Swing blade diving

[woodbeard]

No, not a new sadistic olympic event, just a problem I encountered today cutting a bunch of poplar 2x8s. The blade, usually toward the end of the cut, starts wandering downward in the horizontal position, and to the right in the vertical position. This happens mainly on full width or depth cuts. When it first started happening, I checked the blade temp, and it was still fairly cool. After playing around with various adjustments, I thought I had it fixed and finished up the log. It started doing it again as soon as I began cutting the next log and it was only with much aggravation that I got the next 5 boards cut, with increasing problem of cuts not intersecting.
Started diving so bad on the last cut I had to shut it off in the middle of the log. At that point, the blade was quite warm, but not so hot I couldn't keep my hand on it.
I am not running water to the blade cause the valve is busted, and until today, the blade has stayed quite cool without it. However, this is the first time I have run it this hard.
I am going to replace the valve and try it again with water, but what I want to know is: Is the blade dive caused by heating and changing tension, and can the blade cool off quickly enough afterwards that it doesn't feel hot?

[BW_Williams]

I had a similar experience with some Lombardy poplar awhile back, but chalked it up to log tension, kept the water on full and the saw sharp and it was ok.  Bosslady was pullin' lumber that day and the boards would jump off the log, she'd jump back and look at me and say "I didn't do that!",  hehehehe, we were cutting 16'ers and some boards would be bowed up 4-6" in the middle.  I worried the boards would be pretty bowed, so we stickered about every 16", weighted the pile down and got some nice fencing for my neighbor down the road.  It's kinda cool to drive by projects that are done with your lumber, especially trees that would have been burnt or sent to the landfill.  Good luck, BWW

[D._Frederick]

Wood,

Just a wild guess, Did you loose the corners on a couple of your saw teeth, is your drive belt slipping, is the blade parallel to the saw travel?

[Captain]

Woodbeard, be very careful that your track sections are not low in the middle, sometimes it happens after being setup in the same spot for awhile.  If the track section is low in the middle, the blade will go into a dive that you can not recover from as it heads back "uphill" on the other side.  

You also have to be careful when sharpening the blade not to introduce any "set" in the teeth (face angle), they should be zero degrees.  A blade with set in the teeth will dive, HOWEVER it should also be effected in the vertical cuts also.

Let us know how you are doing!!

Captain

[KiwiJake]

1) Check that your tracks are parallel and not sagging in the middle.
2) Check that your centre unit roller wheels have not accumulated sap and sawdust (tends to lift the back of it up giving the dive down effect) also check your carriage roller wheels are rolling on the same groove.
3) Check that the blade is not cooked, does it vibrate alot when running? Does it make excessive noise when you flip the blade? Put a new blade on if so.
4) Check that the centre unit roller gaps are not overly worn and that your stainless angle guide can not move due to the rivets coming worn. If so you'll need to rerivit the angle and buy new rollers.

 Allright, now you can check for adjustment.

Cut your self a flat slab, then drop down a click on your vertical drop winch. Skim a max width cut, does it dive? If so adjust the front white pads of the centre unit down so as to lift the front of it (fifth of a turn equally at a time). What you want when making the horizontal skim is a perfect radiul criss cross with no zing sound on the exit of the cut (you should be able to bring the blade back into the log while still in the same position with out back cutting on the reverse of the blade).

Once you get the horizontal running flat to the tracks you'll need to check for lead in. Move the centre unit sideways to achieve another max horizontal cut, cutting your full width gives the worst case scenerio for the lead in line to show. Does it leave a tiny JUST visable mark between both cuts? If it does it's perfect. The adjustment is the mid sideways stainless bolt (this is the tilt adjustment, if it doesn't show any line, adjust to give more tilt on the cutting side of the blade, if it shows it to much of a line give less tilt.). If the adjustments were way out, the locking machanism will need to be adjusted to a nice easy lock.

