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View Full Version : What filler for lawn mower blades?



AiR_GuNNeR
07-12-2010, 10:07 AM
When the timing belt on my lawn tractor let loose, the blades smacked together several times before stopping. I want to TIG fill the gouges and regrind. What would be better, stainless filler or regular steel filler?
Eric

lazlo
07-12-2010, 10:31 AM
I'm not sure what to recommend for filler, but I just forged a knife out of a lawnmower blade last week :) It's 5160 -- spring steel.

I think either filler would work, but not sure of the advantage of the stainless filler.

RancherBill
07-12-2010, 10:41 AM
Welding on blades is generally not a good idea. Get some new ones.

lakeside53
07-12-2010, 10:44 AM
A lot of blades are heat treated 1095. Welding that may lead not be a good idea. Why do you want to fill them?

Weston Bye
07-12-2010, 12:12 PM
Ordinary steel filler will be softer than the original metal - and will wear away quickly. Indeed, heating to weld heat will anneal the blade in the area of the heat, making it softer and less wear resistant.

Attempting to heat, quench to full hardness and draw to temper may produce iffy results. the worst case is a blade that is almost file hard and will shatter into fragments if it hits a hard object.

Back in my kid days, I've brazed hardfacing rod (nickel, chromium, manganese alloy) onto the cutting edge of blades and reground, but never really quantified the result.

Evan
07-12-2010, 12:27 PM
Grind them down and balance. Otherwise buy new blades. It is a major safety issue and you don't want somebody hurt.

Black_Moons
07-12-2010, 12:38 PM
Definately grind them down and do not weld, Infact, don't even grind out the gouges, just sharpen them. Call it a serrated lawnmower blade if it makes you happyer, the grass does not care.

Blades are disposables, $20~40 each Don't risk your safty with a weld weakened blade.

914Wilhelm
07-12-2010, 12:41 PM
I'm still using my dead fathers 30 year old Monkey Wards riding mower and recently decided to replace the blades which were missing chunks from the edges. I have just about the most miserable piece of property that continuously extrudes cantaloupe sized cobbles to the surface so I'm hard on this. The old blades seemed like really tough stuff. Long story short I found some blades at wallyworld that fit which seem to be made of paperclip metal. After about a week I hit a cobble and the blade turned Ito a pretzel. Maybe they have decided to use annealed metal to prevent explosion risk. The other non-rock damaged blades edge was rounded over from cutting grass and weeds. I guess you get what you pay for. Anyone have an online source for the 1095 steel so I can make my own blades?

Evan
07-12-2010, 12:57 PM
Harrow disks. 1095 is too brittle, use 1075 if you cannot buy decent blades. You will still have the problem of cutting without destroying the properties. Look around for some decent blades before you try to make your own. I have the same problem here. The hard clay is full of glacial till and erratics. New ones come up every year. I make sure that the blade sits 1/2 inch higher in the housing than the lip of the housing. That way the housing hits the rocks first.

Black_Moons
07-12-2010, 01:05 PM
Oh oh: Solution!
What you guys really need, is a mod for your lawnmowers

Stick this puppy on front:
http://www.langtool.com/images/stumpcenterimage.jpg
Grind all the rocks down for ya before they damage the blade.. :)

Hmmm. Carbide indexable lawnmower blades...

Or maybe just a couple of ganged 9" abrasive masonary disks up front.

lazlo
07-12-2010, 02:19 PM
Attempting to heat, quench to full hardness and draw to temper may produce iffy results. the worst case is a blade that is almost file hard and will shatter into fragments if it hits a hard object.

5160 is super forgiving to heat treat, which is why it's traditional for smiths to forge their first knives out of lawnmower blades.

I annealed mine, forged it to shape, normalized it, reheated it to non-magnetic, quenched in oil and tempered in a toaster oven, and it came out great.

leesr
07-12-2010, 02:50 PM
I purchased a lawn mower back in 2003 after the big fire in San Diego.
mine got toasted. The new lawn mower is a pile of junk. the blades
are soft so it dulls quickly or easily. it falling apart.
the old weed mowers would run & run , as long as it was stored out of the weather.

the motor was marked as 6 HP but cuts more like 2 hp.

It is possible the blades on some lawn mowers are induction harden at the cutting edges, so it cutting edge is hard while the rest of the blade is
core harden.

Leesr:confused:

Evan
07-12-2010, 03:35 PM
Yeah, all this new fangled stuff is crap. Whatever happened to the good old days... :D

http://metalshopborealis.ca/pics/mower.jpg

laddy
07-12-2010, 03:40 PM
I had a cousin that bought a used bush hog. I was visiting his dad one day when he walked in white as a ghost. The previous owner of the bush hog had apparently welded the balade and he was using the machine when the weld let go. He said the blade past his head doing about 200 MPH and he came inside to lay down for a minute. It was too much for him. Get new blades. Fred

AiR_GuNNeR
07-12-2010, 04:00 PM
I wasn't going to be welding the blade together in any way, just filling in a few gouges on the sharp edge. I hadn't considered that it might be heat treated however.
I'll just sharpen gouges like a cerrated knife and rebalance like someone mentioned before. John Deere wants $60 for a set of two blades!

lazlo
07-12-2010, 04:07 PM
It is possible the blades on some lawn mowers are induction harden at the cutting edges, so it cutting edge is hard while the rest of the blade is core harden.

Good point -- we have a pile of old scrap-yard mower blades at ACC, and they're all Made in USA. Everything is so cost-engineered now, Lord only knows what kind of steel they're made of.

