So, we've come a long way on the second-hand homemade mill, but we've still got a problem that's really bugging us. On most of the pine we cut, the blade climbs into the cut for about 6 inches and then dives back down close to where it's supposed to be after another 4-6 inches, and then it levels out for the rest of the cut, (knots cause problems, but that's beside the point).
- We've got adjustable blade guides on it, (there's a thread on those somewhere), and we've got them tweaked so that there is a ¼" of down pressure across the blade. We've also verified that the blade is parallel to the bunks both left to right and front to back.
- We've had the same problem with multiple blades and multiple brands of blades. All have been 10° 1.5" blades, but they have been Lenox Woodmaster C and C Sharp, and Cook's Black Tip and Silver Tip.
- We didn't notice the blade doing the same on the ERC and Chinese Tallow we just cut. I'm thinking both of those are softer than yellow pine. But we literally took cedar boards off the mill that were nice and straight, put some pine flitches on the mill for edging, and they came off with the hump at the beginning of the cut.
- We've tried slowing down when pushing through the log, easing into the cut and then stopping to let the blade "equalize", trying to make sure the blade is tensioned, etc. Some of it sort of helped a little, but we still had the same problems.
Any ideas what we could try? Any idea what's causing it? Is the blade bending or rolling front to back as it goes through the wood? Is the angle of the blade changing as it goes into the log? Do we need more tension? Less tension? Smaller blades? Wider blades? Are we not holding our tongue right and dancing the right rain dance before we start the engine?
We've got 6 or 7 logs on the yard that we're going to mill up on Saturday. I think we're going to play with changing the angle the of the roller guides and maybe even put a narrower, (1"), blade on the mill to see if either of those make a difference. We haven't had many other species on the mill, so I can't say it is only happening with the pine. Of course, that's 99% of what we're going to be milling. I'm just stumped... Thoughts?
Do your blade guide rollers have flanges on the back? If so, keep reading.
Stand behind the blade (teeth on the side away from you). I'm going to assume the blade is moving from left to right right to left.
Which way do the blade guide rollers point?
1 - straight down the length of the mill? Bad.
2 - Slightly to the left? Awful.
3 - Slightly to the right? Good.
4 - don't know? Better check.
Here's what can happen. in case 1 or 2, if the blade gets pushed back against the flange, the point where the blade first encounters the roller is the part of the flange that is moving down. This will tip the back of your blade down, causing the blade to point upward so it rises in the cut. If you aren't pushing the head too hard, the blade can contact the flanges on entry into the log causing it to rise until increasing tension snaps it back down. If you're pushing the head really hard you'll get continuous rising and falling -- long ripples.
In case 3, if the blade gets pushed back against the flange, the point where the blade first makes contact with the flange is moving upward. This will tend to push the blade more firmly against the roller and all is well.
A good way to check this is to hold a straight edge across the face of the roller, and check it against the back of the blade.
Another thing you can check while you are looking over the guide, with the mill off and blade tensioned, tap up on the blade at each of the rollers if it chaters your guide is not putting even downward presure across width of the blade and needs realigned.
MSSawmill: What are you running for bandwheels? I encountered similar problem with my rubber tires. Found out the blade was having the set taken out on bottom side in contact with tires causing blade to want to rise. Had to turn rubber off more for tooth clearance. Make sure the blade is about 1/4" away from back flanges of roller guides if you have them. Then I could increase blade tension. Was a real nail biter till figured out what the H was going on.
I would be happy to show you the blade guide alignment procedure outlined in my WM Operator's Manual. Probably could also make some copies for you. :) A perfectly aligned sawmill is essential. Blade guide arm horizontal adjustment, aligning the blade ¼" deflection, vertical tilt, flange spacing, and the horizontal tilt that Brucer described above.
Do you notice this when sawing the "second cut" on a Pine log? Does it happen when you enter the small end on a butt log?
Sometimes even with the blade guides aligned and using a sharp blade, the blade will deflect when entering the log. LINK (https://forestryforum.com/board/index.php/topic,73155.msg1106639.html#msg1106639) The link is to a thread that was asking essentially the same question.
