About three weeks ago, fellow FF member rjwoejk, aka Bob from Canada, was driving his semi over the road in the US and managed to time one of his required downtime stops at my place in Illinois. He got here about noon and wanted to do some milling for a change of pace from all driving he'd been doing non stop for 3 months. He has the same mill as me back in Canada- a Woodmizer LT15. So we milled some cherry logs and the last log was a Honey Locust about 20 inches in dia. with some branch knots. I was cutting as many 4x8 pieces of brace stock (timber frame knee braces) as I could get.
(https://forestryforum.com/gallery/albums/userpics/16191/IMG_3209.JPG?easyrotate_cache=1490444062)
I first slabbed 3 faces and on one of them I had a wave(dive) about 3/8 inches. Bob asked me why that happened? I didn't know. I've been milling for a little over 2 years and have had my share of waves and dives. Sometimes you get a wave, and sometimes you get a dive that won't come back up. He thought I should have a little more blade tension. It was set where woodmizer recommends, but we increased the tension to where Bob says he has his mill set. So then we continued milling and cut 4 inch thick slabs. I set up 3 of the pieces to cut down to the 8" dimension. I had the live edge plus another 2.5 inch to take off so I decided to make some 4" boards. I started cutting and the blade dove. Bob was really getting curious why this was happening. He studied the outside piece and could see grain runout about 45 degrees toward the mill head(start of cut) where the wave started, see figure (1). Bob suggested that when the blade hit the runout grain from the knot, it followed the grain and thus dove. Since milling with the grain is much easier than cross cutting, it followed the path of least resistance. It did cut across the grain, but was being pushed down by the harder grain lines. It eventually cut through and came back up, leaving a significant wave.
(https://forestryforum.com/gallery/albums/userpics/16191/Blade_dive04152017_0000.jpg?easyrotate_cache=1492310567)
Bob suggested an experiment - turn the can't around so that the runout grain would go up and away as you cut as seen in figure (2). It worked! So I wasn't sure why it worked at the time, but somewhere in my brain it kept rolling around. Then recently it hit me- the guide rollers! They keep the blade from moving upwards. So if the blade wanted to follow the grain in figure (2), it is more difficult because the guide rollers support the blade or resist against the blade in that case. On the other hand, there is nothing to resist the blade form tipping down except blade tension. Blade tension is not enough to resist the blade twisting downward away from the guide rollers.
(https://forestryforum.com/gallery/albums/userpics/16191/IMG_3294.jpg?easyrotate_cache=1492312514)
In conclusion, I think grain runout in the direction of the opening end of the log and hardness of the wood can cause a wave or dive. Having a sharp blade helps cut across grain with runout, but is not a solution by itself. Adding tension above the factory recommended is of little help. I'll keep mine at the factory recommended tension. Orienting the log so the runout points away from the front of the log helps the most.
Many on here will indicate to orient a log with the small end at the front. This makes sense for a fairly straight-grained log. If the log has a lot of taper, orienting this way points the grain runout away from the front, consistent with what I've been saying. But when you have a log with large branch knots, you may want to make the butt the front of the log(starting point) so the grain runout from the large branch knots points away.
This is my thinking from this experiment. I will have to put this into practice more to gain more confidence in this. It seems logical to me.... or maybe I'm sniffing the wood too much? Weigh in.
(https://forestryforum.com/gallery/albums/userpics/16191/IMG_3217.JPG?easyrotate_cache=1490443242)
Overall, it sounds like a good time was had by all, Brad! 8)
Seems that when 2 sawyers get together, at least one of them learns something new! :P
With all the questions that come up on waves while cutting, I'm surprised there hasn't been more commentary on this?
I have been struggling with my red oak to overcome waves. Sharp blades,10 deg, 9 deg, 7 deg, faster, slower, frozen, not frozen, log orientation. Here is what I have found so far. Playing with factory tension settings for blade and drive have made no difference. Sharp 7 deg blades at moderate speed are doing well, want to try some 4 deg as I found improvement moving from 10 to 9 to 7 deg. My LT35 25hp will slow when it hits hard spots so I tried adjusting speed control as this occurred but have found it easiest for me to apply a little pressure by hand approaching and going through the knots to prevent taking off before I can turn down speed when the blade comes through the hard spot. Frozen logs did not wave as much as thawed do, I figure the freeze must outweigh natural changes in grain and hardness. Partially frozen logs were a disaster, moving from freeze to thaw the blades went all over the place. Overall the biggest impact I have found is orientation. The butt of the bottom logs from the tree are hard, hard and I get dives just as I start into that end but do much better starting from the top end so I hit the butt after already moving along. The second logs up the tree tend to saw about the same either direction as there are few if any knots. The third logs start to have a lot of knots which lead to waves. Sawing these from the bottom end is working better because I get dives at the knots if come from the top. Had one dive so hard it broke the blade. I agree that the guides provide resistance from rising as opposed to dives where the blade is getting stressed all the way out to the pulleys. Anything above that third log is firewood.
