After looking around and getting prices on thumbs I came to the conclusion that thumb manufactures are on crack. Way out of line on prices. So I started to design and build my own progressive thumb. Here is the steps I have gone thur so for in my design build. First my machine is a Kubota KX-71-3. I started buy taking pictures and getting dimensions of the stick and the connection links and the pin sizes. One of the problem that I began to notice when I started looking at thumbs was that they were either to small or to large or they welded on and had poor travel amounts. My other excavator is a Cat 312-CL with a hydraulic thumbs which has always irritated me that the thumb travel was less than I would like, so when I got the little mini I was determined not to have that problem. The first thing I did was make cardboard cut outs of the stick and the bucket and the control link and the H link and to work out the travel and the pivot positions. after the card board cut outs I made aluminum mock ups to test and refine the pivot positions and linkage shapes and thumb detail. Then on to the solidworks cad program to design the part for flame cutiing.
More on the design -build Just got the burn outs in today. A little explanation on my thumb design. I have a 24 inch bucket and a 12 inch bucket. if you have a wide thumb you can not dig past the bucket pivot without removing the thumb so I have designed a bolt on tine attachment to the center 2 tine thumb when needed. I still need to make the pins and machine all the pivot points but it is a start.
H Link Still in Solidworks but going to Surfcam for G code and the machining center next. I added a picture of the little beast.
Looks like a good plan wolf44:thumbsup Keep us posted on the thumb project.
Looks like you have thought this out well. You are right on with the pricing of some of this stuff but keep in mind cost of overhead, labour, mark-up, shipping, distributor and all the other costs of what goes into making a product. I built some snowmobile tie down clamps (Superclamps) several years ago for exactly the same reason. By the time I had all the pieces flame cut and I welded it up I saved about 70% of what buying in the store cost plus I had the satisfaction of doing something productive. Cant wait to see the finished product!
hate to ruin your parade, but your design sucks. that thumb will stink for picking up logs and rocks with out any curve
Looks like some top notch work you do, but i think i agree on the curve of the thumb, If it were mine i would want some curve in the tines, but I'm assuming you have a reason for going with that design
Design Issues There is more hook than it appears. The teeth on the bucket and the thumb have apposing angles. This design is a test run for modifying my 312 thumb. If it works as planned great, if not I will modify it.Half the fun of doing this.
Man thats some mad skills .:drinkup
I built thumbs for my backhoe and then my 45,000 lb. trackhoe and have been using them for better than ten years on several machines. They are both straight. I like them much better than curved ones for picking up logs. They are equal with big logs but the straight ones are much better for small and medium ones. the curve of the bucket is enough. Both my thumbs are much narrower than my wide buckets and I have not wanted them wider for demo debris or vines and clearing debris.
If you can do all that with the computer and with aluminum mock ups why would you buy any part through the dealer, that is really impressive nice work.
Diet Plan Some times it is cheaper to buy things than build them. I can always build the trickest parts around I just have trouble finding the time. Here is a few pictures of machinining the control links and some weight removal. They started a 6.9 lbs and when milled on both side like the pictures show they weigh 3.9 pounds. more to come:usa
Is that your CNC machine?
My shop Here is a look at the machining bay.
so i think you have the tools part covered... I take it your a machinist by trade.
Engineer,business owner,
I am sure there are lots of people drooling over your shop picture. Thanks for sharing with us!
So are you selling thumbs too? Working on a tacheuchi tb53fr...
Gee, Let's finish this one first and make sure all is well and then lets talk.
For us guys with standard link thumb, how hard would it be to convert? You can do anything if you throw enough money at it I suppose. I was also thinking of a way to add to the rotation when you need it and then change it back when you you are mostly digging. Something like the folks with a mechanical thumb do. I find that the rake is almost horizontal when it grabs small stuff and it brings a lot of dirt to the pile. More travel would keep the brush piles cleaner. Didn't mean to hijack your thread. This should have gone to the thumb thread above in full size excavators. Mods could move it?
