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View Full Version : How often do you change blades?


jeasley
09-25-2010, 09:39 PM
Do you guys change blades daily, as needed, or after XX hours/acres?

Also, how does everyone prefer to change them, air impact in the field, manual wrenching in the field, at shop first thing in the morning? Just curious. We just watch our cut, and change when we can tell they are in need. We typically change once a week. We are part time, but run about 70 man hours a week.

(first time I have started a thread, I am enjoying the site alot, thanks for all the info you guys pass on)

ShooterK2
09-25-2010, 09:50 PM
I am part time, mowing approximately 20 properties a week, and I made 3 sets of blades last all season on my Scag 36". Well, I just got a new mower a couple days ago, but I used the Scag until now.

Like you, I just watch the cut and watch/feel the edge on the blade to know when to sharpen. I usually change them out every other week. Sometimes sooner, if I think it needs it.

ShooterK2
09-25-2010, 09:52 PM
Oh, and I change them with manual wrenching. It's not hard at all on a walk-behind, and almost as fast as an impact. I messed up the threads on a blade bolt with an impact once, and decided to stop doing that.

Florida Gardener
09-25-2010, 10:00 PM
I have 25 properties, some bigger, some smaller. In the summer I like to change out every 3 days or so. I would rather have the blades sharp as often as possible.

br549oicu8
09-25-2010, 10:05 PM
Daily.
On big days, twice a day.

Bumpmaster
09-25-2010, 10:15 PM
Oh Yae I do that too.

rain man
09-25-2010, 10:22 PM
Every 3-4 days if the grass was easy on the blades.

JCLawn and more
09-25-2010, 10:28 PM
if you mean sharpen, If I do it right I am on about almost 40 acres of grass and they still feel ok. One blade is getting dull. My last set of blades lasted about 250 hours.

Bumpmaster
09-25-2010, 10:30 PM
Every 8 hours is a good gauge.

JCLawn and more
09-25-2010, 10:37 PM
Every 8 hours is a good gauge.

I would die if I had to sharpen my blades everyday. Twice a week at most for me.

sweetz
09-25-2010, 11:06 PM
I would die if I had to sharpen my blades everyday. Twice a week at most for me.

I would to, that is why I buy more than one blade. I change mine once or twice a day.:)

JCLawn and more
09-25-2010, 11:22 PM
I would to, that is why I buy more than one blade. I change mine once or twice a day.:)

now my residential mower I started out with I would have to some times. My grasshopper has 1/4 steel blades so I can go way longer, what do you all have?

PlantscapeSolutions
09-26-2010, 02:51 AM
Using two 18" breaker bars makes blade changes super easy. Buy about a dozen sets of blades so you can sharpen a bunch at a time. We'll go about two days on a set of blades.

jeasley
09-26-2010, 08:17 AM
We have a bunch of sets and try to sharpen alot at a time too. But, Dad bought a JD Compressorator this year. We keep animpact wrench and grinder in the truck, we can sharpen anywhere anytime if needed. use the trailer ramp for a jack, can be done in no time.
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jeasley
09-26-2010, 08:24 AM
I have another question. Exmark blades are easy to see if they are bent since they are a straight blade. However JD blades are mfg with a slight bend to them. Anyone have a method to determine if they are bent? I lay the blade in question on top of a new blade and look for differences. This works fair, but it's hard to see slight warping in the blade.
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Matt S
09-26-2010, 08:28 AM
I have another question. Exmark blades are easy to see if they are bent since they are a straight blade. However JD blades are mfg with a slight bend to them. Anyone have a method to determine if they are bent? I lay the blade in question on top of a new blade and look for differences. This works fair, but it's hard to see slight warping in the blade.
Posted via Mobile Device

Lay them on top of a good blade and see how well they "nest".

LushGreenLawn
09-26-2010, 09:54 AM
Each morning before we go out we put a fresh set of blades on the ZTR. We have multiple sets, so we just sharpen them when were doing our weekly maintenance.

I have two push mowers that get used on a few properties, we change them about once a week.

Sharp blades make a big difference. Dull blades will cause a lawn to respond to heat faster, and make it less resistant to disease.

Woody82986
09-26-2010, 10:57 AM
I have multiple sets sharpened but I change out blades once a week or so. I do it at home manually. The only time I ever change a blade in the field is if I bend a blade. That's only happened twice.

HighGrass
09-26-2010, 11:08 AM
Once a week or so. I pretty much watch the cut and change as needed. I keep spare blades in the truck but do most of the changing back home in the garage with a Dewalt Impact driver. Works great and doesn't tighten so hard that you couldn't change with a wrench on the road.
I really think some folks change too often, or maybe I should say more often than needed. I think you loose that "Sharp" cut right after the first lawn or so and then the quality of the cut sort of flat lines for a while.

rwaters
09-26-2010, 12:13 PM
I have another question. Exmark blades are easy to see if they are bent since they are a straight blade. However JD blades are mfg with a slight bend to them. Anyone have a method to determine if they are bent? I lay the blade in question on top of a new blade and look for differences. This works fair, but it's hard to see slight warping in the blade.
Posted via Mobile Device

the magnamatic blade balancer has a bar you can use to check if a blade is bent. it is the most acurate system I know of.

