Diving blade mystery

[bunst]

I've built my own bandsaw mill (first mistake?) and can't get any consistency in cuts. There are times when I can mill out a whole log with good results and other times every cut has problems. Most often, it is a diving blade issue. When the diving starts to appear, I'll put a new blade on and it is good for a few cuts, but soon will also dive. I know the blade is still sharp and the set is not off, so I'm thinking it could be something else. Everything seems to be alignment.

My first thought is blade tension. My tension is acheived with a screw bolt. I have no way to measure the actual tension; I'm just going on feel. Is there a way to know the proper tension and how could I measure it?

Second thought being the wheels. I'm using inflated tires. They are not perfectly round as I notice a wobble when up to speed. Also they are not balanced. Would I benefit by upgrading to steel or cast sheaves with v-belts?

Thanks in advance.

[bandmiller2]

Welcome Bunst,tough question with no pictures could be many causes.First do you have band guides that the band rides on fixed and movable.If not thats the first step, best to buy,theirs alot in past posts on that subject.Your tires could be taken off and balanced at a tire store.Out of round,if you could setup a grinder to hit the high spots wile its running or try different tires or pressure.I'am sure outhers will have advice shortly,tell us more about how the mill is setup.Frank C.

[bandmiller2]

Forgot to ask where are you located?? Frank C

[fishpharmer]

bunst, welcome to Forestry Forum.  You are at the right place to solve your mill problems.  I couldn't have built mine without the help I received here.  Made some good friends too.

First of all we need pictures to truly assess your problem ;)  I am no expert but will regurgitate some of what I have been told.  It sounds like the blade is not perfectly parallel to the track or log bunks.  That was a problem I had with my mill. You also need some way to determine if the blade is parallel. A blade alignment tool can be made or purchased. Here is one from Cooks Saw
http://www.cookssaw.com/shop/index.php?target=products&product_id=30156

To maintain correct blade alignment you need some good roller guides for the band. This was a major issue for my mill.  Woodmizer and Cooks both make some great guides, although a bit pricey.  Good roller guides will take care of some issues with the tires being a slightly out of round/out of balance.  When building my mill I went through several different tire and wheel sets before getting some that run true. But don't be discouraged about tires for band wheels, lots of people use them for homemade mills, they work fine.  At least one company uses them for the mills they sell (Turner).   

I think tension could be a factor.  Woodmizer, Cooks and several others make tensionometers to check the tension.  Again here is link to Cooks
http://www.cookssaw.com/shop/index.php?target=products&product_id=30148

You can also search these subjects by looking near the top of this page and using the search button.  Also, it helped me to look at the pictures in some of the member photo galleries. 

Don't hesitate to ask any questions, most folks here know way more than me about sawmills.

[robnrob2]

There is what ya call a flutter test, where you remove your blade guides and carefully engauge the blade and bring it up to full speed, and then watch it for fluttering,, tighten up the tension till the flutter goeas away, and then give the tension bolt another full trun,, when lossening up the band when done opperating, count your truns,,
You want your blade guides, to be pressing down on the band about a 1/4"  this will have an effect of stearing your band balde,, also you will want your guides ponting or aiming your blade, streightaway,, nuther words, paralell with the bed,, this is done with a simple to make blade alignment tool, or one could be bought from Cooks saw Mfg,,
Out of balance and nonround tires can cause some of your problems,, but based on what you have described so far, I would say some of your problems is not enough tension, and blade alignment,, You really want the blade tight enough to nearly make a musical note when plucked,,
I think you would benafit from going with say 19" sheeves,and a V-belt isnert, over tires,, although its done lotsa times with sucsess with tires,,

[Magicman]

I can't add to the above advice and recommendations this early on because they nailed the potential problem areas.

But I can say;   Welcome to The Forestry Forum.....

[bunst]

Thanks for the quick replies. I'll post pictures within a couple days even though I'm kind of embarrassed to show what I've done. I used plans I bought off ebay that turned out to be not that good. The guides are adjustable but are fashioned in a redneck manner. Probably you guys will tell me to get rid of them. Anyway, once the pictures are posted we can discuss the issues in better detail.

[pineywoods]

What kind of logs are giving trouble ? If you are sawing pine, you need a bunch of set, new blades out of the box typically have about 20 thousands set. That can be  marginal for pine logs. What blade thickness ?? Thin .035 blades will loose their set rather quickly. If the guides are doing their job, the bandwheels shouldn't be that picky. It sounds to me like you may have a combination of problems instead of just one problem. If it saws ok for a while and then starts diving, What changed ? Most likely the blade.. Dull, not enough set, or not enuff tension. Don't forget. blades will heat up and expand...
From the school of hard knocks,  make sure the problem is not the blade before you go making adjustments on the mill.

Edit   
Where are you located ? There may be somebody like fishpharmer close by, we help each other...

[TblRxDave]

Have you tried a torque wrench to set your tension? I had to experiment with different settings until I got the flutter to stop. At least I have some consistancy for fine tuning. My Oscar 28 starts at 20-25 foot pounds and may go as high as 35 foot pounds.
Dave.

[bunst]

As a matter of fact most of my problems have occurred trying to cut pine. I'm using Lenox .042 blades that come with .021 set. What do expect the set should be for pine or other similar soft wood? And yes, I will experiment with more tension before moving on to the mill itself. For all interested, I'm located in Maine.

[Magicman]

Just a note:  Pine will/could have a considerable amount of "compression" stress in the butt cut which will make a blade do "bad" things.

[Tom]

Your Lennox band should do just fine.   Twenty One thousandths is the accepted "average" band-set. 

