Stihl 084 dives into can't during cut

[Ima Doher]

I'm new to milling so I miss spell cant in the title.
On my logosol look alike mill I used a ms440 for a couple days till the cylinder puked the plug.
the 440 did pretty good with a skip chisel and a 28" bar.
so I turned to the 036 which did ok but was kinda slow cut though, 20" bar and chian, I filed the chain 10 degree on the teeth and cut every other two for rakers.
No diving with those two setups pretty good cutting and I could push the saw through the wood.

I picked up a stihl 084 last week that is in good condition.
It has a 30" bar on it. I filed every other 2 teeth for rakers and filed to 15 degrees on the teeth.
I was cutting a small 13" or 14"inch round oak log for the first time using the 084 saw.
The cuts were slanted so the outer part of the log little lower than the side closer to the saw.
I got 3 sides cut with slight slants then on the 4th cut it really took a nose dive about half way down the log. I found that side of the mill was off a quarter inch or so but I wouldn't think it was off so much to cause a nose dive, but I may be wrong I dunno.

When I filed the rakers on the 084 chain I messed up twice and cut an extra raker off.
I also filed to 15 degrees instead of ten that I had filed the other chain to.
So I don't know if the raker boo boo's or the 15 degree angle would make that big of a difference.

I haven't ever cut with a 120cc saw before so I'm wondering if the torque is too much for the blade?
Or maybe with that much power I need to take care and go slower taking care not to push the blade but let it go at it's own speed.

None of the other chains and bars I have will fit so I can't try anything else till I buy a shorter bar and chain, probably a 20" is a good fit for this use but I'm wondering if it really needs to be a beefed up blade. The 16 or 17" blade on the old remington 754 which is a 88cc saw, seems to be a much stronger blade than the stihl 30" however I'm sure they use different and lighter metals for blades now with all the metallurgy improvements over the years.
Any others experienced with a saw that big on a mill that could throw some ideas at it?

 

[john taliaferro]

Welcome to A S ,what helped me the most is Bobs stickies at the top of the milling page on sharpning with a digital angle finder .It was one of those Dha moments .

 

[Grande Dog]

Howdy,
Take your bar and stand it on it's edge on a good hard surface like a table saw table. The bar should stand on it's edge and be square to the table. If it's not square, or falls over, it's probably an issue with your bar.
Regards
Gregg

 

[Gypo Logger]

Also, if the bar groove is worn more than 8 thou than the drivers the chain will lean causing the dive.
If the bar is 058 see if a 063 will fit.

 

[BobL]

It has a 30" bar on it. I filed every other 2 teeth for rakers and filed to 15 degrees on the teeth.

I don't understand what you did here

The cuts were slanted so the outer part of the log little lower than the side closer to the saw.

This is caused by the bar bar being too long for the mill so the bar is tipping over or drooping. 24" is about the limit on these mills.
To make a wider cut you will need a two ended mill where the bar is held at both ends.
You can fit an outrigger but it will not be as effective as being supported directly at both ends

The diving down in the cut could be due to a number of things

Unevenly worn bar rails
If the bar rails (edges) are not both the same height and square to the flat of the bar (and hence as Gredd says it won't stand up on its edge) then this needs to be fixed by dressing the bar.
You can do this by mounting a thick grinding wheel in a table saw and running the bar lightly up against the side of the bar.
There are also hand dressing tools that use a file but you will need a new quality file and some hand strength to do this.
Do not use an angle grinder.

Worn bar groove
As Gypo says if the bar groove is worn this will also allow the chain to tip over. This can be corrected by closing the bar groove.
To do this you will need a bar rail closer to close up the gap
They look like this and to be used repeatedly along the bar to close the gap up slowly by small amounts with each pass - do not use pliers or multi grips or a vice to do this


Mill geometry.
There could be a slight angle between the bar and the mill rails. You need to check this with a digital angle finder (DAF).
Zero the DAF on the rails and then measure the angle on the bar.
The the bar rails are even slightly out and the groove slightly worn, then a slight angle will result in a diving cut.

Uneven chain sharpening.
If the cutters are unevenly filed with the lower cutters being longer than the upper cutters the chain will also dive. More important than cutter length is raker angle.
This is the angle between the top of the raker - the cutter tip and the wood. If these angles are greater on the lower side of the chain the chain will dive that way.

