Backhoe Ripper tooth design - need your advice

[Coyote machine]

The following pics are of the second generation of what was originally made for Island Tractor. I asked the manufacturer to add teeth to both the front and backside of the ripper tooth and nicknamed it "The Claw".
The pics are not in any particular order, however they show the claw from different angles and at work ripping out some frozen roots in the bottom group of pics in freezing temps a winter or so ago.
I'm a big fan of using the curl to tear at the roots while lifting up with the serrated edge of the claw to effectively immobilize the root from sliding off the inner curve of the claw. And though it might also be effective to push down and out, as already stated it is an odd maneuver and not easily mastered. So, I prefer to bring the root toward me and up while cutting it/breaking it as the root's natural slipperyness allows or not. Once torn some it is easier to cut further until it submits to hydraulic pressure and gives way completely.
This tooth/ripper is not perfect but it gets the job done, and well at that.
Designed and manufactured by MIE, an approved advertiser on TBN. I have NO affiliation except for having bought numerous of their products over the recent years.

 

[bluehog]

~Coyote Machine~
Appreciate the pics and the description of the technique you use. I reviewed your pics and I have a couple questions:

1. You have 2 shots showing the jaw exiting the ground looking straight down on the teeth... Is there a side cutting edge on the teeth or are they full width of the shank thickness with no side angle modifications ?

2. What is the thickness of the steel used that the bucket pins go through. It looks like 1/2" with the additional round collars welded to give the pin engagement and locking bolt installation. I have contemplated/designed using 3/4" but think it might be overkill. This thing is going to be heavy and I'm second guessing some of my choices.

 

[Coyote machine]

~Coyote Machine~
Appreciate the pics and the description of the technique you use. I reviewed your pics and I have a couple questions:

1. You have 2 shots showing the jaw exiting the ground looking straight down on the teeth... Is there a side cutting edge on the teeth or are they full width of the shank thickness with no side angle modifications ?

2. What is the thickness of the steel used that the bucket pins go through. It looks like 1/2" with the additional round collars welded to give the pin engagement and locking bolt installation. I have contemplated/designed using 3/4" but think it might be overkill. This thing is going to be heavy and I'm second guessing some of my choices.

You're welcome- glad to be of assistance.
Teeth are cut from the width of the curved blade, just a mod of the CNC software to cut the tooth profile.
I believe the bushings for the pin/bolt attachment are the same or slightly wider than what Kioti uses on their buckets; I don't know exact but my guess like yours is 1/2".If you have to know exactly I can measure. Let me know.
I put things like the claw on a dolly and wheel it into position on my shop floor and then line up pins. It was a breeze to install, no work at all. I dropped 18" bucket on a dolly, moved claw into position and drove in the pins.
My latest fabrication is a 'bra' for my hoe bucket which covers all four teeth and gives me a straight edge for smoothing ditches, etc. Haven't tried it yet, but I had my local welder make it from a picture of another TBNer's similar but not as robust version.

 

[bluehog]

You're welcome- glad to be of assistance.
Teeth are cut from the width of the curved blade, just a mod of the CNC software to cut the tooth profile.
I believe the bushings for the pin/bolt attachment are the same or slightly wider than what Kioti uses on their buckets; I don't know exact but my guess like yours is 1/2".If you have to know exactly I can measure. Let me know.
I put things like the claw on a dolly and wheel it into position on my shop floor and then line up pins. It was a breeze to install, no work at all. I dropped 18" bucket on a dolly, moved claw into position and drove in the pins.
My latest fabrication is a 'bra' for my hoe bucket which covers all four teeth and gives me a straight edge for smoothing ditches, etc. Haven't tried it yet, but I had my local welder make it from a picture of another TBNer's similar but not as robust version.

Do you see any advantage to having a side angle on the teeth to help cut the roots? The straight side walls (perpendicular to curved blade) would not only be easier to produce but seems like it would hold up better to abrasion. I like the dolly idea... I'll start with that approach and adjust as needed. Sounds like you have quite a collection of attachments... I'm just getting started

Also if you could measure for me I would greatly appreciate it as I would like to order my material this week. I have provided a sketch with 4 areas I would like input on.

My drawing has A (left & right sides)= 3/4" B= 3/4" C= 3/8" D= 3/8"

 

[Coyote machine]

The teeth work the way they are, no need to design them further. I'll get you the measurements.
What's up with the end tooth?

 

[IslandTractor]

The teeth work the way they are, no need to design them further. I'll get you the measurements.
What's up with the end tooth?

