# Whats the Maximum allowable cylinder head temperature during milling?



## SkippyKtm (Apr 9, 2012)

I see a lot of you that run chainsaw mills have a temperature monitoring setup (and for good reason I'm sure).
So my question is: what's the maximum cylinder temperatures do you run at? Does temperature increase over time, or does it level off? Do any of you run special cooling setups? How often (if at all) do you lose the top end? Typically, how many minutes do you get until you give it a rest? I suppose on that last question it would depend on the width of the board ambient temperature, chain sharpness, etc.

I have a 3120 that has never been used in that way, and I'm afraid a fellow new to milling is gonna burn it up. I called the Husqvarna dealer that I usually deal with and they say they wouldn't warranty a saw if they find out that it has been used to mill with...

Just for the record, I do mill quite a bit of wood, but I use a Woodmizer LT40. I consider chainsaw milling to be very hard on any chainsaw and the risk for mechanical failure would be high. 

Thanks for the help!


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## chaikwa (Apr 9, 2012)

SkippyKtm said:


> I called the Husqvarna dealer that I usually deal with and they say they wouldn't warranty a saw if they find out that it has been used to mill with...


You should probably find a new Husky dealer. I had a CS mill with the 3120 Husky and burned it up twice. Husky corporate stood behind it both times knowing what it was being used for.


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## BobL (Apr 10, 2012)

SkippyKtm said:


> I see a lot of you that run chainsaw mills have a temperature monitoring setup (and for good reason I'm sure).


I wouldn't say "a lot" a running temp monitoring. My guess is there are only an handful of people doing this



> So my question is: what's the maximum cylinder temperatures do you run at?


This depends on location of the sensor.



> Does temperature increase over time, or does it level off?


In narrow softwood cuts with a sharp chain it levels off or at least climbs very slowly as the chain gets blunt.
In wide hardwood cuts it clearly increases as the chain gets blunt. 


> Do any of you run special cooling setups?


Nope - but there are many things you can do to reduce temp loading.
eg Muffler mod, keep the chain sharp, don't push too hard, use an aux oiler, amount of B&C oil used etc


> How often (if at all) do you lose the top end?


What do you mean by this - do you mean lose a P&C?


> Typically, how many minutes do you get until you give it a rest?


Until the fuel runs out or the cut is complete, whatever comes first.
A hot saw needs 3 - 5 minute of idling to get back to normal idling temp.



> I suppose on that last question it would depend on the width of the board ambient temperature, chain sharpness, etc.


How hard the operator pushes is also a factor.



> I called the Husqvarna dealer that I usually deal with and they say they wouldn't warranty a saw if they find out that it has been used to mill with.


That is pretty standard for any CS.


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## mt.stalker (Apr 11, 2012)

A hot saw needs 3 - 5 minute of idling to get back to normal idling temp.


Pro's and Con's of shutting off vs idleing , to cool the engine ?


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## Jredsjeep (Apr 12, 2012)

after having a saw just lock up on me in the middle of a cut i would be interested in knowing what temps i should be seeing also. is there any general rule of thumb? i suspect i might have lost a seal and been pulling air but the saw ran fine until it just stopped.....


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## BobL (Apr 12, 2012)

mt.stalker said:


> A hot saw needs 3 - 5 minute of idling to get back to normal idling temp.
> 
> Pro's and Con's of shutting off vs idleing , to cool the engine ?



Idling cools the saw internals both inside and outside. The gas in the mix provides substantial internal cooling, while the fan cools the externals. Shutting off does neither and so stresses the saw more than necessary.

If you shut off and listen to a really hot saw you will hear more creaking and groaning than from a saw that has been left to idle for a while.