Your theory of the "wave" in your case, seems more than plauseable. I tend to cut "butt first" most of the time as Ive had similar probs,results over the years. Butt about a year ago(see what I did there :D), I was cutting 20 inch wide sitka spruce planks and I could not cut strait to save my life. Blade guides were accurate, blades sharp and set properly. Turns out, my band wheels were not on the same plane as eachother(idle side had tilted and I was using the guides to correct the situation). I've yet to figure out why this affects my blade performance in such a drastic manner but as soon as I made the correct adjustments, the mill cut strait and true. So, in conclusion, I havent helped this disscussion at all, only made it more mysterious.... ;D ;D
I had found that cutting from the butt end has help a lot. I saw a lot of different oaks. But, some times if there is a lot of stress in a log, I find it just so much better to just stop and put that sucker in the burn pile. :D I tried those and had just never won. >:(
Had a second cutting off a log the other day. Talk about a wild log. :o After the second cut, my blade dropped almost 1 1/2". :o But the butt log sawed out good. Just don't know what happen, but other then more firewood. :D
As I said, my theory for orientation depends on the situation:
For a fairly straight log without big branch knots, Saw from the small end, but sawing from the butt end should work too.
For a tapered straight log without big branch knots, Saw from the small end.
For a log with big branch knots, or severe grain runout, saw from the butt end.
That's my theory that comes from this one log test. I plan to practice more with it to gather more empirical evidence.
It's very interesting and I look forward to following you in your findings. Thanks for taking the time to share this with us.
Any saw wants to follow slope of grain. The smaller the blade and the farther apart the teeth the worse. On a circle mill, sawing small end first going down into a curved butt hemlock or spruce sometimes you have to inch or jog thru because the grain will bend that heavy saw spoiling the board and cant face.
Seeing as we're brainstorming this wave/dive problem I have a theory I have yet to prove. One piece of advice often given is more set in A band that is waving or diving. I think less set may help as the narrower kerf will tend to support the body of the band and aid in a straight cut. I walk along with my band mill head and keep an eye on the flanged Cooks guides if they start to slow down its an indication the band is starting to dive. Most of the time I can slow the feed and keep it on the guide. It helps if you put a white mark on the back of the guide roller to view its rotation. Frank C.
In my experience of sawing around 500mbf waves and diving are caused by dull, mis set blades or poor guide alignment, or drive belt slippage. I can saw faster and flatter with the Baker at work than most can. Avg. around 5-6mbf daily in 8ft oak.
My waves and dives have gotten few and far between since I switched from 9-10* blades to 4*. Also, running the mill by the sound of the engine instead of a setting on the feed speed seems to have helped. I hit the wood at close to the speed I think I can cut, then adjust the speed to where there is a constant pull on the engine. The first time I hear the belts start to sing, I replace the blade because the next time it sings, it typically makes a wave or dive. I'm pretty new to running a mill, but this is what I've noticed in my learning curve.
Is there a noticeable difference of cut quality through big nasty knots with 1 1/2 and 1 3/4 bandsaw blades vs a 1 1/4 blades with same horsepower motor
The 1 1/2 and 1 3/4 do run flatter on my mill through knots, when sharp. When dull nothing cuts knots. Now is that due to the width of the band, the fact they are thicker, or a combination of the two?
There is no substitute for a sharp blade.
I have a couple of 1½" bands in circulation and when they start to dull, a large SYP knot will make them wave.
Besides a sharp blade, proper tension, and log orientation I find speed helps prevent waves. My LT35 will slow when it moves through knots, sloped grain, or just plain hard areas in an oak log (like the butt of a big old white oak). It seems that after the initial slow down it will recover and start to speed back up and that is when I see waves. So, I set the speed a little slower than I want to run and then provide a little push with my hand on the control panel as I walk along with the head. If I feel /hear a slow down I give a little extra pressure to keep moving steady or if it wants to pickup speed a little I can back off.
Had a major dive yesterday in a white oak when the head suddenly dropped the 4 inches I had on simple set for fence posts. The blade popped off rather than break. Since I was almost through I brought the head up, put the band on, backed up a bit and finished the cut. I figured I may have accidently hit the down lever but was pretty sure I did not so finished the log on manual. I then tried the simple set without a log...ran it several times and it happen again..oh no what does that mean.
