Home Brew Bandmill

[GoManGo]

Please let me first apologize for my missuse of grammar, and my terrible spelling.  

My Dad and I have been hard at it all winter trying to get this beast up and running.  Last weekend we cut our first log, and found several things that needed to be redesigned.  It took us a full day to cut seven 2X4's but it was worth it.  We are currently trying to solve a blade breakage issue, so a lot is going to change.



This saw is running 16" V-belt pulleys, and a 22 horse bailer engine as the powerhouse.  The blades were ordered from woodmizer and the saw designed arround the blade.  We have been pinching dollars, so most of the mill was built from our scrap Iron heap out back.  The only iron purchased was the angle iron track, and the square tubing that makes up the head, and blade guides.  We werent able to find a heavy enough, matched set of pulleys, so those were purchased new.  So far I belive the total cost for the mill is arround $700 not counting the blades.  




We origanally designed the blade guides with bearing rollers on the top, and bottom of the blade, but have changed that over to eliminate clearance issues.  




We added a blade lube delivery system, made from a couple propane jets as nozzels, and a windshild washer pump from an old broken down Datsun.  




If you look close, you will see that the drive belt tension pulley is on the wrong side of the belt, so that is going to be redesigned.  

I will be adding these and more photos on a webserver at a later time so you can see them a bit better.  For now, I just uploaded them to the forum.  Sorry bout the postage stamp size photos.  Ill try to get that done this weekend.

[Norm]

Welcome to the FF GMG, no need to apologize for bad grammar or spelling. Most folks here spell and grammerize (is that even a word) just as bad as me. Well maybe not as bad but they're trying. :D Lots of folks here have built their own mills so I'm sure if you have questions they can help.

Ya know I've been to other places on the net where if you don't know the kings english so to speak they give you a hard time. I have never seen that here, not once, makes me proud to be a member.

[GoManGo]

One thing we are lacking here is experience.  I appreciate all of you out there that have posted and shared your knowledge.

We are about to redesign the blade guide assembly now, but are not sure how to align the guides. Any suggestions here would be most appreciated.

What we are running is a set of bearings sandwiched together for the top roller guide, and a single ball bearing in the rear.  When we had the last break, the duel roller was pushing down on the blade approximately 1.5 inches.  We have come to the conclusion that this might have been (in combination with over tightening) the cause of the blade breakage.  The blade broke irregular and jagged witch might indicate metal fatigue.  Upon further inspection of the blade, we found that it had several cracks starting in the gullet.  Not sure what might be causing this, but we are hoping that this vertical deflection was the cause.

So I guess what I am asking is... How much vertical deflection (rollers pushing down on the blade) if any should we have?  Should the rear roller be set slightly away from the blade when running without a load, or should the rear rollers be adjusted to constantly touch the blade?  

Also... The adjustable side of the blade guide arm seems to vibrate and can be manhandled into moving slightly in all directions by hand. We welded a brace in, and that seemed to help a bit, but when operating without a load, it still dances around quite a bit.  This translates from the rear roller directly into the blade, and cant be good for it. It seems that the hammering stops when we put the blade into a log with normal load, and resumes when exiting the log.  Is this normal on all saws, or are we special? It would seem that if we were able to eliminate the vibration from the engine, it might help quite a bit, so we plan to later beef up the engine mounts.  The drive belt is responsible for its own share of the vibration as well, so we are going to have to redesign the stiff-arm belt tensioner we have now.   I will try to get photos of what I am talking about up on the web tonight after work.  Thanks for all your help.

[shopteacher]

Gust like to WeLcoMe you to the F Foram. SPelliNg is Vary,vary iMportAnt her. All kidding aside we're happy to have you aboard and the more experienced sawyers here will be more than happy to answer your questions and give you advice on just about any subject from roller guides to food, especially the food section.
  Looks like you and your Dad have done a fine job of putting that mill together and with a little assistance I'm sure you'll have it up and running like a store bought one.

[ronwood]

GoManGo

Welcome to the forum. Deflection on the blade of my Woodmizer is only about 1/8 in. Works fine with that amount of  deflection.