Quote from: Brucer on March 06, 2014, 12:15:18 AM
Stand behind the blade (teeth on the side away from you). I'm going to assume the blade is moving from left to right.
I pretty sure Brucer meant to say "right to left". :)
You want the rollers just barely skewed in relation to the blade. With a 12" ruler placed across the front of the roller, you want about 1/16" difference to the back of the blade from each end of the ruler. The more you skew the rollers the more the blade is sliding over the rollers vs. rolling them. This could, over time, cause premature wear of the rollers.
If you're creeping into the log with a sharp blade, the back of the blade shouldn't be pushing against the flange. Try entering the cut at or near regular sawing speed. I used to have a similar problem in hardwood until I stopped creeping into the cut. Also, check the drive belt tension. It doesn't take much slippage to cause trouble. Also, dried out log ends can deflect a blade, especially if you're tension is low or your blade is dull.
How long has the pine been sitting, if a for a while it may be that the ends are much harder and much dryer then farther into the log, if fresh pine, I will leave it up to some that know of the Southern pine sawing.
5quarter, that is a good and timely point about the drive belt that is easily and very often overlooked. The results from a loose/slipping drive belt can/will be erratic depending upon the species/hardness of the logs being sawn and the cause/cure can be elusive. smiley_dizzy Now if that sentence makes you dizzy, then start dealing with the problems caused by a slipping drive belt. ;D
Thanks for the input, guys! This gives us some stuff to try out tomorrow.
Quote from: Brucer on March 06, 2014, 12:15:18 AM
Do your blade guide rollers have flanges on the back? If so, keep reading.
We don't have rollers with flanges. They're actually just cam follower bearings on top of the blade with a small bearing behind the blade. I think I'll look a lot closer at how the blade contacts both, though.
(https://forestryforum.com/gallery/albums/userpics/32038/2013-05-19_18_13_12.jpg)
Quote from: backwoods sawyer on March 06, 2014, 01:30:42 AM
Another thing you can check while you are looking over the guide, with the mill off and blade tensioned, tap up on the blade at each of the rollers if it chaters your guide is not putting even downward presure across width of the blade and needs realigned.
We've got ¼" downpressure, but I'll check to see if that's enough.
Quote from: MikeZ on March 06, 2014, 02:57:07 AM
MSSawmill: What are you running for bandwheels? I encountered similar problem with my rubber tires. Found out the blade was having the set taken out on bottom side in contact with tires causing blade to want to rise. Had to turn rubber off more for tooth clearance. Make sure the blade is about 1/4" away from back flanges of roller guides if you have them. Then I could increase blade tension. Was a real nail biter till figured out what the H was going on.
We actually have "real" bandwheels on it. They're metal wheels with a v-belt in them. We have wondered if the teeth were riding on the wheels or on the guide rollers and losing set that way, but it doesn't appear to be doing that. I am going to look at the spacing between blade and the back rollers, though. Should be set to about ¼", but it won't hurt to make sure.
Quote from: Magicman on March 06, 2014, 08:03:45 AM
I would be happy to show you the blade guide alignment procedure outlined in my WM Operator's Manual. Probably could also make some copies for you. :) A perfectly aligned sawmill is essential. Blade guide arm horizontal adjustment, aligning the blade ¼" deflection, vertical tilt, flange spacing, and the horizontal tilt that Brucer described above.
Do you notice this when sawing the "second cut" on a Pine log? Does it happen when you enter the small end on a butt log?
Sometimes even with the blade guides aligned and using a sharp blade, the blade will deflect when entering the log. LINK (https://forestryforum.com/board/index.php/topic,73155.msg1106639.html#msg1106639) The link is to a thread that was asking essentially the same question.
Even though it doesn't apply to my mill, the concepts in that document would be nice to see...
And we notice it on every cut we make. There is less travel with a new, sharp blade, but that's to be expected. It doesn't matter if we're on the first cut of a log, last cut of a cant, or even just edging flitches.
Why would it deflect even with the guides aligned and a sharp blade? I'm just curious...
