What we learned: waves and blade dives

[ladylake]

 In ash make sure you have enough set and your down pressure is set at 1/4".   Steve

[Southside]

Is the sawdust wet and packing in the cut or clearing out? 

[Rhodemont]

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.   

[Walnut Beast]

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. 

[Walnut Beast]

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

[Walnut Beast]

Didn't even hardly run these and switched out on the ash. Going to try that citrus degreaser. 

 

 

   

[Magicman]

Thankfully I saw very little Ash.  To me, Ash bark is worse than the log/wood itself. 

[Larry]

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.

[Don P]

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.

[Southside]

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.   

[Walnut Beast]

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 

[Rhodemont]

Does diesel cause stains or hold sawdust on the boards?

[ladylake]

   

 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

[DocGP]

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

[SawyerTed]

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.  

[Walnut Beast]

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.  



 

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.



 

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.



 

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.



 

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. 

[Walnut Beast]

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.

[Walnut Beast]

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 

[ladylake]

  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

[Walnut Beast]

Sounds good Steve 👍

[barbender]

I'm with Steve on that down pressure- get you some! I run 1/4" as well.

[mtmeatpole]

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.

[esteadle]

Didn't even hardly run these and switched out on the ash. Going to try that citrus degreaser.  

 

 

 


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.

[Walnut Beast]

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. 

 

 

[Magicman]

Much of that blade gunk could come from the bark.  If the bark will come off, get it off.