homemade bandsaw mill, help

[gww]

Ox
On the chain, yep you guessed right.

Gf

I love you ideals.  I did read that thread when I was building.  My problim is I was only using the stuff I could find when I build and I tried to keep those guidlines in mind but I didn't want to buy much stuff cause I wouldn't be creating anything and if that was the case I would have looked for a used one on craigs list and tried to bargine for it.

On the guide with the pipe that slides.  I put two pipe going up and down.  One is just a support that slides up against the head of the michine so it can't move up and I am using down pressure on the blade so I didn't worry about it bouncing down. 

I don't know if it will work good.  I looked for square pipe that would slide in and out of each other but I don't live in a town with a lot of bigg stores and am too impatiant to order and recieve it later.  If they would have had square pipe when I shoped, I would have got that,  they didn't but did have pipe.  I may have to redo it someday but that didn't seem to be my problim. My problim was destruction of the bearings I am using. 

I cut one tree today and got two eight foot and one 9 foot log from it today.  The smallest end out of all three was 15.5 inches.  I don't have many trees this good on my place.  I almost took another log out of it that would have went above 10 inches on the small end but it had big branches on it and I thought it might be two squirly to cut and try to dry.

Thanks
gww

Ps I also read on that site (I think) that they had a blade they recomend running at 8000 fpm

[GF]

You may want to look at this calculator http://www.rbkmfg.com/calculat.htm.  If your bearings are 1 5/8" (just guessing) in diameter and your running 9000 fpm across them the bearing is turning 21155 RPM, not sure that the bearing is going to last very long at that RPM, even if you put on some Cooks blade guides.

GF

[gww]

gf
Yea I know,  I might have to end up with the pinch plate type guides it I can't get anything else to work.  I really wanted the down pressure if I could get it cause from my point of veiw, I thought they might help cover shoddy workmanship if something else is a bit out of wack.  I worked hard enough to get the blade parralel to the track and think I have it (maby), perhaps a differrent type of guide will work.  I am going to try the down pressure guides just a bit more before going a differrent rout.  A  2 inch pully on the motor (if they make them) would probly bring the speed down to the 5000 fpm though I didn't run the numbers on the caculator you posted.  One good thing that comes with the higher speed is torque. 

The only way I could change the wheel pully would be to rap some flat iron around it and baiscally build another pully inside the current one.  Lots of balance issues with something like that when using the meager tools that I own.

I see your point and had seen it before building but I was hoping it wasn't a deal killer and pushed ahead anyway.  I did see one site that said the tiller motors from briggs was 1700 rpm.  I didn't put a lot of creadence in it cause you know what is on the internet.  I did however see that the rated horse power on some was at 2500 rpm which brings my mill back in the game.  I thought about running at a lower rpm by just not opening the throttle all the way.  They run the harbour fraite mills with 7 horse power motors.

I am not saying the thoughts above make sence to a normal person but they are the things that were going through my mind while I was building. 

I could see the speeds affect on bearings but would not have thought it would eat blades.  The mill cuts good with out taxing the motor althoug by good I mean speed wise not wonderful cut although a few times the cut was wonderful.  The only time I saw real heating of the blade was when I used soap and water and also had a guide freeze up.  It turned the sawdust between the wood black.  Even then the blade must cool quickly cause I have never felt it so hot I couldn't hang on to it.  the bearings however are another story.  I would not leave my finger on them for long.

Besides just trowing the mill away.  What are your thoughts on addressing the speed issue?

Thanks
gww

[gww]

I am hoping to take this:



 

And not make it into this:



 

This was a very nice tree for my place.  I will start on it if my wife will let up on the honey do list, I have my doubts that that will be soon though.
Cheers
gww

[Ox]

On the speed issues why not just try throttling back and see how it does?  It might have enough grunt to pull it.  Engines very rarely make their best torque at max rpms anyway, usually it's around 3/4 or so.

[gww]

ox
I may have to half throttle if I can't find a bearing that will hold up.

I have actually cut that way on accident and it will do it,  It does seem to to it better at full throttle though.  I knew when I made the homemade pully that it might cause issues.  I had another choice,  I could have used a front wheel drive wheel bearing with a shaft and put any size pully I wanted on it.  I have several sizes laying around.  It may sound stupid but I decided to go this route cause I watched a youtube vidio where a guy said he had to reduce his 12 inch pully to 10 inches because he was using a small engine and it didn't have enough torque.  He mentioned he thought eight inch pully would even be better, so me being me, I went aginst all conventional wisdom and went with the guy who was saying what I wanted to hear.

