Hand sharpening harvester chain

[cuttsey]

I started hand sharpening my harvester chains after my boss suggested we gave it a trial, its worked out bloody well with a smoother, faster cut. Also theres less vibration which is helping with bar maintenance, the bar I've got on now has been there since Feburary, the boss is rapt.  The one problem I'm having is that my chains arent lasting the distance, the bar and chain speed have been both set to the Waratah manufacturers recommended settings , theres plenty of oil flowing down the bar and still the chains are busting after about three weeks processing. Broken drive links, broken rivots and snapped side straps both sides of the chain and never in any kind of pattern, mate it does your head in. I'm wondering if any of you guys have or are experiencing the same problem and what your trying to do to fix it.
  Cheers Cuttsey

[Gary_C]

First about the chain. I use mostly 18H Oregon chain with some Woodsman Pro thrown in. That is .404 pitch chain with .080 thick drivers.

And I never hand sharpen chain. When I am cutting, downtime is my enemy and I would never shutdown an expensive machine to sharpen chains. It takes me just a minute to throw on a sharp chain and back to cutting.  I carry at least a dozen sharp chains and rarely use more than 2-3 per day. I have over a hundred on hand at any time.

From what I know about how a chain cuts wood, vibration is not to be avoided. From the information I have seen, as each cutter cuts some wood it actually rocks back till the raker hits the wood and then the tension in the chain pulls it back down on the bar as it carves out a chip. So with the higher depth gauge setting on harvester chain, you should see more vibration while cutting properly.

As far as breakage, it mostly happens to me when I get the chain caught or pinched. And that is rare when that happens even though I do cut some large dense hardwood trees at times. However I do not have a surplus of power to break chains when they do get caught.

Here most harvester operators figure to need about a new bar per week they operate. So I do not know if saving that bar for four months is bad or good.

[Kevin]

Chain speed causes breakage.

It is well recognized that higher chain speeds
and/or feed forces (with attendant power input)
generally equate to faster cuting speeds. It is also
well recognized that faster chain speeds equate to
a shorter service life of the chain, bar and sprocket.

http://www.oregonchain.com/pdf/harvester/MechanicalHarvesting_2005.pdf

[Gary_C]

Kevin, that is certainly true, but all harvesters are set up with some fixed chain speed that is theoretically below the breakage speed. What usually causes the breakage is the chain getting pinched and perhaps at zero speed but full power on the drive motor, the chain gets stretched or actually broken. If it gets just stretched, the next time it gets run at full speed it may fly apart with sometimes serious consequences.

The machine manufacturers certainly do push the chain to maximum speed for faster cutting, but with a good chain, you should never get breakage at the set speed. The problem is in seeing the overstretched drive plates, rivets or side plates and fixing the chain before it gets used again. That is another reason to not sharpen the chain on the bar and hopefully you will see any damaged parts when you sharpen the chain.

I actually get more bent drivers than broken ones. They usually get bent when the chain gets thrown off the bar and hits something at high speed. The other problem is when the bar gets flexed too much and the chain gets stuck somewhere. Those chains will not hold that head when you move it away from something so it is usually time to change chains.

[Kevin]

Right on Gary, I don't know anything about them but I stumbled across that information and thought it might be useful.

[cuttsey]

Thanks very much guys but I'm running the bigger 3/4 harvester chain, Gary it takes me 5 minutes to sharpen my chain and I also get to stretch my legs and get some fresh air, I just process so the breaks good. I dont think my boss could afford for me to have 100 spare chains handy as they are about 200+ dollars here in New Zealand. I've seen harvesters with the .404 chain they cut wickedly fast but they don't last out on the skid, a little to much mud and rough operators over here aye ha ha. Have a go at that hand sharpening Gary I recommend it, its even faster sharpening the chains on an old bar in a vice after work.

Cheers for the info Kev we are going to run a timing gun on the chain sprocket to really see what rpm its doing, I am starting to wonder wether the 10 tooth sprocket may be the problem I might go back to the old 9 tooth.

  Cuttsey

[Gary_C]

Yes, I suspected you may be running the 3/4 harvester chain. I have run that on an older machine and yes those bars are expensive. But as I recall the bars were almost $300 and the chains were around $35. I still did not sharpen chains on the machine and probably only carried one or two spare chains as I did not change them often.

My sharpener is setup with a vice for those 3/4 pitch chains.

Is that Waratah head computer controlled so you know where the bar is while cutting?

[cuttsey]

yeah thats right Gary we are running waratah super C's on our landings and the bigwoods out felling in the bush. Oh boy prices are alot different in the States than over here, Bars are $600+ and a roll thats over a $1000.  Thats why I'm trying to find out whether anybody has had similar problems,  when we fix the problem the boss can shout more beer on Friday,  thanks Gary   
      Cuttsey