At the recent gathering known as the "Sawing project 2022" there was a rep/tech from Woodmizer and he said that when you encounter harder sections of a log, what happens is that the power belt tension slips. His recommendation is to first make sure all your blade alignments are correct, as far as angle and tension.
Then check your power belt tension.
The belts will stretch until they find a "happy point" where they don't stretch any more. But they can still wear, and this can lead to slipping within the pulleys.
He said you should check your drive belt tension at lease every 40 hours, sometimes less.
Jim Rogers
Sounds like the wider blade is the way to go! For the most part everything is usually dead flat and straight except nasty knots and crotch wood can cause some variation. But I've had a devil of a time with some ash with nasty knots!!
Osage is at 2,620 on the hardness scale.(https://forestryforum.com/gallery/albums/userpics/59695/7317B048-8B4A-4EFE-88C2-DCF1D5501BBD.jpeg?easyrotate_cache=1649704930)
I see that hickory is the hardest American species on Walnut Beast's list. There are several harder American species not on that list. Live oak, persimmon, and Osage orange.
I think you get more stability in the cut from a thicker, rather than wider, blades. However, you lose flex life with thicker blades. I've settled on 1.5"x.045" as my go to, if I have something like siding where waves are a big no-no I keep some 1.5x.055 on hand. I would just run those as far as cutting performance, but I don't get as many bf out of them and they are a bit more difficult to handle when installing or sharpening and setting.
From what I've learned here, reading other places, and firsthand personal experience is that when you lose band speed, you get a wave. Causes of band speed loss could be a hard knot or wide cut loading your engine until it starts to lose rpm, or your drive belt slipping. A slipping drive belt is tough to diagnose because you don't hear it slipping. Also, being that it slips it is freeing your engine from the load that would otherwise bog it down and tell you to slow down the feed. If you are consistently getting humps or dives in wide cuts, check your drive belt. Actually, just get a belt tension guage and check it anyways, and keep it properly adjusted. Save yourself the headache😊
Rhodemont, I'm not sure I completely understand the technique you are describing, but it sounds completely backwards. Read the log and slow down before you get to the tough spot, listen to your engine for how fast you should feed. If I hear the engine pull down in a hard cut, the damage is already done and there will be blade deflection there.
I run nothing but the widest blade that my pip squeak sawmill can handle:
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If'en ya ain't ah runnin' wid da big dawgs, din stay yoself on da porch.
(https://forestryforum.com/gallery/albums/userpics/48503/image13.jpeg?easyrotate_cache=1622656166)
Mine got a little hot on the little saw grinder.... :D
Mesquite usually doesn't make the list when comparing hardness for some reason. From what I read it is harder then oak and some of the hardest woods. I have been milling 90% Mesquite for 20 years and have tried all the different blades that Woodmizer makes, some better than others. But the best so far is the Woodmizer BiMetal. They really do last at least twice to three times as long and can cut thru a nail and keep going. And I have tried the carbide which although amazing, they can't handle a nail. Now what am I going to do with all those 4 degrees, 9 degrees and 747 turbos?
I've sawed osage orange many times through the years and it's most definitely the hardest species I've dealt with. And incredibly heavy.
There's a 6' long chunk at my operation and it may be too large for my mill. It's been laying out in the sunshine for at least 2 years. I bet that joker would ruin a whole box of new sawblades. I'll find out one day. But not today.
Going to have to check things over everywhere. Having several dives in this ash I had to back out of with new blades. Everything is good on entry and cutting straight and then diving nasty several times. My feed rate is definitely not to fast
In ash make sure you have enough set and your down pressure is set at 1/4". Steve
Is the sawdust wet and packing in the cut or clearing out?
I think I am saying that I help read the log with a little hand pressure on the panel. I feel a slight bit of slowing before I see or hear it in the engine. Usually once I find a hard spot I do not have more waves because I know to adjust when I get there on the next passes. I do check my belt tension but probably not enough so maybe slipping delays my hearing the engine start to bog down just enough that I feel it first.
Quote from: Southside on April 12, 2022, 07:55:14 AM
Is the sawdust wet and packing in the cut or clearing out?
it didn't seem to be sticking. The sawdust was shooting out. Sometimes the sawdust looks like it's sticking to the band wheels but seems to come off. Maybe I need to back off the water dish soap heavy drip. I checked the levelness on the band wheels and they are fine. Measured the blade to the deck and it's the same with guide roller in on each side. Put a level on the blade and it's up slightly towards the front. So I'm going to adjust that. This is really frustrating! When I'm going along I can see and hear when the band starts to dive. The guide wheels stop turning and the sound is different.
