Depth gauges again....

[Mike Kunte]

So I've been thinking..... on most sharpening threads, when it comes to lowering the depth gauges, it seems the consensus that the curve of the bar is a problem, i.e. that you will achieve the incorrect depth gauge setting. I've let my brain go on this one, and I think it's probably only an issue when using the constant depth gauges (for example a fixed depth of 25 thou). That's because the gauge rests on the preceding 2 or 3 cutters to achieve its level state, and the curve of the bar can make this difficult to get right, since it's now "rocking".

When using a progressive gauge, though, the problem goes away. Even if your first reaction is that the curve of the bar will cause the depth gauge setting to be too low, this is not the case. At the end of the day, the cutters are presented to the wood on that very curved bar, which means that, relative to this bar, the depth is perfect!

Think of it this way - you clamp your chain in a flat-topped vise, and file your depth gauges. Now, when you mount the chain to the bar, your gauges are in fact too low, since the curve makes the depth gauge "drop away" from the tooth following it... make sense?

Anyway, this means that you can happily file your depth gauges on your curver bar, and they will be at the perfect depth for that bar. Simple!

Your youghts?

 

[Timdog]

What's a curved bar

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[Mike Kunte]

What's a curved bar

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Just a normal guide bar, but since very few of them are truly flat on the top and bottom, they are mostly "curved" - a slight "belly" on the top and bottom, to enable the chain to properly engage the bar, without drooping...

 

[Huskvarna hotellgäst]

What you say is true but not for the reason you have given. As it bites, each cutting tooth leaves the bar rails as it is drawn into the timber, only being pulled back when the following tooth begins its journey away from the bar.

 

[pioneerguy600]

What you say is true but not for the reason you have given. As it bites, each cutting tooth leaves the bar rails as it is drawn into the timber, only being pulled back when the following tooth begins its journey away from the bar.

ie: porpoising as in the way a porpoise swims.

 

[Mike Kunte]

Guys,

Perhaps I phrased this thread incorrectly. I'm not on about the porpoising of the cutters. This topic has been dealt with extensively in other threads. This thread was to address the concerns some folks had in other threads regarding the filing of their depth gauges on the rounded portion of the guide bar. I am in fact postulating that it is indeed an accurate way of setting the gauges.

Apologies for causing confusion.

 

[Huskvarna hotellgäst]

Guys,

Perhaps I phrased this thread incorrectly. I'm not on about the porpoising of the cutters. This topic has been dealt with extensively in other threads. This thread was to address the concerns some folks had in other threads regarding the filing of their depth gauges on the rounded portion of the guide bar. I am in fact postulating that it is indeed an accurate way of setting the gauges.

Apologies for causing confusion.

All good

 

[CR888]

I'm not sure setting your DG's on a curved bar is fine because the chain runs on a curved bar. The angle of 'attack' say 6-7° is a fact of trigonometry independent to bar curve. If they are set right it won't matter where the cutter is on the bar. Chain moves around a bar and can function in any position including the nose. The curve on a bar varies and should not have any relevance if DG's are set by degrees.

 

[Mike Kunte]

This is what I'm trying to establish. It's a known fact that the chain is more "grabby" around the nose, precisely because of the curve. The DG now "drops away", and exposes more of the cutter to the wood than it should. If you were to file the DGs on the nose curve, the chain would not be grabby there, but probably would not cut anywhere else on the bar.

I am convinced that filing DGs on the main portion of the bar indeed almost guarantees that the cutting angle remains near-perfect. Think about my "vise" example. Thanks for the reply!

 

[farmguywithasaw]

I think you are overthinking it