Now once you've reskimmed the whole face, turn off your motor and lock the blade into vertical, move it to rest above your skimmed slab, rotate the blade until the tooth is at it's lowest point, the tooth should be 3mm from the slab, adjust accordingly (top mid stainless bolt). Locking mech needs to adjust to suite aswell.

Allright, cut your vertical full depth board, does the vertical face give a nice criss cross patern, no zing on exit? Can you push the mill back into the cut while still in vertical with out reskiming the side of cut? The adjustment for this is located behind the operators right centre unit wheel, they are just simply washers, add a washer to bring the front side of the blade to the right, remove to move the front side of the blade to the left. It is important to note that when you do this adjustment, do it according to where you most likely pull the mill, also some times stress can give illusion to the adjustment process so try and adjust to a nice soft wood log if you can.

OK this is the full monty adjustment process, most problems come from simple replaceable wear items, guys get into trouble when they look past these and attempt to adjust without understanding the whole adjustment process, things get adjusted way out. So hopefully things havent been adjusted too much and it remains a couple of roller wheels, rivets or something. I've givin you this process on the assumption you have a Peterson, Lucas will follow the same principle of adjustment.

[KiwiJake]

I missed out the whole blade check process, teeth set etc, the guys touched on this though. If you've got a Lucas, they use a much thinner blade steel they actually suggest cutting your wide horizontal boards in two sections ie, 4" come back and do a further 4" to get your 8" wide boards, the problem is exagerated when you cut tension wood, this could cause the thinner blade to drift side ways just like a band.

I had to do it on our automatic when I was down south, although they were some monster tensioned logs, usually on a Peterson, tension just presses against the blade slowing the motor and blade down, thats when you know to take it in two bites.  

Good luck, hope I havent flooded you with too much info.

[woodbeard]

Glub, burble, cough, No, Jake, splutter, that's, cough, quite alright. ;) Actually it's a whole heck of a lot better than the info that came with the mill. And yes, it is a Peterson, 8"WPF, 20hp, bought used, built in '98
This is what I got:

Blade: one tooth does have a nick in the corner. The blades I got with the mill have 9 teeth and the guy had just had them worked on. I didn't get the impression that he really knew what he was doing in this regard, so it's possible they were not done correctly for this application. I will try the other blade, and check both for set, etc.

Tracks: If anything, I noticed a slight rise in the middle which I shimmed back out.

Roller wheels ( center unit): The right hand one was a little wonky when I first got the mill and I think I got it fixed by replacing the bearing clip and cleaning out the groove the clip fits in, but I will check it again.

Angle guide: not sure exactly what you are referring to, but I will check it anyway :P

Log tension: The diving started occuring on the very first face cuts. Some boards were a little bowed as they came off, but the cut faces of the log still looked straight.

Thanks all, I will give an update soon.

[woodbeard]

Well I have decided that since the blade is so prone to diving that I am going to give it to Fla. Deadheader. :D
I will include a couple sawfish as well.

But seriously, folks... Both blades do indeed have a slight set to the teeth. I assume I can take this out by sharpening them correctly, but I do not have the bracket for the sharpener that came with the mill. Is this something I can fabricate, or gotta get from Petersons?

Ok, I figured out what the stainless steel angle guide is, it's the track the front of the center unit sets on, right? It seems OK, but I noticed the circlip had popped back out of the wonky wheel I mentioned, so I put it back, and after removing both adjusting washers, the vertical cuts are much better. Still pulls a little to the right, but not nearly so bad. The cut pattern looks right, anyway.

Managed to get it good enough to cut some 6x6 cedar.

[Captain]

Woodbeard,

I hope you have the DIAMOND WHEEL for the sharpener, iffin you don't have the bracket.  

I JUST ORDERED a new bracket AND diamond wheel to replace mine which was STOLEN (along with 2 chain saws, another thread...)  It is far more economical to buy the sharpboy grinder here in the states.

Bracket : $21
Diamond Wheel : $108.50
Plus shipping.  

Call Angela on the freephone and tell her Captain sent 'ya.  Maybe she'll figure out who that is....