blade diving

delvis · July 13, 2012, 10:58:04 PM

Hello there, Wondering if anyone has any thoughts on a question of mine. Last November, my father and I bought a brand new Woodmizer LT40HD. We went for most of the bells and whistles except the diesel engine. Before this mill I owned a Timber Harvester. The WM is incredible in speed, precision, and accuracy. The question I have concerns blade dive in knotty softwood. I don't remember seeing nearly as much of that on the old mill as I have with this one. We switched from a 10 degree hook angle to a 7 and the mill seems to have more than ample power to run the blade. (39 horse Kohler) The 7 degree blades make a huge difference, but I still see more blade diving in knotty pine than I care to. Even in narrow cants. The blades are 1-1/4, .045, 7/8 pitch. We have tried to stay on top of our alignment(s) and proper blade tension as WM is now recommending much more tension than they did at one time. Anyone have these same issues and how have you dealt with them?

Thanks, Mike

POSTON WIDEHEAD · July 13, 2012, 11:08:02 PM

Delvis, Welcome to the Forestry Forum.

I have an LT40 HD G28.
I run my blades at 2800 PSI
I use the 10 degree blade.

I saw ALOT of knotty Pine
When I saw good clear Pine, I can "walk the dog".
When I am sawing knotty Pine, I do slow down a bit. I keep my eye on the cant at all times when sawing knotty Pine and as I come up on a knot, I will slow down a bit as I go through it and then pick up speed after I exit the knot. I don't see as much as a dip with a brand new sharp blade....speed is the answer. Be sure to move your blade guide in closer to the cant, that helps also. Also make sure your blade is clean from sap build up.

All in all, I have a pretty nice board doing this. Sawing knotty lumber, you will tend to have a little dip if you don't slow your speed down accordingly.
All band mills will show a little dip, if you exceed the 55 mph speed limit, that's why it's called "Rough Cut Lumber".

delvis · July 13, 2012, 11:16:47 PM

Thank you for the welcome. I actually joined three years ago but never got around to posting until being reminded of the forum through a WM publication.

I think the extra horsepower engine may actually be part of the problem. It allows for some pretty fast feed rates and in the knotty pine that if I go too fast it shows.

POSTON WIDEHEAD · July 13, 2012, 11:24:07 PM

I went through the same thing when I got my WOODMIZER.
I couldn't get anything right. say_what
I soon found out, it was not the mill but the "LOOSE NUT BEHIND THE MILL". :D

Buck · July 13, 2012, 11:48:10 PM

Lots of "us" loose nuts out here ;D Welcome!

ladylake · July 14, 2012, 04:18:33 AM

Try a 4* blade with good set, that should do better but as mentioned we tend to feed knotty pine too fast. Steve

customsawyer · July 14, 2012, 05:36:36 AM

Keep in mind that there is changes in the density of the wood when sawing through the knots and it will make a blade do some funny things. There is also changes in the grain that is going to have effect on the blade. Welcome to the forum. Where are you located?

terrifictimbersllc · July 14, 2012, 06:02:20 AM

Knotty softwoods are here to remind us we are only human.

Chuck White · July 14, 2012, 07:02:23 AM

I think pretty-much everything was described by David in his post!

The only other thing I can think of would be a dull blade!

Change your blades a little sooner than normal!

I don't think there is a blade made that you can just "zip" right through knotty wood!

I saw mostly pine, but yesterday I had 5 or 6 Spruce logs in the pile and was reminded that the knots are "still" hard. I cut my feed speed to about half and kept the tension and lube up and sawed out some pretty nice boards!

Magicman · July 14, 2012, 07:21:25 AM

Since you have been here for a while, I'll say Welcome to Posting.

If you are properly aligned and the blade is running parallel to the bed rails, the only thing that I can add is that entering the log from the small end will minimize knot wave.

bandmiller2 · July 14, 2012, 07:58:51 AM

Sometimes dispite your best efforts you will get the "wave" opening up a knotty log.Take a slow corrective cut and don't let it ruin your day. Frank C.

ladylake · July 15, 2012, 06:07:47 AM

You made a big improvement with a 7* blade, a 4* should do even better. Last time sawing wide spruce a brand new 10* blade looked like the ocean on a windy day, 4* went straight. Steve

bandmiller2 · July 15, 2012, 07:36:14 AM

What Steve says is true,hook angle has alot to do with wave.Compare to a wood chisel push it along a board at angle say 10* back it will tend to dig in and vary with the hardness of the wood.At 4* it acts more like a scraper and has little tendency to dig in and less affected by hard/soft such as knots.Less hook tends to make a manual mill harder to feed and uses more HP.Theirs no free ride in this old world. Frank C.

ely · July 16, 2012, 09:47:50 AM

in knotty pine my manual mill will dive, i guess any mill will dive for that matter. mine dives because the sap from the knots builds up on the outside blade guide roller , in order to counter this action i turn the soapy water mixture up a few notches until the sap goes away, when that fails to do the trick, i turn the water off and use my squirt can of oil mixture on the blade as i saw. a couple squirts every couple feet or so will get me thru the toughest pine knots.
its the same oil i use on the rail wiper pads,50-50 bar oil and kerosene.

delvis · July 29, 2012, 10:40:29 AM

I have thought about trying the 4 degree blade but wanted to make sure my engine will handle it. I have the Kohler 39 horse. I love the extra power but I think it makes it easy to oversaw a blade, especially one that is dull. Thank you all for the welcome and the advice. Look for the next question soon. Lol.