Usually these dives are caused by a combo of all of the above.

 

[Ima Doher]

That is all alot of good to know info, thank you alot for your input's. Living in the information age does have it's rewards.
I checked the numbers on the blade and it's not a 30" it's a 24", my mistake.
I was thinking it was slightly larger than the 28" bar on the 440 saw but it was slightly smaller.
It is an es bar 3002 000 9731 404 06.

I didn't cut today but took the blade off this evening and checked. It does fall on one side but stands on the other side.
So it is worn down at the very least, I may just buy a replacement and worry about learning to apply the fixes you guys posted.
Be nice having the info above to get me started on blade maintenance later when I get to a free rainy day.

About the filing of the chain. Maybe I didn't describe it well.
I'm sure you know what I'm talking about but I'll describe it better to clear up my earlier post.
It is where you take a full compliment chain that is stock 35* angle on the teeth to alter it to a home made ripping chain.
Sharpen the teeth to between a 5* to 15* angle and I think one person I read said 10* works good. Then cut off the teeth so there is just two (lft & RT) raker (straight knobes)
going through that clear out the chips. Supplies a faster cut and makes more chips than dust.
So two stubby (left & rt) rakers then two cutters and so on.
Also supposed to take a little height off the little guy (depth guage?) in front of each tooth that determines how deep is the cut. I think one post said file off about a 16th but I can't find that article at the moment.
So the 20" chain I altered for the 036 at 10*was done ok because it worked on the 036 and the mill fairly well.
I didn't cut any extra rakers off on that one like I goofed and did with the 084 chain.

When I tried to cut with the full compliment 036 chain it was slow and dusty.
After the mod it was much faster and chippy.
Wishing I had cut wood with the 30" on the 084 before I modded it so I would have seen the before and after.

I'll measure the cutters on the teeth to see they are the same shape per your insight too.

If I ruined the 30" chain I'm probably going to regret altering it - but, not thinking it will cost that much to replace maybe cost will be 30 to 40.00.

And to answer gypo's question it is an .063 bar.
the ms440 chain I bought is a .056 bar

 

[BobL]

Then cut off the teeth so there is just two (lft & RT) raker (straight knobes)
going through that clear out the chips. Supplies a faster cut and makes more chips than dust.
So two stubby (left & rt) rakers then two cutters and so on.

I reckon I've heard of most systems but I have never heard of this one. Do you leave the rakers on the cutters you do leave behind?

Also supposed to take a little height off the little guy (depth guage?) in front of each tooth that determines how deep is the cut. I think one post said file off about a 16th but I can't find that article at the moment.
So the 20" chain I altered for the 036 at 10*was done ok because it worked on the 036 and the mill fairly well.
I didn't cut any extra rakers off on that one like I goofed and did with the 084 chain.
When I tried to cut with the full compliment 036 chain it was slow and dusty.

If you are making dust that just means your rakers are too high

On a short bar like a 24" the absolutely fastest cut you can get is using ALL the cutters on a chain and you drop the rakers to increase chip size and minimise dust.
Skip chains and modified ripping chains are for long bars and long cuts as only then does sawdust clearance become an issue.
I gave up on skip chains many years ago - full comp all the way and learn how to sharpen properly and manage the rakers gives me the fastest cuts.

 

[Ima Doher]

Here is a guy showing how to do it.
From my understanding this is just for milling and would be too aggressive for just sawing.

 

[BobL]

Here is a guy showing how to do it.
From my understanding this is just for milling and would be too aggressive for just sawing.

OK - I get it. This is fairly common milling chain mod but quite unnecessary when using an 084 with a 24" bar.
This approach is typically used by folks who don't know how to set rakers correctly.

Keep all the cutters on and repeatedly drop the rakers and try it until you start to get chips, then slowly go a bit more until the chain starts to get too grabby.
You will be surprised how much you can drop the rakers and how fast a CS will cut even with an old chain

If you want a systemic approach to how far to drop the rakers look up "progressive raker setting" - try this thread in the "Hot saws- Sharpening" forum for a starter.
http://www.arboristsite.com/communi...ly-progressive-depth-raker-generators.114624/
This is not just for hot saws its for all saws including milling

This is another post that explains all the cutting angles especially in relation to milling
http://www.arboristsite.com/communi...nts-tips-and-tricks.93458/page-6#post-4107285

Progressive raker setting will consistently give you the fastest cuts, longest time between sharpenings and longest lasting chains.

