Well. That is exactly what I ended up doing today. Made a bunch of wavy cuts and got completely stumped and frustrated in the process.
The story goes: I have been sawing white pine for the past several weeks when I have the time and the temperature is above 15F. The trees have been down for about two months and are most certainly frozen as frozen can be.
I bought a box of .055 7 degree blades and was amazed how well they behaved in frozen wood. I was doing well last week and the week before, but today I could not make a decent cut. The blade was diving so bad that I could see the tension/pressure gauge rising 200-300 psi and the blade would drop down 1/2-3/4" in a foot or so. I had to stop, lower the head to decrease tension and slowly back out of the cut as I raised the slab with an axe or pry-bar. It would even dive
where there were no knots. The cant and slabs had caked on frozen sawdust that had to be scraped off.
I didn't manage to make a single cant as I didn't want to ruin the logs.
Here is what I did:
I checked alignment, good
blade deflection, good
new blade
B57 belts, good
blade tension 2200-2300psi
even gave the drive belt a bit of extra tension (will take that out)
Finally called WM and the tech very patiently talked to me for 30 minutes. He thought the blade dives because there is too much sawdust left by the blade. He suggested that I add a healthy amount of soap to the lube (windshield washer fluid) to reduce friction and increase feed rate to help get rid of the sawdust.
Anything else I should do or check? I really need some advice so I can work this out in the cold tomorrow.
ps: I thought it was going to be an easy productive day. It was not meant to be. :(
Sorry to hear about your dismay GD, if all you check is for sure good, this is a bonified head scratcher for sure. Are you starting your cut from the small end of the log? This is what I really try to do, just my way, I would give the drive belt another look, not saying you have not as you mentioned, but this is a real possible culprit. I don't know your mill, but if you are aligned, it sounds like drive belt tension. If the blades are good, and sure you have changed them. Been there! Roller bearings and lower wear pad? Might consider checking the blade guide tracking for and loose v-wheels, david
I had the same problem. Could not figure out what the problem was. Had the saw techs look at the mill. Got the saw back Everything was in order, straight and in line. Started back to sawing and same thing happened. Wavy boards. This went on for about a three weeks. Finally I sent the new blades back to the Co. and found out it was the blades and not the mill at all. Blades where set wrong.
I have gotten new blades that weren't set enough to cut straight.
I would put another log on the mill and start over. I've had bad logs cause dipping. But do as the others say and use a lot of pine sol (or dish soap) in your water lubrication and try again. Good luck...and I HAVE felt your pain before! :D
Seems like a bunch of possible issues working against you
Same band as when you sawed the last time?
Roll the problem log 90Deg and try another cut with same band see what you get
measure the set on the band you had problems with as compared to the last good one and a fresh one.
Is your sawdust freezing in the log?
couple thoughts,
let us know,
DGDrls
Feed belt tension isn't on most lists if your mill isn't traveling at a constant speed that could do it too
Have you checked under your belts for sawdust build up? 1 good clump will cause your blade to ride up and over, changing the tension and blade movement. I had that problem for a week before I figured it out. Just clean your belts and check the wheels when you get blade flutter and after every blade change.
As planman suggested try a new log[different tree] and a new band.Some logs will give you fits for no aparent reason.Outher than that I think most wavy is caused by improper set. Frank C.
GD:
You said you checked alignment. Did that include putting the blade guide on the blade and checking to see if the blade is parallel to the bed rails?
The blade tension gauge gives you a number that is all. The proper load or sweet spot for a 1.25" x .045" W-M blade is a load of 25000 to 27000 pounds. So using the equation of elongation (e) equals load (P) times the length (L) divided by the Area ((A) blade thickness times the minimum blade width) times The modulus of elasticity (E). For the Modulus of elasticity use 30,000,000 and it will be close. Tighten your blade as you normally do with the machine running, then; turn off the mill clamp a vernier with the distance you used in the equation onto the blade and the elongation for your blade then release all of the blade tension and see how close you are to the length you used in the equation. The length you use will depend on your equipment. Hope this helps you and please keep us posted as I would sure like to know what the problem is. Thanks, Gerald
Thanks for the suggestions gents!
To answer a few questions:
I tried a total of three logs.
The first one (18-20") I actually "squared up" but pretty much all the sides gave me trouble. The blade would always dive and at a larger knot it even made a perfect bowl. The sawdust froze right onto the log and I had to scrape it off. I quit before I ruined the chance of making at least some boards out of it when it thaws out.
The second log went fine. It was only about 10". I turned that into 1x6 lumber, no issues, waves or diving.
The third one gave me fits as I opened up the first face. The blade dove 1/2", then I called it quits.
Between the first and second logs I changed the blade, cleaned the belt grooves and the B57's.
I checked the blade alignment with the mill bed, checked guide roller blade deflect and the blade position on guide rollers. Also tensioned the main drive belt some.
The first blade I used today was perfectly fine when I used it a week ago. It only cut about 3-400bf and the temperature was even colder.