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## sun64 (Apr 15, 2012)

I am going to make a chainsaw mill similar to a procut that runs on tracks. I was going to make a counterweight system to evenly pull the mill through the wood. This way also I wont be near the heat, fumes and saw dust.
What I was planning on doing was mounting 2 x 4 to 6 inch fans over the top of the chamber / barrel to aid in cooling.
I have the 6 ft double ended bar here for my 2 x saws to run on. Hopefully with two 090's, one on either end and running 8 or 9 pin rims I will acheive what I hope to be a decent Chainsaw Mill.
The saws are to be ported as well.
I will be milling African Mahogany, a semi hard wood.
I also run 25:1 oil on all my saws with 95 octane fuel. I seem to get away with it living in the tropics. May foul a plug every so often but more forgiving with tuning etc and less internal wear.
Has anyone ever considered running fans on a chainsaw mill before to aid cooling?
Regards Wayne


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## BobL (Apr 15, 2012)

sun64 said:


> I am going to make a chainsaw mill similar to a procut that runs on tracks. I was going to make a counterweight system to evenly pull the mill through the wood. This way also I wont be near the heat, fumes and saw dust.



Automated counterweight or constant drive systems provides constant forces but this is not the way to get optimum cutting speeds for CS mill. Too much force and the saw will overload and bog down. What is needed is a variable force that can respond to the sharpness of the chain (that varies as you keep cutting), hardness of the wood (even on the same log there is a +/- 10% hardness variation), and of course even more importantly the width of the cut which changes during the cutting of every log and in some cases along the length of a trunk. Placing the trunk on a slope provides some constant downward force and the rest has to be topped up with either a winch or a push/lean on the mill. If counterweights are used then the same thing applies otherwise to get optimum cutting speeds you will have to keep adjusting the amount of weight on the counterweight. I tried this for 5 minutes and then went back to using logs on a slope.

Fans are unnecessary (and just another thing to worry about) if the saw is tuned right and run a little rich by increasing the amount of fuel (not oil). 
If you are going to use 090 then 25:1 is appropriate for that saw but just remember that running 25:1 is leaner than 50:1.
If the saw is running too lean extra fans won't make much or any difference in preventing cooking a saw.


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## sun64 (Apr 15, 2012)

[
Fans are unnecessary (and just another thing to worry about) if the saw is tuned right and run a little rich by increasing the amount of fuel (not oil). 
If you are going to use 090 then 25:1 is appropriate for that saw but just remember that running 25:1 is leaner than 50:1.
If the saw is running too lean extra fans won't make much or any difference in preventing cooking a saw.[/QUOTE]

Hi Bob and thanks for your reply. I appreciate your advice and imput Bob. 
There are a couple of things I am confused with, or perhaps mayby I dont understand it that well.

I ALWAYS THOUGHT THAT 25:1 MEANS 25 PARTS FUEL TO 1 PART OIL. You state it will be LEANER than 50:1 ??? How when I have twice the amount of oil to the mix than 50 to 1
Have I got it around the wrong way?

You also state that by tuning it correctly , which I agree , and adding more fuel will make it richer ( Not Oil )

Does'nt the fuel contain oil, so therefore when adjusting the carb for more fuel, you are really adding more fuel / oil mix to the air ratio, which of course will make it richer as it is getting more fuel/oil to it ?

Bob I am still interested in my counterweight system. I agree that by adding too much weight it will bog down and especially with dull chains etc. I have thought of the slpoed method but I am not going to add that much weight to it, just enough for an even feed that the saws / timber can handle.
I thought with this method at least I hopefully will get an even and constant feed rate. 
I have seen some great milled wood by hand and have seen some very ripply cuts, even by an experenced Lucas mill operator up the road. 
There are a lot of variables to milling as you state and one needs to be constantly monitoring the process.
I am just trying to get a decent finish. With our heat at 39 degrees celcius and fatigue / heat stress etc I thought about working smarter.
Like I said , I appreciate your imput and the experience you have , just confused with a few statments.
Wayne


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## BobL (Apr 15, 2012)

sun64 said:


> There are a couple of things I am confused with, or perhaps mayby I dont understand it that well.
> 
> I ALWAYS THOUGHT THAT 25:1 MEANS 25 PARTS FUEL TO 1 PART OIL. You state it will be LEANER than 50:1 ??? How when I have twice the amount of oil to the mix than 50 to 1
> Have I got it around the wrong way?



It is easy and very common to confuse the gas-air ratio with the gas-oil ratio.

