# How long between sharpening?



## Redbull (Nov 24, 2005)

How long do you guys go between sharpening your chipper blades?

I know this depends on what you are chipping, but on average?


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## wbs (Nov 24, 2005)

we dont sharpen. we just replace them when needed.


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## Redbull (Nov 24, 2005)

On average how often?


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## DDM (Nov 24, 2005)

We touch them up every morning and replace them when they become Dinged Badly.
There not resharpened just replaced. I'd say on the average about 8 weeks. I Believe touching them up daily greatly increases there life.


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## PTS (Nov 24, 2005)

wbs said:


> we dont sharpen. we just replace them when needed.




That sounds expensive


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## PTS (Nov 24, 2005)

I think we are getting around 80-100 hours on ours. Don't quote me on that but this chipper we have changed twice and we have put around 200 hours on it. Keep in mind that when the chipper is started it rarely pauses.


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## Redbull (Nov 24, 2005)

This is an interesting read that I found on Morbarks website. Some good info here.

BRUSH CHIPPER KNIVES – STAYING SHARP
by Jolene Priest
As is true with many tasks, there’s more to brush chipper maintenance than meets the
eye. Proper maintenance includes a daily inspection of chipper components, including but not
limited to tires, safety chains, grease points and belts. However, there’s one commonly missed
feature hidden under the hood: chipper knives. By spending ten minutes each morning
inspecting knives, operators will ensure a safer working environment, less down time, and a
quality end product.
Knife Life
Keeping chipper knives operating for their maximum life potential begins long before the
morning chipper inspection. It starts right in the field during the actual chipping process. The
quality of material chipped, the chipper style, and the type of wood being processed have a direct
impact on the wear of chipper knives. Although operators don’t have full control over the type
of wood chipped, they can be mindful of possible contaminants.
Chipping material contaminated with rocks, pebbles, or even mud can reduce knife life.
Under normal operating conditions, meaning running clean wood without any foreign
contaminants, knife life can range from 50 - 60 hours per side on a drum-style chipper. Given no
damage such as chips or cracks, knives on a disc-style chipper should be flipped or changed
every 25 –30 hours. The differences in life span can be attributed to the angle in which the brush
chipper chips material; a 37-1/2 to 45- degree angle on a disc-style chipper and a 90-degree
arch angle on a drum-style. The 90-degree angle benefits the knives by ensuring a more even
knife wear.
The type of wood being processed also has a direct impact on knife wear. Hard wood
such as oak or maple dulls the knives quicker than soft wood like pine.
Daily Knife Inspections
Before inspecting knives, it’s important to adhere to the proper safety guidelines. Wear
protective gloves and use lock pins and drum wedges where they apply.
Every morning before beginning a job, perform the 10-minute knife inspection. First,
check each knife for dullness. If a dull knife needs to be flipped, inspect it for chips and cracks,
and then remove debris that may have become wedged under the knife. Clean out the pocket
with the dull side of the knife before putting the other side down or installing a new knife.
Next, check every knife for chips and cracks. Running a chipper with a chipped or
cracked knife is dangerous, and can result in knife breakage. This can damage or even destroy
the brush chipper.
During the knife inspection and whenever replacing or flipping a knife, make certain it is
torqued to the manufacturer’s torque specifications. An improperly tightened knife will allow
wood to become wedged underneath, putting stress on the knife. It can also push the knife out to
a point where it can strike the anvil.
Sharpening Knives
Knife life isn’t necessarily over once a chip or crack is found. If the knife is in good
condition, it can be sharpened as many as three times per side. However, never sharpen a knife
that has a chip or crack deeper than one- inch.
Only use an industrial knife grinder when sharpening a knife. This machine will keep the
knife cool. If the knife becomes too hot during the sharpening process, the Rockwell hardness
will be affected, resulting in premature wearing. An industrial knife grinder, unlike a hand-held
grinder, prevents this from happening. An industrial grinder also holds the knife edge to a
greater tolerance than a hand-held machine. It contains jigs made specifically to set the grade to
a certain tolerance. The grinding wheel will not touch the blade once the tolerance is met. A
hand-held grinder, however, doesn’t hold an even cutting edge. It would be like trying to draw a
straight line without a ruler or guide.
When grinding, remember the one- inch rule. Only sharpen the knife down one- inch from
its original size. The cutting edge is hardened only to that depth. A hand-held grinder has no
way to gauge that depth, and if the knife edge isn’t ground evenly, chip quality will suffer.
Before reinstalling a newly sharpened knife, inspect it again for chips or cracks since
even the smallest imperfection can lead to knife failure.
Anvil Clearance
Inspecting knives each morning is not enough to ensure proper knife function. There’s
one more factor to consider: anvil clearance. It’s recommended to check anvil clearance every
time a knife is changed. Proper tolerances between the knife and anvil must be maintained for a
smooth chipping process. All manufacturers give suggested tolerances between the knife and
anvil. If the anvil is not reset after installing a knife that has been sharpened one or more times,
the knife may hit the anvil and cause breakage.
When inspecting the anvil look for a sharp edge, which keeps the chipper efficient.
Anvils generally have four sides and can be flipped two to four times, depending on the
manufacturer. The final step is to check anvil bolts for proper torque.
By following these guidelines, as well as the guidelines found in manufacturers’
operator’s manuals, operators will reap the benefits of long- lasting chipper knives and a high
quality end product. After all, spending 10 minutes a day on chipper knife inspection is a small
price to pay for safety, less downtime, and mone y saved.