Ready to weld Finally got the machine back to the shop. I have spent the last several days making weldbushing and fixtures. I am ready for pre heat and welding. here are a few pictures
bending T1 Bending some plate to weldto the thumb.
bending T1 Bending some plate to weldto the thumb.
opcorn
Are you keeping track of your time ? It looks like you'll have the the worlds prettiest, most expensive mini-x thumb in the world!
And I won't be posting any pictures of my hack job thumb created in the shed.
More Parts Here is the Y link for the clyinder. I am down to making a few pivot pins for the control links and plumbing up. And a test fit.
All Welding and Machining Done Here it is all ready for the paint shop. And get it mounted on the machine. Alll parts weigh 97 lbs. not to bad I think.
Wow. That has to be fun to do. Looks great.
I have a TK 145 and have been starting and stopping for quite a while on building a thumb. My issue is time. I don't have a CNC machine, but I have a friend who is the manager of a really large metal fab shop. My problem is that I don't have dimensions of what I need. To put it bluntly, I've built about everything I've ever needed. It just takes me longer using my plasma cutter and having to make cardboard cut outs (over and over) to figure out what I need. And, honestly, I have no CAD program and I have no engineering degree and could very well spend a couple hundred hours building something that doesn't work right. Just when I get to the :Banghead stage, I see the price to buy one. Then I begin the whole process over once again.
Allgood have a little faith in yourself. You can do it. Go back to the top of the thread and look how I started. Make cardboard cut outs to start with. then make plywood model to check out the size. Make the plywood model just like you would make a steel one. If all works well you can give your wood patterns to your buddy in the fab shop and he can burn the shapes for you. You don't need cad or a CNC machine but it does make it faster. the other way to get a design if you don't want to start from scratch is if you see a machine like yours with a thumb take your cardboard over to it and make a pattern:drinkup.
Funny thing you said that. I think I may go by the dealer and take some pics of machines with thumbs on them.
My favorite definition of R & D is rip-off and duplicate
Test Fit Here is some test assembly pictures of the first assembly. All fits and works well I need to mill two areas for some added clearance. The Thumb travels the full rotation of the bucket no problem. Hope to get it painted Tuesday. I still need to get the special pivot pins head treated. I am waiting on new pivot bushings from Kubota. They are worn out at 384 hrs. But this is another thread.
One more
Looks terrific!
Awesome job! You should be happy with the way it turned out. I keep looking at that and wonder how hard it would be to convert a non progressive to progressive.
That is what I am going to be doing next. This entire project has been a test bed to convert my standard hydraulic thumb on my 312 to a progressive link to give me more thumb travel. In general all you need is a Y link and two control arms. The cylinder may need to be relocated but other than that you should be good to go. When I get going on the 312 project I will post some pictures.
Definitely keep updating your progress. I am interested in the conversion on the 312 as well.
:thumbsupGreat job been watching your porgress from the start and it really did turn out great! just out of interst did you use mild steel for the link arms, i know Kubota use some kind of cast steel? Also what did you use for your pins, are they hardened or just mild, also have you got hardening equip? Also the is one great shop you got there, what your main line of work? general fab, milling turning? Im full of questions today, eh! like i say, thats a great job! CPS
paint pictures got it painted today!!!!!!!!!:drinkup:drinkup:drinkup
Material Used
Kit Here is a picture of your $5000.00 progressive link kit!!! Lol lol...
That looks really good! Any pics with it back on w/ paint?
Reassembly Still waiting on heat treat on the pins they will back in the morning. What I was able to get done today is get the hydraulics hooked up and tested. Got the lines made and the big win for today is moving the line on the right side of the boom to the left side to match up with the cylinder ports. Went to the local Kubota shop Mason Tractor yesterday and got new bushings for the bottom of the stick and new seals so I can have a fresh tight new install. Also picked up a little touch up paint to spruce up the under carriage.
Our bobcat mini the Aux hydraulic line crosses on the top part of the boom so it does not obstruct your view. Thumb looks great. You sure do some excellent work.
Its hard to see but you can kinda see it in the picture.