Lean means more air relative to gas, or a low "gas-air" ratio.
Rich means high "gas - air"ratio.
Oil has nothing directly to do with how rich the gas-air ratios is - that is determined by the gas-air ratio.

However, oil affects the richness indirectly but in an opposite sense.
If your mix has more oil and less gas (eg 25:1) then if the same amount of mix enters the chamber as a 50:1 mix, then the 25:1 mix produces a leaner gas air ratio.
Some of the oil components do not burn but scavenge soot and smoke (ie unburnt oil and gas) this robs the mix of gas and effectively leans the gas-air ratio.
The difference is small but it may be enough to cook a saw if someone switches from a saw tuned for 50:1 to 25:1 without retuning.

The solution of course is to retuned to allow more mix into the saw which richens the air-gas ratio. But on low "gas-oil" ratios this then injects more oil (which for modern saws is totally unnecessary) as all the does is fog the air around the operator with crap. The difference between 25:1 and 50:1 and even 40:1 on modern saws is significant and I find it leaves my chaps, skin and hair all greasy after a days work, plus I get a headache.

I find it ironic that operators put more oil in their mix which pollutes their working environment and then have to invent drive mechanisms to get away from it whereas if they were a bit more careful about how much oil is used they can still operate up close and personal with the saw. The other mod that is useful is a muffler mod which allows the saw to breath easier and if carefully implemented directs the exhaust and saw dust away from the operator.

A constant feed rate is not needed to getting a good finish, and, just like like using log slope alone, an unchanging counterweight system will not produce a constant feed rate anyway. As the saw works its way down the log the chain gets blunter and will slow down, so extra counter weight will be needed to maintain a constant feed rate. Also most logs vary in cutting width so if you start at the fat end the maximum feed rate will be slow, and as the saw gets near the skinnier end the feed rate will increase. When cutting slabs that are not so wide you will need one weight, while cutting wider slabs will need heavier weight to maintain constant feed rate. When I tried a counter weight system I found I was spending too much time putting weights (bricks in a hessian bag) into and out of the bag. I quickly found I could always cut faster by just sloping the log and being up close and adjusting the additional cutting pressure (needed to maintain optimum cutting speed) on the wrap handle with my left knee or thigh. This leaves arms free to drive wedges into the kerf. Unless an operator can find a way to automatically drive wedges in while away from the saw they have to be reasonably close to the saw anyway.

A constant feed rate is possible using a big powerhead cutting relatively soft and narrow wood, and a constant speed drive - either hydraulic or electric. However, when the wood gets big and hard the saw will simply not cut a constant rate. While constant feed rate will produce a good finish it is not essential to producing a good finish. Variable force cutting can produce remarkably smooth cuts provided the force is not varied too quickly. The main thing is to just be gentle eg not to FANG the saw back into the cut when for whatever reason the stop mid cut. The other problems with finish from alaskan type mills; eg not seesawing the saw down the log, should not be a problem for a carriage mill. I reckon a better solution to applying a constant force than a counterweight is a winch because the operator can easily vary that force in a smooth way.

I don't usually mill above 38ºC but there are a lot of people that do without any problems.


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## timw128 (Jun 29, 2012)

EGT is the only way to go on a 2 stroke. I run 40:1 Super TechniPlate and 93 Sunoco on all my saws and work the dog #### out of them. Never blew one yet!


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## hardhat (Jul 2, 2012)

I just finishEd milling about 15 pine logs with a 394xp. 8-14 inch boards. Ran the heck out of it. Went through 10+ gallons of gas, 2 chains. Used poulan bar oil and poulan synthetic engine oil at 40 or 50 to 1 with saw tuned rich where it had quite a burble unloaded. This saw I bought used in 1999 for $500 and have abused it something fierce. It is none the worse for all this and still runs like a top. It had milled quite a few logs before this and cut a buttload of trees. Was kind of hoping it wold die so I could get a 3120 but oh well. Now that milling is done I dont need another saw


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## SkippyKtm (Jul 30, 2013)

"Whats the Maximum allowable cylinder head temperature during milling?" I never really got an answer to this question in this particular thread, but I did find it elsewhere. So I'll include it here...



timberwolf said:


> Here is the data I measured during a muffler modification on my 260.
> 
> Saw is was new 3-4 tanks of gas, sharp .325 Stihl RS chain on a 16" bar.
> 
> ...



