing more than a reservoir, controlled by a valve, above the blade guide and the basic gravity system. This is an important part of the bandsaw in that it not only keeps the blade lubricated and cleaner, but it also serves to cool the blade in a wide cant. Some experts claim that they use kerosene, some use light oil as it reduces friction of the saw blade as it saws. They claim they can reduce blade tension by 1/2, get the same professional results, and no carryover staining or odor in the lumber. Also reduced tension results in longer blade life. I use water, a squirt of Jet Dry, and Ivory dishwashing soap. My own inexpensive creation and I'm very happy with the results. Water injection not only lubricates the blade, but keeps the blade clean, and reduces heat. Keeping a constant tension on the blade is diffiicult due to sawing friction and ambient outside air temps. Normally, the manufactured mills run a hydraulic tensioner and as the sun hits the machine, the fluid expands and increases the tension. For this, you have to adjust and readjust during the day. If the tension increases as you are sawing a board, a little more flow of water brings it back within limits readily. Erik, you mentioned seeing cracks and fractures in your blades after awhile. Too much blade tension and probably the most important is proper sharpening. Woodmizer has an excellent Resharp program or as an alternative - an excellent sharpener and set adjuster. In either sharpening, the grinder follows every profile of the blade and grinds metal away and hopefully the fractures and stress cracks. Thier sharpener for the person who wants to do his own blades is not cheap and it will take a lot of blades to recoup the original purchase. I have a little over 9,000 hours on my mill, on the 3rd engine, and I think I have run across most of the problems one might see in sawing. Feed rate and blade tension are two of your biggest concerns. Naturally, machine setup and alignment are constant issues I address routinely. The deck on my machine is 3 1/2 foot wide and I allow no more than a deviance of .001" from left to right. I can't control cupping or warping once the customer stacks his wood but I do supply him with a 5 page pamphlet that I have paid copy right to the writer for as a guide. Erik, you will receive a lot of good advice in this forum from more knowledgeable people than myself. I will try to help you answer any questions that I think I can at least lead you in the right direction. Best of luck and you made a fine machine - Clyde

Renze · Mar 11, 2006

( The blade moves around 6500 linear feet per minute (I geared it this way when I ordered the blade per reccommendeation of the manufacturer). Its the equivalent of those 16 inch wheels travelling at about 55 miles per hour. )

Erik, are you sure about those numbers ? 6500 feet per minute is 117 km/h and 55 mph is about 90 km/h. /forums/images/graemlins/ooo.gif

I have an old Volvo car rear axle, with 14" wheels. I think those are pretty much the size i'm looking for.

Will steel wheels really be tensioning the saw band more than rubber inflated at 3 bar ?? How hard are you tensioning them actually ?

I'm just thinking about my own band saw to build. I want it PTO driven because i hate the stink, noise, high fuel price, servicing cost of a gasoline engine.
I am trying to figure out to drive it with plenty of cheap and reliable diesel power using a PTO shaft... i guess i need to keep thinking a bit on how to make the PTO power available over a bed length of 6 meter.. /forums/images/graemlins/grin.gif

KYErik · Mar 12, 2006

Renze,

Good point about my mismatched speed numbers- I did the calculations about a year ago, so I must have slightly mistaken one (or both /forums/images/graemlins/blush.gif). The blade manufacturer will tell you exactly what speed you will need to run it. Oh and be sure you plan it so that you will have the blade running in the correct direction as well.

I used rubber tires/wheels because it was the cheapest option with durable tapered roller bearings and I have seen on the internet that others had done it as well. I believe that you will need a rubber strip covering the steel rims if you use them without tires- this strip will protect the edge of the blade from being dulled by riding on the steel rim. I wish that I would have gone with larger tires- they are 16 inches in total diameter (8 inch rims) and this is the minimum diameter- this puts extra strain on the blade as it must bend at a tighter angle.

I inflate the tires to about 40 psi. I honestly don't have a tension guage (I should make one), I just tighten it up until the band "feels" fairly tight.

The long pto shaft would be a problem- if you could find a 6 meter piece of rigid square tubing, attach it to the tractor pto, and if it was perfectly parallel with the track that the saw head rolls on. This square tubing could rotate and remain stationary while it slides inside of another piece with a well greased square hole that was attatched to a bearing on the moving saw carriage- but its unlikely you could find square tubing that long and rigid. If it was to flex and bend it would start acting like a jumprope as it spun!