Quote from: Southside on April 12, 2022, 07:55:14 AM
Is the sawdust wet and packing in the cut or clearing out?
I think Southside is right on the problems. I talked to the Timberking gang today and Jason said he's had several calls on similar problems since the ground is thawing out and sap is flowing. He said it's probably the pitch buildup that's causing the issues. He recommended Citrus concentrate degreaser. So I'll pick some of that up and try it. We talked Diesel but he seems to think it's hard on the belts and plastic. Southside had some good advice on this https://forestryforum.com/board/index.php?action=quotes (https://forestryforum.com/board/index.php?action=quotes)
Didn't even hardly run these and switched out on the ash. Going to try that citrus degreaser.
(https://forestryforum.com/gallery/albums/userpics/59695/BD473700-DA78-4673-9C8E-A794FD0B6F2C.jpeg?easyrotate_cache=1649803184)
(https://forestryforum.com/gallery/albums/userpics/59695/14122043-4D28-42EA-8A66-4A6F5FAB1687.jpeg?easyrotate_cache=1649803201)
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Thankfully I saw very little Ash. To me, Ash bark is worse than the log/wood itself. :-X
I see two things that bothers me.
In the first picture I see sap build up on the band teeth which means your lubricant is not doing its job. The build up is hard and sticks to the band. Nothing good comes from that buildup. To cure I might turn up the drip or add some kind of additive. My normal band set is 28 thousandths but if I have a bunch of ash I might push the set out to 32 to give a bit more clearance from sap build up.
In the third picture that board has huge grain run out which easily cause a wave if your band is the least bit dull, or if the band speeds drops from a slipping belt or lack of power.
You asked earlier about wider bands. I've switched completely to 1-1/2" .050 Kasco bands and know for sure I saw flatter lumber. I push my TK hard, with maximum width slab cuts in junk hardwoods.
That looks about like my circular blade that I took in after getting hot in ash. The sawdoc said to mix poplar in to clean the blade.
Yea, it's definitely a hard pitch build up issue, so you are getting friction and heat. See what the citrus does, but myself I don't even bother with any of that anymore, believe me I tried and tried as I wanted an alternative. The answer was to plug the bottom nozzle and just run the red fuel in the lube tank. Pitch is a thing of the past now. This evening I noticed that the lube tank level was just above the outlet, and it's been at least four weeks on that tank since I started to pay attention to it.
Sounds like I should just go right to the diesel. I'll give the degreaser a shot but I have a feeling it's going to be I told you so and running the diesel
Does diesel cause stains or hold sawdust on the boards?
You use so little diesel it doesn't bother at all.
Walnut, maybe your sawing to slow which might heat up the blade causing pitch to stick.. Yes go right to diesel. Steve
Ran 4 hrs on SYP this weekend and used about a half inch of diesel in the lube tank. I will say, it only took about 2 minutes to tell when my very slow drip stopped. Blades looked like those above. Takes very little.
Doc
I used a spray bottle to spray a few drops of diesel in addition to the water-based lube on my LT 35. It worked well enough but the convenience of lube in the tank would be much better. No customers ever complained about the diesel and lumber I've used had no diesel smell whatsoever.
Quote from: Brad_bb on April 15, 2017, 11:34:35 PM
About three weeks ago, fellow FF member rjwoejk, aka Bob from Canada, was driving his semi over the road in the US and managed to time one of his required downtime stops at my place in Illinois. He got here about noon and wanted to do some milling for a change of pace from all driving he'd been doing non stop for 3 months. He has the same mill as me back in Canada- a Woodmizer LT15. So we milled some cherry logs and the last log was a Honey Locust about 20 inches in dia. with some branch knots. I was cutting as many 4x8 pieces of brace stock (timber frame knee braces) as I could get.
(https://forestryforum.com/gallery/albums/userpics/16191/IMG_3209.JPG?easyrotate_cache=1490444062)
I first slabbed 3 faces and on one of them I had a wave(dive) about 3/8 inches. Bob asked me why that happened? I didn't know. I've been milling for a little over 2 years and have had my share of waves and dives. Sometimes you get a wave, and sometimes you get a dive that won't come back up. He thought I should have a little more blade tension. It was set where woodmizer recommends, but we increased the tension to where Bob says he has his mill set. So then we continued milling and cut 4 inch thick slabs. I set up 3 of the pieces to cut down to the 8" dimension. I had the live edge plus another 2.5 inch to take off so I decided to make some 4" boards. I started cutting and the blade dove. Bob was really getting curious why this was happening. He studied the outside piece and could see grain runout about 45 degrees toward the mill head(start of cut) where the wave started, see figure (1). Bob suggested that when the blade hit the runout grain from the knot, it followed the grain and thus dove. Since milling with the grain is much easier than cross cutting, it followed the path of least resistance. It did cut across the grain, but was being pushed down by the harder grain lines. It eventually cut through and came back up, leaving a significant wave.
