Making a big chopper with old lawn mower blade

[spader]

Hi All

Trying to make a big chopper with old lawn mower blade. It is about 4mm thick and 50cm long. All I am using is an angle grinder and files.
The blade has been softened in the coal stove, and cut to the rough shape I want it to be.

Next step is to flatten the blade more, put working edge on, and then harden it in the garden stove forge and motor oil in the used coffee tin

As soon as it is cut to shape, did a quick chopping with light edge on the softened metal, and already it was splitting and chopping the logs quite well.

 

[crosslandkelly]

Certainly going to be a beast. I look forward to seeing it finished.

 

[mick91]

Should be half reasonable steel being a lawnmower blade. Interested to see how that pans out

 

[Everything Mac]

I nearly picked up a few of these on my last visit to the scrappy. Though they were about 8mm thick. Ended up picking up a huge leaf spring though.

I'm interested to see how this blade comes out. Are you going to use a flap disc on the angle grinder to clean up the angular portions of the handle? I reckon this could be a good blade.

Andy

 

[Robson Valley]

Make certain that your local wood carving fraternity knows what you're making.
We need and use a "froe" to split quality carving wood. The straight grain
takes a whole lot of the grief out of carving when compared with wood that's come through a sawmill.
My froe is 3/8" thick, 3" wide with an 11" edge, single bevel on one side of the edge.
In western red cedar, I can split off 1/8" sheets or divide a 40lb x 24" shake block.

 

[richardhomer]

I am looking forward to seeing how thus turns out.
It looks like its going to be a beast !

 

[badoosh]

Waiting for this
Got a blade in the shed just waiting for a new project .

 

[spader]

Yes, I will further work on the sharp ends around the blade with angle grinder and files. Because the blade is heavy and large, it was chopping and splitting logs with much efficiency. It worked like an axe rather than knife, and that's with its unhardened rough temporary edge. I expected it would embed on the logs, have to be taken it off, and hit a few times to split 6 - 8 inch logs, but it just kept on splitting them by single blow, or when embed, a few battoning worked wonders. Afterwards, the sharp edge was gone, but it got very sharp in no time by a few stroke on the cigar sharpening stone.

I will be heat treating to harden it on either gas cooker in the kitchen or wood stove in the garden, quench it in the motor oil or just water, then temper it in the gas oven for 2 - 3 hours. I will keep updating the progress here. cheers.

 

[mick91]

Yes, I will further work on the sharp ends around the blade with angle grinder and files. Because the blade is heavy and large, it was chopping and splitting logs with much efficiency. It worked like an axe rather than knife, and that's with its unhardened rough temporary edge. I expected it would embed on the logs, have to be taken it off, and hit a few times to split 6 - 8 inch logs, but it just kept on splitting them by single blow, or when embed, a few battoning worked wonders. Afterwards, the sharp edge was gone, but it got very sharp in no time by a few stroke on the cigar sharpening stone.

I will be heat treating to harden it on either gas cooker in the kitchen or wood stove in the garden, quench it in the motor oil or just water, then temper it in the gas oven for 2 - 3 hours. I will keep updating the progress here. cheers.

If you're water quenching try dissolving a cup of salt into hot water. Any more experienced correct me if I'm wrong but has something to do with the lindenfrost effect by making the steam bubbles smaller and collapse quicker giving a better result. It seems to anyway!
Consider differential hardening too, I do it on larger blades following the tradition of original bowies. It supposedly makes a difference, and isn't all that hard

 

[spader]

Yeah I was wondering what would be difference between blade quenched in motor oil and water. In the past I used cooking oil and quenched carving knives made of hacksaw blades, and they work great.

6 year ago, when I made utility knives out of vintage circular saw blades, I quenched them in the water of the bath tub. I have been using them everyday opening and packing parcels made of thick cardboard. They are scary sharp and work great.

 

[mick91]

Yeah I was wondering what would be difference between blade quenched in motor oil and water. In the past I used cooking oil and quenched carving knives made of hacksaw blades, and they work great.

6 year ago, when I made utility knives out of vintage circular saw blades, I quenched them in the water of the bath tub. I have been using them everyday opening and packing parcels made of thick cardboard. They are scary sharp and work great.

I've played around using everything from used transmission fluid to my cold tea on the side. To a degree quenching is quenching imo, but salt water brine is cheap, readily available and seems to be very effective, had no complaints yet!.
I like that little blade. Looks usable, and a nice homage to spyderco intentional or not! End of the day start with good steel you'll end up with something half decent, start with crap it'll stay crap.

 

[spader]

Thanks for your info. I will try the salt water this time.

That utility blade cutting edge is 7 inches, and yeah pretty can do anything tool really - carving, chopping, splitting, stabbing, throwing and battoning, anything thrown it handles very well. Full tang blade, as you noticed, the design was borrowed from the Spyderco. The handle was just epoxied 1 cm thick vintage leather on both side of the blade no rivets. 6 years on still works like first day it was made. Vintage saw blades are good stuff for making tools. Not sure how the lawn mower blades would be like. Will see.

 

[Chaard]

Quick health and safety note. Most modern engine oils contain ZDDP that will breakdown anywhere above 70oC. This will give off H2S a fairly poisonous gas. Interestingly if you can smell it, it is in safeish concentrations. If you can't smell it, its either not there or its slowly poisoning you.

 

[spader]

That suits me fine as I have no used motor oil. Don't want to use new Castrol GTX stuff for quenching.

Weighed and measured the mower blade, and it is 850 grams, and 22 inches long.

 

[Everything Mac]

H2S is a risk out here on the rigs. Nasty stuff.

https://www.osha.gov/SLTC/hydrogensulfide/hazards.html

This has claimed more than a few lives offshore.
Andy

 

[mick91]

H2S is a risk out here on the rigs. Nasty stuff.

https://www.osha.gov/SLTC/hydrogensulfide/hazards.html

This has claimed more than a few lives offshore.
Andy

Indeed it is funny stuff to handle. Flammable in the right concentrations too so probably not a good idea to have a flaming oil bucket in a garage full of it

 

[spader]

Never heard of H2S before. Good to know it can be dangerous and gets produced by Motor Oil above 70 centigrade. Will steer well clear from it. Also, in the future I plan to live in a rural area, where cars are not needed and not used

Anyhow when I had an hour or so last night, did some smoothening work around the the mower blade especially on the handle with the angle grinder and files. Afterwards, it fitted into my hand very well, and blade was well balanced feel.

Next step is to soften the metal in the forge, and more straighten it on the anvil and with hammer, which will be time consuming task.

 

[mick91]

Time consuming but worth it. Will be keeping an eye on this one

Sent from my LG-D855 using Tapatalk

 

[petrochemicals]

That is a big chopper, but it's a very nice one though sir.

 

[spader]

Thank you sir. It is a good fun DIYing these tools with materials which were going to go to the bin . That blade had been in the shed for many years just rusting away.

The handle is now shaped just right. My pinky fits nicely into the groove, grabbed like that, feel as if the blade wouldn't go anywhere away from the hand.

Then some chopping test. Works ok as is.