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Bumps/rises in pine boards

Started by Solstice223, August 02, 2015, 12:16:06 AM

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Solstice223

Hey guys I just bought a like new Norwood hd36. I'm getting rises/bumps when milling through knots on pine logs. Should I increase the band tension or maybe replace the ceramics?

Brucer

Usually this is caused by the blade slowing down as it bites into the knots. By the time the governor picks up the slack you're through the knot and the damage is done. Increasing the blade tension may compensate some, but it doesn't solve the basic problem. Some things that will reduce the problem:

  • Saw more slowly.
  • Diesel engines are better than gas at maintaining a constant speed.
  • Electric motors are better than diesel.
  • Smaller blade angle helps: 4° or 7° rather than the usual general purpose 10° blade.
  • Keep the blade sharp.
  • Be fanatical about blade and carriage alignment.
Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

bandmiller2

Sometimes its hard to avoid but can be reduced as Brucer says less hook slow down going into knots and generally good band maintenance will help that being sharp and proper set. Take a scrap pine board and a hand chisel hold the chisel at 10 degrees and push it over the board, it wants to dig in. Try it now with a 4 degree that acts like a scraper with almost no tendency to dig in. Going from soft to hard is problematic for bands they tend to deviate. Frank C.
A man armed with common sense is packing a big piece

Magicman

Welcome to the Forestry Forum, Solstice223.  Adding your location and sawmill to your profile helps with answering questions. 

4° blades and entering the log from the top end rather than the butt end helps, but will not eliminate "knot wave".  All of the above suggestions are very vital to sawing.
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

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Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

Chuck White

Welcome to the Forestry Forum, Solstice223!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

drobertson

If the blade tension is not enough then yes crank it up a bit,  pine knots show up at times, the faster speeds will produce more rise at times, it's kinda a touchy feely thing.
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

Solstice223

Hey guys thanks a bunch! Completely new to all of this so all the info is a great help!

Banjo picker

Quote from: Magicman on August 02, 2015, 08:42:46 AM

entering the log from the top end rather than the butt end helps, but will not eliminate "knot wave".  All of the above suggestions are very vital to sawing.

I nearly always load the log butt first, but I can see the wisdom in turning a knottly log the other way...thanks Lynn I will give that a try.  Banjo
Never explain, your friends don't need it, and your enemies won't believe you any way.

deadfall

I generally prefer attacking the log from the upper end.  I will often turn them around to get it that way.  I just feel I can see what's in the log easier from that end.  I don't know why that is.  Never did any analysis of that idea. 

The tree we get here in the PNW where the knots will have their way with you is Sitka spruce.  I love the wood (between the knots).  It is so light and so strong.  I wonder how many piano, violin, and guitar sound boards it took to make that Spruce Goose? 
W-M LT40HD -- Siding Attachment -- Lathe-Mizer -- Ancient PTO Buzz Saw

============================

Happy for no reason.

beenthere

QuoteI wonder how many piano, violin, and guitar sound boards it took to make that Spruce Goose?
The wood most used in the "spruce goose" was birch.  ;)

The press called it the Spruce Goose and Howard Hughes didn't like the name, as he thought it was disrespectful of those who worked hard to build it.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

customsawyer

You might also check your drive belt tension.
Two LT70s, Nyle L200 kiln, 4 head Pinheiro planer, 30" double surface Cantek planer, Lucas dedicated slabber, Slabmizer, and enough rolling stock and chainsaws to keep it all running.
www.thecustomsawyer.com

Cutting Edge

Quote from: Solstice223 on August 02, 2015, 12:16:06 AM

....maybe replace the ceramics?


Yes,  that would be the best long term solution.  The ceramic guides actually compound the issue(s) of wavy cuts.  I've been down this road w/ a similar guide system.

Each time the blade deviates from it's straight-line path, it makes contact with the ceramic.  This generates heat which is transferred to the blade body.  Once this occurs, the blade looses tension.  Blade begins to make more contact w/ the guides, more heat generated, even further loss of tension.  As you can gather from the description, it is a downward spiral once it starts.

Does increasing the amount of lube help... kinda-sorta.  But then you have a soupy mess to deal with on everything/everywhere and you're only camouflaging the root cause of your problem.  Increasing the tension while the blade is hot/running only further damages the blade body.  Not to mention the additional stress placed on the carriage and components that it wasn't designed handle.

Upgrade to a roller guide system that applies down pressure and gives FULL adjustability... similar to what most consider as the industry standard.  Once you do, you won't look back.

http://store.cookssaw.com/sawmill-parts/roller-guides/standard-roller-guides/for-1-1-4-blades/1-1-4-complete-retrofit.html

Hope this helps
"Winning an argument isn't everything, as long as you are heard and understood" - W.S.


Cutting Edge Saw Service, LLC -
- Sharpening Services
- Portable/Custom Milling and Slabbing
- On-Site Sawmill Maintenance/Repair Services

Factory Direct Kasco WoodMaxx Blades
Ph- (304) 878-3343

Jim_Rogers

Rise and bumps are a sign of dull blade.
Put on a sharp one.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Solstice223

Thanks guys, cutting edge, do you have a picture of that device installed on your mill?

ladylake

 

I agree with cutting edge, put on some roller guides with at least 1/4" down pressure . Then the sharp blades, less hook, enough set and a clean blade plus I'm really liking 3/4 pitch blades better than 7/8.  Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

gmmills

   As Cutting Edge suggested, upgrade to actual roller guides.  He is also right on the money with the issues of heat induced loss of tension as the blade contacts the ceramic pads. 
Custom sawing full-time since 2000. 
WM LT70D62 Remote with Accuset
Sawing since 1995

Cutting Edge

Quote from: Solstice223 on August 03, 2015, 12:14:09 AM
... cutting edge, do you have a picture of that device installed on your mill?

I'm sorry, I don't have any pics of the upgrade.

But, I can do you one better.  ;D  I did some digging and found the image below, from a LOGOSOL sawmill (re-badged Norwood sold overseas). 

Direct swap/upgrade with no modifications ??  Might be worth investigating further.

Edit:  These roller guides don't have the adjustability as the ones from Cooks, but it would be a BIG step in the right direction.



 

"Winning an argument isn't everything, as long as you are heard and understood" - W.S.


Cutting Edge Saw Service, LLC -
- Sharpening Services
- Portable/Custom Milling and Slabbing
- On-Site Sawmill Maintenance/Repair Services

Factory Direct Kasco WoodMaxx Blades
Ph- (304) 878-3343

Solstice223

That's really slick. I'm going to have to buy that. Sure would near buying ceramics all the time. How long are you guys seeing the ceramics last before you need to change them out?

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