It really seems like it should work.  When it cuts, it can do well and I am not blazing through stuff but it doesn't seem slow and the motor dosn't seem taxed.  It just only last for one log and my blades are toast.  I am waiting to see what it does without guides on something bigger, like what is sitting on it now. 

However,  my wife has gotten jelious of the mill and I now have a pretty large honeydoo list.  I can probly sneak some cutting in in the mornings.

I tell you how confident I am that a couple of the boards will be usable.  I painted the end of the logs with some bright pinkish paint cause I heard it is easer to seal that way before cutting then it is after it is boards.  If it ends up as fire wood it will atleast give some color to firing the stove.

Ox
I am glade your bad time 5 years ago is better.  Most things are worse at the time then they end up being later. 
Thanks
gww

[1967Stroker]

what is the size of your tires in inches. 28" ? what pulley is driving them and what pulley is on the motor? and what motor is the HP? i will figure your speed up with what you got now. and see what maybe you could change without costing much?

[gww]

stoker
It's all been gone over a few post back.  The motor 9 horse briggs tiller motor,  motor pully 3.5 or 3.6 inch, wheel pully 7 or 8 inch I can't remember exacly.  Wheel 20.5 inch.  Depending on the motor rpm, if it is 3400rpm I am around the 9000 fpm range.  The only possible cheap way to change it is maby a smaller motor pully.  I am guessing a two inch would bring it to the 5000 fpm but did not take the time to caculate it for sure.  The wheel pully is part of the wheel bearing and it can't be changed.  I cut a tiller wheel up and welded the ring I cut off it to the back of the wheel bearing to make the pully.
Thanks
gww

[1967Stroker]

yes a 2" pulley would slow it down and let you use the torque of the motor better. it would put it at 4560 feet per min. your setup now is 8207 FPM. if you could find a B type 2" pulley and run a 1/2 inch wide belt it would help.

[1967Stroker]

also if you could move the motor over closer to the wheel pulley and use a shorter belt, it would help you if your having belt slippage.

[Andre]

Looking back at some of your pictures it looks like there may be room for a countershaft or jackshaft between the engine and the drive wheel.  That way you could stay with larger pulleys on the engine and the second pulley on the counter shaft.
With very small pulleys the belt does not bend around it very well and you lose a lot of contacting surface area, then slippage becomes a problem.

[Hilltop366]

Other options to reduce tire speed?

I can think of two that may or may not work, one would be to add a shaft with a step pulley or 2 different size pulleys and a second belt to reduce speed, the other idea would be to cut a grove or flat on the tire behind the blade to run the belt on. Not sure how well belt on a tire would work.

[gww]

andre
Whats the math to put it all together? In other words what size extra pully are we talking about to end up in the 3500 to 4000 fpm range?


Stoker
I don't think I am getting much belt slipping at this point except when I first start the blade and maby when I forget to squeeze hard enough.  Some times I am consintrating on the cut or something else and I just forget to keep squeezing.  I do put some stresses on the michine pully assembly cause I added a heavyer spring and welded a bolt on the idler pully so when I pull it it doesn't go all the way around.  It is the light duty idler that came off the tiller and it has broke once at the swivil and I rewelded it.  It is holding up and I don't think I am getting much slippage, I am pinching the belt further around the pullys when I pull the idle pully tight.
Thanks
gww

[1967Stroker]

if he could find a 6 inch and and 4 inch pulley he could make a jackshaft and slow it down. his ratio right now is 2.2222 he needs it to be around 3.5 ratio. so a 3.5" on the motor into a 6" would give a 1.71429 ratio on the other side of jack shaft would be a 4" and his homemade 8" would be a 2 to 1 ratio. so 1.71429 x 2 = 3.42858 ratio.

[Andre]

Looks like Stroker beat me.
The two ratios are just multiplied together to get the overall ratio.

[1967Stroker]

find a car belt tension thing off a junk car to put on one of the two belts and use your handle on the other one 

[gww]

Ok first.  Does the belt from the pully to the drive wheel have to have a tension pully also or is that just so the belt is easy to change?

what issue is the fast blade causing.  Just the burning up of my blade guides?  Or is it contributing to the blade dulling really fast?

