Advice on running a big bar (50"+)

[Doss]

Okay, so we were running the 66" double-ender today with ripping chain (ripping chain rocks! ). We have a helper handle with roller on the end of it. Here's my question, how much slack do you have in your chain? We could never seem to get it tight enough (Granberg kit) to our liking. Anyone use this set up or something similar? I'm just wondering if we need to crank it down tight to the bar and how much sag (deflection at center span (motorcycle term)) it should have.

Thanks in advance.

 

[mtngun]

Pics would help.

The chain does not need to be particularly tight. An inch of sag is not unusual.

 

[Doss]

At one point, it loosened up and the drive teeth were leaving the top of the bar (about 1/4" gap). That can't be right. We stopped using the chain at that point and are looking to maybe drop a link or two. Is that normal (it's a brand new 180 link chain)?

I say this b/c we run our other chains (41" bar) with very little sag... about about 1/8-1/4" off the bottom of the link (not the drive teeth).

Thanks again mtngun.

 

[mtngun]

We stopped using the chain at that point and are looking to maybe drop a link or two. Is that normal (it's a brand new 180 link chain)?

That is odd if you are out of adjustment with a new chain.

 

[Doss]

Well, when we put it on, the tensioner on the 880 was maxed out already (or really close). I'm guessing either we didn't install the roller correctly (the instructions are terrible, but I doubt we did) or the chain may have stretched just a little (it does that on motorcycles occasionally too). There aren't too many ways to put on a roller like that, but it still seemed to leave a little to desire in terms of set up and securing.

It's at the saw shop for a tune up today. It's running fine, but I was just making sure we're getting all the revs we can out of it. It seems to just a little out of adjustment (on the H and the idle is low). I know we could tune it, but since I have a normal 9-5 that just takes time away from my milling.

If it's not sorted when I pick up the saw, I'll snap some pics and let you see.

 

[dustytools]

Well, when we put it on, the tensioner on the 880 was maxed out already (or really close). I'm guessing either we didn't install the roller correctly (the instructions are terrible, but I doubt we did) or the chain may have stretched just a little (it does that on motorcycles occasionally too). There aren't too many ways to put on a roller like that, but it still seemed to leave a little to desire in terms of set up and securing.

It's at the saw shop for a tune up today. It's running fine, but I was just making sure we're getting all the revs we can out of it. It seems to just a little out of adjustment (on the H and the idle is low). I know we could tune it, but since I have a normal 9-5 that just takes time away from my milling.

If it's not sorted when I pick up the saw, I'll snap some pics and let you see.

Have you tried to adjust the chain at the helper handle. Its a lot easier to do it there than using the saws tensioner.

 

[gemniii]

or the chain may have stretched just a little (it does that on motorcycles occasionally too).

Every non Stihl chain I've put on my mix of bars has stretched.

 

[SDB777]

Not to be silly or anything.....but are you sure there were only 180 links? Someone might have mistakenly counted an extra link....people are only people.



Scott B

 

[BobL]

All my new chains (even stihl) stretch on first use. On a first pass with a new chains and a long bar it would not be unusual to have to re-tension after 3-4 ft of cut in Aussie hardwood

The other thing to watch out for is chain temp. If the chain gets too hot too quickly it can expand faster than the bar and get so loose that it comes off the bar/sprocket. This can be an issue if the bar is cold and the chain is blunt.

I tighten my long chains quite snug up against the bar.

. . . . . . but I was just making sure we're getting all the revs we can out of it. It seems to just a little out of adjustment (on the H and the idle is low). I know we could tune it, but since I have a normal 9-5 that just takes time away from my milling.

Be careful about tuning a milling saw to get the max rpm. If anything a milling saw carby setting should be richened up a little so that it runs ~500 rpm below its normal rpm.

 

[Doss]

Hey everyone, sorry for not responding. I was on a tour of the Abita Brewing Company all weekend :cool2:

Dusty, tried that but it was maxed out as well.

SDB777, that's what I thought could be the case. Since we were standing out in the Mississippi sun, we decided not to count links and to just go home and drink beer on the porch instead.

BobL (and geminiii), I was pretty sure it was going to stretch some (all chains do to my knowledge). I should have clarified when I said "get all the revs out of it." I am not looking to run the thing at whatever it can do. I was just trying to get it above what it is now (seems low even for milling). It seems to be down a few "usable" RPM's and the idle is off a little bit. The chain was new and sharp (checked). I had the external oiler flowing pretty good on it as well.

In the end, it's fixed now. Had to tinker with it some but it's good to go. The chain blew through red oak pretty easily.

I do have one more question (at least right now), do you put the oiler on the roller or the bar and chain contact point? I aimed it at the roller for now (helper handle on upside down).

Thanks y'all.

 

[Doss]

Found the culprit... it was the spur gear and tensioner slide.

Parts
1124 007 1008
1124 640 1900

The screw caught when you'd turn it, but it had a little play in the threaded part of the slide and the vibration would cause it to walk back down and lose tension on the chain. That, plus the normal amount of chain stretch probably added to why it was so loose. :msp_ohmy:

Anyone know a good source to get these parts? My local Stihl places said it'd be a minimum of the middle of next week if I'm lucky and they have to order more stuff. Otherwise, I'd have to pay freight confused::mad2: they weigh about 1 ounce combined :censored: ).

It took totally disassembling that thing and checking it to find that problem. When you turned the tensioner as you normally would, it worked fine.

 

[mtngun]

The screw caught when you'd turn it, but it had a little play in the threaded part of the slide and the vibration would cause it to walk back down and lose tension on the chain.

Sounds like the bar nuts were not tight enough. If the bar nuts are tight, there is no load on the chain tensioner.

Didn't see those parts on the 'bay, so you'll have to do business with your local dealer. There are no online sources of Stihl parts, other than whatever shows up on the 'bay, used parts on Chainsawr, and special order parts at Baileys.

 

[Doss]

Thanks mtngun. Yeah, I'm the second owner of this saw, so I'm going to blame it on the previous owner :msp_tongue:

I usually crank down pretty good on the bar to make sure it's on good. It was run with a 41" bar for I don't know how long now as a normal chainsaw... so I'm sure that may have had something to do with it. Does anyone know the torque number for those nuts (I'm a torque wrench freak)?

I may have to start milling some of these parts with a CNC machine and billet. Stihl obviously forges them from platinum and then uses alchemy to change them to hardened steel. 17 bucks for each part = $34 + freight (and yes... I actually mean freight).

I'll just go ahead and order some parts for a mini-CNC and hide them in my workshop (once they get dust on them, I can tell the wife I've had it for a long time and just now am getting around to using it :msp_thumbsup: ).

 

[mtngun]

17 bucks for each part

Not surprised. Bailey's lists $22 for each part. Part prices for the 120cc Stihls are outrageous.