blade steel for tree grubber knife edge?

[kossetx]

I'm building/built a tree grubber. It is 3/4" mild steel for a 3ph. The first tree I tried it out on pulled out no problems, even in dry dirt. It was a 3" scrub oak. The results went downhill from there.

It will pull out any tree that has a Y somewhere close to the ground. Unfortunatly, most trees don't have this. The grubber has a V cut into the 3/4 plate with no beveled edge on it. I can cut a "edge" on the steel to cut into the trees, but I think the mild steel won't keep the edge so I'd like to use some blade steel bolted on to the mild steel. A lawnmower blade may be good for this, but the lift edge on the lawnmower blade won't work. I need flat bar of a high grade steel. Anyone know what kind of steel I need and where to get it?

How do I cut steel like this to keep temper? Can I just use a chop saw? TIA for any help, MP

 

[jeffinsgf]

In your shoes, I would start by grinding a bevel edge on what you've already got. If it turns out that you really need a hardened edge, you haven't lost any ground, but I think you'll find that once you cut a a bevel on that mild steel, it will cut into the trunks just fine. You're not trying to cut the tree down, you're just trying to get a grip on it.

Nice design, by the way. Clean and simple. Think I'll try one just like it.

 

[BobG_in_VA]

Nothing beats a chain wrapped around the tree base about 2 or 3 times. Weld/attach about 10 ft of chain on one side of your deal. Have grab hook on the other side. Back up the tree, wrap the chain a couple of times and lock it down to the grab hook. We used pull fence posts (even with concrete around the base) with just a drawbar and chain this way. BobG in VA

 

[shaley]

You could bevel the edge and then use a hard surfacing welding rod to cover the edge to increase abrasion resistance.

 

[schmism]

How do I cut steel like this to keep temper? Can I just use a chop saw? TIA for any help, MP

jig or band saw (bandsaw is the best) a chop saw is an abrasive type (unless its a multi-thousand dollar cold saw) meaning it heats the surface and grids it away.

a bansaw ill actually cut the steel and keep the surrounding metal relitivly cooly to which will keep the temper of it.

 

[kossetx]

Thanks for the re[lies. I would rather try a cutting edge rather than bevel the existing edge for several reasons.

1. A bolt on edge would be easy to sharpen and also to replace if ever needed.

2. If I bevel the existing edge and don't like it I'm still stuck with it. It would be easier to do that way but much harder to sharpen. I thought about welding a harder edge on the existing mild steel but grinding the bevel down in the crotch of the V isn't easy, if possible at all unless I do it by hand with a file. The reason for using a tempered cutting edge is ease of use. I definatly don't want to to use it to cut anything off. The idea is to pull it out. That is pull it out without having to get off the tractor.

As for cutting it, I forgot I bought a sawzall a few weeks ago. I knew I didn't want to use a chop saw. I can use the sawzall and take it slow.

 

[kossetx]

By the way Jeff. The frame is a Howse middle buster frame. It has 3/4" shaft installed with 2 3/4" bolts. I simply unbolted the MB shaft and installed my grubber in it's place with the 2 3/4" bolts. It is now a truely multi function implement.

 

[jeffinsgf]

Thanks for the re[lies. I would rather try a cutting edge rather than bevel the existing edge for several reasons.

1. A bolt on edge would be easy to sharpen and also to replace if ever needed.

2. If I bevel the existing edge and don't like it I'm still stuck with it. It would be easier to do that way but much harder to sharpen. I thought about welding a harder edge on the existing mild steel but grinding the bevel down in the crotch of the V isn't easy, if possible at all unless I do it by hand with a file. The reason for using a tempered cutting edge is ease of use. I definatly don't want to to use it to cut anything off. The idea is to pull it out. That is pull it out without having to get off the tractor.

As for cutting it, I forgot I bought a sawzall a few weeks ago. I knew I didn't want to use a chop saw. I can use the sawzall and take it slow.

I still say you don't need a hardened edge. I think your tool will get sharper with use, instead of duller -- unless you start using it to pull up rocks along with trees. Look at the wedge on a log splitter. They're usually fairly mild steel and mine is just about like a razor, after using it hard for a couple years. When it was new, the edge was blunt. Edges typically dull from hitting the wrong things or from abrasion due to speed. This is a no speed application where you're going to be pressing the tool into the trunk slowly. I think if you put too keen an edge on it you'll have a heck of a time getting the tree off.

But, it's your project and it sounds like you really want to work with that hardened stock, so more power to you!

 

[RonR]

I like the grubber.

I think one thing I would add is a tube at the top that formed a "V" to keep the top of the bush/tree away from the tractor (and me).

Ron

 

[vmarc]

You can use a leaf spring from a car or truck.I don't think you'll cut it with regular blades.An easier way might be to use mild steel .Shape it with ordinary blades and then heat it cherry red and then quench the blade in salt water.There's enough carbon in mild steel to get it pretty hard this way.You won't be able to drill or cut it after this treatment,so make sure it's the way you want it.