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## chicken89 (Nov 25, 2005)

we sharpened our roughly every 50 hours. but we only used our when we needed to chip, so it would run for maybe 10 minutes then shut down and restart when needed. we would sharpen them in the shop one time (double sided) then send them out to be professionally sharpened the next time. so maybe sent out once every other month


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## a_lopa (Nov 25, 2005)

i get between 5 hours and 50 hours this week it was 5 hours,the knives i use cant be touched up there 2 hard,the sherril, zenith ones can be touched up.


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## Jim1NZ (Nov 25, 2005)

100 hours - chipping pine, popular, salix nothing to harty usually, things grow fast round here


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## JimL (Nov 25, 2005)

we get a couple hundred hours prolly, usually change them when the chute starts pluging. End up with truck loads of bent and broken sticks, not many chips


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## begleytree (Nov 25, 2005)

*replacement*



PTS said:


> That sounds expensive



PTS, this goes back to your other statements on sharpening prices. To sharpen mine is around $70, while if I catch a sale, I can get a new set for around $100 shipped. Mine normally run $24-$26 each, on sale they're around $17.
That said, I change mine out as needed, or every 3 months, whichever comes first. A new set will be sharpened 2X, then replaced. 
-Ralph


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## daveyclimber (Nov 25, 2005)

depending on your model of chipper it can be more cost efficient to replace them , that is if you know where to purchase them . I buy from a place that sells all different models of blades for approx 50-60% cheaper than baileys' sherrill and wesspur . Try sdmtools.com . Alot less hassle than sharpening in my opinion. Most good sharpening companies shoul;d only charge $1.00 per inch anyway , I see some of your prices that you guys pay is painfull


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## DDM (Nov 25, 2005)

daveyclimber said:


> depending on your model of chipper it can be more cost efficient to replace them , that is if you know where to purchase them . I buy from a place that sells all different models of blades for approx 50-60% cheaper than baileys' sherrill and wesspur . Try sdmtools.com . Alot less hassle than sharpening in my opinion. Most good sharpening companies shoul;d only charge $1.00 per inch anyway , I see some of your prices that you guys pay is painfull



Thanks for that link the have Good pricing on there knives!!!!!!
http://www.sdmtools.com/index_files/Page350.html

There Vermeer knives are 5.00 less than zenith. I wunder if SDM's knifes are made in Korea like zenith's?


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## daveyclimber (Nov 25, 2005)

They seem to be good quality , havent bought any in a while . Just purchased some 1/2" teeth for the stump grinder . They have a tooth called the shark bite . It uses a serrated carbide tip and they seem to work wonders for small machines . The carbide is also considerabaly harder which can be a very good thing . The shank is also harder than other brands I have used yet this guy has the cheapest prices . Yay for the little guy


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## a_lopa (Nov 26, 2005)

these are good knives http://www.blakeley.com.au/chipper.html


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## rebelman (Nov 26, 2005)

every time a new guy feeds rakeup. Or if construction is around, especially blading or grading.


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## Tree Machine (Dec 4, 2005)

Once or twice a week, religiously. 

I have a string of pictures of the chipper knives being sharpened. I'll string them all together for you to see, but I need to choose some music for it. 

What kind of tunes for knife sharpening, sparks flyin' and such? Something heavy rock and roll, some terrible Ned Nugent or Van Halen ? Any suggestions?


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## treesurgeon (Dec 4, 2005)

about every three months. or until it spits out long twigs. which might be about 40 to 50 hours.


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