I'd like to come up with a blade profile that fits 80-90% of the sawing I do. There'll always be the exception but if I can standardize on one profile for the most of my work then it will make it easier to jump in and buy a CBN sharpener if I don't have to buy multiple grinding wheels.
For the experienced sawyers here lets see what your advice would be.
I've got an '87 LT40 that's 20 hp (Onan) It was originally a manual mill but I've added hydraulic log clamp, turner, side stops, and toe boards.
With this older mill I suspect the blade tension isn't up to what new machines are running. It just has the spring tensioner so I have no indicator of tension.
I'm running the original style guides that don't have a support plate under the blade, and currently I've got urethane belts on the band wheels.
The majority of what I saw is walnut, red oak & white oak. Virtually no pine in my area. Occasionally I'll saw some eastern red cedar, black locust, or cottonwood but not much.
The sizes can reach at the limits of the mill so I'm sometimes making as wide a cut as the guides allow.
I originally had some 10° blades, but recently have tried Bi-metal 7°-39 in .042 and some 4°-32's x .045
The 7's seem to work pretty well but I probably won't continue buying bi-metal on price, especially if you hit metal.
Haven't been as happy with the 4° blades. Seems like they take lot more power to get them to cut.
As far as the mill goes, I have to feed much slower than optimum to avoid pulling the engine down too much. In a wide cut I'm down to as slow as the mill will feed....not great. I do have some problem with wavy cuts through hard knots. Pretty good on a fresh blade but it can show up before the blade gets close to dull.
My nearest guess is that 7° is a decent all around blade, but on WM's site there are 3 different 7's. Plain 7°, Turbo 7, & 747 but it doesn't say what back angle each of these have.
BTW,
I have tried talking to WM a couple of times but some away frustrated. I start out trying to ask a general direction I should lean for blade choice, but they don't seem to be willing to give me recommendations for how my mill is set up now. I get advised to upgrade the band wheels and belts, guides, drive belt, and add a hyd. tensioner.....and possibly repower with new engine. All those things would be nice but cost a lot of money.
The only thing I came away with is I should be using .045 thick blades, if that sounds right.
When I mention anything that's not genuine WM parts on the mill, or modifications I've made, I catch a little condescending attitude. Sorry, but that rubs me the wrong way.
Sorry for the long-winded post.....Any advice I get will be appreciated.
Regular 7 is 7/34. Turbo is 7/39. 747 is 7/47. Second number is back angle from horizontal. IMO 7/39 is by far best of these. If it suits 20 Hp, don't know.
Try some 7° kasco or ripper 37s. They work well for me in both hardwood and softwood. The rippers are faster but they both cut true for me. I have 23 hp.
I'm surprised at your comment the 4* blades take more power. They have a smaller tooth angle taking a smaller chip and my experience is the opposite - they cut where a more aggressive hook angle will create waves, especially at a knot or in tension wood on a dense butt log. I am standardizing on 4* because they will cut an oak or ash and a pine or poplar while a 10* blade will not cut the hard wood like the oak or ash and will even want to jump over a knot in pine or spruce.
Good luck on your decision. I agree on standardizing where possible but you have to use what works best for your mill.
I have only ever used 4°, 9°, 7/47, and 7/39 W-M blades.
The 7/47 sawed well however the beam strength of the tooth at the tip is less than desirable and I will not purchase anymore of them in the near future.
When the 9° blades are done I have no intentions of ordering any more of them.
Recently I purchased four 15 packs of 7/39 blades.
I have many 4° blades in my inventory.
Bottom line is I am concentrating on 4°, and 7/39's.
GAB
Have you checked your drive belt tension? If not that is likely contributing to your issues. Recommended interval is 50 hours and mine is always loose if I go that long so I check it weekly.
It doesn't take much slip of the drive belt to drop band speed when you hit a hard spot such as a knot. The result is blade dive, and you get waves.
Being an older engine HP may not line up exactly with modern ratings. My gut tells me you likely have a bit more than a 20 HP rated engine of today. Torque is the real key however.
Personally I only run the Turbo 7 profile on both mills. My 35 has a 25 HP rated Kohler and that is by far the best performing band in all wood.
I would also invest in a band tension gauge so you can read actual band tension and dial that in.
Just having both dialed in will make all profiles perform better in their intended species and let you push the boundaries of the list.
I agree with VW sawmiller. I switched from 10° to 4° for everything and won't go back. It does make finer sawdust but I wear a mask so as to not inhale sawdust.
Quote from: WV Sawmiller on December 07, 2021, 08:08:54 PM
I'm surprised at your comment the 4* blades take more power. They have a smaller tooth angle taking a smaller chip and my experience is the opposite - they cut where a more aggressive hook angle will create waves, especially at a knot or in tension wood on a dense butt log. I am standardizing on 4* because they will cut an oak or ash and a pine or poplar while a 10* blade will not cut the hard wood like the oak or ash and will even want to jump over a knot in pine or spruce.
Good luck on your decision. I agree on standardizing where possible but you have to use what works best for your mill.