(https://forestryforum.com/gallery/albums/userpics/16191/Blade_dive04152017_0000.jpg?easyrotate_cache=1492310567)
Bob suggested an experiment - turn the can't around so that the runout grain would go up and away as you cut as seen in figure (2). It worked! So I wasn't sure why it worked at the time, but somewhere in my brain it kept rolling around. Then recently it hit me- the guide rollers! They keep the blade from moving upwards. So if the blade wanted to follow the grain in figure (2), it is more difficult because the guide rollers support the blade or resist against the blade in that case. On the other hand, there is nothing to resist the blade form tipping down except blade tension. Blade tension is not enough to resist the blade twisting downward away from the guide rollers.
(https://forestryforum.com/gallery/albums/userpics/16191/IMG_3294.jpg?easyrotate_cache=1492312514)
In conclusion, I think grain runout in the direction of the opening end of the log and hardness of the wood can cause a wave or dive. Having a sharp blade helps cut across grain with runout, but is not a solution by itself. Adding tension above the factory recommended is of little help. I'll keep mine at the factory recommended tension. Orienting the log so the runout points away from the front of the log helps the most.
Many on here will indicate to orient a log with the small end at the front. This makes sense for a fairly straight-grained log. If the log has a lot of taper, orienting this way points the grain runout away from the front, consistent with what I've been saying. But when you have a log with large branch knots, you may want to make the butt the front of the log(starting point) so the grain runout from the large branch knots points away.
This is my thinking from this experiment. I will have to put this into practice more to gain more confidence in this. It seems logical to me.... or maybe I'm sniffing the wood too much? Weigh in.
(https://forestryforum.com/gallery/albums/userpics/16191/IMG_3217.JPG?easyrotate_cache=1490443242)
Funny I overlooked your original post. After Larry made a comment I did the same thing and turned the cant around and didn't have any trouble.
A combination of the hotsy degreaser , running more lube and turning the cant I didn't have any problems. I didn't pick any citrus cleaner up for lube yet. To try for the problems of the pitch of the ash. I did use some hotsy degreaser I put in and ran with no trouble but that ash stuff is nasty and is still sticking to the blade. I did a little test of diesel on the pitch with a paper towel rubbing a band and then the hotsy degreaser. I was surprised the hotsy degreaser took it better rubbing but the diesel not so good. But the diesel was super slick on there. I guess the real test would be running the diesel. I might do that after I try the citrus degreaser that Timberking guys are talking about. I think it's the Zep stuff they are referring to.
Quote from: ladylake on April 12, 2022, 04:32:12 AM
In ash make sure you have enough set and your down pressure is set at 1/4". Steve
I think I could use a little more down pressure. Timberking doesn't seem to do it that much
TK only recomends 1/8" down pressure while most other manufactures recommend 1/4 " down pressure which controls the blade better. Adjusting that was one of the first things I did when I got my mill. There is no downside to running 1/4". Steve
Sounds good Steve 👍
I'm with Steve on that down pressure- get you some! I run 1/4" as well.
I have an LT 15 wide. Have always had problems with waves. Talked to my woodmizer guy and didn't have much to help me. I would fight on wider logs and white pine knots. After reading this I pulled out my manual and woodmizer settings for down pressure is 1/4" so next day I adjusted them according to the manuel and they had very little down pressure probably an 1/8" or so. Much better! Been off since it was new. Thanks for the great I fo you guys put on here.
Quote from: Walnut Beast on April 12, 2022, 06:40:48 PM
Didn't even hardly run these and switched out on the ash. Going to try that citrus degreaser.
(https://forestryforum.com/gallery/albums/userpics/59695/BD473700-DA78-4673-9C8E-A794FD0B6F2C.jpeg?easyrotate_cache=1649803184)
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I think you need more set on these blades. If you are getting black marks on the blade body, it's touching wood. That means the teeth and groove are not clearing enough of a gap for the blade to move through it. When it rubs on the wood, it causes friction, hot enough and it will 'burn' and it picks up carbon. Widen out the set on your blades and see if it fixes this.
The Osage, Ash and the cottonwood have some nasty pitch. Got some zep citrus degreaser and see what gives. The Osage pitch was like concrete on the blade.
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Much of that blade gunk could come from the bark. If the bark will come off, get it off.