By the way, wasn't there a Home Shop Machinist email tip that was sent out about hardfacing mower blades? I'll check when I get home...

leesr
07-12-2010, 04:11 PM
Yeah, all this new fangled stuff is crap. Whatever happened to the good old days... :D

http://metalshopborealis.ca/pics/mower.jpg


ROFL

leesr:D

leesr
07-12-2010, 04:12 PM
I wasn't going to be welding the blade together in any way, just filling in a few gouges on the sharp edge. I hadn't considered that it might be heat treated however.
I'll just sharpen gouges like a cerrated knife and rebalance like someone mentioned before. John Deere wants $60 for a set of two blades!

$60 is cheap.

hospital bill $$$$$

leesr

oldbikerdude37
07-12-2010, 04:45 PM
I had a cousin that bought a used bush hog. I was visiting his dad one day when he walked in white as a ghost. The previous owner of the bush hog had apparently welded the balade and he was using the machine when the weld let go. He said the blade past his head doing about 200 MPH and he came inside to lay down for a minute. It was too much for him. Get new blades. Fred

Amen, not a place to get all cheap. Myself I think new blades are cheap and dont want to put my limited metallurgy skills to the test.

Black_Moons
07-12-2010, 05:18 PM
Yep just sharpen the existing blades till they are beat up enough to warrent the $60 replacement.

914Wilhelm
07-12-2010, 05:33 PM
I had a cousin that bought a used bush hog. I was visiting his dad one day when he walked in white as a ghost. The previous owner of the bush hog had apparently welded the balade and he was using the machine when the weld let go. He said the blade past his head doing about 200 MPH and he came inside to lay down for a minute. It was too much for him. Get new blades. Fred

I've got a brush hog as well. The "blades" are 1" x 4" x 2' bars of metal whipping around on a 2' diameter disc. It pretty much destroys anything it hits like small trees or rocks. One problem is that it can throw stuff quite a ways and I try not to use it next to the hiway for that reason. Years ago I was knocking down a huge patch of blackberries (about an acre) when I heard a clank, explosion, whizzing sound and saw a shadow pass by my head. Turns out I encountered the lid of a barrel which became a frisbee which hit and explosively deflated the rear tire before the lid went vertical past my head. I had to come inside and sit for a while before I could come back and change the tire. Only a couple hundred dollar tire job. Nothing to lose your head over :) .

jdunmyer
07-12-2010, 06:53 PM
About 40 years ago, my cousin installed a new blade on his mower, one bought from Bargain City (the Wal-Mart of the day). The blade broke, the end pierced the fender of his Corvair, and ruined the tire. I'd bet that the blade wasn't made in China, either.

I've shortened blades with an abrasive cutoff wheel, but I'd never, ever weld on one. (My mower uses unusual blades, as it rotates "backwards" from most)

Your Old Dog
07-12-2010, 07:36 PM
I'm not sure what to recommend for filler, but I just forged a knife out of a lawnmower blade last week :) It's 5160 -- spring steel.

I think either filler would work, but not sure of the advantage of the stainless filler.

Hey Bro, I was only kidding about the breaking the first beer bottle over your head :D

I've been resharpening nicked lawnmower blades for years with out problem. 1/8 or less nicks don't need welded in my opinion but anything larger should be replaced, again, in my humble opinion! Blades just aren't expensive enough to risk a welding job on. If you live in the city I certainly would buy new blades.

darryl
07-12-2010, 08:03 PM
I had a blade fly past my head at 200 mph once. Not a lawnmower blade, an RC helicopter blade. Thing was working fine, less than a second later it was a pile of scrap, part of the blade had gone by my head, and other parts flew towards the street where a couple of kids were watching. Nobody got hit, luckily. I think a control rod got loose and one blade flew downwards into the boom. End of model.

That incident really made me wonder about the hub. Being made from aluminum I'd think it could easily reach the point where one day it would simply let go. Then there's the two 'micro' bolts that hold each blade to the hub. All it would take is for the wooden blade to develop a split at that point, then off it goes.

Some things are just inherently dangerous, even if they don't fly apart.

ADGO_Racing
07-12-2010, 08:21 PM
$60 is cheap.

hospital bill $$$$$

leesr


Let's not forget our little friend Murphy. Inevitably, the blade will break once nationalized medicine kicks in. You will then have to wait 6-9 months to get treatment, in the mean time the infection sets in and you die.

Or depending on your age, the death panel reviews your case, and decides you are too old to save. Then they just give you a few pain pills and a room to bleed out peacefully. Well on second thought, probably no pills they cost money, and the room is probably a backyard shed out behind the hospital. :eek:

wierdscience
07-12-2010, 09:21 PM
Just grind the bottoms of the nicks sharp.Infact you can grind a scallop into the cutting edges and they will stay sharper longer in grass with stones,rocks,bricks etc

Dr Stan
07-12-2010, 10:05 PM
2X or more on everyone who has said not to weld lawn mower blades. I did so before I knew better trying to save $ instead of buying a pricey Snapper blade.

1) It did not last long before it discombobulated. :eek:

2) I wasted time & rod on it.

3) I ended up buying a new blade.

Luckily, no one nor anything was injured.

gregl
07-12-2010, 10:26 PM
Just like anything else, there's hay and there's hay that's already been through the horse. To get good blades, find where the professional landscapers go. The professionals won't stand for junk. Know the part name and number, wear a khaki work shirt, long pants and work boots, and tell 'em you don't have an account yet but perhaps they can do something for you on the price if you pay cash.

airsmith282
07-12-2010, 10:29 PM
dont weld them , replace them its safer ,