 

[Ima Doher]

I'll go that route next time and look for good results.

Examined my bar again today and I guess it is a goner. There is a split in the middle of the bar on the edge that won't stand up. Imagine it needs tig welded which I don't do yet, then dressed like you said, prob. will be more than it's worth.
Tried to upload a picture but the site keeps error-ing out, maybe don't have privileges yet.

 

[Ima Doher]

I can tell you one very very positive thing about the DIY Ripping chain method that I described above where the other two teeth were cut off for rakers to clear out the cut.
I used the sharp full comp stihl chain and bar to cut one cant and I was having to spray the bar with water after cutting about 2 feet it was overheating so bad, peeled the paint and turned the metal different colors.
Then after I did the diy ripping chain method I refered to above at a 10* tooth cut to the same bar and chain - I was moving at almost double speed - was not overheating the blade at all, not even a little smoke on the bar tip.

 

[BobL]

I can tell you one very very positive thing about the DIY Ripping chain method that I described above where the other two teeth were cut off for rakers to clear out the cut.
I used the sharp full comp stihl chain and bar to cut one cant and I was having to spray the bar with water after cutting about 2 feet it was overheating so bad, peeled the paint and turned the metal different colors.
Then after I did the diy ripping chain method I refered to above at a 10* tooth cut to the same bar and chain - I was moving at almost double speed - was not overheating the blade at all, not even a little smoke on the bar tip.

This just demonstrates you didn't sharpen the full comp chain. There should definitely be no smoke. Full comp chain on a short bar on an 084 has to outcut a skip chain as there are more more cutters.

 

[Ima Doher]

No it was an 036 that the smoky bar was used on.
Good, When I get a chance I'm going to try the full comp sharpened with rakers going down. Hopefully won't be too long till I get a bar in for the 084 to try it on.
If the 084 is any faster than it ran when I made the slant cuts with the DIY chain then I'm gonna be tickled pink!

 

[BobL]

No it was an 036 that the smoky bar was used on.

So you are comparing the cutting speed of a smoking bar 036 with a fair running 084??
Sorry, but that's like comparing a clapped out VW beetle with a big V8.

Good, When I get a chance I'm going to try the full comp sharpened with rakers going down. Hopefully won't be too long till I get a bar in for the 084 to try it on.
If the 084 is any faster than it ran when I made the slant cuts with the DIY chain then I'm gonna be tickled pink!

Don't forget you must drop the rakers considerably as I describe above to see the speed improvement.

 

[Ima Doher]

well no.. I was comparing the speed of the chains - before modified and after, on each saw. Not comparing the saws, I know the 122cc will blow the doors off of 62cc.

 

[BobL]

well no.. I was comparing the speed of the chains - before modified and after, on each saw. Not comparing the saws, I know the 122cc will blow the doors off of 62cc.

OK, but the nose should not be smoking on any bar just by swapping the chain - its either a blunt or incorrectly set up chain.
If you post a close up side on pic of some cutters on your chain maybe we can help diagnose the problem.

 

[Ima Doher]

Let me see what happens with a full comp at 10* with rakers down like we talked about and see how it goes. If it is faster and no heat then that is the way to go from now on.
Any problems and I'll post pics for some help.
Thanks.

 

[Ima Doher]

I think I picked up 15% or better in speed with the full comp chain today, that 036 was moving out.
I'm running a 28" stihl ES bar and chain on an 036.
I had a new old stock 036 pro and another that had already seen a new top end, and had been using this old one up till just before I posted this thread.
The old one was a little power house but I never had to use the decompress valve to start it.
The new one snatches your arm if you don't use the valve, factory cross hatch on the piston.
So with the new 036 and this full comp chain I'm moving on these old stored logs I have.
Didn't see any smoke from the bar.
Nice going Bob, great tip on the full comp chain! I think I took the rakers down to just about the line I believe.
I did read something yesterday that it is best to round the raker, I left it flat. So I may need to go back and round the rakers.
maybe on my next sharpening.
Too bad I messed up a couple nice chains with that other method. But, at least I didn't mess up any more.