How to tell if a chain is dull?

[softdown]

Referring to chains that are off the saw. I recently bought a LOT of chains, perhaps from a chainsaw and lawnmower blade sharpening shop? They all seem sharp when feeling the tips of the cutting blade. Must be a way to get a decent idea - short of mounting the chain and trying it out.

 

[SweetMK]

Simply look at the tooth,, (if you are as old as me, you need a magnifying glass)
The sharp tooth will be sharp like a hand chisel..

If the tooth is "double beveled" or flattened, that is an indication of a dull chain.

 

[user 122190]

Referring to chains that are off the saw. I recently bought a LOT of chains, perhaps from a chainsaw and lawnmower blade sharpening shop? They all seem sharp when feeling the tips of the cutting blade. Must be a way to get a decent idea - short of mounting the chain and trying it out.

If it looks okay, it is okay. You're going to take a file to it anyways. $1/2 off or more and 90% of the cutters is still there, buy it!

I'd be more concerned with overall condition of the chain. Does it show signs of overheating. If you grab, hold the chain at either end, what is the bend like. If that is excessive then the chain has been abused due to a lack of oil, and can fail quickly.

This isn't some old DVD player, right. It's pretty simple to appraise its condition.

 

[arborist]

The first thing to look for is a clean, smooth cutter. If you don't see any nicks, this means the chain hasn't at least hit a rock, nail in tree or dirt at least. If you see any small nicks, then the chain is very dull and needs to be sharpened.

If you're trying to figure out their worth, then like MontanaResident said above, you want to see how much cutter has been removed. I don't think you need 90% to buy it. If she's only been filed down 50% or even just 25% it could still be used for many, many, many hours worth of cutting, so just but it accordingly is all.

If it's just dull who cares though? If there's plenty of cutter left and the price is right, just buy it, so long as there's nothing else wrong with it like stated also. You can sharpen it in a few mins and if you can't, perfect! Buy it just for the practice and the experience to get learning how to sharpen a chain. Consider it an even better buy. You get a discounted chain and you get to gain experience sharpening the chain and nothing beats practice and experience. Those are worth paying for anyway.

 

[old CB]

Sharpen a chain well, or grab a brand new one, and hold up a tooth from the sharp chain next to any other and compare. You should see the difference, if there is any.

On sharp chains the leading edge, or cutting edge, of the tooth will have a crisp sharp edge, When dull, that edge will be more rounded, with scuff marks leading away from it.

Like said above, you'll do better with a magnifying glass and good light.

 

[softdown]

I already have a few dozen used chains. Trying to figure out which ones need sharpening. Even my dull chains seem sharp when touching the sharp end of the chain "cutter blades".

I wonder if manually pulling it over, say a 2" x 4", might give a good clue.

 

[Clearwater]

I already have a few dozen used chains. Trying to figure out which ones need sharpening. Even my dull chains seem sharp when touching the sharp end of the chain "cutter blades".

I wonder if manually pulling it over, say a 2" x 4", might give a good clue.

Use your eyes and look for that clean crisp edge with no shine or reflection of any type, that means it is sharp. Any shininess along that edge is dullness. No need to touch the edge with fingers to check sharpness, just look at it.
You might need to file - grind these chains to get the cutter shape you want, but you still use your eyes to check sharpness. Your observations will be confirmed when the chain hits wood.

 

[arborist]

Yeah and sometimes you'll still be wrong lol. Sometimes I'll forget how a saw was cutting last, I'll take a quick peek and usually I can get it right but sometimes I'll get it wrong too and try it. It only takes a couple seconds to know you got it wrong and take it back to the truck and touch her up lol.

 

[Philbert]

Couple of ways: If it 'looks' sharp or 'feels' sharp, but isn't, you might need to recalibrate your looks and feels. Not trying to be sarcastic here, but take a similar chain that you know is sharp, and compare it with these others, until you can tell the difference. Might be subtle; might not be something that you can put into words. Or file a few of the cutters until you are satisfied and compare those to other cutters on the same chain.

I was about to type something similar to what @Clearwater posted, but he beat me to it! On forums like this, I learned the term 'glint', and put together the diagram below to help explain it. It helps to have a bright light source, like the Sun, or a really bright flashlight or lamp.

Philbert

 

[cookies]

I like the finger nail test, the chisel tip should fee sticky against your nail tho I guess a raker height check might be necessary with the nail test. If I had a pile to sort I would likely touch up one chisel on each chain with a stroke of a file to see if the edge rolls over like a sharpened chain's would then separate the dull from the sharp.