TWIDDLING MY THUMB

[BobQ]

I am in the process of making my thumb, I am planning to use my top link, is the top link still working out for you guys? any reason not to use it?

Thanks Bob

 

[dfkrug]

New mechanical toplinks are cheap ($25) and they are quickly obsoleted when you convert to a hydraulic toplink. Hence I have a bunch lying around. Another reason to use them is you do not always know how much adjustability you want with such a custom installation. I am also glad that I chose a flat, rather than curved thumb. The flat face facilitates digging dirt.

 

[BobQ]

I don't understand why a flat thumb is better? Why is it better for digging? It is definatly easier to make!!!!!

I am planning on using a top link, I just wonder if it will bend under the given load.

Thanks for all the help!!

Bob

 

[dfkrug]

I built the flat thumb cuz it was easier. The excavator
thumb I operated on a rental machine was flat, too. It seems
to help holding dirt in the bucket. I had no problems gripping
logs. The toplink endures much less stress in this application
than it does using a box blade with rippers. The weak point
will be your dipper stick, since the steel is not real thick. Also
mild steel wears very fast with rock handling.

 

[BobQ]

How thick is the steel on the dipper? I am going to measure so I have a comparison. It looks like you have about three inches of weld along the sides of the dipper? Does that sound right? I want to make sure my pads that I weld are wide enough, so I don't rip them off.

Thanks Bob

 

[dfkrug]

The upper thumb support on the dipper stick is in
compression and under shear forces, so the weld is not so
critical. The lower dipper stick support is in high tension,
so I wrapped my support around it. My dipper stick is 3/16"
thick so it would be easy to distort it if you mount the lower
weldment to the surface only.