How about buiding a stationary head and a attatching the log to a rolling "dolly" and rolling the log past the blade? It would require lots more metal, rollers etc. (your track would need to be 12 meters) and care with alignment, but you could easily use the pto on your tractor to hook up to the fairly stationary cutting head (cutting head would still need to slide up and down but the u joints of a moderatlely long pto shaft should be able to permit this).

But you probably can't move a 12 meter track around very easily so it wouldn't be very portable. Have you thought of electric power? My motor is fairly quiet and I can shut it down quickly and electricity is very cheap (or at least it is here in the USA). I wish that I had a stronger motor though- a 10 hp electric would probably be sufficient for most work. I only get 5 hp out of mine because I am only running it on 2 phases and its a 3 phase motor.

Good luck with your saw if you decide to do it.

Renze · Mar 12, 2006

Erik,

WoodMizer leads the industry with a 61 hp Caterpillar (Perkins) diesel engine. I dont know if that much power is really needed or just a marketing thing for the guys that like to brag about the power of their truck, tractor and sawmill /forums/images/graemlins/smirk.gif

Anyways we have 400 Volt 25 amp power service. If i understand the calculations correctly, that is 10 Kw. With the new standard of 35 amp connection that my brother's new house next door is going to get, i would be able to take 14 Kw off the net... When my father runs the pig feeding machine, my brother an electric heater in his new house being built, and i run a 180 amp welder at the same time, we can manage to melt the main 25 amp fuse.

I am just afraid that with electric drive, i would be able to take only 10 Kw even on the new 35 amp net connection, because of the other energy consumers like climate computers and air blowers, the welder, pressure washer etcetera.

the 40 Psi inflate equals 2.75 bar exactly.. Normal car tires are matched perfectly for it. I could allways mount tires of commercial cars and trailers, which can be inflated to 5 bar (72.5 Psi)

calculating roughly, taken the saw band blade is 3 centimeter wide and the projected bearing surface (equals the wheel diameter) is 55 cm, and the pressure is 2.75 bar (2.75 kg per square centimeter) the max. strain that the tire could put on the saw blade would be 8318 kilogram... I assume /forums/images/graemlins/grin.gif that 8.3 metric tons will do the trick here...

If the saw band was 3 cm wide and 2 mm thick, it would have a surface of 60 mm2, by two is 120 mm2. 8318 kg divided by 120 mm2 is a steel pull strain of 700 N/mm2, which is absolute madness as only special construction steels have these yield strengths.

Anyways this is just a very rough calculation and the practise would turn out different i suppose...
anyways from this simple calculation i can conclude that an air inflated car tire will be more than sufficient to pre-stretch a band saw blade...

about the 6 meter shaft. i have been thinking: I have some 5 inch pipes around, two pieces of 5 meter. I was thinking of cutting this into 2 meter parts, connect them inline with a 30 mm shaft and mount a bearing eye block on every end. when teh bearing eye blocks are mounted to a 1 cm (3/8") support plate, the slot between the driveshaft pipes would only need to be 1/2" wide... On this 5" driveshaft (or 6 meter long pulley in 3 parts if you desire) i could drive another car tire, which is connected to the saw carrying tires with a short U-jointed driveshaft to power the saw. The short driveshaft will allow to move the sawhead up and down.

This would be a lot of work, needing a very rigid construction and the expense of lathed parts. At least it would be no more expensive than a stationary saw head with a 12 meter bed to ride the tree along the saw... /forums/images/graemlins/crazy.gif

Maybe i can use the hydro pump/motor set i have in the yard, which was from a dismantled truck trailer mounted manure tanker to drive the manure pump.. /forums/images/graemlins/smirk.gif

mitchell574 · Mar 12, 2006

Could you post a up close picture of the drive wheel?