I have not checked the feed belt as I put a new one on the mill about 50 or so hours ago.
On the bad logs the sawdust froze right onto the log in the cut. I had to use a mud knife to scrape it off. I did not see that before.
How do I measure tooth set? What tools are required?
GAB, That is a great and scientific way to check blade tension, but I must admit I could not quite understand, grasp, comprehend the task.
Thanks again
If the logs are dirty, that can ruin a blade really fast, even a new one.
How wide are your blades?
If you're sawing frozen wood, you'll have better luck with 1-1/4" blades than with 1-1/2" blades.
I'm with Brucer, have heard that before... Seems even my 1-1/4 blades that have sharpened several times cut better in frozen wood than new ones. Steve
The logs are clean and the blades are 1 1/4" .055. Thanks again for the pointers and ideas. I might not even try it again today. It supposed to be a windy day with 4F for high temp and snowstorm the day after that.
I use those plastic logging wedges to back out of a cut. That's all the advice that I can give ya. Good luck.
The very first job I did was in January, about 5 years ago, and I was sawing frozen white pine for a friend. We had trouble with wavy boards right from the start. We did everything you have mentioned, and we finally found that the ONLY thing that kept us from having wavy boards was to increase the set. My bands were .045", x 1-1/4", 10 degree. To make the mill saw without waves I had to increase the set to 0.028" minimum. Band tension only served to keep my boards a consistent thickness from side to side. Tooth sharpness only caused the sawing speed to increase or decrease. Lube only kept the band clean and kept the frozen sawdust from sticking the band in the kerf.
My observations ::
A sharp, improperly set band will cause waves in the board, but will cut fast
A dull, properly set band will cut straight as a die, but slowly.
I haven't cut a wavy board since I learned how to set my own band teeth properly to suit the wood.
That's all I got ....
John
Do you have any 4 degree bands available? if so, switch to those. In the spring, summer and fall, I saw with 7 degree but in the winter, I move right to 4 degree. Although I could saw perfectly flat lumber with 7 degree in the winter, I would need to slow my speed down to much to produce the quality that I want and subsequently, spend more time doing it.
What hp mill are you running?
I have been sharpening for a few years now and sharpen A LOT of bands for many customers all over the state and I have converted them to the way that I saw with 7 and 4 degree. If it didnt work, they would surely tell me!
Running heavier bands is a plus to which you are already doing so you have 50% of the battle won. Change to 4 degree and try it out. Youll be surprised.
duplicate post .... oops!
That's tough there GD. I have had those days. There is little White Pine where I live but I did cut some a number of years ago when I was newer to this business. It was late spring and the logs were thawed (I know this doesn't apply to your problem but anyway) and there is a little skin under the bark that kept going under the blade and causing it to ride up. What a drag!! Had to take an axe and cut the bark off.
I was going to mention the same as others about increasing the set of the blade to at least .028". That means you would have to set to around .030 and then sharpen to square off the teeth which takes a little set off. You can check the blade set with a digital caliper. You have the thickness of the blade already. Now check some teeth on one side of the blade and take average reading and subtract from blade thickness to get the average blade tooth set on that side. Do the same for the teeth on the other side. Once you have a tooth that is .028 " set then you can take a piece of heavy sheet metal or thin flat iron about 2-3" long and file a flat notch out about .25" long on the edge. Place the piece you have made on edge on the side of the blade and your notch up against the tooth. Keep filing the notch until it fits exactly on the tip/edge of the tooth. I guess you could file the notch the same depth as the thickness you want using a feeler gauge or the like. You should end up with a quick tool to use to check blade teeth set. Of course your piece of iron has four corners so you could do the same on the other corners for different tooth set. Hope this helps.
That's a great tip there NM. I've tried increasing the degree but haven't tried to decrease to 4 degree in the winter.
A bit of update. Yesterday I got a hold of a local sawyer who has been working in the area for 15 years. He was super nice and helpful. He lent me a 1 1/4 .055 9s blade, saying that is what he uses in these conditions and said turn off the blade lube. I tried it and it worked like a charm. I mean I made a pile of nice 4/4 lumber out of the logs that I quit sawing the day before. The temperature was around 4-8F. I was really happy at the end of the day.
Thanks again for all the help and suggestions. The more I learn about sawing the more I realize how little I know.
Quote from: GDinMaine on February 08, 2013, 10:01:15 AM
A bit of update. Yesterday I got a hold of a local sawyer who has been working in the area for 15 years. He was super nice and helpful. He lent me a 1 1/4 .055 9s blade, saying that is what he uses in these conditions and said turn off the blade lube. I tried it and it worked like a charm. I mean I made a pile of nice 4/4 lumber out of the logs that I quit sawing the day before. The temperature was around 4-8F. I was really happy at the end of the day.
Thanks again for all the help and suggestions. The more I learn about sawing the more I realize how little I know.
Mr. Weed knows his stuff. ;)