I find 4° take a bit more power but they cut straighter, I run 4°. Steve
When I had my LT15, with a 15 Hp Kohler engine, I used the Woodmizer standard 7/34-.045, what they call their "frozen wood blade" and I used it for every species you mention. Feed was with a hand crank, and I could get 1/2 inch feed per revolution of band, which at the time for me was a pretty good clip.
With an LT-40 Diesel, I could get 1" or more per revolution with the same band. So the band will stay stable at higher feed speeds than you have the horsepower for.
That is a very good way to gauge feed speed, look for the one always out of set tooth on the blade and measure the distance between its reoccurrence on the surface of the board. A you work with the different bands, the actual feed rate is easy to quantity.
Anyway, with a 20hp engine, I would expect 1/2" to maybe up to 3/4" of feed per revolution of band in an average sized log, 15" to 18" give or take.
If your sawdust is packing like flour, then that is robbing power and will also cause waves.
If your bands are not dead clean and shiny when cutting that residue greatly impacts band performance.
Are the bands sharp and in good shape? I assume they are, but I had to ask.
Quote from: YellowHammer on December 08, 2021, 07:44:50 AM
When I had my LT15, with a 15 Hp Kohler engine, I used the Woodmizer standard 7/34-.045, what they call their "frozen wood blade" and I used it for every species you mention. Feed was with a hand crank, and I could get 1/2 inch feed per revolution of band, which at the time for me was a pretty good clip.
With an LT-40 Diesel, I could get 1" or more per revolution with the same band. So the band will stay stable at higher feed speeds than you have the horsepower for.
That is a very good way to gauge feed speed, look for the one always out of set tooth on the blade and measure the distance between its reoccurrence on the surface of the board. A you work with the different bands, the actual feed rate is easy to quantity.
Anyway, with a 20hp engine, I would expect 1/2" to maybe up to 3/4" of feed per revolution of band in an average sized log, 15" to 18" give or take.
If your sawdust is packing like flour, then that is robbing power and will also cause waves.
If your bands are not dead clean and shiny when cutting that residue greatly impacts band performance.
Are the bands sharp and in good shape? I assume they are, but I had to ask.
Without measuring, I don't think I'm getting anything close to the feed rates you mention.
The bands I've been using are new so a bad sharpening job is out of the equation. I been using water only on the blade, especially on Ash (forgot to mention I'm sawing quite a bit of it too) Perhaps I need an additive to the water. I'm going to have to switch to something like washer fluid pretty soon anyway with cold coming on.
The original guides have the tube for blade lube on the stationary side which, isn't ideal and it does leave a small amount of debris on the blade. I would think having it ahead of the cut would be more effective.
One reason for updating the guides I guess.
I'm going to check the high idle speed of the engine today just to be sure part of my lack of power isn't related to engine speed. Onan rates it up to 3600 rpm....pretty fast for a small engine. On this engine the high idle is a pain to adjust. Basically you move the governor rod to a new hole in the arm and hope it changes the amount you want. A screw adjustment would be much easier.
I use and am happy with 4* kasco blades with pretty much the same woods in NW Iowa (more Bur and less Red oak). I'm also running a 20hp motor on an old Timberking B16. I tried 4* blades from Woodmizer and found that for me they didn't seem to cut as well. I've never tried 7* blades.
On really wide cuts (20+") in oak/ash logs that have been sitting for a few years I really have to slow it down to a crawl but fresh logs are better and if I keep the cuts under 15" or so it will cut pretty quick. I pretty much lost interest in getting really wide pieces so generally shoot for 12" boards and under but when cutting up a big log you still can't avoid taking some wide cuts as you whittle it down.
Alan
In ash or dried out white , bur oak if I end up with a 18 inch cant I'll cut it down to 12" and throw the top 6" on the loading arms, then finish the remaining 12" to 2 6 " or 12" boards or planks rather than 18" which is slow even with a 30 hp diesel. Steve
Haven't had a chance to test it out yet but I may have found a couple of things that should help my power problem.
Checked the high idle speed and found it about 200 rpm low.
The other was a small crack in the fuel line that hangs down in the tank, allowing it to suck air. It seemed to be running ok but I wonder if under full load it may have been starving it for fuel a little.
Thinking of getting a tension gauge. Anyone familiar with this model?
https://www.ebay.com/itm/154651079847
It's a little cheaper than the Lennox gauge if it's any good.
If I find the tension way low I may replace the tension spring. Don't know what WM is using but it looks like a standard die spring.
I looked in the Danley die spring catalog and an 1 1/2 x 3" extra heavy duty spring will have 1,444 lb. force at 3/4" deflection.
With the cross sectional area of the blade (times 2) that calculates out to about 16,000 psi.
If that's not enough they make an ultra heavy spring that way stiffer yet.
On my TK with a yellow die spring about 2 1/4 long I compress it about 1/2 " and it cut good, back when the TK gauge used to work that was 1100# . Now I compress it down to 1 7/8" which cuts good. I've tried more tension which doesn't seem to help at all. Steve