CSM speed in softwoods

[Kicker_92]

I've been slabbing up some douglas fir with the alaskan mill and my 385xp, 30" bar and found it very slow at times.

For a 22" wide pass, 12ft long, I will go though an entire tank or more of fuel. The saw doesn't seem to be pulling strong at the top end, and I'm questioning if it's tuned right.

I've set the mixture about 1/8 turn below the peak rpm for the high circuit. It seems to have a fair amount of grunt at lower rpms, for then dies off once the speed picks up. When I'm cutting thin stuff it goes quick and the rpms stay up, but the slabs are causing it to bog.

The saw is unmodified, and I'm using a full chisel skip chain, ground at 10° angle. The chain is cutting well, but the saw just doesn't pull it.


Is it just not enough saw for this width of cut, or does this sound like a problem?


Thanks,

Ryan

 

[BobL]

I've been slabbing up some douglas fir with the alaskan mill and my 385xp, 30" bar and found it very slow at times.

For a 22" wide pass, 12ft long, I will go though an entire tank or more of fuel. The saw doesn't seem to be pulling strong at the top end, and I'm questioning if it's tuned right.

I've set the mixture about 1/8 turn below the peak rpm for the high circuit. It seems to have a fair amount of grunt at lower rpms, for then dies off once the speed picks up. When I'm cutting thin stuff it goes quick and the rpms stay up, but the slabs are causing it to bog.

Is it just not enough saw for this width of cut, or does this sound like a problem?

Provided the chain is set correctly the 385 should have no problems with this size and type of log. A whole tank of fuel sounds like a bit too much.

Some questions for you
What's the compression like? measure the actual cold and warm PSI not just "it's OK"
What raker setting are you using?
Is your bar parallel to your mill?

 

[SilverBox]

I've been slabbing up some douglas fir with the alaskan mill and my 385xp, 30" bar and found it very slow at times.

For a 22" wide pass, 12ft long, I will go though an entire tank or more of fuel.

An entire tank for 12' feet? How long does it take you? 20 min? Thats like 8 seconds an inch? Seems awful slow, I'd expect more like 1-3 seconds an inch..

 

[chainsaway]

thin stuff?

Since you said thin stuff goes fast, could it be that the slabs end up pinching the "top" of your chain/bar thereby robbing of power?
cheers alain

 

[redprospector]

Since you said thin stuff goes fast, could it be that the slabs end up pinching the "top" of your chain/bar thereby robbing of power?
cheers alain

I'm not a chainsaw miller, but that was the first thing that I thought of.

Andy

 

[dallasm1]

On a 12 ft doug fir of that width, even when cutting thin planks I would use at least 8 wedges, 4 each side every three feet. Not only does it keep the pressure off of the chain, but it maintains a parallel cut. Where in BC are you?

 

[Brmorgan]

Hey Ryan, where ya at in BC? Must be farther south to be milling this time of year! I cut primarily Douglas Fir around here. Last summer I cut a bunch of beams, and I was getting 1-1/2 20' cuts on a tank, each about 8 minutes with my 395, in about the same size of wood as you're working with. 28" bar, full comp chain at 25°. I know my saw's a little bigger, but not THAT much.

You might not need to richen it up by 1/8 turn - that's quite a bit on some carbs. Are you using an 8-pin sprocket by chance? If so, that would explain the engine bogging easier. The importance of proper sharpening can't be overstated with milling, either. Every tooth needs to be the same length and every raker exactly the same depth.

That being said, seriously consider modding the muffler of the saw. It improved my 395 greatly, and as an added bonus it runs cooler which will help the engine last longer.

 

[SilverBox]

Last summer I cut a bunch of beams, and I was getting 1-1/2 20' cuts on a tank, each about 8 minutes with my 395, in about the same size of wood as you're working with. 28" bar, full comp chain at 25°.

That sounds like what I'd expect, 2 seconds per inch.. 4x faster.

 

[Kicker_92]

Wow, thanks for all the reponses so far!

Brmorgan: I've been following your fir milling threads, thanks for all the great info. I'm just outside of Vancouver, BC so it is much warmer down here than up north.

BobL: I don't have a compression gauge, I'll try and find one to borrow to get some actual numbers. The saw is older, so I wouldn't be surprised if it were pretty worn.

I've been using wedges about every 2-3ft, will check on the sprocket to see if it's an 8-pin. Would a 7-pin be much better for keep the rpm up? It's a 3/8" pitch.

Average has been about 30mins per 12ft cut...

 

[dallasm1]

Wow, thanks for all the reponses so far!

Brmorgan: I've been following your fir milling threads, thanks for all the great info. I'm just outside of Vancouver, BC so it is much warmer down here than up north.

BobL: I don't have a compression gauge, I'll try and find one to borrow to get some actual numbers. The saw is older, so I wouldn't be surprised if it were pretty worn.

I've been using wedges about every 2-3ft, will check on the sprocket to see if it's an 8-pin. Would a 7-pin be much better for keep the rpm up? It's a 3/8" pitch.

Average has been about 30mins per 12ft cut...