Clyde · Mar 12, 2006

Renze - I also have to ponder the need for a 61 horsepower diesel engine. The entire cutting and sawdust ejection principal is the same blade run on the other smaller gas engines. Efficient ejection of the sawdust also leads to less wavy cuts. My mill has a 25 horsepower gasoline engine and it supplies whatever I need. Engine longevity and perhaps a small increase in fuel economy is all I can think of. Perhaps I missed your intents in prior posts but what sort of productivity as far a bd ft per hour are you looking for? If I were just a hobbyist looking for straight boards as the end result, I'd look at the LT10 Woodmizer if production wasn't an issue. I like the Woodmizer and that is why I bought it. That is not to say that there aren't similar machines and for even less money that do the same job. Some of those mutihead machines by you are pretty darn impressive but they probably don't come cheaply. I envy the man who can take a pile of steel and produce a usefull product. It is not one of my skills however and I have to rely on the ideas and skills of someone else and naturally pay their price. Good Luck in your endeavors - Clyde

KYErik · Mar 13, 2006

Here's the drive wheel. The edge of the pulley is welded to the edge of the steel rim (I was able to do the welding with the tire still on it)

I know I am a very sloppy stick welder- but I am still learning /forums/images/graemlins/smirk.gif

jmc · Mar 13, 2006

( calculating roughly, taken the saw band blade is 3 centimeter wide and the projected bearing surface (equals the wheel diameter) is 55 cm, and the pressure is 2.75 bar (2.75 kg per square centimeter) the max. strain that the tire could put on the saw blade would be 8318 kilogram... I assume /forums/images/graemlins/grin.gif that 8.3 metric tons will do the trick here...)

Renze,

I think a lot of that calculated force is soaked up in stretching the sidewalls of the tire and, therefore, never reaches the blade.

Probably, if you ran that same calculation on the total force in 4 car tires that support the weight of the car, the car's weight would be so small in comparison that there should be almost no tire deflection. Yet the tires do compress because most of that pneumatic force is stretching the sidewalls. (I think.)

John

Renze · Mar 13, 2006

JMC,

Yes you're correct... but i said "rough calculation" and didnt mention the word deflection... Anyways my point was made, a tire is able strain the blade more than what is healthy for it... Anyways in practical situations that much tire deflection wouldnt be wanted because it will soak engine power. With a more realistic stretch on the saw blade, lets say 100 N/mm2 the 2.75 bar inflated tires can do their job without excessive power soaking deflection.

About the car tires, the projected bearing surface of the tire, if there was NO deflection, would be theoretically just a pencil mark as long as th tire is wide !!
As soon as the tire starts to deflect it will get more projected bearing surface.

the band saw blade bears on a projected surface of 55x3 cm is 165 cm2
The tires i was talking about are exactly 165 mm wide, which is 16,5 centimeter. that means that the saw blade has the same projected bearing surface as a tire that deflects untill it gets a 10 cm long flat end on the ground... A car would be difficult to steer at 50 mph with that contact area...

So 5 hp isnt enough, and with 15 hp you have more than enough ?? would a 10 to 12 horse engine be the optimum between hp and sawing capacity ?

KYErik · Mar 13, 2006

I think a 10 hp electric would have enough power, but I'm not sure that a 10 hp gas would have enough. From what little I understand about electric motors and gas motors is this, a 10 hp electric motor can do the equivalent work as a 15-20 hp gas motor because the electric motor can be overloaded slightly whereas the gasoline hp value is absolute maximum at wide open throttle.

Anybody else out there heard of this? Or maybe I have been misled into thinking this...

I now have a 220 volt 1 hp electric motor on a front tine garden tiller. It seems to till just about as well as when it had the original 3 hp gas engine on it. The electric motor has overload protection but I never have tripped it while tilling. It does take a bit of planning to make sure that I don't hit the power cord while tilling /forums/images/graemlins/shocked.gif

Renze · Mar 13, 2006

You can compare electrical motors to tractor engines: they are made to deliver 100% of power for extended times. truck engines can deliver 75% of their power continuous, while passenger car engines are 50%, according to John Deere Mannheim R&D. (i've read this in The Furrow, JD sales lecture)

Small gas engines arnt build to be loaded 100% continuously.

Hey i have another question about band saw blades, how long does it take before they need resharpening, and can you resharpen them with an angle grinder mounted in a special jig ? How much do companies ask for sharpening a band blade ?

How often do they break ?

and compared to chainsaw mills, wouldnt you wear out a lot of chainsaws in short periods of time when you make so many hours on them ?

