Saw video thread

[jmssaws]

Then why is it so critical with auto engines that only rev 1/2 the RPMs?

I'll answer that, cause the parts are bigger and not so over built.

Because it has opposing pistons.

I'll say it again.
They are balanced but the piston doesn't affect it.
How can it? It doesn't rotate.
All it does is apply load

 

[Deets066]

If the piston was made out of some nonexistent material that has no weight the saw would still not be out of balance.

If it was made out of lead..... it still would not be out of balance.

I'm with J on this one

 

[huskihl]

I'm curious as to why does it matter? Who in the hell gives a flying f### about whether a chainsaw is balanced from the inside, or outside, or at all?

Who gives a shìt?

Go cut wood

 

[jmssaws]

I'm curious as to why does it matter? Who in the hell gives a flying f### about whether a chainsaw is balanced from the inside, or outside, or at all?

Who gives a shìt?

Go cut wood

To cold to cut wood.

 

[huskihl]

To cold to cut wood.

Pfft




Pfpfpffffffffftttttt

 

[huskihl]

I'm curious as to why does it matter? Who in the hell gives a flying f### about whether a chainsaw is balanced from the inside, or outside, or at all?

Who gives a shìt?

Go cut wood

And get a damn video and post it here ffs

 

[P.M.P.]

I thought this was pretty cool but a big waste of wood.

 

[Deets066]

And get a damn video and post it here ffs

Speak on it Kev

 

[huskihl]

Speak on it Kev

Thread killer

 

[drf256]

Because it has opposing pistons.

I'll say it again.
They are balanced but the piston doesn't affect it.
How can it? It doesn't rotate.
All it does is apply load

Not trying to argue, but why is there a counterweight in the crank if the piston and rod cause not rotational load at all? Why not just simple crank with no weight or a full circle to take up case space?

On auto cranks, the piston, rod and rings are weighed and a bobweight is attached to the crank of equal weight to balance the assembly. On a boxer engine, perfectly opposed, I believe there are no counterweights on the crank. On a straight 6, there's a counterweight for each cylinder.

I think it does apply force, but its so little that a difference in weight is hardly noticeable in a saw.

Just my $.02.

 

[Deets066]

Just my $.02.

 

[concretegrazer]

Always thought these saws were cool.

 

[Deets066]

Always thought these saws were cool.

These are badass saws! I ran @awol 's at the gtg

 

[awol]

Always thought these saws were cool.

Now we're talking! No antivibe, but smoother than any saw with antivibe. All because it has a factory "balanced piston"!!

 

[Keith Gandy]

Pfft




Pfpfpffffffffftttttt

Lol!! I cut a load at 26° this mornin

 

[jmssaws]

Not trying to argue, but why is there a counterweight in the crank if the piston and rod cause not rotational load at all? Why not just simple crank with no weight or a full circle to take up case space?

On auto cranks, the piston, rod and rings are weighed and a bobweight is attached to the crank of equal weight to balance the assembly. On a boxer engine, perfectly opposed, I believe there are no counterweights on the crank. On a straight 6, there's a counterweight for each cylinder.

I think it does apply force, but its so little that a difference in weight is hardly noticeable in a saw.

Just my $.02.

If the weight of a piston affects balance,in a single cylinder engine not anything else
Then compression and rpm will.
The crank has counter weights to balance the the weight of the crank pin and rod bearing and the rod journal.

I'm almost done with a 83cc 044
Will it be balanced?

 

[Frank bierce]

If the weight of a piston affects balance,in a single cylinder engine not anything else
Then compression and rpm will.
The crank has counter weights to balance the the weight of the crank pin and rod bearing and the rod journal.

I'm almost done with a 83cc 044
Will it be balanced?

Nope...not at 83cc...possibly 84cc though .

 

[Deets066]

I still need someone to balance my hybrid

 

[jmssaws]

I cut today at 15 degrees but 0 wind and wasn't bad. Wood is froze

 

[Keith Gandy]

Quote: any material that you can remove to reduce the reciprocating mass (piston/wristpin/ring/top half of rod) will make an improvement in engine performance, maybe not noticeable at lower rpm's but certainly at high rpm's plus it reduces stress on the engine parts. This will affect the balance of the engine but not greatly. However, it is a fact is that it is IMPOSSIBLE to balance a single-cylinder engine. The best that can be done is a compromise. The crankshaft counterweights will partly balance the reciprocating mass (piston/ring/wristpin/top half of rod). but this will introduce an out of balance at 90 degrees to the line of the cylinder but we have to put up with that.
Use a good quality scales, digital if possible. Take apart the crank assembly, weigh the bottom half of the rod and then the top half of the rod. Then weigh the piston/ring/clips/wristpin as one assembly. Add the weight of the top half of the rod to the weight of piston/ring/clips/wristpin. Now you need to take a percentage of this weight of between 50 to 60%. Lets say we use 55%.
Add this 55% to the weight of the bottom of the rod and machine a piece of brass or steel of this weight to fit over the crankpin. Reassemble the crank with this weight in place and balance the crank on the ballrace surfaces on 2 knife edges. If the crank rotates because its heavier one side than the other( which it will do) you must grind metal off the heavy part of the crank-webs around the crankpin area or wherever until it does balance. At this point you will have balanced the engine to a balance factor of 55%. This balance factor will vary from engine to engine and is rpm dependent to a certain extent but at 15,000 rpm a factor of 55% is not too far off.
N.B. Bear in mind that it is not possible to balance a model engine with a single sided crank to anywhere near the optimum balance factor. All that can be done to improve the situation is to remove as much material as possible from around the crankpin area of the rod and if possible add weight to the counterbalance by installing tungsten or copper inserts such as used sometimes by CMB and Novarossi.