Thumb

[kaiser715]

I wanted a thumb on my BH77. Got a titan weld on, but as usual for me....couldnt leave it stock. For the brace, I wanted to use the Kubota mount point already on the dipper.....so I started by cutting up the titan weld on mount. I also thought the 24" was too long, so shortened up the main toothy thing by about 4"

This is what I ended up with, open and stored. Brace is 1.5" .25 wall....held up so far in testing. Pin mounts on brace are 1"IDx.25 DOM.

Gotta clean up and paint still.

 

[kaiser715]

This is what I started with:

 

[kaiser715]

And what I cut off the titan base plate...

 

[scdeerslayer]

It took me a while to figure out the other two pin holes but I see it now. Since they are only used to store the thumb I wouldn't worry about them breaking out, otherwise I'd want them fully encased in the square tubing.

You should just convert it to hydraulic anyway. Might not store as tightly against the stick but that's not that big of a deal. I converted my factory manual thumb by teeing into the bucket lines and using a solenoid valve on the thumb cylinder port. Push the button and both sides get pressure. Put the bucket against something leaving the thumb free an set the thumb into position, or just grab something allowing both to move until they are into position. Let go of the button and the bucket works like it should, allowing you to get a tighter grip.

 

[kaiser715]

I'm going to try it for a while and see how it goes as a manual thumb. I have a couple of cylinders that are probably close enough to try if I go that route.

 

[MattN03]

It took me a while to figure out the other two pin holes but I see it now. Since they are only used to store the thumb I wouldn't worry about them breaking out, otherwise I'd want them fully encased in the square tubing.

You should just convert it to hydraulic anyway. Might not store as tightly against the stick but that's not that big of a deal. I converted my factory manual thumb by teeing into the bucket lines and using a solenoid valve on the thumb cylinder port. Push the button and both sides get pressure. Put the bucket against something leaving the thumb free an set the thumb into position, or just grab something allowing both to move until they are into position. Let go of the button and the bucket works like it should, allowing you to get a tighter grip.

Any pics or part numbers you used in your setup? I recently added a Kubota thumb to my BH76. I think the only thing better than this setup would be to convert it to hydraulic Having a thumb sure is handy!

 

[kaiser715]

Any pics or part numbers you used in your setup?

This is what I started with:

http://www.palletforks.com/24-backhoe-thumb-attachment.html

I cut about 4.5 inches off the pivot end of the thumb part, and drilled new pivot holes. It is about 2" longer now than the teeth on the bucket when they make contact. Then drilled new holes for the brace pin about 4.5" below the existing brace holes. Made new brace out of some 1.5" x .25 wall square tubing I had in the shop.

I did a lot of figuring to get it to lay as flat as possible to the dipper stick when stored, so it would be less in the way when digging.

 

[kaiser715]

Oops....back on my computer, not my phone, I now see that Matt was asking that question of scdeerslayer .... (who ought to come up to NC and slay a few so I'll quit doing it with the truck bumper).

 

[scdeerslayer]

First I'll say that I got the idea from a guy on TBN (who got it from someone else on there) who also had a youtube video on doing this. I'm pretty sure he did it on a BH76 so you may want to check that out.

These are some of the parts I used that would also work for you:
Valve:http://www.clearwaterhydraulics.com/index.php/hy-sv10-24-0-n-00.html
Solenoid:http://www.clearwaterhydraulics.com/index.php/valves/by-type/solenoids/hy-6956093.html
Valve body:http://www.surpluscenter.com/Brands/Hydraforce/HYDRAFORCE-SERIES-10-2-WAY-HOUSING-7024260-9-7024260.axd

I had to buy those three parts separately since I couldn't find anyplace selling them as a package. You can get different wire connections on the solenoid and different threads and sizes on the body, the link below has links that will give you the different part numbers. If you go with the solenoid I used you'll need to get the weatherpack body, wire connectors, and seals to make the connection on the other side. I got the weatherpack because I wanted the ability to disconnect it if necessary, and I wanted that connection to be weather resistant.
http://hydraforce.com/Solenoid/Sol_html/1-064-1_SV10-24/1-064-1_SV10-24.htm


Switch:https://www.zoro.com/cpi-weatherproof-switch-push-button-b7151-516/i/G1687077/
Switch housing:https://www.zoro.com/cpi-back-switch-housing-hs002-502/i/G2506445/

Kind of pricey for the switch but anything else would have probably been too bulky to mount on the joystick and/or not weather-resistant. Once I tightened down the zip ties with a zip tie gun it stays in place pretty well. I also added a SPDT toggle switch that can switch from "on all the time/off/controlled by the push button" but I don't really think that's necessary and I probably wouldn't add that if I were to do it again. I got power from the implement wires at the back of the tractor. They are a keyed power source so that works out well. I installed a 12V power plug (cigarette lighter socket) so that it can be detached easily when I take the backhoe off.

The hydraulic fittings on my backhoe are 1/2" JIC. I just put a tee where they attach to the bucket cylinder. You've got to mock everything up and then see how you want to run the hoses, measure, and order them and whatever fittings and adapters you'll need. You've also got to watch out for clearance on the fittings on the thumb cylinder, I had to remove some material from the thumb to add clearance, and turn the solenoid valve 90 degrees from how I wanted for clearance on the boom.

I don't know the size of the pins on the BH76 but on the BH92 the upper thumb pin is 1.25", so I struggled to find a cylinder that would take that size pin and wasn't too large of a diameter. The one I used was from a place called Magister Hydraulics and was listed under "Loader cylinders". Bailey's Hydraulics had the same thing listed but was out of stock when I ordered.
If your pins are 1" or smaller you should have no problem finding any number of cylinders that will work. The other pin on mine is 1" so I had to make a bushing for that end. I also had to use some washers as shims on the sides of the cylinder ends.

It really was a bigger project than I anticipated, but it was still a lot cheaper than the OEM hydraulic setup, actually around the same cost or a little less than just the OEM cylinder. I think I also like the push button better than I would a foot controlled valve. It would be nice to be able to control the thumb independently, but this works just fine.

 

[MattN03]

Thanks scdeerslayer!