Ron

[chet]

Welcome GoManGo, hang around dis place awhile an dat saw will be up an running in no time.    First off I agree, your blade deflection is way to much. I run about 1/8" also. Also when the blade is not in the cut it should not quite be touching the rear bearing in your guide setup.

[D._Frederick]

GoManGo,

Here are my thoughts on your blade breakage problem. If  I was you with 16 inch band wheel, the Maximum thickness of the band would be 0.035 inches. and I would keep the down force on the guides to less than a 1/4 inch. The back of the blade should clear your back-up roller by less than 0.030 inches when the blade is tensioned and turned by hand. Check your band wheels alignment, they should be in the same plane with each other. You should have a method of checking how much force you are applying to the band wheel to tension the blade. With a 0.035inch blade you should have about 1800 lbs if it is a carbon blade. And about 2000 - 2200 lbs with a 0.042 inch band. Also make sure your bands are flex back blades, and not hard back. The last thing that will help blade life is how fast your are running the mill. With your 16 inch wheels, I would keep the band speed under 4000 ft per min. Hope this helps.

[Swede]

GoManGo;
Lox lajk ö very godd handicraft Jo hävv dann! Try to get away from that vibrations too and get in business.
Do´t worry about grammar & spelling, I´ll do what I can do to defend my position as Master of Broken Language here! (^__^)
Good Luck!

Swede.

[Tom]

Pretty good images can be obtained by following the instructions for putting a picture on the forum.  They can be found in Forum Tools at the top of the page. Putting a link to pictures may find your posts here missing pictures one day when you no longer use that site.  You must be careful of widths  on the posts too.  Over-size pictures will disrupt the format of the forum.

You would really be better off, in the long run,  to try to use the forum gallery and posting procedures.  

[rbarshaw]

Look at "The Bandmill That I Built" here on this site. I've found that anything over 1/4" deflection at the guides causes lots of trouble, you said yours was 1.5" deflection-that will bend the blade around a small curve and cause cracking in the gullets fast, leading to rapid blade failure. changing the deflection to less than 1/4" should also reduce the adjustible guides vibration.

[GoManGo]

Well folks...

Thanks for the warm welcome. Its great to see that everyone is willing to help out where they can, and I cant stress enough how valuable your advice is.  ;D

I am trying to figure out this jpeg optimizer, so the photo uploads are not going as fast as I would like.  Here is what I have come up with so far.

Here is the mill sitting right where we built it.  The rails are 4x4x1/4 angle iron, and the frame on the saw is made of 2x2 box tubing 1/8th inch thick.  The band saw is spanned with 2x2x1/4 angle iron, and the guide arms are 2x2x1/4 square tubing.




The saw is lifted in the frame using this worm drive steering box from a very old vehicle of unknown make.  It was a toss-up between this and a retired rototiller gearbox.  We found that the gear ratio in the steering box was more favorable in this case.  The worm drive turns an old 1-1/8 drive axle from another donor vehicle, witch in turn winds the cables thus lifting the saw.



This is the braking mechanism used to lock out the worm drive when the saw is running.  It is made of a donor clutch disk from a datsun, and the brake is just a couple plates of 1/4 inch steel with a cam between them.  We are using some old belting for brake pads.   the pressure is supplied by two valve springs.



Here are the blade guides that didn't work.  The bearings on the bottom have since been done away with and the whole assembly has been re-adjusted to eliminate the massive deflection that we had.  Ill get new photos of that after we get them installed.



Ok... Here is our precision tension screw.  I know its ugly, but it works.  The silver thing is a swivel socket with a socket extension on it, and this entire assembly is welded to a piece of rebar that sticks threw the saw guard.  As you can imagine, it would be quite difficult to measure the belt tension with this setup.  Perhaps I can find a math guru that can figure out the pressure using a torque wrench or something of that nature.



