Thread: new saw?

Originally Posted by fubar

Now I know this isn't on the same scale of milling as the dedicated slabbers but have a look at this video at this site http://torqueworkcentres.com/ (sorry I don't know how to just show the slabbing part) for the new attachment I'm fitting to my torque work centre for small backyard logs and according to the guys at twc because the saw is held so securely there is very little vibration and the finish is very smooth

Interesting device, not unlike the Wombat mill.

Firmness of saw hold and vibration, and finish are not as related as one might think.

It doesn't matter how firmly the saw is held, if the operator drives the saw too quickly into the log the chain cutter top and side plates will bite extra hard and the chain will dive sideways into the log causing a gouged stripe across the log. Remember the chain lifts up off the bar to cut and then has the freedom to dive sideways irrespective of how firmly the saw is held.

I see this problem with inexperienced operators who for example stop to add wedges, when they restart they FANG the saw back into the cut and make lots of gouges. A skilled operator learns to (re)start a cut slowly and work up to full WOT this avoiding sideways chain dive and minimising gouges.

On a new chain where the cutters are of equal length the chain makes a gouge on both sides of the cut. If the left hand cutters are not the same length as the right hand cutters the gouge will appear greater on one side than the other. Since the bar is flexible, the potential for this type of gouging is worse for saws only held at one end like minimills and probably the torqueworkcentre.

Using top plate cutter angles that are around 10º will reduce the above effect and improve the finish but is not a guarantee.

Where the fixed saw position helps is when the chain is well beyond it's "due for sharpening time". On alaskan mills these operators start to sideways see-saw the mill down the log. During the see-saw action they reduce the load on the saw and push too hard, once again creating gouges. A fixed position saw CSmill does not allow the operator to see-saw so this improves the finish. An experienced Alaskan operator knows this and tries to keep a constant cutting position - it's not that hard to do with a bit of practice.

Well I bought a MS660 this morning.. So now have to build my mill. I have not got a long bar yet, Soon I hope, but if I make the mill about 1.2m long I can use the 25" bar for now.. i will drill the bar for bolts as Bobl said. This bar is a Stihl Rollomatic E. So I can drill in the middle of the 6 rivets of the roller? I guess nothing moves in between the riverts so as long as I don't get too close to the rivets it would be ok?

a milling we will go, hi ho the merry oh a milling we will go

Whats the $$$$ for the saw

Originally Posted by Glenlara

Well I bought a MS660 this morning.. So now have to build my mill. I have not got a long bar yet, Soon I hope, but if I make the mill about 1.2m long I can use the 25" bar for now.. i will drill the bar for bolts as Bobl said. This bar is a Stihl Rollomatic E. So I can drill in the middle of the 6 rivets of the roller? I guess nothing moves in between the riverts so as long as I don't get too close to the rivets it would be ok?

a milling we will go, hi ho the merry oh a milling we will go

Whoo - Hooooo! Aint nothing quite like a new saw.

Now you really should run it in BEFORE you use it on the mill.

With a spare chain about $1800. Had one quote for $1750 but this bloke is closer. How long does it take to run in a saw?

Originally Posted by Glenlara

With a spare chain about $1800. Had one quote for $1750 but this bloke is closer. How long does it take to run in a saw?

Some users run like they stole them out of the box but if you are going straight to milling I'd recommend some sort of run in period.

The simplest run in is to use the saw as a firewood saw on small logs for the first 10 tanks.

The "full belt and braces" run in is something along the following lines.
5 full tanks minimum varying the RPM slowly up and down the range (7 - 10 k rpm in the cut) while blocking up small-medium (<15") logs don't sit on WOT for too long (<10 secs). Nice long cool down idling (5 minutes) between tanks.

Then another 5 tanks of mix where RPM can vary but the saw gets a chance to sit on WOT for 20-30s, then ease off and let it run at 7-8 k rpm for 20-30 secs. You can do this while milling if you tackle small logs and stick to the intervals. again - nice long cool down idling (5 minutes) between tanks.

Next 5 tankfuls stick to smaller logs and go WOT for 2-3 minutes - then ease off for 20-30 s, repeat.

Big saws take 15-20 tank fulls to reach optimum power development.

Thanks for the info Bobl. There is no information in any of the paperwork from Stihl. Should I run 50-1 like Stihl says or 40-1 as I have read in your column ?

Originally Posted by Glenlara

Thanks for the info Bobl. There is no information in any of the paperwork from Stihl. Should I run 50-1 like Stihl says or 40-1 as I have read in your column ?

