slabber drift upwards

Started by SEALOG, February 10, 2015, 12:17:40 PM

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SEALOG

I will keep this short with details.
Our LucasMill PH260 is a two-pass swing blade with a slabber attachment that can be swapped. We recently hit sand in a cypress burl and ever since then it has not cut the same. The reoccurring problem produces upward traveling bowed cuts that eventually bow upwards at such a degree it makes it nearly impossible to keep cutting, becoming so bowed and pinched that even pulling the bar back out of the cut seems impossible. We have tried flipping the bar with no luck, grinding the bar down to get rid of imperfect edges and tracks that seat the chain, heavy and light preloading (even no preload), chain maintenance including rakes and teeth and different tensions across the bar, hard and soft pushing force, and even talking softly to it asking whats wrong.

We are at a loss and are wondering if anybody here has had similar issues and what they did to correct this upward bow. We believe it is the rakes and teeth on the chain but not sure, wondering if there is something else we can try before ordering new chains and a few other new replacement parts. 

Thank you very much,
Nathan

ps. the harder we push on the mill the quicker the upward bow and tension

beenthere

Welcome to the Forestry Forum.
You will find some great help here, and even some heartfelt sympathy besides.

For starters, I'm thinking you are on the right track with the chain and would concentrate on it.

Others may see some other things happening as an apparent result of the sand.

Hang tight...
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Ianab

Has the actual bar mounting moved?

Try laying a straight edge on the bar, in the milling direction, and check it's aligned with the mill rails. It may only be out a tiny amount, but the longer edge lets you see it.
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

SEALOG

thanks guys, will look see and get back to you!

fishpharmer

It sounds as it the rails may not be parallel, if everything else is aligned and your carriage rollers and roller bearings are good. You may want to talk with Left Coast Supplies or even directly with Lucasmill. 

What model mill is it that your running? 
Built my own band mill with the help of Forestry Forum. 
Lucas 618 with 50" slabber
WoodmizerLT-40 Super Hydraulic
Deere 5065E mfwd w/553 loader

The reason a lot of people do not recognize opportunity is because it usually goes around wearing overalls looking like hard work. --Tom A. Edison

logboy

A Lucas PH260? It sounds like youre mixing the model of a Logosol molder with a Lucas Mill. There is no PH260 Lucas. Since you said slabbing attachment, you probably either have a Lucas 1030 or a Lucas 830 swingblade. Either way, troubleshooting is the same.

Are you cutting with a brand new chain or the same old chain youve had all along?

First the obvious. How did you sharpen the chain? What did you use? The majority of climbing issues are either due to a dull chain or improperly sharpened chain. If youre using a grinder with a pink wheel, did you reshape the wheel to the correct profile? They change constantly and must be reshaped. You should have a 10 degree top plate angle and 50 degree top plate cutting angle. 15 degrees is too sharp. What are your rakers at? If you hacked them off then the chain might not be clearing the chips. When that happens the sawdust builds under the bar and it climbs. Try doing this: after each foot forward, pull it back, then cut forward again another foot. This makes sure youre clearing the chips without climbing. Does it still climb?

Second, if it was cutting fine before the sand, but now it isnt, then chances are the sand wore out the groove in your bar, and/or wore out the bottoms of the drive links on your chains. Put a chain on the bar and tension it. Try and wiggle it up and down in the middle of your bar. If it moves more than a 1/16 or so in the groove, then that is your problem.  Put a brand new chain on and check it again. If it still wiggles then your bar needs dressing. If the bar is worn then you need to get a bar rail closer to slowly pinch the lips back together. Put it in a vise and slowly close it an 1/8th turn at a time with a bar rail closer. Careful, most are cheap China crap that will break.  It could be the chains as well though. My older chains have more play in the groove because the bottom of the drive links gradually wear off. Look at the bottoms of your Oregon 27RX chains. When they are new they are black, and have a pronounced 27 stamped in them. As they wear, the black starts to wear off, and then it starts to wear down into the 27. If the bottoms of your chains are worn, they will be shiny silver with no black, and the 27 will be almost worn off. If you cant even read the 27 on some of them then toss the chain and stop cutting sand.

As others have mentioned you may need to go through the bar alignment procedures to make sure the bar is in perfect plane with the rails. It is on another forum thread.

Are you set up on level ground? You can cut lumber on imperfect ground but you cant slab. All four corners need to be in the exact same plane. Crank your rails up a little bit so theyre not resting all the way down. Put a long level on the push bar of your swingblade. Roll it under one set of uprights. See where the bubble on your level is. Now roll the powerhead to the other set of uprights. Read the bubble again. It doesnt have to be level, but they do need to be in the same plane. If one corner is low by even 2 inches mine will climb. Pay attention as youre pushing the powerhead. If one trolley wheel is barely touching or turning then your mill is teetering on two wheels and the uprights need shimming underneath. I always have a 6' level for making sure my rails are in the exact same plane.

If you can, post photos of the chain(s) causing issues.

What are you cutting now that is climbing? If youre cutting softwood, then every foot or so you need to pull it back to clear the chips then cut forward again. The sap makes the chips stick and then they get under the bar and make it climb. Pulling it back every foot or so fixes this.

Are you hammering in a wedge to keep the slab from pinching the bar? Not wedging can make it climb as well.
I like Lucas Mills and big wood.  www.logboy.com

logboy

Hey @SEALOG, did you get your problem sorted out?
I like Lucas Mills and big wood.  www.logboy.com

Seaman

Logboy, that is a most excellent reply ! It needs to be added to Sidgis thread.
Hope this fella gets it figured out !

FRank
Lucas dedicated slabber
Woodmizer LT40HD
John Deere 5310 W/ FEL
Semper Fi

terrifictimbersllc

Sounds like what I went through over several jobs last year.  In short, if your chain, bar and setup are correct, like mine were, you may have a bar groove that is wallered  out wider as it goes deeper.  Take a set of thickness gauges that make up 0.063 or whatever fits in tight, and see how much you can tilt them from side to side (or does the groove keep them firmly straight up parallel with the bar).  The former was the condition of my bar.  In my case I fixed it by flipping the bar but then I had not used that other side yet for cutting.  I believe the condition I describe above allows just a bit of "cocking" of the chain during the cut, and it goes downhill from there  :D  or uphill in your case.
DJ Hoover, Terrific Timbers LLC,  Mystic CT Woodmizer Million Board Foot Club member. 2019 LT70 Super Wide 55 Yanmar,  LogRite fetching arch, WM BMS250 sharpener/BMT250 setter.  2001 F350 7.3L PSD 6 spd manual ZF 4x4 Crew Cab Long Bed

logboy

Quote from: Seaman on March 22, 2015, 06:43:28 AM
Logboy, that is a most excellent reply ! It needs to be added to Sidgis thread.
Hope this fella gets it figured out !

FRank

Yeah, I like it when I type out a long reply with valuable info only to have the person ignore it.
I like Lucas Mills and big wood.  www.logboy.com

Seaman

Lucas dedicated slabber
Woodmizer LT40HD
John Deere 5310 W/ FEL
Semper Fi