Here are the pillow block bearings.  I found these and the shafts in a couple commercial blowers that were on top of a restaurant that I re-roofed.  The blade guards were also off these blowers.  I wasn't quite sure what I had when I brought  these 200 pound blowers home, and was quite pleased to find four matching pillow block bearings and shafts.  We had a neighbor mill the keyway into the shaft on the drive end, and presto... instant sawmill.



Here is how we mounted the lube nozzles.  The nozzles themselves came from an old "instant" hot water heater that melted down and found its way into our scrap heap.  I simply soldered 1/4 inch copper tubing to the jets, and mounted them to a sheet metal bracket.  The pressure is supplied by a salvaged windshield washer pump from an old datsun.



D._Frederick...
The blades we are using are .045 x 1-1/4 x 158 with a 9 degree hook. Being new to running a sawmill, we simply took the advice of wood-mizer on what blade to use.  It was my understanding that the .045 blade would handle the 16 inch pulleys with no loss of life.  Is this incorrect?  You indicate that with a 16" wheel, I should be using a max of .035.  Threw my correspondence with wood-mizer I was under the impression  that the determining factor on blade thickness was horsepower.

Woodmizer indicated that 5500 SFPM is the correct speed for this blade.  I'm sure that is all good and well in the lab, but out here, my logs are knotty and crooked.  What advantage is there to running the saw at 4000 SFPM?   Is this just to insure longer blade life with the smaller diameter wheels, or is there some advantage to performance as well?

While I was at work today, My dad started to redesign the blade guide mounts to accommodate the lesser deflection, and is also trying to find a way to add a flutter dampener to the top center of the blade.  Any advice on this device would be most appreciated.

[D._Frederick]

GoManGo,

I think I see one of your problems of blade breakage, you don't have the right size Vee belts on your band wheels. I don't know the  size of your pulleys, but here is an example, if your band wheel pulley is for a "A" size belt, You use a "B" size belt. That way there is some rubber between the blade and the band wheel.  WM blades for your 16 inch wheels will give you even less blade life, they are too thick at 0.045 and they are HARD BACK.
 I suggested using 0.035 blades because the flexing of them going around the small diameter pulleys will not work harden them as fast. Also reducing the blade speed is to increase blade life, a blade has only so many times around the band wheels before it work hardens and starts to crack.
You got to come up with a way to know what your blade tension is, I had the same problem on by mill and I built a hydrualic system with a handpump, cylinder,and pressure guage. Simond Saw has tensioning meter that clamps to the band blade and will read the tension in lbs per inch squared.
Give MENOMINEE SAW a call and see what they can do for you.

[GF]

I used a 4 ton porta power pump and the 4 inch ram to tension my band, I also put a hydraulic pressure gouage on it to set the tension, once I reach the correct tension on the gauge I use the acme threaded rod tensioner to set it, this way should the hydraulic pressure leak off the threaded rod keeps it at the correct tension.

[Captain]

Great piece of engineering, GoManGo.  Looks like you have the picture thing figures out.  

I'm learning right along side of you.

Captain

[Minnesota_boy]

GF,
You should check that the tension hasn't changed every so often as temperature changes and normal wear will make the tension change.  I've seen the hydraulic pressure guage on my Woodmizer go up and down like a yo-yo on a partly cloudy March day.  The mill was facing south and the bright sun would warm the sawhead frame and the pressure would go up to near the max and then a cloud would cover the sun and the pressure would drop well below what it should.

[cluckerplucker]

go man   I built my mill too. I built my first set of guides but thay dont last long no way to lube the bearing as the blade lube washs the oil out of them So i bought a set of guides from cooks 235.00 .Idont set any tension with the guides. when I was mounting the guides I just let them  rest on the blade and leave about .30.clearance from the rear surface. I tension with the band wheel adj. just till the blade smooths out and not bounce.Ihad the same problem with my first set of guides that the adj. one would shift .(the arm lock was not long enough )

.

[Mark M]

Hi GoMan

That's a pretty nice saw you got there!

I agree with D_Fred, a little "tire" between the wheel and the blade would cushion things a bit. On my Norwood saw the belt sticks out of the pulley about 1/16 - 1/8 of an inch.