Thanks to Timberwolf for taking the time to do the research! 
What I got out of this was 105 degrees C(221 F) maximum at the cylinder head and 184 degrees Celsius (363 F) maximum at the muffler. 
I know the research was done on a MS260, but it should still apply to a much larger milling saw.


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## Big Beech (Jul 30, 2013)

sun64 said:


> Hopefully with two 090's, one on either end and running 8 or 9 pin rims I will acheive what I hope to be a decent Chainsaw Mill.
> *The saws are to be ported as well*.



from my question relating to the above = http://www.arboristsite.com/chainsaw/239454.htm

but I am going to ask, you must be milling some MIGHTY BIG TREES to need a double 090 power head setup 
something like this :hmm3grin2orange: !!!


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## BobL (Jul 30, 2013)

SkippyKtm said:


> "Whats the Maximum allowable cylinder head temperature during milling?" I never really got an answer to this question in this particular thread, but I did find it elsewhere. So I'll include it here...
> Thanks to Timberwolf for taking the time to do the research!
> What I got out of this was 105 degrees C(221 F) maximum at the cylinder head and 184 degrees Celsius (363 F) maximum at the muffler.
> I know the research was done on a MS260, but it should still apply to a much larger milling saw.



I agree Timberwolf's research is excellent and is why I modified my 880 muffler, but I don't think the actual temperatures provided in that test applies all that well to milling with a big saw.

If anyone was to repeat this test on a bigger saw they should firstly be aware that it would take a lot longer than 3 cookie cuts to get to max temperature.
What the test doesn't take into account for milling temperatures is that the cuts are much longer and more stressful on the powerhead and that the temperatures are chain sharpness dependent so they increase slowly but surely as the chain gets blunt. It's not only temperature that is is important but time. What we want to know is what temps still allow the saw to survive to cut another day after a long slow cut in hardwood with a blunt chain. This is the sort of test for someone with deeper pockets than myself.

Another problem with using TW's temperature readings outside his experiment (its fine for measuring relatives differences for his experiment) is that IR sensors can be surface emissivity dependent and if this is not taken into account especially on shiny surfaces the readings can be inaccurate.


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## scogar (Jul 31, 2013)

Wow coincidental that this popped up after a year. This thread was one of the reasons I started my "Don't Want to Fry My Saw" thread currently running.


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## Timberframed (Jul 31, 2013)

I know this won't help much but there are concrete/demolition/rescue saws out there that are designed to run 24-7 WOT and are perfect for milling though they are $$$. The ICS 633 GC I use has the same bar mount as an 090. As far as the dealer is concerned crosscut or rip is none of their business, hence stand behind the product you sell. Just do what they dealer told me; 25:1 (or whatever your manufacturer says) and NOTHING else. Just saying if the motor calls for 30 weight, don't put gear oil in it in a pinch. Not siezeing a 2K powerhead over skimping on a buck & a 1/4 bottle of Stihl ultra. Back to my beer. 6 more days till the middle of Summer.


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## JBarn (Sep 29, 2022)

hardhat said:


> I just finishEd milling about 15 pine logs with a 394xp. 8-14 inch boards. Ran the heck out of it. Went through 10+ gallons of gas, 2 chains. Used poulan bar oil and poulan synthetic engine oil at 40 or 50 to 1 with saw tuned rich where it had quite a burble unloaded. This saw I bought used in 1999 for $500 and have abused it something fierce. It is none the worse for all this and still runs like a top. It had milled quite a few logs before this and cut a buttload of trees. Was kind of hoping it wold die so I could get a 3120 but oh well. Now that milling is done I dont need another saw


New to milling. Tuned rich refers to turning the H pin on the carb counter clockwise, yes? Also, did you buy the specialized carb tool or did you manufacture another way of doing it.


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