Green Tractor Talk banner
1 - 6 of 6 Posts

·
Registered
Joined
·
120 Posts
Discussion Starter · #1 ·
Bought a 18" mechanical thumb for my backhoe attachment but it is really oversized for my needs. Quite heavy and needs to be welded on but the bottom of my 4-3/8" wide boom stick has tapered sides so it will not be easy to weld into place. The bottom plate at 4" wide is flat but the side plates are welded on and are tapered.
Does anybody know of a different brand thumb that is 18" but a little narrower and not as robust? I was looking at the one offered by BXpanded Barracuda for the model 260 backhoe and was wondering if the taper on those is the same as an old Model 7.

BXpanded Barracuda: BXpanded Barracuda Backhoe Thumb for John Deere 260 Backhoe
 

·
Registered
JD4600 loader/backhoe, JD2210 loader mower, JD332 mower,
Joined
·
147 Posts
I ended up going around in circles looking for an aftermarket thumb for my model 48 backhoe. I ended up building (with help from people on this forum, and others), a custom hydraulic thumb just for my machine. Mechanical thumb is good, and far better than not having one, but hydraulic is yet another huge step up in goodness.
796370
 

·
Registered
Joined
·
120 Posts
Discussion Starter · #3 ·
Looks like your boom stick was already setup to add a hydraulic cylinder from the manufacture of the Backhoe.

I sent back the 18" Backhoe Thumb I received for credit and now looking to either make one or modify another manufactures type that may fit. Not many options out there for the model 7 Backhoe though.
 

·
Registered
JD4600 loader/backhoe, JD2210 loader mower, JD332 mower,
Joined
·
147 Posts
@Keith460: I went through the same thing you are going through now, but I gave up trying to find an aftermarket product.

There was nothing on my dipper arm when I started. Everything had to be modelled and checked out before any cutting or welding. Once this woodworking was done, then it became much more clear. Here are pics of the first and second wood models. The second model was used as the template for the final metalwork. The model was finalized once the cylinder was in hand.

It helps to have someone local that will take this on for a price that you can afford. I didn't realize that it took a full year to get all this done, plugging away with bits of spare time. But I will never regret doing this. The process was a tremendous learning experience, and the machine is so much more capable.

Here's a link to the thread where everything was worked out. There were a number of people on this forum that provided valuable input. I'm sure you'll find it valuable if you decide to build one yourself.
 

Attachments

·
Registered
Joined
·
120 Posts
Discussion Starter · #5 ·
A mock up in wood is a very good idea. One thing I have in abundance is wood working equipment.

Did you have to replace the pin on the buckets pivoting axis to a longer one? My JD pin does not extend far enough and would need to be replaced or will have to make a new pin. Never pulled it but I imagine it is hardened with grease grooves and drilled for a grease fitting. I have a hardness tester I can use to determine its HRC or HRB Rockwell Hardness.

Hydraulic cylinders laying around at work are in endless abundance being in the bakery equipment business so that won't be a problem. I know hydraulics well and would not be difficult to make work in unison with the existing valving for the bucket curling feature. I already have that schematic in my mind for the flow control. But I don't really know if I need hydraulic thumb or not. Don't plan on lifting that much with the little Backhoe. We will see what I decide to do.
 

·
Registered
JD4600 loader/backhoe, JD2210 loader mower, JD332 mower,
Joined
·
147 Posts
I had to make new pins. The existing bucket pivot pin was soft, so I replaced it with 4140 TGP material I got online. I have a lathe, so I drilled the new pin and added zerks in the end of the pin. One tricky aspect of this was how to get grease into all of the pivot points. Originally, there is one zerk in the center of the dipper, and the pin rotates with the bucket. But once the thumb was added outside the bucket, I didn't want to weaken the pin by drilling through it. So the retaining pins were eliminated and I added super heavy snap rings on the outside. The square holes in the bucket bosses were filled in with little square steel blocks and held in place with JB weld epoxy. One one side, a zerk was added to the steel block so grease can get in there. I was unsure of whether the JB Weld would hold, but it holds up nicely. I have since broken off one of the zerks, not by digging, but by being sloppy with my grease gun (long story)!! The work on the bucket pin is covered in the thread on the TBN forum. If you go through the effort to build the thumb, adding full hydraulics is a small amount of additional work in comparison.
 
1 - 6 of 6 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top