You might be right I did not see that till I posted the picture. I sometime get so involved I can't see the forest for the trees. I will try it as is for a while and if it's in the way I will change it. now that I have a better look at the assembly. Thanks for the help.
Almost Just a few few items to finish.
Looks good but the only thing I would suggest is to route a solid hydraulic feed pipe to the bottom of the thumb cylinder, if you get something stuck in the thumb and lift it up, it may damage the hose.
Definitely agree with Hendrik on the steel pipe for the retract side of the cylinder but I would suggest an additional guard to protect it....or at least the bottom hydraulic fitting anyway..............
It's DONE! Well it's been a lot of work and about a month in the making but at 5:24 this afternoon I finished the thumb project. I am going to do a recap of what I have spent money wise and the time I have invested in this project for your fun. Here are the final pictures. The first picture is the left over parts Second picture is the tooling needed for the project
one last picture The last picture
Looks good, hate to think how much the total cost is, including labour. Guess quality costs? Do the sides of the thumb unbolt, so you can just have the center section?
Recap hydraulic cylinder $92.50 Design time 32 hrs leader pin thumb $52.00 tooling time 16 hrs leader pin y link $74.57 welding time 4 hrs S7 bucket pin mat$28.00 machining time 32 hrs heat treat $150.00 paint prep time 4 hrs Touch up paint $24.00 assembly time 23 hrs Paint and painter $ 258.00 4140 mat 1.25 dia. $25.00 Total time 107 hrs 4140 2.5 dia. $45.00 3/4 x 8 gr8 bolts $ 45.00 hydraulic lines $170.70 Bushing and seals $156.07 T1 laser but shapes $ 355.00 Materials total $-----$ 1475.00 Design time 32 hrs tooling time 16 hrs welding time 4 hrs machining time 32 hrs paint prep time 4 hrs assembly time 23 hrs Total time 107 hrs It's been fun I am glad it's done. I got what I wanted. thanks for all your input and watching my progress :usa
see the recap post for the costs Yes the sides unbolt when I use my 12" bucket
Test Report I got to put the thumb to the test in the boulder pile tonight. If anybody had any doubts about if the shape of the thumb picking up rocks or any thing else, fear not. This thing has exceeded my wildest hopes. Holly cow can you grab massive rocks, logs and trees any way you want. I am super pleased. Worth all the time I put in this project. The bolt on tines are rock solid. The machine as a hole is much better since I removed a lot of the slop in all the joints. A win in my book. I will modify my 312 for sure now wolf44 :drinkup:usa
It is nice when a project works as expected the first time around. I find made from scratch projects usually need a few mods to a complete redesign before working as expected. Good planning and experience were a asset to your job.
Looks brilliant whilst still being functional- well done.
So wolf what about the bigger 312 your going to do, any start made yet?
The 312 thumb redo is about 2 weeks away. We are finishing a gun clubs impact berms and drainage system. This thumb redo will be done in Solid Works completly not card board cutouts this time. I have just upgraded to solidworks professional which will give me full motion sumulation and structural analysis as well as full photo rendering. Hope you guys will enjoy the process of the design and build. I will post this thread in excavators. If you want to have a look at the solfware http://www.solidworks.com/sw/products/fea-cfd-simulation-sofware.htm way cool stuff Thanks Wolf
The solids works, can you recall what it costs? Beautiful work on hte thumb by the way.
Solidworks professional is about $8500.00 and then there is the yearly solfware support of $2000.00 and then there is the training for the solfware and last but not least the mini super computer you will need to run it. But still way cool.
wolf44, had my doubts, at first, about building your own thumb. But after seeing your level of expertise and some of the equipment you are working with, let me just say, Sir, very impressive job!
Nice work on the thumb, you can't buy quality like that. If you ever build a quick attach for a loader I would sure be interested to see how you go about it.
I have an excavator of similar size. Would I be able to get a copy of your part files. I currently have a fixed thumb and would like to build a progressive link one similar to yours. I have a friend with a plasma table, but do not have access to the CNC mills; however, with the linkage ratios I could design one that I could fabricate.