Box Blade Hydraulic Scarifier Conversion

   / Box Blade Hydraulic Scarifier Conversion #1  

downsizingnow48

Elite Member
Joined
Jul 29, 2013
Messages
2,749
Location
Sacramento, California
Tractor
Kubota B21
I recently installed a Top and Tilt setup, and am getting a lot more use out of my Bush Hog box blade. The manual scarifiers are the limiting factor in terms of utility and flexibility.

There is a Cammond model that uses manual scarifiers, but can also be got with either mechanical or hydraulic scarifiers. See Photo 1.

I decided to modify the Bush Hog along the same lines.

Photo 2. The brackets for raising and lowering the scarifiers are made from 1.5 x 4 x 3/16" tube. The middle bracket is also the bottom cylinder mount.

Photo 3. This shows how the brackets and gussets attach to the scarifier lifting beam.

Photo 4. The Bush Hog with pin retainers cut off and old welds sanded down.

Photo 5. Measuring for the top cylinder mount. The cylinder is 1x4 with retracted length of 10 inches.

The back brace was right in the way of everything, so I cut it out. Some Bush Hogs of this design do not have a back brace anyway. I am still thinking whether I should make a replacement brace.

Photo 6. Marking locations on the lifting beam to be sanded to fresh clean metal preparatory to welding.

Photo 7. Brackets clamped in place ready for tacking.

This next part was tricky at least for me. Over on the Welding Forum I asked for advice on how to weld the 5 brackets to the lifting beam so as to avoid warping the beam.

This method of lifting the scarifiers is inherently subject to binding. Several parts of the design have to be got right to avoid binding, and having a straight beam is one of them.

I got some really good guidance on how to end up with a straight beam, and followed it here.

First I checked the straightness of the beam (2 x 2 x 1/4"). One axis was straight, the other was bowed about 3/32" in the five foot length. So I marked that side as H for High, and made sure to tack the brackets on the high side. After tacking all five brackets, the bow went away, and the beam was perfectly straight. That gave me some idea how the beam would respond to the heat of full welds.

Photo 8. I clamped the ends of the beam to a heavier tube (4 x 4 x 3/16"). I put a piece of 1/8" strap in the middle and bent the beam down over it. This method was suggested by Shield Arc. Based on how the original 3/32" bow disappeared while tacking, I figured this "artificial" 1/8" bow would just about offset the first full bracket weld. This was guesswork but it turned out OK.

Then I welded the middle bracket and let it set for 40 minutes to completely cool.

Photo 9. When I unclamped the beam, it was perfectly straight, no sign of warp at all.

I had to stop then and get back here to Sacramento, so it will be a few days before I can return to the workshop and continue. I will use the same "clamp over 1/8" strap" method to weld the remaining four brackets.
 

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   / Box Blade Hydraulic Scarifier Conversion #2  
That is very nice I wish my box scraper had that modification. I like the fact you could raise the scarifiers like that I could see that being handy breaking roots that stop the tractor and it would put the strain on the scraper rather than the tractor. If you hooked a root you could drop the box all the way down then raise the scarifiers putting all the strain on the implement rather than the tractor.

Mike
 
   / Box Blade Hydraulic Scarifier Conversion #3  
Very nice so far! Ambitious project for your spare time!
 
   / Box Blade Hydraulic Scarifier Conversion #4  
:thumbsup: Subscribed.
 
   / Box Blade Hydraulic Scarifier Conversion #5  
Fun project.

It looks like the Cammond scarfiers rise and fall on an arc and the scarfier "holes" in their cross beam are designed to allow some front to back movement caused by the arc. How will you deal with that?
 
   / Box Blade Hydraulic Scarifier Conversion
  • Thread Starter
#6  
It looks like the Cammond scarfiers rise and fall on an arc and the scarfier "holes" in their cross beam are designed to allow some front to back movement caused by the arc. How will you deal with that?

Yes that is a problem with this design. What I have in mind is:

1. Put the pivot point for the radius arms about 18" back from the scarifier pin. This flattens the arc over the 4" stroke to about 3/16".

2. Put the pivot point 2" above the scarifier pin (1/2 the cylinder stroke), so the 3/16" shift is in the middle of the arc rather than close to the full lift or full drop positions.

3. The holes in the scarifiers are 5/8" and same for the brackets. I plan to use 9/16" bolts. This will accomodate some of the 3/16" shift. The Bush Hog used 1/2" pins and I can go to that if need be.