Did you say 30 MINUTES per 12ft cut? NO WAY, something is wrong. WAY wrong. On a 12ft cut, I would expect if you are not getting through in 5 minutes or less you have something seriously amiss. Is the saw running near top rpm and not cutting? or is it bogging down and not cutting? Perhaps you should try another saw with a standard crosscut chain, just for a comparison.

 

[BobL]

Wow, thanks for all the reponses so far!

Brmorgan: I've been following your fir milling threads, thanks for all the great info. I'm just outside of Vancouver, BC so it is much warmer down here than up north.

BobL: I don't have a compression gauge, I'll try and find one to borrow to get some actual numbers. The saw is older, so I wouldn't be surprised if it were pretty worn.

I've been using wedges about every 2-3ft, will check on the sprocket to see if it's an 8-pin. Would a 7-pin be much better for keep the rpm up? It's a 3/8" pitch.

Average has been about 30mins per 12ft cut...

Yeah - way too slow for a softwood - even slower than any of the hardwood I cut.

Any chance of you posting some pics of close ups of your cutters?

 

[carvinmark]

That's WAY slow. Is the chain getting enough oil ? We need to see the cutters. Something is wrong, you should be going about 4 times faster IMO.

 

[hazard]

When I read your post I thought the same things that everyone else did.

1. Pinching the blade with the weight of the board
2. No oil or bad oil on the bar
3. Dull chain

What kind of bar oil are you using. To me this makes a big difference. Do you have an auxillary oiler? If there is not enough oil on the bar the chain cuts like crap.

I would love to mill some soft wood to see how fast the 066 would make boards.

In a 24" walnut log 7' long takes me around 15 minutes. This seems to be alot harder to cut then say oak, cherry or maple for me.

Chris

 

[BIG JAKE]

Wow, thanks for all the reponses so far!

Brmorgan: I've been following your fir milling threads, thanks for all the great info. I'm just outside of Vancouver, BC so it is much warmer down here than up north.

BobL: I don't have a compression gauge, I'll try and find one to borrow to get some actual numbers. The saw is older, so I wouldn't be surprised if it were pretty worn.

I've been using wedges about every 2-3ft, will check on the sprocket to see if it's an 8-pin. Would a 7-pin be much better for keep the rpm up? It's a 3/8" pitch.

Average has been about 30mins per 12ft cut...

Most milling chain I believe is round chisel. Round chisel is said to leave a smoother finish in your lumber but also cuts a little slower(not as aggressive cutting). Just how much I don't know and I haven't done timed cut comparisons. With a skip chain I would think your saw would pull that chain no problem with 8pin but maybe not with the full chisel. If you run too rich it'll rob you of enough power to give you very slow cuts like you have but you need to be careful so you don't burn your powerhead up. Find out first what your compression is. I would think 120-130 psi would be end of life for milling especially with lower horsepower saws but no experience to draw from to assure you of this-my 066 is still at 155-160psi and that saw is 7.1hp to your 6.3 hp. Others here can tell you for sure. You'll probable gain a half horse at least if you mod the muffler right. At this point baseline your saw: compression, sprocket probably should be 7 pin, filters clean, spark plug good, adequate bar oil, rakers to recommended height etc. Also, the cutters should be same length and sharp(you can use calipers to confirm this but be very gentle). If all this is good you could also try higher octane gas, and try varying your pressure on the mill maybe your bareing down too hard. As far as tuning goes I'll defer to those more experienced but will tell you what I do. I always warm the saw up before cutting and at that point I richen until it blubbers or as some call it 4cycles a little. Then I'll make a cut or two and listen to it again-I want it to blubber or run rich all the time as the extra fuel helps cool the saw, but I also want it to cut decent as well. The reason I check it again is that the saw will lean out if the operating temp goes up and I want to make sure it's running rich. I don't use a tach I go by ear and I retune at least every day, but listen constantly. Finally, always use fresh gas and alcohol free preferrably, and top quality oil. Keep us posted.
To any of the longtime millers if I'm off on any of this pipe up and thanks in advance.

 

[mtngun]

I mill a lot of doug fir to 12 foot lengths, and it takes more than 5 minutes. I haven't actually timed a cut, but 10 - 15 minutes sounds about right.

I have never been able to cut more than a dozen boards in one day, though that is mainly due to the time it takes to set up the cut and move gear and boards.

When my chain is sharp, a 12 foot board will use 1/2 - 2/3 tank of gas (on an 066).

When the chain is the least bit dull -- typically after about 5 boards -- then a 12 foot board will use 3/4 tank of gas, or more, though I have never actually run out of gas while milling a 12 foot board.

I use Bailey's milling chain, full comp.

I recommend a 7 pin rim with full comp chain. Perhaps skip chain would allow an 8 pin, but I suspect you will get faster cuts if you run a 7 pin and keep the revs up.

I wedge the kerf about every 2 feet. If I am cutting in the forest, there are usually twigs laying on the ground that serve nicely as wedges.

Since I started using an auxilary oiler, I notice the saw revs a little faster in the cut. If I forget to turn the oiler on, the saw seems to work harder and cut slower.