I don't know what a jackshaft is but am assuming by the conversation it is a shaft with two pullys on it.  Do I have this correct?

On the wheel being the pully also, I actually saw a mill on utube that the blade ran on the drive pully.  That would probly take a pretty large motor pully if I tried that.

I hope for some imput on what issue running to fast is causing.

I had not thought of any of the suggestions except a smaller motor pully.

Trying the 2 inch pully seems simplest if I didn't get slippage, 4500 is still fast for my motor but should not be to fast for the guides. 

Does anyone agree with my last statement? 
Thanks for the comments given and any to be given.
gww

[gww]

stoker
What fpm does the 6 inch to 4 inch extra pullys give me?
Thanks
gww

Ps 900 rpm correct?

[Ox]

I don't know why I didn't pick up on this before but that blade is running WAY too fast as you guys have already figured out.  I actually ran a belt around the drive tire on my first mill the first time I built it and a belt on a tire works really well!  I needed more blade speed and had a pulley laying around so I welded the pulley sheave on the backside of the rim which made the driving side a smaller ratio, thus increasing blade speed.  If you could line up the engine pulley you have and run the belt around the tire I think you'll like the results and it's probably the cheapest way to decrease blade speed.  I think you're cooking your blades and guide bearings with blade speeds around twice as fast as should be.

[1967Stroker]

stoker
What fpm does the 6 inch to 4 inch extra pullys give me?
Thanks
gww

Ps 900 rpm correct?

Should run around 5000 FPM. where is the big pulley off the tiller? you could use it.

[1967Stroker]

yes 900 rpm at the axle of the tire. here is a jackshaft idea i was thinking about


  

give you a idea.

[GF]

Just a thought.  Think about cutting metal or wood with a sawzall , if you run it to fast it gets hot and the teeth dull very quickly, if you run it at the correct speed it cuts and the blade does not overheat and dull nearly as quick.  I would almost guess your blade is running so fast through the wood the tips are overheating and dulling.  Will it cut with a blade running fast, sure, but not for very long.

Two things I would look at doing at the very least:
   1 Get the blade FPM in the correct range for the HP of the motor.
   2 Make sure the blade guides are level with the deck lengthwise.

One thing I also did on mine was to balance the wheels, this will take additional vibration out.

GF

[gww]

Ok
I cut some more wood today cause I get up before my wife and get a little time each day from other pojects.  The stupid thing is cutting pretty good through some real knotty oak.

I looked at my pullys and I have a 12 inch and a seven inch.  I was thinking that a twelve inch from the from the 3.5 inch motor pully and then a 7 inch which is close to the wheel pully size making it about 1 to 1 ratio.  this would give me if I am correct somewhere in a 3.4 reduction from motor speed.  Does this sound correct?  The issue may be the shaft and belt sizing as it would be a lawnmower type axil and the pullys would be more the origional tiller type belt width.  what will the extra friction do to motor torque?

I have the tiller pully still, I think it is a ten inch pully if I am not getting mixed up with what I am measuring.  I have a lawm mower pully that I didn't measure but looks to be in the 4 to 6 inch range.

The tire is 20.5 inch.  I am guessing I would need about a 5 inch pully on the motor if I tried that.  I wonder it the trailer tires are wide enough to fit a belt and blade on also. 

I did notice on my board cutting that I am getting the log squared up and it is about 1/8th inch out of square.  The thickness is uniform on both sides of a cut board for the lenth. Am I correct that this could be cleaned up by losing a very small portion of board width to a table saw?

I tried the 1/8th inch shim under one edge of the log for one cut and it seemed square but when measuring the ends of the squared log it was 1/8th inch longer on both sides.

looking at the board it doesn't look like a problim, will this really cause issues when trying to built with a board that is off square that small of a amount?  It doesn't sound like it would ad up on a two by four.  One side was 10 inches and the other side was 11 inches for this 1/8 th of measurement.

I am sure I explained the above clearly, right  .
Thanks
gww

[1967Stroker]

If you use 3.5 to 12 then the 7 to the wheel pulley it would gjve you around about 3.75 that would be great.

[1967Stroker]

That would be around 4921 FPM.