The flutter test was developed for Silicone bands and  most everyone's bands, except Timberwolf, are carbon steel and perform best with more tension. There is a homemade device and a formula for determining blade tension that is found on some old posts in this forum.  It uses a dial micrometer and "C" clamps.

Automotive tires have been used with success as bandwheel tires.  the best success comes from balancing and making sure that they are round. There are posts here about that too.

Diving regularly is usually a set problem.  One side set more than the other.

Since you are getting it with new bands, the band might be being damaged on a piece of the saw, flattening one side.  I don't think that the pressure from the rubber tire would do it, but it might.

If the band isn't being damaged, then the other causes are:

1. driving the band too hard and having it follow the grain
2. having too little set and having it follow the grain
3. the buildup of sap on the band, causing too little of kerf which results in too little set.
4. The buildup of sap/resin on one side, dragging the band into a dive.
5. Too little tension will exacerbate #1 and #2
6.  The band needs good and properly adjusted guides to perform up to expectations.

[Chuck White]

Your Lennox band should do just fine.   Twenty One thousandths is the accepted "average" band-set. 

Since you are getting it with new bands, the band might be being damaged on a piece of the saw, flattening one side.  I don't think that the pressure from the rubber tire would do it, but it might.

I agree with Tom.  It just may be that the inside teeth on the band are losing their set due to making contact with some part of the mill!
My guess is either blade guide rollers or rigid (non-roller) blade guide!

With no (or little) set on the inside teeth and good set on the outside teeth, the outside will really be biting in and the inside will just follow their lead!

[ely]

are you cutting green or solid pine... or are they trees that have been standing dead., as in the wood is getting a little bit doady.?

[bunst]

The current log giving me trouble is a white pine that was dead.

[ely]

i would change your log to a hardwood of some sort just to check out and see if it cut well.
i have a manual mill lumbermate 2000. and it will give me living fits when i am cutting the dead pine that has two different consistences of wood in the log. when i throw on an oak or a fresh pine the "problems" seems to dissappear.

if my mill is not 100 % true the dead pine cause me problems, i have learned a few tricks that help me, but i have a friend with a mill like you are describing and it is the same as yours. the best i can tune his is not good enough for dead/doady pine. he can saw fresh pine logs or any hardwood perfect.

[Planman1954]

Being an absolute rookie at this, what I say will probably be scoffed at by everybody here. But I didn't notice anyone mention lubrication of the blade. The first thing that caused me problems was not enough water (with dawn dish soap in it) running on the blade. The detergent and water remove the sap great. Pineywoods uses pinesol. Anyway, if I cut pine without soapy water just one time, the blade will dive soon thereafter. Good luck.

[Fla._Deadheader]

 From experience, using ANY soap, pinesol, Diesel, etc. on inflated tires will more than likely cause blade slippage and tracking problems.

  We had this problem with SYP, Heart Pine, and found just lots of plain old water, and a scraper on the inside of the blade, worked just fine.

  I'm guessing knots and differences of heart-sapwood, and causing enough problems, but, blade set would be the main culprit.

I sharpened all our blades, and followed the deep gullet of Monks blades, even on a couple WM blades with shallower gullet. Moving the sawdust out of the cut makes a difference, also. At least, it did for us.  ;D

[fishpharmer]

Tom,
I just happened to be randomly looking at Larry_Copas mill pictures and found his picture of the homemade tension gage you mentioned in this thread.
IT IS NOT MY PICTURE.
I borrowed it , for the benefit of all.  Thank you Larry_Copas.

[John Bartley]

When I first started sawing I was cutting frozen white pine and it was a disaster. I learned very quickly that if I wanted to keep the cut straight and smooth I needed to do this:

• keep the pitch off the band (pinesol in water w/WW fluid) (solved diving and climbing in clear wood problem)
• keep the set in the teethup in the 0.028" to 0.030" (solved the diving in knots problem)
• keep the set consistent (solved the crosscut marks from an excessive set on one or more teeth)

Once I did these things all was fine.

Also, I found that keeping just enough pressure on the band that the motor started to "work" was a big help in keeping the face of the board smooth and clear of sawdust. I also grind my bands with a Monks depth in the gullet.

just my experience - I hope it helps a bit

cheers

John

[bandmiller2]

Bunst,don't be too hard on your mill mayby you just have "one of those logs".I've got one sitting in the yard now it tipped the scales and got me to go back to circular mills.Later I'am going to throw it on the Chase De Lane and see how the big wheel handles it.Bunst before you go too far get a nice freash pine log and cut it, some logs are just destin to keep you warm.Frank C.

[bunst]

 





Here are a couple pictures of my mill. Hopefully I did the upload correctly. I do have a blade guard but took it off for a better view of the wheels. In response to the great tips I've gotten so far, I will first check/adjust my blade tooth set and apply more tension. I will hold off making any changes to the mill until I hear the criticism...please be kind!

[Magicman]

please be kind! 

Please be kind  ???  You deserve praise !!!  As you work through the suggestions, you will solve your "diving" problem....I like your mill.   

[Fla._Deadheader]

 Shoot yeah !!!!!!  Everyone doesn't have the Cajones to try to build a mill. You done good. It's just yer Garden Variety simple as can be, Band mill.

  As you getRdunn, you can add upgrades for a LONG while.  8) 8)

  I agree with "get a fresh log and try IT". Blade set could be out OR lousy log. We all get 'em.

[Planman1954]

I echo that remark. Good luck! I don't see a water bottle though. I know somebody else said don't use water with wheels. That's a call that is above my pay grade. I hope you do well!