Go luck and keep sending pictures.

Mark

[GoManGo]

I just ran out and looked at the V-belts, and I seem to have about 1/8th inch cushion.



Here is a look at the new blade guides.  We havn't gave them a run yet.  The deflection is now almost non nonexistent, so the blade will be under a lot less stress.



We are currently looking into changing the tensioner system over to hydraulic, perhaps with a porta power similar to what GF has set up.

Dad added a flutter dampener to the top of the blade.  We have never actually seen one of these devices, and can only speculate on the proper use and adjustment of it.  In theory, the nylon guide will keep the flutter under control during normal operation.  Does anyone have experience with these?  I believe the nylon should have about 1/16th to 1/8th inch clearance.  

[D._Frederick]

GoManGo,

I guestion if you even need a vibration dampener, I think that they are more problems than they are worth. Guides look good, should work OK.

[Fla._Deadheader]

Good looking job. ;) ;)
  We built our own mill, and maybe you need to add an additional piece of tubing across the top back side of the sawframe. We used 2 pieces of tubing, one above the other. It helps to keep the wheel housings from being pulled together from the blade tension and SAWING tension. If you had the hydraulic gauge in the blade tensioner, I would believe you would see a DRASTIC drop in tension as you saw a log. The blade will pull the wheels together. 1/8th wall tube is VERY light.

  The rest of the input from the guys here, is, RIGHT ON ;) ;D ;D

[redpowerd]

i may have missed some stuff in an earlier post.
do you have problems with the moveable blade guide linkage?
have you found the reason for the arm shakin? i wonder whats causing the blade to shake? whats it do in wood? do you have a pic of your arm mechanics? thanks

[GoManGo]

The cross members between the band wheels are not made of 1/8th tubing.  They are made of 2x2x3/8th angle.  The receivers for the adjustable wheel is made of 2-1/2 x 2-1/2 x 0.238 wall tubing, and the actual sliders that the band wheel is mounted to is 2 x 1/4 square tubing welded to a 5/16 thick plate.  I dont think that we will have a flexing problem, but I guess it is possible.  I will keep an eye on it and make the mods you suggested if there are any problems.  The cage chassis is what is 1/8th tubing.

redpowerd...

The arm shaking is just when extended when cutting slabs into boards.  It doesn't shake when the guides are far apart.  The guide arm has no linkage to speak of.  It's locked in by turning a T-handled that is threaded into the receiver tube.  We seem to have eliminated a great deal of the vibration by welding a couple braces to the receiver.  The remainder of the vibration is easily eliminated by a couple stiff bungee cords.
I wont have a decent photo for you until this weekend, but for now, here is what I have.  I will try to get a better shot for you later.  



As for the upper blade flutter dampener... its in, and doesnt seem to effect the preformance of the saw, so we are going to rip a few logs with it and see what happens.  I guess I wont know if it helps until it's removed.  Currently, the blade is a lot more stable on top than before all these modifications. (blade guides, bracing, and all that)

[Fla._Deadheader]

Ahhh, I SEE said the blind man. ;D

  Just thought when ya showed the photo laden post, that you was talkin about the sawframe and the 2 X tubing about the same time. Goes to show ya can't ASSUME nuttin on here.  You have built the mill plenty heavy and done a fine job.

  You may also try adjusting the engine RPM when sawing. On ours, a certain RPM will produce a slight "flutter" and just a bump of the throttle will eliminate it. It creates a harmonic frequency vibration. Them $30,000.00 mills don't get that : ;D

  Most guys use the high torque on the blade tension. We prefer to use just enough to get a smooth cut, with NO slippage. We use a 3/8ths ratchet and socket to tighten the blade. We cut 36" wide boards in Red Oak, 2 days ago, that has been on top of a brush pile, for 10 years. We gots HARD RO down here. :D :D :D

[buildthisfixthat]

?

[lostyooper6]

On another subject, what did you use for the guide wheels, I'm looking at builing a slabbing mill and have been digging around the internet for something suitable to use that is cost effective.