Bucket Thumb or Dipper Thumb for mini-ex

[oceanobob]

Over the last few years have been occasionally renting a small Kubota KX model and in the more recent past the U15 model Kubota (no tail) - both these are the models with those narrow / expanding tracks - in order to access backyards and other confined areas. Have a couple jobs needing to break some concrete and some tight area trenching and the U15 machine became avail for purchase from the rental company, so signed the forms and joined the ranks of parked backhoes and am proceeding to run the smaller equipment.
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Am considering a thumb to help with demo materials. In researching, there were a couple attributes may I ask about:

• Should the thumb be on a pivot on the same point as the bucket to maintain a clamp as the bucket rotates?
• What is the method with the hydraulic controls to limit excess clamp force - is there a such a thing as user adjustable pressure regulator valve, for example?

If the thumb is indeed considered notably more useful if it is mounted to effect a clamp regardless of bucket rotation, what are the thoughts on the Bucket Thumb idea where the pivot point consideration is moot as a part of the bucket and then (when not needed) the 'bucket w clamp' weight can be removed/dettached: such as in my application when I would install the hammer breaker?

For whatever reason, I seem to only find these thumb style buckets for these smaller machines (U15 is 2 tons) in Australia or New Zealand or a chinese to english marketing website. Wonder if I should weld up my own by purchasing a spare Kubota bucket and extending the mounting tabs/ears and installing the small ram in that newly created and protected pocket? I am surmising this is better than say the other variation of the thumb bucket by placing the rams on the heel of the bucket.

Maybe a fab project is necessary if experienced folks like/prefer the idea of a thumb/grapple mounted on the bucket.

 

[Ronsii]

I always like the thumb pivoting on the bucket pin, just a lot better for placing stuff and when you have to reach up high to dump and need to pivot the piece of demo out and away from the stick to get in into the dump truck or can... but I haven't used the 15 size so not sure how much they differ from the next sizes up 25,36,50's....

We have a breaker for the 36 and I just strap the thumb up when the breaker in on it.

 

[oceanobob]

Sorry folks that should have been U17, not fifteen.

 

[Tags]

I would just look into a kubota made unit, it may be the simplest solution, change the main bucket pin and install the thumb with the new pin supplied. Your machine may already have the upper bracket welded onto the stick. I was real happy with the Kubota made unit on my old 161

 

[oceanobob]

Good suggestion for the source of the thumb: Kubota. But their catalog shows the thumb attachment is for the U25 and larger. Perhaps the dealer knows if it will fit, I will inquire of they.

 

[007]

The U20 has expanding tracks also which i like due to a little more weight.
I didn't want a thumb there all the time so i opted for four way bucket.
I am happy with mine but after buying mine i found better ones which i would have proffered but that's life.
You can get adjustable pressure control devices should you desire.
I had bleed back issues as the aux circuit is a motor control spool and i had to fit valves to hold the pressure.
The Aux on the U15 and U25 is 3250psi hy flow and i had to fit restrictions to slow the grab speed down also.
This style of bucket allows you to grab things as well as dirt up close which is a plus.
If you are grabbing bushes clearing land it is on its own also.
The factory bucket show in the pictures has the hoses all over the place so i changed mine and tidied it up a bit.

 

[oceanobob]

Thank you for the post. glad to learn you like that style. And also thankx for the details about the hydraulics.

Do you find it too powerful when clamping on some wood? such as some cribbing etc.

 

[007]

Because i have slowed mine down you could be quiet sensitive with the bite.
The Hoses act like a Bourdon Tube and flex up as you increase the pressure so you can see how hard it is grabbing by just looking at the hoses.
The heavier the object the harder you have to grab of coarse.
So if you are picking up a large log you do get grip marks from the teeth.
A lot of thumbs are narrower grip so a log would probably mark more as the object twists.
If you are making something custom you can leave the teeth off if you are working with lumbar and don't want marks.

 

[Cammscapes]

I run a thumb bucket (i call it a grapple bucket here in aus) on my vio27, however I was dead set on getting a machine with a stick thumb.
Ended up with the grapple purely because they had one in the yard and was half the price of getting a stick thumb installed.
We use it mainly for landscaping, placing big granite rocks etc and a bit of demo/clearing trees etc.
Now I wasn't sure about it when we got it but I actually think it suits me better than a thumb, as when your not using it its not adding weight to the stick or getting in the way.