Chipper knives sharpening vid

[Mick!]

Fair enough, sorry if it appeared brusque, what I meant was that I understood that a less acute angle on a blade can mean less flaking, off so yes I thought I completely "got" it. In an Emporers new clothes sort of way.
Then later in the thread you (I think) pointed out that he was filing 90degrees across the edge and I realised that in fact I didn't know what was going on.

 

[MasterBlaster]

All I know is I won't be doing that anytime soon, lol.

 

[cory]

It gets filed back one or two light strokes. Makes the former point to maybe the width of a ball point pen line. Drum chipper knives always stay sharp way longer than disc knives, btw. Justin and others above touched on it, and it is mentioned in the vid, a sharp point is much more subject to damage. And of course, moving at the speed the knives do, they don't have to be razor sharp to do their job.

 

[MasterBlaster]

So, you do it?

 

[cory]

Yes.

I file off the edge too, my knives last for 4-6 months at least.

 

[MasterBlaster]

So, who's gonna be the next to practice this sorcery? I wanna know more about this.

 

[cory]

There's no downside to it.

 

[squisher]

Hmmm. This is interesting timing. I'm sitting on a ton of sets of knives right now an my sharpening guy is MIA. Was no big deal I've been stockpiling and buying new locally. Now my local supplier was cut off as a new agreement was made with the manufacturer so I can't buy locally at all anymore. Now my situation is dire and I haven't figured out a suitable way to order/ship knives for anywhere near what they were costing me.

Maybe I'll look through my sets and touch a few up. Gotta have near a dozen sets of one use knives on hand.

If Cory does it and says it works I have no doubt it does.

 

[cory]

I certainly appreciate the vote of confidence, Squish, but what I've been talking about above is only for unused knives. Just taking the point/edge off a little from a new knife.

 

[squisher]

Ahhh I see. Damn. I'm still in a knife pickle then. Gotta hunt my knife sharpener down. He's a pro. Seems sawmill planer knives are very similar. Atleast sharpened the same. With all the mills around here there's literally pro filers. Just gotta buy the right bottle and I can get my knives back like knew. Every set perfectly even.

 

[MasterBlaster]

So, like I mentioned earlier, it's kinda like a stropping thing?

 

[cory]

With all the mills around here there's literally pro filers. Just gotta buy the right bottle and I can get my knives back like knew.

You mean the right bottle, as in compensation/incentive?

 

[cory]

Stropping is sharpening/honing afaik. This is very light dulling.

 

[squisher]

You mean the right bottle, as in compensation/incentive?

Yup. I know a guy who works the filing room.

 

[cory]

Interesting way to make a living, sharpening.

I remember seeing how the big band saw blades were sharpened by machine in a big mill, fascinating.

 

[Thor's Hammer]

I used to do commercial chipping. Large wood run through continuously hour after hour. No way would I do that stupid trick, I used to give the edges a quick hone with a 12v grinder and flapdisc every 2 hours and switch edges / spin the knives every 4 hours. It's amazing how much your output drops and fuel consumption goes up with dull edges.

 

[Al Smith]

I think if one were to look at that file deal it's much like the edge on a straight razor as opposed to an axe .The knives on a chipper actually act more like a chisel than perhaps the knife of a hand held carpenters plane .Delayed cut .

With a razor edge what it would do is stress the thin sharp edge and be more prone to breaking off than with a less aggressive edge . For example compair a wood chisel with a cold chisel .

You can sharpen a wood chisel so you could shave with it .With a cold chisel you'd just break the edge off if done like that .

 

[HolmenTree]

I can see the video method work better on a large drum chipper as the video shows, but a 25-40 h.p. disc chipper not so good. Big high h.p. machines can't afford a weak edge, but a small machine relies on perfectly milling machine sharpened knives, some of the money you save with a small chipper you sacrifice in proper sharpening expenses.

 

[Reddog]

I used to do commercial chipping. Large wood run through continuously hour after hour. No way would I do that stupid trick, I used to give the edges a quick hone with a 12v grinder and flapdisc every 2 hours and switch edges / spin the knives every 4 hours. It's amazing how much your output drops and fuel consumption goes up with dull edges.

Agreed Ed, with out a good load sensor for power usage you have no idea what a certain cutter geometry is costing you. Sounds like you had a good handle on it.

Similarly on big production machining jobs we would try different rake angle's to see what gave the longest life and fastest feed rates. Using the same power settings all needing to achieve the same surface finish.
A dulled or negative draft cutter never won.

 

[brendonv]

This reminds me i gotta flop my knives, really eating fuel last week or so.

 

[cory]

I used to do commercial chipping. Large wood run through continuously hour after hour. No way would I do that stupid trick.

I learned it from Morbark, I don't know if they recommend it for whole tree chippers, but they do for 18" brush chippers.

 

[Merle Nelson]

So, like I mentioned earlier, it's kinda like a stropping thing?

So, who's gonna be the next to practice this sorcery? I wanna know more about this.

If I understand stropping from old hand sharpeners properly it is aligning the structure of the steel molecules all in one direction along the knife edge but, does not remove any appreciable amount of metal. This removes metal at or near 90 degrees with a file and it removes metal when ‘truing’ up the edge with a carbide sharpener/scraper.

I have been doing this for a year or so after watching this vid on Bandit site. Started when first acquired my 6 inch Bandit and wanted to optimize it’s ability to chip so can’t compare it to not having done it. The flat file trick I can only say that I would hope Bandit knows better than me and will do it until I see a reason not to. The carbide sharpener trick is not a perfect solution as Willard points out (my blades develop a bit of a squared up C shape over time since I can’t scrape the two ends of the blade.)

However, I can notice that my chipper’s 37 horse wisconsin is not feeding brush as well as normal and after I have taken ten or fifteen passes over blades it is back to chipping great. I usually do it after a days work. I was on one job next to dunes at the coast and fog had helped windblown sand to stick to the brush. In that case it made all the difference in the world to stop and take 10 strokes on the blades every couple of hours.

The blades pictured at the beginning of video would see by far the least benefit from these efforts in my opinion.

I would love it if all chipper knives had ‘worn out lines’ marking them. I have never seen that. They all do have tolerance specs though. Get down to x amount of metal from center of bolt holes and must toss them.