DIY thumb for backhoe

[lennyzx11]

After starting to make a thumb for my Woods 7500, I noticed that Titan had a weld it kit for a 24” pin type. For 140 bucks. Hard to buy the metal for much less.

DIY 24" Weld On Backhoe Thumb Hoe Clamp .5" Steel Plate Assembly CNC Plasma Cut

It came in a sturdy well wrapped package. That was heavy at 60 lbs.




1/4” steel throughout and the holes were close enough with a little grinding to be done to mate everything up properly. Chinese tolerances you know.

Then I noticed that no matter which way I Tried to do it, it wouldn’t fold down to the boom.
The geometry appears wrong in the hole placements.

In the above picture, the backbone is laying down on its back, the brace is inside and one jaw close toward camera.

The three holes are aligned in the backbone and brace have pins in them. The one hole toward the middle does not have a corresponding hole in the brace inside the backbone.

The two holes line up in the jaw and backbone but not the brace.
Trying to fold it together the way you would think leaves two end holes blocked by the jaws not allowing a pin to be inserted for storage.

This shows the jaw on the far side blocking the two holes in the backbone. With the brace ready to fold down inside.

The easiest way to get something that will fold up to me is to drill two holes in the brace to mate with the middle set holes in the jaws and backbone I think.
Drilling to match the jaws to the other holes on the tips would compromise their strength I believe.
Trouble is, my way I think it will be a PITA from now on to unfold and fold because of having pins through all 3 pieces that have to be removed means you get to juggle the jaws and brace in your hands all at the same time as no one pin can be left in place to unfold and pivot on.

Thinking of cutting one end of the brace off to shorten it or drilling another hole in the brace to offset it away from one end. This would allow one pin through the jaws and backbone to remain as the pivot all the time.

I’m in the “pondering “ mode for a bit before I weld it all together or bore holes in 1/4” steel.

Open to thoughts from the brain trust.

Lenny

 

[3Lfarms]

I got one of the Titan thumbs too.
You’re right. The holes don’t line up so that it can be folded up. Its a stupid design. I don’t know what the second hole in the support arm is even for.

This is what I did to solve the “storage” problem.


Since this thumb is actually too heavy for a tractor backhoe, I am planning on welding up a separate storage location on the backhoe to pin the thumb pieces onto to take the weight off the dipper when I want to dig a trench or something.

 

[dfkrug]

After starting to make a thumb for my Woods 7500, I noticed that Titan had a weld it kit for a 24” pin type. For 140 bucks. Hard to buy the metal for much less.

I looked at the website and the specs on it are very limited. One reviewer notes that there is no storage position up against the dipper, as you found. I saw no specs on the pin sizes. I hope they are at least 1" or 25mm.

$140 seem reasonable otherwise, as long as you did not have to pay $100+ for shipping from MS.

With the Woods or similar hoes, using a continuous welded support along the dipper is important since the formed tube is not very thick.

 

[shootemup604]

I used the Titan bolt on thumb on my B/L4520B backhoe (Kubota branded Woods 650-2). The dipperstick is a little narrower, requiring shims. I cut and drilled two 1/8" plates for shims on either side that are welded to the dipperstick. The bolts for the thumb mount go through the holes in the plate as it extends on either side of the dipper. I can install or remove the entire assembly in about 3 minutes, and the permanently welded shims strengthen the dipper with the bolt through holes, the assembly can't move about. The thumb folds away against the dipper, with the link out. It was certainly worth the money and I recommend it in this configuration for guys using it on a similar backhoe.

 

[lennyzx11]

I looked at the website and the specs on it are very limited. One reviewer notes that there is no storage position up against the dipper, as you found. I saw no specs on the pin sizes. I hope they are at least 1" or 25mm.

$140 seem reasonable otherwise, as long as you did not have to pay $100+ for shipping from MS.

With the Woods or similar hoes, using a continuous welded support along the dipper is important since the formed tube is not very thick.

Yes the pins are one inch. And it was free shipping. So that was good.

I did go ahead and drill that third hole. In retrospect I should have moved it over more and had the brace offset from the hinge so the thumb didn’t have to be detached to get the brace off the same pin.
Oh well. It should only be moved occasionally for me as a homeowner not working commercially.

If it does get to be a pain, I know how to add hydraulics thanks to your prior thread!

Here’s where I am tonight. Going to sleep on it before welding it all together.


.

 

[dfkrug]

Going to sleep on it before welding it all together.

Well, it looks very substantial. A thumb is a must-have, IMO.

Thanks and good luck.

 

[spitter]

THat tap magic is like liquid gold . Great for drilling and tapping. Only problem is that the idiot kid that works for us put it in the tap bag with out top on it and turned bag into a goey mess . Gotta hate when you buy something that's supposed to work and you have to spend hours to get it to work like it should have out of the box. Some chineese engineer probally said on Friday afternoon ah grood enuf sell it to wround eye American they will frix. :drink:

 

[lennyzx11]

After looking closely at this, this may be too large for the Woods 7500. So I’m hesitant to weld this to the boom.

On another note. And I know I saw this somewhere before. Is there a place to get pins that are longer than the original for the bucket mounts?

Like the one on this BH77 for the thumb and bucket. It’s also a 1”.



Thanks,
Lenny

 

[dfkrug]

On another note. And I know I saw this somewhere before. Is there a place to get pins that are longer than the original for the bucket mounts?

The best source for 1" or 25mm pin stock is your local steel yard. I was in Bennington last year, and it is a small town, but I do see some steel fabricators there. If not, you can buy steel pins or round stock online, too. I once bought some cylinder rod stock that was chrome-plated at a local disti. 1-inch bolts are a little under-sized in my experience, tho they can be used, too.

As for sharing pins, that can be problematic. You need to provide grease access to multiple points on the pin, and the extra-long pin may break under these loads.

 

[lennyzx11]

The best source for 1" or 25mm pin stock is your local steel yard. I was in Bennington last year, and it is a small town, but I do see some steel fabricators there. If not, you can buy steel pins or round stock online, too. I once bought some cylinder rod stock that was chrome-plated at a local disti. 1-inch bolts are a little under-sized in my experience, tho they can be used, too.

As for sharing pins, that can be problematic. You need to provide grease access to multiple points on the pin, and the extra-long pin may break under these loads.

Good points. Yes there is a great place that lets me pick through their cutoff racks and pay by the pound. I had wondered about making pins from round stock but thought I would check on “store bought” ones availability.

Thanks,
Lenny