Meg-Mo
09-26-2010, 12:13 PM
With the MEG MO blades we can run 8 to 10 times longer before have sharpen. We can do this since the knives are free swinging we can have the knives made out a lot better steel and then they are rockwelled 10 points harder. Then all you every need is the knives.

towtruck212
09-26-2010, 03:19 PM
We do maintenance every Thursday afternoon.

soloscaperman
09-26-2010, 03:31 PM
I have OCD over my deck every morning I scrap it and scrap the blades then sharpin them. I also do a quick wipe down on the mower inspect everything even tire pressure. Every month I will spray down the blades with a full solution of that purple cleaner. Then I use a metal wire brush attachment for my drill and Clean and polish the blade. When I am done I spray it with WD 40. Grass hardly sticks on the blades for that month then repeat the process.

Magna-Matic
09-26-2010, 04:30 PM
Hello All,

Generally speaking 8-12 mowing hours is a good maintenace interval for lawn mower blades. Try not to use "one week" or "three weeks" as a service interval - because the amount of mowing hours can greatly vary based on weather conditions. (i.e. how fast the grass is growing and soil conditions)

The determination of whether a blade is dull or sharp is based on the pointed TIP of the blade - or cutting tooth. If the tip of the blade is rounded - the blade is dull. If you would like more info about the relief angles of a mower blade see our info on blade geometry here: http://www.magna-matic.com/page/blade-education

We have tested various lawn mower blades from various manufacturers including many blades claiming to be substantially harder than the norm. We have found after hardness testing lawn mower blades off-the-shelf they generally range between 20-40 Rockwell. Hardness of lawn mower blades follow safety standards of the outdoor power equipment industry - therefore there is a limit to how hard a mower blade can be - so it does not shatter when it impacts a rock or foreign object.

As a point of reference for everyone here is a very general scale of Rockwell hardness examples.

Mild steel = approx 10 Rockwell
Lawn mower blades (austempered) = 20-40 Rockewell
Hardened tool steel = 60-70 Rockwell
Hard Chrome plating = 70-80 Rockwell
Carbide = 80 and greater

As you go up in Rockwell hardness the material is more wear resistant if paired with something softer - however the drawback is that high-Rockwell hardness material is brittle - it will crack or shatter.

Lawn mower blades are in this lower range of the hardness scale so that when they impact an object they bend rather than have pieces break off and eject from the deck.

Thank you,

Meg-Mo
09-26-2010, 09:42 PM
As Magna Matic just posted is why all mower blades are so soft. With the knives are free swinging on the MEG MO system we can have a rockwell of50 and only get like the tip of a ball point pen and out wear 3 to 5 set of bar type blades.

LushGreenLawn
09-27-2010, 09:48 PM
As Magna Matic just posted is why all mower blades are so soft. With the knives are free swinging on the MEG MO system we can have a rockwell of50 and only get like the tip of a ball point pen and out wear 3 to 5 set of bar type blades.

Have you checked to make sure your blades are complient with CSPC and OSHA regulations since they are harder than the laws allow? Is there specific verbage in the laws exempting free swinging style blades?

I would hate to think someones insuance could deny a large injury claim because they find out the blades someone is using are not complient with national safety laws.

TroyLawnService
09-27-2010, 10:01 PM
I change out my blades every day (8hrs)

SkinnyVinny
09-27-2010, 10:44 PM
really? everyday and twice a day? that seems alittle over the top to me..

Meg-Mo
09-27-2010, 11:04 PM
Yes we took our blade design to two people that worked for mower mfg. and were told that with the swinging knife we more than meet the rules of blade MFG and the mower co.but none of them will use the MEG mo blades as our customers is 5 yrs. before they need new knives.

rcslawncare
09-28-2010, 12:30 AM
Its about every week for me. But I only mow three days outta the week. Sharp blades are everything

LushGreenLawn
09-28-2010, 06:42 AM
really? everyday and twice a day? that seems alittle over the top to me..

Twice a day, mabye. Once a day is pretty Standard. Anything more than once a day, and your looking for problems. Dull blades are very harmful for the lawn. I am willing to bet the guys changing blades once a week are part timers who are not mowing 8-12 hours a day.

JCLawn and more
09-28-2010, 07:54 AM
Twice a day, mabye. Once a day is pretty Standard. Anything more than once a day, and your looking for problems. Dull blades are very harmful for the lawn. I am willing to bet the guys changing blades once a week are part timers who are not mowing 8-12 hours a day.

your right, 8-15 hours in a day. My record is 26 acres mowed and trimmed solo, put over 100 miles on my truck all in a 15 hour day and with a 1994 721D grasshopper. I notice my blades getting dull after about 30 acres on a bad week when it is dry. When I sharpen I dunk the blade in water after every pass on the grinder so it is cool to touch. I helps out the edge a lot. Once the blade looses its hardened edge from the heat of the grinder you can forget trying to keep your blades sharp for a whole week.