To sum things up, your cut times and gas consumption don't sound "wrong" to me. The best single thing you can do to improve cutting speed is keep the chain sharp. An auxilary oiler might help, too.

 

[Brmorgan]

Most milling chain I believe is round chisel. Round chisel is said to leave a smoother finish in your lumber but also cuts a little slower(not as aggressive cutting). Just how much I don't know and I haven't done timed cut comparisons. With a skip chain I would think your saw would pull that chain no problem with 8pin but maybe not with the full chisel. If you run too rich it'll rob you of enough power to give you very slow cuts like you have but you need to be careful so you don't burn your powerhead up. Find out first what your compression is. I would think 120-130 psi would be end of life for milling especially with lower horsepower saws but no experience to draw from to assure you of this-my 066 is still at 155-160psi and that saw is 7.1hp to your 6.3 hp. Others here can tell you for sure. You'll probable gain a half horse at least if you mod the muffler right. At this point baseline your saw: compression, sprocket probably should be 7 pin, filters clean, spark plug good, adequate bar oil, rakers to recommended height etc. Also, the cutters should be same length and sharp(you can use calipers to confirm this but be very gentle). If all this is good you could also try higher octane gas, and try varying your pressure on the mill maybe your bareing down too hard. As far as tuning goes I'll defer to those more experienced but will tell you what I do. I always warm the saw up before cutting and at that point I richen until it blubbers or as some call it 4cycles a little. Then I'll make a cut or two and listen to it again-I want it to blubber or run rich all the time as the extra fuel helps cool the saw, but I also want it to cut decent as well. The reason I check it again is that the saw will lean out if the operating temp goes up and I want to make sure it's running rich. I don't use a tach I go by ear and I retune at least every day, but listen constantly. Finally, always use fresh gas and alcohol free preferrably, and top quality oil. Keep us posted.
To any of the longtime millers if I'm off on any of this pipe up and thanks in advance.

I never thought about the air filter... Douglas Fir bark is about the worst stuff I've seen for a filter besides concrete dust in a cutoff saw. That red powder it produces is so fine it gets in every nook and cranny in the saw (and the operator!), and can quickly clog even the best filters. And given that a 24" tree can have bark 3" thick or more at the base, it can get messy very quickly if you can't get the bark off. That being said, my 395's air filtration is so good that I only have to clean the filter once during the day if I'm spending all day milling, or at the end of the day on smaller jobs. I would think the 385 is fairly similar.

 

[Kicker_92]

Update:

Brought the saw home tonight to start working on it, so here's some updates:

1.) Compression: 140psi cold (it's too late to fire it up in the neighborhood and warm up) What psi should this saw be?

2.) Pulled the plug and it looks to be slightly fouled, with a thin black build-up (plug is only about 6-8 hours old)

3.) Air filter: looks pretty good, definaltly has some of the fine red powder on the screens. I'll give it a good wash and that might help with it running too rich.

4.) Sprocket: it is a 7 tooth sprocket, 3/8" pitch.

5.) Mill: Bar is straight, and sits parallel to the guide rails when mounted on the mill. Tried cutting with a new full chisel semi-skip chain and it cut bigger chips, but still bogged down.


Could it be as simple as just a somewhat clogged air filter and running a bit too rich?


Thanks for all the suggestions!

 

[Kicker_92]

Update 2: Cleaned the Air Filter

Well, I pulled the air filter to start cleaning it, and might have found the problem. There was a lot of dust inside the filter, a couple of the pleats were torn and allows sawdust to pass.

Whats the standard fix when this happens? Can I just blast out the intake/carb with some carb cleaner, or should I be tearing down the engine to clean it out?

I'm guessing there'd be dust drawn down into the crankcase and ports if it made it past the filter...

 

[mtngun]

140 psi sounds fine, maybe even great, depending on your altitude. A brand new saw might have 150 psi at sea level.

Husky's are supposed to have superior air filtration, but on my Stihl 066, I clean the filter after every day of milling, and sometimes in the middle of the day, I'll remove the filter and shake off the excess dust.

Can't help you with carb tuning over the net. I tune in the the cut (easier said than done, since the carb screws are on the bottom side of the mill), just lean enough to let it rev but no more.

While conventional wisdom says to tune it rich for milling, if you tune it too rich, then it doesn't make as much power and has to work harder and longer.

For those who haven't milled douglas fir, even though it is a softwood, it is one of the harder softwoods, and has thick bark designed to protect the tree from wildfires. It usually isn't feasible to debark the log while you are milling in the forest. The bark seems to increase cutting difficulty noticeably.

 

[mtngun]

There was a lot of dust inside the filter, a couple of the pleats were torn and allows sawdust to pass.

Whats the standard fix when this happens? Can I just blast out the intake/carb with some carb cleaner, or should I be tearing down the engine to clean it out?

I'm guessing there'd be dust drawn down into the crankcase and ports if it made it past the filter...

Not the end of the world, as proven by the 140 psi compression. It is very common for saws to leak a little around the air filter. Just get a new filter and keep an eye on it so it doesn't go this far again.