I only use 40:1 because I also have an 076 and I don't want to keep 2 different mixes around. if you use quality 2 stroke lube, 50:1 will be fine. If you want extra protection I would suggest getting a fully synthetic oil rather than standard stihl oil.

Originally Posted by Glenlara

Thanks for the info Bobl. There is no information in any of the paperwork from Stihl. Should I run 50-1 like Stihl says or 40-1 as I have read in your column ?

Make sure you run 50:1 if thats what the book says otherwise you will void your waranty, with the new saws of today it is critical to run the correct ratio as the tollerances are a lot finer they take a lot less to stuff them. Even running them at 40:1 can cause them to grab a piston as they run to lean and become overheated. The more oil in the mix the leaner it runs the less oil in the mix the richer it runs. if you want long life from the saw run the recomended mix.

ps Stihl wont repaire or replace anything under waranty if you don't use the correct fuel ratio.

Ok 50-1 it is. Just got a 36" bar and 2 rip chains. Now if I only had some logs.. It will take me a while to run in the saw so I will keep my eye open for logs. Got a chair course to do starting Sunday then a turning course, got to build a mill, clean out and paint my shed, build some benches, Keep the misses happy. In case I forget Merry Christmas everyone.

Ho, Ho, Ho.

Originally Posted by swing mill

The more oil in the mix the leaner it runs the less oil in the mix the richer it runs. if you want long life from the saw run the recomended mix.

Reducing the mix from 50:1 to 40:1 makes very little difference in terms of leaning out the mix. There is a greater effect from daily natural changes in air pressure to the air/mix than there is going from 40:1 to 50:1 or VV. Anyway - all it takes is a small tweak of the H screw to set it dead right.

To show you the effect is more or less irrelevant my 076 Stihl service manual says to "use a mix at 40:1 when using stihl 2-stroke lube, and 25:1 when using other lubes" - it doesn't even mention needing to retune. In the 066 and 088 service manual it says a similar thing. What the user manuals do say is to always use good quality petrol and lube. I always use premium petrol from a high turnover petrol station. I try to use fresh mix and anything older than about a month goes into the whipper snipper or Subaru.

I have switched from 32:1 to 50:1 and VV with no problems whatsoever. There is a possibility that a badly tuned saw is running 50:1 and then running 40:1 takes it over the line to seizure but the saw would have to be so badly out of tune that the next time the atmospheric pressure dropped it would have done the same thing anyway.

AT the opposite end of the scale more mix lube is not necessarily better for the operator. On small 2 strokes like CS 20-30% of the mix never gets burnt and adds the the hydrocarbon fog around the operator. Unlike earlier mix lube that created a pall of blue smoke if too much was used modern lube are very good at suppressing smoke formation but just because it cannot be seen doesn't mean it's not there forming and invisible cloud around the operator.

Ok I'll bite, what is VV?

Originally Posted by Glenlara

Ok I'll bite, what is VV?

Vice versa.

The effect of running a lower mix leaning a saw comes from the very old days of two stroke mixes going from say 16:1 to 8:1.

At
50:1 98.0% of the mix is petrol,
40:1 97.6% is petrol
32:1 97.0% is petrol
30:1 96.8% is petrol
25:1 96.2% is petrol
20:1 95.2% is petrol
16:1 94.1% is petrol
10:1 90.9% is petrol
8:1 88.9% is petrol

The difference between 50:1 and 40:1 is 0.4% less petrol. The same effect on the air/mix ration can be obtained by a daily change in atmospheric pressure.

The difference between 50: and 25:1 is still only 1.8% - not uncommon over a few days of air pressure difference

The difference between 16:1 and 8:1 is 5.3% - this is more serious and can potentially mess with a saw.

AP certainly is something to consider, with serious race car engines it is measured on the night/day.....thinking (typing) out loud here, low pressure=less dense air=skewed air fuel mix towards richer and VV means high pressure = leaner mix and therefore on a hot fine sunny day we are more likely to have the saw rev more but also more likely to lean out and blow a piston If I have my thinking right, add to that a gradually blocking air filter, allthough that's only reducing total airflow and not necessarilly effecting the air fuel mix, just a saw that won't rev.....feel free to correct me on anything I have said here... and then I wonder how if we have low pressure and increasing humidity (rain) how does that then effect performance? much? a bit ?heaps? air full of water can't be good
I wonder should we tune for the difference in atmospheric pressure? specially for long milling runs.


Pete