Root rake material

Rio_Grande · Jan 15, 2014

E have an 80 hp tracked skid steer. We need a a root rake and a new one is in the 1k range. While that's not a bad price it's a lot of money for what it is. I want to be able to rake about 8 inches deep, nothing crazy.

Would 3/4x3 be tough enough for the rakes in that application? I am thinking spacing them a foot apart and notching them into a frame with a chisel tooth on the dirt end. I would extend the teeth all the way up the frame to tie everything together.

swick1 · Jan 16, 2014

How many tines do you want to build? What is the distance from the chisel tip to the bottom of the crossmember spacing them apart? Is this mild steel or something else?

Rio_Grande · Jan 16, 2014

Mild steel, I would say from the point to the frame 8 ish inches, was thinking 1 per foot so 6 foot wide.

Taylortractornut · Jan 16, 2014

I've made several from junk yard steel like this for smaller dozers D20 Komatsu up to D3 Cats without problems. I just did a cut out kit for a friend's loader the other day. He is making the mount and the cross bar and rack. I just cut the teeth out.

swick1 · Jan 16, 2014

My calculation:

Assuming a cantilever beam loaded at one end, fixed at the other.

Length of beam = 8 in
Load on end of beam = 10,000 lb (skid steer weight)
section modulus of rectangle = base*height^2/6 = .75*3^2/6 = 1.125

Maximum bending stress: Load*Length / section modulus = 10,000*8 / 1.125 = 71111 psi for one tine

bending stress each tine: 71,111 psi / 6 tines = 11,851 psi in each tine

In reality we don't know the loads it will face so this is just an educated guess.

Since the maximum bending stress for each tine (11,851 psi) is less than the yield strength of mild steel (36,000 psi), your material should work well, assuming you have perfect penetration in the weld joint.

You could still break it by snagging a tine on a big rock while moving fast because a point load on one tine is greater than the yield strength of your metal.

You could also mess it up by turning with it underground.

Rio_Grande · Jan 16, 2014

This is what I have in mind. Looks like they are spaced on 6 in centers though, I would follow that lead. I buy a lot of equiptment from this company, they treat me right. I just have 2 24' lengths of 3/4 laying around rusting and plenty of channel iron.

swick1 · Jan 17, 2014

If you study the design you will see that they have added gussets between each tine to stiffen them up. I suggest doing the same. If not on every tine, at least do it to the end tines.