4. The existing scarifier slots are about 2 5/8" vs the scarifiers 2 1/2". So there is some clearance there.

Of course having a straight lift beam is important.

Probably these steps will do the trick. If not I have two other options.

First, the distance between top and bottom holes of the scarifiers is 3" not 4". I would like to have the additional inch of lift. But if need be I can just use 3" of the cylinder stroke and reduce the arc movement to about 1/8".

The second fall back is that I can whittle the slots a bit (maybe 1/8" off the back of the top slot) to get more clearance without excessive banging around of the scarifiers.

So it is definitely a problem but some or all of these steps should do the trick.
 
   / Box Blade Hydraulic Scarifier Conversion #7  
Yes that is a problem with this design. What I have in mind is:

1. Put the pivot point for the radius arms about 18" back from the scarifier pin. This flattens the arc over the 4" stroke to about 3/16".

2. Put the pivot point 2" above the scarifier pin (1/2 the cylinder stroke), so the 3/16" shift is in the middle of the arc rather than close to the full lift or full drop positions.

3. The holes in the scarifiers are 5/8" and same for the brackets. I plan to use 9/16" bolts. This will accomodate some of the 3/16" shift. The Bush Hog used 1/2" pins and I can go to that if need be.

4. The existing scarifier slots are about 2 5/8" vs the scarifiers 2 1/2". So there is some clearance there.

Of course having a straight lift beam is important.

Probably these steps will do the trick. If not I have two other options.

First, the distance between top and bottom holes of the scarifiers is 3" not 4". I would like to have the additional inch of lift. But if need be I can just use 3" of the cylinder stroke and reduce the arc movement to about 1/8".

The second fall back is that I can whittle the slots a bit (maybe 1/8" off the back of the top slot) to get more clearance without excessive banging around of the scarifiers.

So it is definitely a problem but some or all of these steps should do the trick.

Sounds good. Thanks. Would a pivot slot instead of a pivot hole in the radius arms work too?
 
   / Box Blade Hydraulic Scarifier Conversion
  • Thread Starter
#8  
Pivot slot is a great idea!

When I first started thinking about this, a month ago, I was planning to have the cylinder mounted low, so that it pushed the beam up and back. I considered a slot at that time, but it wouldn't work with the cylinder oriented that way.

In the meantime I decided to mount the cylinder high, pulling up rather than pushing back. But I failed to factor the slot option back in! With the cylinder pulling up and a bit forward, the slot should easily accommodate the 3/16" movement. A much better solution than the various work-arounds I listed. Many thanks!
 
   / Box Blade Hydraulic Scarifier Conversion
  • Thread Starter
#9  
I finished this yesterday and used it to break up 80ft of hard packed gravel/dirt driveway to be planted in bushes and trees. The scarifier conversion worked fine.

Photo 1: I welded all five brackets to the lifting beam using the welding forum advice. It turned out perfectly straight. I decided not to use the gussets, they would have been overkill for strength, and I didn't want to push my luck on warpage.

Photo 2: The swivel is a 5/8" shoulder bolt with .75" x 2.25" shoulder. I made the slots by drilling two overlapping 3/4" holes with a carbide-tooth hole cutter, then used a small Makita belt sander to grind out the remaining material.

Photo 3: This shows the radius arm installed. The tube is 2" which leaves a 1/4" gap to the side of the box. I used 1/4" Williams washers as spacers, they are just a bit less than .250" so the operating clearance is perfect.

Photo 4: Beam and arms set up for welding.

Photo 5: Welding the upper cylinder mount.

Photo 6: Cutting the scarifiers for clearance.

Photo 7: Cylinder installed.

Photo 8: Scarifiers up.

Photo 9: Scarifiers down.

It was a pretty simple conversion, even taking account of the new-to-me anti-warp welding technique. The total cost was about $210. Cylinder was $95, hoses $35, hardware about $20, the rest was steel. Definitely worthwhile for the improved utility and productivity.

I thought there might be some creaking and groaning when the scarifiers move up and down, but it is silent except for a clunk when they reach the end of the travel. Will leave it in primer until I can locate some Bush Hog yellow paint.
 

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   / Box Blade Hydraulic Scarifier Conversion #10  
Gooder-un :thumbsup:
 
 
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