Lucas Slabber cutting downward

[Seaman]

Yet another case of my Lucas not cutting straight! Not the fault of Lucas, it always comes down to the bar, or my chain sharpening. So frustrating!
There are so many variables, I usually do not know what fixed it when it improves.
Did I mention frustrating?

I can find nothing wrong with the chains I sharpen, but if I put a brand new chain on it cuts straight!
Frustrating!

Bar is flat
Chains are at 10%
Rakers are filed to Carlton guage

Just had to rant. One of you may know something I do not.
Thanks

[sealark37]

If a new chain fixes the problem, there must be some difference in the sharpening you do to a used chain.  It is easy to sharpen left teeth slightly different than the angle used on right teeth.  You state that the bar is flat.  Is it possible that one rail of the bar is worn lower than the other rail?  You may need to have the bar rails ground to true.  Don't be discouraged, it's not magic, but it can be a very small problem.    Regards, Clark

[terrifictimbersllc]

Bars wear out.  The wear can be minimized by always keeping the front edge dressed square, and by running the chain tight. 

I believe the wear that destroys a bar and makes it no longer able to cut straight, is the widening of the groove, not at the top, but down deeper, where the bottom of the drive links are contacting. In other words the bar groove is now worn in a trapezoidal shape, the walls are not parallel to each other.  A bar with such widening is no longer able to hold the chain straight at 90 degrees. I would also add that I have observed that when bars are climbing or diving, I have also observed the phenomenon of it not cutting until I push it a bit harder, then observe that the chain "cocks" in one direction or the other, even if ever so slightly, after which it begins cutting again. Once on this path,  one is on a slippery slope of increased bar wear and poorer performance.

I plan to cut a used up bar in two to look at the cross section of the groove, to verify and show what I am saying.

If you haven't, either flip your bar over if the other side is unused, or less used.  The back side of a bar does not wear appreciably in use, compared to the front. Or put on a new bar. 

This may not be your problem, but it has been mine.

In my slabbing experience my bar (using both sides) has a life of about 150 slabbing hours or so.  I remember the first time I flipped a bar.  I was 125 miles from home, the sun was going down, and I had used all of the dozen or so chains I had with me trying to finish the customer's log without ruining the work.  It came to me that the only thing I hadn't tried was flipping the bar.  What a difference.

[Hilltop366]

Worn bar + new chain = less slop.

Worn bar + worn chain = more slop.

Chains, like bars don't always wear evenly.

For what it is worth the ripping chain I had I ended up grinding to 0° after a while, the less angle I used the smoother the cut.

My theory was the less sideways stress on the bar and chain the longer it would last, the smoother the cut and was easier to sharpen (grind) all cutters the same.

Also make sure the bar is parallel to your mill rails.

[Don P]

one more to add, we discovered that when the sharpener was swung for the other side we also need to adjust the tooth stop, it was not cutting the teeth the same length from side to side. I picked up a digital caliper to check the tooth length... it isn't what you set, it's what you get that matters.

[xlogger]

Keep us informed what you found out Frank. I've been lucky so far with my slabber but not even cranked it up for over a month now. Been able to cut everything on bandmill. Good luck.

[terrifictimbersllc]

one more to add, we discovered that when the sharpener was swung for the other side we also need to adjust the tooth stop, it was not cutting the teeth the same length from side to side. I picked up a digital caliper to check the tooth length... it isn't what you set, it's what you get that matters.

I do the same exactly.

I sharpen at 15 degrees top view,  and 60 degrees from horizontal.

[TKehl]

Are you freehand sharpening, using a jig, or a machine?

[terrifictimbersllc]

Chain grinder and occasional filing with a 15 deg  file holder. Monitor tooth length with digital caliper and keep raker depth .05-.06 "

[Chop Shop]

What kind of wood?

I have to run different angles on different chains for soft vs hard wood.

I battle softwood sawdust building up under the bar pushing the cut upwards.  On soft stuff I have to back up every so many inches to clear the cut out.

Is this a Lucas slab attachment or a dedicated slabber?

[Seaman]

Sorry fellas, I wrote a long reply yesterday, and somehow it did not post. So here is the short version.

The bar is freshly dressed on both edges, 90 hrs on the machine and the bar has had to be dresses 3 or 4 times already. The bottom edge ( of the drive teeth groove) has started grooving faster than the top.
TT, the inside of the groove may be wearing as you suspect, I will check.

Sharpen on a Oregon electric grinder, and both right and left are 10% and same length. Checked with dial caliper.
Rakers filed down to the lesser slot on a Carlton gage, not sure of the spec.
Set at 10% top and 60 horizontal.
Oil with 30wt.

