Backhoe Thumb

[downsizingnow48]

When I first built my hydraulic thumb, I bought a Kubota thumb to save time. The B21 never had a thumb. The one I got is made for a B76, but by comparing bucket pin part numbers I figured out it would also fit a B21 hoe. It fit perfectly.

After a while I added a quick coupler to the backhoe so I could change easily between digging bucket, landscape bucket, ditching bucket, and root ripper. That changed the relative positions of bucket and thumb and messed up the thumb closure.

I tried to live with it but too much functionality lost. This winter I decided to make a new thumb. Photos show the wood template, cleaning up the main rails, tacking everything together, test fit, and final installation. Fit is again perfect. I added a bit of extra curvature because the factory thumb was too flat, had a tendency to squeeze stuff out.

The main rails are 1/2" steel, all the gussets are 3/8". I followed the design of the factory thumb on bracing.

Photo 1 - perfect fit.
Photo 2 - not a perfect fit.
Photo 3 - template.
Photo 4 - cleaning up the main rails after plasma cut.
Photo 5 - tacked up.
Photo 6 - test fit.
Photo 7,8 - installed.

 

[Gofast]

Nice job. It looks great.

 

[Gofast]

Did you build your sander? That thing looks sweet. Does it go adjust vertical?
I have been thinking about building one and looking at different designs. It looks like this one was very well thought out.

 

[downsizingnow48]

I studied them for a couple months. Finally bought the grinder from a place called The Belt Grinder in Minnesota. I got the motor and controller separately.

I started out wanting to make one from scratch but I have too many projects lined up.

I added a hinge so can be used either vertical or horizontal. Both positions are needed at least for what I do.

For years now I have been using an upside down belt sander as a grinder, it has worked well. Based on that I decided to get a real belt grinder. It is much more powerful and versatile.

 

[mpsmith60]

When I first built my hydraulic thumb, I bought a Kubota thumb to save time. The B21 never had a thumb. The one I got is made for a B76, but by comparing bucket pin part numbers I figured out it would also fit a B21 hoe. It fit perfectly.

After a while I added a quick coupler to the backhoe so I could change easily between digging bucket, landscape bucket, ditching bucket, and root ripper. That changed the relative positions of bucket and thumb and messed up the thumb closure.

I tried to live with it but too much functionality lost. This winter I decided to make a new thumb. Photos show the wood template, cleaning up the main rails, tacking everything together, test fit, and final installation. Fit is again perfect. I added a bit of extra curvature because the factory thumb was too flat, had a tendency to squeeze stuff out...

Well done! I just recently bought the BXpanded Barracuda Factory Fit Thumb for my BH77 backhoe. I chose it over a Kubota OEM thumb for three reasons: First was the BXpanded thumb costs less. Second, I felt the BXpanded design with the curved jaw was better. Finally, this one is the long jaw version which was specifically designed to work properly with my BXpanded quick-on bucket connect so that the thumb meshes properly with the bucket edge and teeth. There is a shorter version for folks without the quick-on bucket connect. Attached is a picture of the thumb and how it meshes with my 16" bucket and BXpanded Quick-on Bucket Connect, which makes switching to my trencher bucket or ripper tooth really quick and easy.

Here is a video of me installing, and testing the thumb for anyone interested:
BXpanded Backhoe Thumb for My Kubota - YouTube