I would say that the teeth without "cutting" edges work simply as devices to keep the root from sliding up the ripper. They would not cut the way a sharpened edge would cut or saw. Keeping the root from sliding is great as it allows the full force of the curl to be brought to bear but if the edges were sharp they would cut better. When was the last bread knife you used that had blunt or squared off serrations? It's all about pounds of force per square inch at point of contact and a knife edge will always beat a flat wider surface when the same hydraulic force is applied. Again, I'm not arguing that there is no benefit from the "blunt" serrations because they will hold the root so it can be broken but they will not be as efficient as "sharp" edges when exerting force. Kind of the difference between having a good grip on something that you can they pull to break versus having a grip but using a knife or saw to cut through it.

 

[IslandTractor]

My drawing has A (left & right sides)= 3/4" B= 3/4" C= 3/8" D= 3/8"

View attachment 337236

Not sure I can get to my tractor this week. Maybe Coyote Machine can. However, I am pretty sure my A and B plate thicknesses are less than 3/4". 1/2" is my guesstimate and when I check a Woods bucket technical drawing it appears to be 1/2" for the hinge plate too. Remember there will be bushings that stand proud of the plate and that those add structural strength as well. Basically there is no need to build the mount any stronger than the mount of a standard bucket. The ripper just concentrates force but doesn't exert any greater total force on the mount than a standard bucket would. The braces front and back as well as the gussets will provide strength not just for the blade but for the mount as well. Mine weighs something over 90-100lbs and believe me you don't want it any heavier when time comes to mount it.

 

[Coyote machine]

I would say that the teeth without "cutting" edges work simply as devices to keep the root from sliding up the ripper. They would not cut the way a sharpened edge would cut or saw. Keeping the root from sliding is great as it allows the full force of the curl to be brought to bear but if the edges were sharp they would cut better. When was the last bread knife you used that had blunt or squared off serrations? It's all about pounds of force per square inch at point of contact and a knife edge will always beat a flat wider surface when the same hydraulic force is applied. Again, I'm not arguing that there is no benefit from the "blunt" serrations because they will hold the root so it can be broken but they will not be as efficient as "sharp" edges when exerting force. Kind of the difference between having a good grip on something that you can they pull to break versus having a grip but using a knife or saw to cut through it.

I was a little suprised when the teeth were not sharp, BUT they are safer to the OP for mounting/dismounting, and from the little use I've had time to put the claw through it does serve to grab the root so I can curl and attempt to break out sections of the side of the root facing the teeth. IMHO, once the 'squirrely' edge of an otherwise slippery round, or whatever shaped root is chinked by the teeth the root is significantly weakened and further curling attempt(s) render it into submission in fairly short order. Yes a sharper tooth edge might work faster, but for me the sawing motion that might have to be applied could be as difficult as using a down and back motion to rip with the backside teeth. More experience with the claw will provide further insight.
I do agree making the tool as light and sturdy as possible without unnecessary weight would certainly be advisable.
I can say for sure a $20 H.Depot furniture dolly made the first and only attempt to install the claw a one shot and done deal. I carefully removed the bucket for the first time and then with the claw on it's back on the dolly, moved it under the dipper and lowered it and drove in the pins. Done, easier than I thought it would be....YMMV.
I will get the measurements this afternoon.

Here are the measurements: A: 1/2", B: 3/4", C:3/8", D: 3/8" AND the hole with boss on the outside measures: 7/8" total. Ripper/claw plate is:1/2" thick. Up close the teeth have more of a point to them than may be apparent in my pics, but not a sharp knife like edge. I suspect with more use the teeth could become sharper, but that is pure conjecture on my part without more use.

 

[bluehog]

The teeth work the way they are, no need to design them further. I'll get you the measurements.
What's up with the end tooth?

The end tooth is a replaceable tip. I will be mostly dealing with trenching in clay bases soil with a large amount of volcanic rounded rock. So I figured the solid tooth that you and Island Tractor have would get worn and damaged... so a replaceable tooth seemed logical... to me at least. I know that Island Tractor is not fond of it either. I am a bit worried about the weld of that item to shank as all the force will be of those welds.

In post #19 on page 2 I showed a few pics of the adapter and the replaceable tooth

 

[bluehog]

~Coyote Machine & IslandTractor

Thanks to both you guys for the sizing info. I know it needs to be strong... but overkill will only hurt me trying to move it around. I will modify my plans to incorporate the bucket pin supports (item A) to be 1/2".