I emailed Lucas, and Warren was kind enough to get involved. He suggested I get a strip of 16ga sreel to slide into the groove and hammer the edge closed around the still, so I will try that. He also offered to send me a new harder  bar under development to test. I accepted his generous offer of course.

I will keep you posted, thanks for the help.

[terrifictimbersllc]

What kind of wood?

I have to run different angles on different chains for soft vs hard wood.

I battle softwood sawdust building up under the bar pushing the cut upwards.  On soft stuff I have to back up every so many inches to clear the cut out.

Is this a Lucas slab attachment or a dedicated slabber?

I use 15/60 for everything. Mine is a Peterson WPF 10"swing mill with the slabber attachment and a smaller pulley on the gearbox input side to increase the chain speed when using it as a slabber.  I usually back up every 6 to 12 inches to clear sawdust.

[DR Buck]

This is a long shot, but have you checked where the bar ends mount?    There could be compacted sawdust not letting the bar sit flat against the mounting points on one or both ends, giving you a slight down tilt.

As I have not yet fired up my new Lucas dedicated slabber that I brought home from Paul Bunyan in October, I have nothing else to add, but I am following this thread.  Keep us posed.

[Seaman]

Dr Buck, yes , the mating surfaces are clean and bar is level.
I am sawing more today and will let you know.
Frank

[Grandedog]

Sorry fellas, I wrote a long reply yesterday, and somehow it did not post. So here is the short version.

The bar is freshly dressed on both edges, 90 hrs on the machine and the bar has had to be dresses 3 or 4 times already. The bottom edge ( of the drive teeth groove) has started grooving faster than the top.
TT, the inside of the groove may be wearing as you suspect, I will check.

Sharpen on a Oregon electric grinder, and both right and left are 10% and same length. Checked with dial caliper.
Rakers filed down to the lesser slot on a Carlton gage, not sure of the spec.
Set at 10% top and 60 horizontal.
Oil with 30wt.

I emailed Lucas, and Warren was kind enough to get involved. He suggested I get a strip of 16ga sreel to slide into the groove and hammer the edge closed around the still, so I will try that. He also offered to send me a new harder  bar under development to test. I accepted his generous offer of course.

I will keep you posted, thanks for the help.

Howdy Frank,
Don't feel pregnant, you're not the only one. We've seen this issue for years. It's really as simple as with the increased amount of people running high powered (not brand specific) mills with bar / chain setups, and the large amount of hours that they're being run, issues will show up sooner than later. These are made by Cannon and have a replaceable tip. http://leftcoastsupplies.com/product-category/forestry-supplies/forestry-supplies-bars-tips-forestry-supplies/forestry-supplies-bars-tips-cannon-sawmiller-bars/
Regards
Gregg

[terrifictimbersllc]

.......The bottom edge ( of the drive teeth groove) has started grooving faster than the top.
TT, the inside of the groove may be wearing as you suspect, I will check.  .....

IMO this means the groove inside has to be widening at the back, if when in operation the chain is pressed against the bar, with the the bottom edge a bit shorter than the top edge,  then the chain is tilting down a bit and the groove has to be widened down inside.  Otherwise the chain couldnt tilt because of the drive link, and the bottom edge of the bar couildnt wear more than the top.

I think one could detect this if one had one end of a 0.063 feeler gauge in the bar and seeing how much wiggle there is at the other end.  At least compared to a new bar.   I don't have such a gauge i'm just making a point.

[DR Buck]

.......The bottom edge ( of the drive teeth groove) has started grooving faster than the top.
TT, the inside of the groove may be wearing as you suspect, I will check.  .....

IMO this means the groove inside has to be widening at the back, if when in operation the chain is pressed against the bar, with the the bottom edge a bit shorter than the top edge,  then the chain is tilting down a bit and the groove has to be widened down inside.  Otherwise the chain couldnt tilt because of the drive link, and the bottom edge of the bar couildnt wear more than the top.

I think one could detect this if one had one end of a 0.063 feeler gauge in the bar and seeing how much wiggle there is at the other end.  At least compared to a new bar.   I don't have such a gauge i'm just making a point.

If that's the case, would one of these tools fix it?

http://www.baileysonline.com/shop.axd/ProductDetails?item_no=W%2010001&utm_source=googlepla&utm_medium=cse&id=394057828225&gclid=CjwKCAiA7JfSBRBrEiwA1DWSG2t1JdeOIIz1T7tKfNb_4XomomOo9tL68ZpYSbBMN2q0ucHCw48mMhoCF_UQAvD_BwE

[terrifictimbersllc]

It won't hurt, but that tool, or even hammering, can't close the widened-by-wear gap at the bottom of the groove, which is the problem. That tool will only squeeze the top back shut, if that (until  the bearings on it break).

[xlogger]

Frank, did you get it working good?