Quote from: Ga Mtn Man on March 06, 2014, 08:20:32 AM
Quote from: Brucer on March 06, 2014, 12:15:18 AM
Stand behind the blade (teeth on the side away from you). I'm going to assume the blade is moving from left to right.
I pretty sure Brucer meant to say "right to left". :)
You want the rollers just barely skewed in relation to the blade. With a 12" ruler placed across the front of the roller, you want about 1/16" difference to the back of the blade from each end of the ruler. The more you skew the rollers the more the blade is sliding over the rollers vs. rolling them. This could, over time, cause premature wear of the rollers.
Thanks for the detail. And I'm pretty sure he meant r to l, too...
Quote from: 5quarter on March 06, 2014, 08:28:52 AM
If you're creeping into the log with a sharp blade, the back of the blade shouldn't be pushing against the flange. Try entering the cut at or near regular sawing speed. I used to have a similar problem in hardwood until I stopped creeping into the cut. Also, check the drive belt tension. It doesn't take much slippage to cause trouble. Also, dried out log ends can deflect a blade, especially if you're tension is low or your blade is dull.
Doesn't seem to matter how I enter the cut. I'm definitely going to check the drive belt, though. We've got some adjustment in the clutch that may fix that.
Quote from: isawlogs on March 06, 2014, 08:35:17 AM
How long has the pine been sitting, if a for a while it may be that the ends are much harder and much dryer then farther into the log, if fresh pine, I will leave it up to some that know of the Southern pine sawing.
Good point... but it doesn't seem to matter. We've seen it with logs we just felled or with some that have set on the ground for a couple weeks.
Quote from: Magicman on March 06, 2014, 08:46:26 AM
5quarter, that is a good and timely point about the drive belt that is easily and very often overlooked. The results from a loose/slipping drive belt can/will be erratic depending upon the species/hardness of the logs being sawn and the cause/cure can be elusive. smiley_dizzy Now if that sentence makes you dizzy, then start dealing with the problems caused by a slipping drive belt. ;D
smiley_dizzy smiley_dizzy smiley_dizzy smiley_dizzy
How far behind the blade is that roller bearing, looks close in the pic it should be at least 3/16 to 1/4 behind for the best blade life. It really shouldn't hit the blade unless your pushing a dull blade and if not on the same plane as the blade it could cause the blade to go up or down when it hits the blade. Steve
I see this once in a while on my woodmizer. some causes..
not enough set in the teeth or more set on one side than the other.
dull blade
hard dry butt cut with lots of butt flare, starting with butt end.
not enough down pressure on the guide rollers
not enough blade tension.
mis-aligned guide rollers, ie blade not parallel to bed.
A combination of the above, which is difficult to diagnose
Assuming he has most of the above taken care of I'd really pay attention to those back roller bearings both in how far behind the blade and if they are parallel with the blade, mostly that they aren't too close as they shouldn't even touch with a sharp blade. Steve
Quote from: Magicman on March 06, 2014, 08:03:45 AM
I would be happy to show you the blade guide alignment procedure outlined in my WM Operator's Manual. Probably could also make some copies for you. :) A perfectly aligned sawmill is essential. Blade guide arm horizontal adjustment, aligning the blade ¼" deflection, vertical tilt, flange spacing, and the horizontal tilt that Brucer described above.
QuoteEven though it doesn't apply to my mill, the concepts in that document would be nice to see.
Without flanges on your roller guides, everything except the horizontal tilt applies to your sawmill. The actual method for aligning it may be different, but it all has to be done.
Actually the flange alignement would be the same as he has bearings behind his blade that act as flanges, so the basic alignement procedure would be the same.
Quote from: Ga Mtn Man on March 06, 2014, 08:20:32 AM
I pretty sure Brucer meant to say "right to left". :)
He did :-[. Thank you. It's fixed.
Quote from: isawlogs on March 08, 2014, 08:35:55 PM
Actually the flange alignement would be the same as he has bearings behind his blade that act as flanges, so the basic alignement procedure would be the same.
You are exactly right Marcel. Every item on the alignment applies, including the horizontal tilt.