I read the pros and contras for, and against band saw vs circular saw vs chainsaw mill and i decided to think about it a little more and hear people's advice /forums/images/graemlins/smile.gif

Clyde · Mar 13, 2006

Renze - Depending on the amount of dirt embedded in the log, a person with steady sawing could possible expect 4 hours on one blade. Push a dull blade beyond that and you will start to experience wave and heat buildup on the blade. If I'm doing alot of custom sawing and my blade supply is getting low, I send 15 blades at a time to Woodmizer for resharpening. I usually run an inventory of 250 blades. I have an agreement with Woodmizer that if the blade, determined by width of the blade and the number of teeth missing, they automatically replace it and charge me for a new blade. Price per blade and with shipping equates to around $8.00 per blade. Price for a new blades plus tax and shipping equates roughly to $23.50 per new blade. I did buy the Woodmizer sharpener and setter with the machine and I still use use it in my slack periods. The sharpener has a disc that the sharpener follows and it runs across the entire profile of the blade. Small stress fractures are ground out this way before they become a source of failure to the entire blade. The setter allows me to set my own pitches for frozen wood, soft wood, fibrous wood, or hard woods like dry oak. Incidentally, green wood is preferred to saw over dry logs. I find that after 4 sharpenings, a blade will probably break during that period. With 2,600 lbs of tension, the blade breaking is like an M80 going off as the entire head assembly is relieved of this tension. Then you toss the blade, put on another in less than 3 minutes, and off you go again. With over 9,000 hours on my machine, I think I've seen most of the problems one might encounter. I'm always interested in seeing another manufacturers machine actually sawing. I seldom see ways that Woodmizer could have made theirs any better but sometimes I do. Hope this answers some of your questions. - Clyde

Renze · Mar 14, 2006

Thanks, Clyde ! So here is some more rough calculating from the numbers you mention:

4 hours per sharpening, 4 sharpenings before they snap, is 16 hours on a blade. 4 sharpenings at WoodMizer cost 8 dollar x4 is 32 dollar. The new blade costs 23.50 plus 32 dollar for sharpenings is 55,50 dollar for 16 hours of sawing. which is about 3.47 dollar per hour.
That doesnt sound too bad.

What's the life expectancy of a chain saw ? when i have my chains cut at the local smith i will pay less and the chain lasts longer. I estimate the cost of chain, and sharpening will be half that of the woodmizer.
But how many engine hours can a chainsaw engine make ? 250 ??? what's the price of a new chainsaw ? and how much higher are the fuel costs for a 2 stroke engine vs a diesel ?

I think i need to get in touch with woodmizer Germany for sawblades...

Renze · Mar 14, 2006

Oh one more question:

How wide are these sawbands ? I have contacted a professional tool sharpening company. They say they can sharpen band saws up to 30 mm wide.

I think it's cheaper to have them sharpened locally than sending them back and forth by mail every time...

KYErik · Mar 14, 2006

Renze,

I originally thought of building a chainsaw mill, but the thicker kerf (cut) of the chainsaw chain will require more hp or really slow down the cutting speed.

I believe that my blades are 1.25" wide (this includes the tooth).

KYErik · Mar 14, 2006

Chainsaw engine fuel consumption- I would guess that a 2 stroke chainsaw engine would burn at least twice as much fuel as a diesel engine doing a simular amount of work. Add the extra power needed for the wide kerf and it would probably be closer to 4X the amount of fuel that a diesel would burn driving a thinner bandblade.

A "nice" chainsaw (Stihl etc.)with a 24-30 inch bar would probably be around $500-600.

Clyde · Mar 14, 2006

The most common Woodmizer blade is the 1 1/4", with a .021 tooth set. Left, right and the raker tooth. Blade thickness is .045". Woodmizer is constantly testing new blades with the higher powered engines they are now running. Right off hand, I don't know if there are any Woodmizer Resharp centers available to you without the shipping charges putting you into bankruptcy. I'm sure there are very competent sharpening shops that could do this for you. If you have ever watched a sawmill sharpen their bandsaw blades, you might have noticed that the grinding wheel touches every profile of that blade. This helps to grind away fractures in the metal that are just starting to form. Another option for you would be to keep your eyes on Ebay for a used blade sharpener and also the setter for the tooth pitch. A properly sharpened and set blade leaves no saw marks in the board - just a sort of fuzz from the wood grain as it ran other than parallel to the blade. I have tried other blade manufacturers blades and every one of them had some good things/bad things but the Woodmizer blade outlasts all of the others. Best of luck to you and keep asking questions if you have them. Clyde