Milling cottonwood

[Bigbo1234]

I have some large cottonwood logs. About 30 and they range from 32" inside bark to 18" all about 8-10' long. I'm planning on using them for roof decking at 1" or 1 1/4". But they are a pain to cut. If I find a knot, I get bad waves, almost sea sick. Any ideas on how to prevent this, Or a better use for the cottonwood?

[Kansas]

You can cut cottonwood straight, although there is that occasional log that drives you nuts. The key is the set on the blade. If your cottonwood is like most of ours, its what we call fuzzy cottonwood. The fibers tear as much as cut. We run up about .030 set per side. We have always found that to be the key. While the more normal set of .022 will sometimes work right out of the box, a lot of times they just grab the new blade and increase the set.

[Bigbo1234]

Does a different pitch help, I have 7/8. Should I try 3/4? It is deffinetly stringy wood, lots of fibers.

[Kansas]

Personally, I don't think it would help, and might make it work. What size of blades are you using (thickness, width, set) and do you have a setter to increase set?

[Bandmill Bandit]

I cut a fair bit of the poplar and aspen and here is what i have found to work well MOST of the time

#1. Make sure you have a very well sharpened fresh blade.

#2. Minimum set from 30 min to 33 max.

#3. slow up you cut rate just a tad.

#4. Pour the blade lube to it steady too. I use 5 gal water with 5 oz of super bug eraser
      and 4 oz of a citric acid based commercial cleaning concentrate.   

 

[Kansas]

Sap buildup can indeed cause all sorts of blade problems. In cottonwood, we use little to no blade lube. But its possible cottonwood in other areas, or different species of cottonwood, might act completely differently.

[rmack]

on top of all the issues stressed logs create, my cottonwood is usually full of carpenter ants and much of it is rotten.

some of the lumber is really beautiful, light and strong, but that stuff is a very small amount of the total cut. most of it turns out to be propellers or bananas.

[GeneWengert-WoodDoc]

With a large log, you need a large size gullet to carry the sawdust away.  When you get close to a log, it is likely that you will slow down making the sawdust very fine.  Cottonwood is quite soft, so you need to saw fairly aggressively to avoid fine sawdust and spillage out of the gullet and heating the blade.  This would be especially true with a large log.  Heating causes the blade to cut wavy until the heat is gone.  A cold lube will help keep the blade cool and will remove the extra heat.  Try some cold water on the blade.  Cottonwood also has a very high moisture content (over 100% MC), so you have hydraulic pressure trying to control the blade as well.  So, it is best to use a bit more kerf (tooth set) to help relieve the pressure from all the water.

[Bandmill Bandit]

Wood doc is bang on for sure.

never thought about the speed much but now that you mention it I guess I pour so much water to it that  I can slow the cut rate a tad with out an adverse affects. will have to try a bit faster freed rate and see how that works. 

[mesquite buckeye]

The last cottonwood we cut was a 3 ft thick branch off a 6 X 20 ft main trunk (Fremont Cottonwood) It had been sitting for 2 or 3 months since the tree was pulled down with 2 D-9's. The bark was already loosening, so it started popping off when we started to turn it with the peaveys. Smelled like a big pile of wet cow stuff inside, and there were insect larvae in there, lots of them, that looked like fly maggots. They started to jump off the log when exposed, landing on us and all over the equipment. They can hop over 3 ft. ;D Milling was no big problem, except there seemed to be a lot of tension in the log. The boards all turned into bananas, pretzels and bow ties and ended up being trashed. The main log may have been better, but it never got done before it was degraded. Mixed feeling on wishing I had a Lucas at the time, cutting all that up and no value at the end. Anyway, long story short, I am cured on Fremont Cottonwood. smiley_deadheader alligator

[Bigbo1234]

I have noticed that there is a lot of tension in cottonwood, almost as much as moisture. IDE hate to see these logs go to waist but I'm not sure if its worth my time in milling them. I need material for a roof deck for a building to keep my mill under. And I already have the logs.

[Kansas]

Its interesting in cottonwood in that you can cut a board and it lay flat and straight. Toss it outside, let it sit in the mud, anything you want to do with it, it never moves. The next cut, the board gets up and walks outside. Its been our experience if its not in the blazing sun, summertime, I would guess about 80% lays fairly flat. If by roof decking you mean the underlayer, the key is to keep the boards stacked tight, bundled together and use ASAP. I am assuming smaller gaps won't hurt what you are doing. Green, you can move them around a bit if need be.

[Bandmill Bandit]

I used to think poplar/cottonwood  was all poplar. I now know that there seems to be as many species in side that poplar designation as there are other tree species in this part of the country all put together. I have also learned a bit about what logs to take to get a good chance at reasonably straight lumber and I will try to avoid most of the stuff that doesn't fit in the Aspen family as referred to locally. i think it is what i would call an under rated wood in this area and i will also state that we don't have some of the more valuable poplar species that grows further south. I certainly do like the end product that comes out of the Aspen species with in this family of deciduous trees. it does present a challenge but the end result is worth it i think.     

[5quarter]

Kansas' comments are right on the money. He probably cuts eastern cottonwood, which IMO, is only useful for pallets, blocking or pulp. Though having said that, Cottonwood was used in nearly all the barn construction around here and in many cases is still serviceable after nearly a 100 years of use. Would not be my first choice to build with, but you build with what you have. It cuts a lot like pine, except the pine smells nice.  ;) I use a lot of set like Kansas and I cut it dry; no lube. I have no clue about how it dries cause I've never cut any for myself. I think if you put it up green and kept the weather off it you'll be just fine. lots of good answers to your questions here...btw