Understanding the heat at the tip...with tension...

[traditional-toolworks]

Some comments which Robbin made in another thread have made me curious about the heat produced on carving bars at the tip, and how most people use a slack chain on a dime tip to overcome this problem.

I have a use where I would like to use the 12" dime tip for cutting along the edge of the bar, as most chainsaws are used in the real world.

In this case if/when you do that, would the heat be reduced and not have to be worried about that, at the tip? And if so, it must be that working the tip pushes the chain in the groove, which is what produces most of the heat I 'spose. Is that correct?

From what most folks have told me, it seems logical that if you do not use the tip, you could certainly have the tension higher on a small bar. I would like to use the bar on it's side, so I would like to have a normally tensioned chain to do that.

The other thing I notice is that my GB dime tip is not too different than my Cannon quarter tip. The Cannon is slightly bigger, but not the difference between a dime and a quarter, as far as I can tell. The GB seems like an oversized dime, and the Cannon seems like an undersized quarter. The Cannon dime must be really small...

Lastly, when people talked about burning up a carving bar, what exactly happens? Does the tip get so much heat that it starts to deform? Does the inside of the slot expand open? Curious minds wonder...

[Backwater Bob]

some folks take a oil jug and cut a big slot to cool down their bars. I havent burnt up a bar yet but have seen the delaminated and cracked.

Bob

[traditional-toolworks]

Originally Posted by Backwater Bob

some folks take a oil jug and cut a big slot to cool down their bars. I havent burnt up a bar yet but have seen the delaminated and cracked.

Bob

Bob,

So they dunk the entire bar/chain tip into the oil...interesting. When the bar delaminates do the sides come off? I'm not sure and suspect that different bars are made differently, but you make me believe that both sides of the slot pull off the center portion, is that correct?

If you stay away from using the tip, is it then possible to tighten up the tension on the chain? Is my hunch correct there?

[Rwenzoski]

Hi Alan, Two things will result with the result of excess heat. The first is because the chain is rotating around the tip of the bar at a tight radius this in effect creates heat itself. The less slack there is the more the chain drivers & lower edges of the tie straps apply pressure which results in more friction & heat generated. If there is enough heat generated on the stellite tip of the bar what occurs is what is termed as "Indications" will form. These "Indications" can be caused by excess heat & also by large variations in temperature change such as cooling a hot bar tip in oil, water, by blowing air on it etc. The fast expansion/contraction of hard material such as this will create these "Indications which is easiest described as hairline checks or cracks. You cannot see them with your eyes until you start to see small flakes or pieces falling off like shrapnel. The second effect that will then generate a ton of heat & damage is when the chain is running over the damage creating horrendous friction & heat & the result is the effect of the chain links tightening up on the rivets or actually the joiner shafts that are the (joke on words) povital points of the chain. This damage can also occur to the chain caused by a very badly worn sprocket or rim drive also & is obvious when viewing the underside, inside or drive side of the chain. It will appear shiny & look hammered & the Sprocket/rim drive will have obvious wear associated with this. When a bar tip separates I would suspect this is more caused by a chain with tight links not rotating around the radius of the bar tip & with kinked links it is the same result of running the chain without enough slack .
Thanks, Robbin

[traditional-toolworks]

Robbin,

So, if one was using a dime tip, and not using the tip, excessive heat will still be generated??? This sounds so, but will it be within reason to use as I intend so I can turn the bar on it's side and sweep a horizontal surface?

[Backwater Bob]

Sorry if I gave bad advise. I was tired and didn't think right. I was told to do the dip tip in oil thing on my thumb pump electric before I started carving because it keeps it cool till I get my thumb pumping. After kicking over that jug once I just pour a little over the bar on that saw when I fill the oil tank when the bar is cool. Of course hot metal in a cold liquid is bad.

I resisted having my chain loose but now that I do I see that it cuts better. Don't know why but it does. In my limited experience that includes "sweeping with the bar sideways", my brain tells me it will fall off but it doesn't and cuts as well or as badly as a tight chain.

Bob

[twoclones]

You can see a photo of a heat damaged bar at
carvingpost: blown carving bar ?+-
Apparently damage this severe is being repaired by the folks at Chain Bar Repairing

[quickcarver]

Leverage, think about a bicycle, or motorcycle chain. THe mechanical advantage is highest if the drive source is smaller than the wheel gear. Larger sized sprocket nose and toonie bars produce more torque and less tension on the chain than dime tip bars, (hence the granny gear is used for climbing hills). THe rule of big gear in back, small gear in front applies to saws as well.THe dime and quarter tip bars are so close in size to the drive gear diameter of the saw, This maximizes stress , and heat on the chain, and the bar, which increases heat, and attrition. I use the under side of the tip, and the top of the tip most of the time. When I plunge cut, I don't hold the saw on the cut for very long, just like over pushing a router bit, you heat up and dull the cutting tooth. It's all positioning, and trail and error, observe the size of wood chipp you are producing. General rule #2 big chipps means faster, smother cutting, finer chipps, or fine dust means heat, over stress, and fatigue of crittical cutting parts. The type of chain you run makes a difference too. Squar nose versus round nose filed chains. THe all have differences, and can make or break your carving day. I change chains often, and experiment with a variety of different types of chin cutter profile, as well as variations on raker tuning. Even after over 10 years carving full time, in wood, and ice, I still learn new things about the bars chains, and properties of making iether work, and last longer.

[Rwenzoski]

Hi Quickcarver, I would sure love to see some pics or descriptions of the different types of profiles you are using to sharpen with & any talk about the various types of chains with disadvantages/advantages as I am a sponge to learn!
Appreciated, Robbin

[traditional-toolworks]

Originally Posted by quickcarver

Leverage, think about a bicycle, or motorcycle chain. THe mechanical advantage is highest if the drive source is smaller than the wheel gear. Larger sized sprocket nose and toonie bars produce more torque and less tension on the chain than dime tip bars, (hence the granny gear is used for climbing hills). THe rule of big gear in back, small gear in front applies to saws as well.THe dime and quarter tip bars are so close in size to the drive gear diameter of the saw, This maximizes stress , and heat on the chain, and the bar, which increases heat, and attrition. I use the under side of the tip, and the top of the tip most of the time.

I guess that makes sense, although it's being driven by the sprocket/rim only, on a bike you have gears on both ends, atlhough I guess the rear wheel is like the tip of the bar, in the sense that the power is coming from the other side (pedals in the case of the bike).

I can understand what your saying though, because as the gear gets larger it is easier to pedal. And if I'm not mistaken, this is what your saying about the dime tip vs. the quarter tip, that because the quarter tip is larger it is easier for the sprocket/rim to drive it, hence less heat. Understanding of course that the heat is our biggest factor.

Originally Posted by quickcarver

When I plunge cut, I don't hold the saw on the cut for very long, just like over pushing a router bit, you heat up and dull the cutting tooth.

Yes, this I can understand exactly what your saying. Same with the tip though, keeping the heat down would help as well.

Originally Posted by quickcarver

It's all positioning, and trail and error, observe the size of wood chipp you are producing.

Yes, this makes sense. In looking at my dime tip after I used it, I see some wear from the cutters going around the tip, on the sides. At least some of the paint is gone on the sides, and it seems that must be from the heat and chips being dragged around the top/sides.

Thanks for your comments, as Robbin, I would also like to understand how you modify the cutters. Robbin also mentioned modifying the cutters by grinding them, I'm not sure if it was in this thread or in PM, but he's mentioned that to me before.