by erdinger, published

Excavator by erdinger Mar 21, 2013
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Excavator by erdinger is licensed under the Creative Commons - Attribution license.

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Original is Volvo ec210
M about 1:20
And yes: there is sand at the teeth of the bucket out of my kids sandbox ;-)

I hope the pictures are descibing the project best. On pic SAM_4173 the lower part of the body is shown with holes for batteries. It was redesigned that a big pb battery fits now. The two servos in the arm have about 120 Ncm, the big one in the body about 260 Ncm.
In the tracks and for turnig there are the the cheapest servos ever in there for about 2,5€.
The servos in the tracks are hacked so that the pwm signal still works but they do it continously. Just search the web for "pwm servo hack"!
In the turnshaft i soldered the + and - of the servos togeter to reduce lines from 6 to 4.
The tooth gears are bought:
Maybe you can also print them, I can't.
You can use: http://www.thingiverse.com/thing:333018
The tracks are in fact a derivate from http://www.thingiverse.com/thing:36305
Thank you LoialOtter!

Custom Section

Required part count

You will need every file one time except of the following:
3x washerSpacer
1x bundle (already 2pc in file) trackTightener
tracks (66 elements)
2x either trackGears or powerwheel
2x powerWhlStabi
4x counterWheel
1x loeffel or loeffelPrint
10x trackMiddleWheels

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Great project.
Any recommendation on which servos to get for the different areas of the excavator?

Do you have a model number for the big servo used for the lower arm in the body?

no... sorry
it is just a big one

hi. which channel you used for each function ?

gonna start printing this as my first project. cant wait to see the result

What is this using a 1/5 scale servo in the body for the arm?????

I'm not sure about the size of a 1/5 scale servo... but the servo in the body for the arm is bigger than the other ones... maybe it is already a 1/5 scale one
Mini servo height: 21mm (not used)
Midi servo height: 27mm (not used)
Normal servo height: 37mm (rest of the excavator)
Big size servo height: about 60mm (body)

Hola, Estoy montar este excavadora impresionante, pero hay algunos problemas para mí con el plato giratorio y las conexiones eléctricas. ¿Existen planes, fotos o instrucciones con el espaciador lavadora y el material utilizado en el medio? No sé cómo conectar los dos servos de pista para la caja superior
Hola yo tengo el mismo problema hay algun plano de montaje ,gracias y un buen trabajo

I am assembling this awsome excavator , but there are some problems for me with the turntable and the electrical connections. Are there any plans, fotos or instructions with the washer spacer and the material used in between? I don't know how to connect the two track servos to the upper case.

  • you hack the servos to have continous rotating (many descriptions on the net)
  • then you have still 3 wires for each servo: red (+), black(-) and yellow (controller cable)
  • you can combine the red and black ones so 4 cables are left: 1x black, 1x red, 2x yellow
  • you have 3 connections through the washer and the middle part (turn screw)
  • connect the minus to the turn screw
  • put the 3 other cables through the hole in the washer spacer
  • connect one wire to a washer on each layer

hope that helps (Grüße nach Österreich)

OK thanks to erdinger, you took washers for each layer, that was the answer! :)

Have you or anyone that has printed out post a video yet ?

Jun 1, 2015 - Modified Jun 1, 2015
erdinger - in reply to tibuck

please find work.mp4 in the files...
the sand has a high clay percentage... but it works ;-)
also somebody of the made-people or derivate-people made a video... i think the one who added bluetooth
I can't find it at the moment

Woow , wonderful. I haven't a printer. How much is printing that, do you know?

No... Sorry I have no idea... but as far as I know you can upload the stl files to a printing service company on the internet and then they tell you the price

Yes, I did and they told 270$ :S

But My University have a printer, I will use it. Thank you:)

I'm about to print mine.
I have one question do you put a bearing or something else between the middle wheels and the track tightener?
Same question for the counterwheels?

All moving track parts are designed for bearings type 624. For the counterwheel and track gears I think they are necessary. For the middle wheels you can save the money. They do not like to rotate and the tracks do not need roling middle wheels.

Your answer makes me wonder what's the difference between track gears and power wheels? And if there's a difference where the track gears go? (not in the freecad version I have)
Do you suggest to reduce inner diametre of the middle wheels to 4mm? (I think they'll need to roll if they have a suspension)

It seems that track gears and power wheel are the same... it's a long time ago...
The wheels at every end definitely need bearings, the wheels in the middle (Fusion067 in FreeCAD) not really. If you use them whithout a bearing you need to modify them to the size of your screws (e.g. 4mm)

Seems like what I thought,
Thanks a lot ;-)

Yeah ! great design.
I plan to make one to go with my buldozer ( http://www.thingiverse.com/thing:16234http://www.thingiverse.com/thi... )

RC printed Buldozer

As promised, i have finally uploaded pictures and a few files! new rotary gears (direct fit on the servo, nothing needs purchased) and added a couple files i ended up making, including the rear idler wheel which i couldn't find before

i've finished the build! (actually, a few months ago, but i haven't been on here since then.) i still need to add the electronics and battery, but all the servos are installed. i also drew the gears that allow it to rotate, so purchasing them is no longer required! now, how to upload pictures? i suppose through the "i made one" link?

I'm quite interested in the gears you made if you would like to share them. Looking forward to seeing the pictures!

Exactly... there you can also add more than one ;-)
If you changed something you can also click on "Remix it" and create a totally new thing.

cool! i will get to it soon. right in the middle of finals right now (this is my way of not going crazy, i distract myself for a while)

Thanks for sharing this great work! I am trying to build one, I would like to know which STL file is for middle wheels of the tracks? I couldn't find it. I used FreeCAD to open tracks.fcstd, these middle wheels are named Fusion067.

sorry seemes that I've forgotten it...
now I exported it and uploaded it as trackMiddleWheels.stl
Please post a Picture when you are finished ;-)

Thank you very much!

I am drawing the gears in solidworks, i'll upload them on here when they are finished.
a couple questions about parts i haven't got to yet:
how does the slip rings work for transfering power across the rotating main joint? i see some metal wire fingers sticking in there but they don't look like they go all the way around. can it work in a full circle?
another questions is about the drive wheels, i can't tell why the outer holes in them are tapered cone shapes instead of a place for a bearing to mount.
what size bearings did you use for the tracks to ride on? i'm planning to use 13mm (1/2 inch) outside diameter bearings and make axles for each set of two bearings.

I added some more pics to get you a clue of the construction of the slip ring... it is assembled with 3x washerSpacer.stl and 3x washer (Hornbach for Germany / Home Depot for USA). From the inside the wires are connected to the washers from the outside there are the sliding metal wires. I placed some tape between the different level of washer and washerSpacer. It is going full circle as often as you want (in theory... somewhere I have a shortcut in there I haven't found jet... too much different things).

I use 13mm (outer diameter) bearings. the cone is that it self centers when screwing.
I think that the middle wheels of the tracks do not really need bearings... I have them but the tracks are just sliding in most cases without movement of the wheels.

One other point I found out was that on the trackTightener.stl and pwrWhlSabi.stl you need a cutout for the screws I forgot to design. So I used my Dremel after printing... please find it in the picture with the blue arrows.

I expect a video or at least some pictures when you finished it!

There will be pics and videos! i'll have to learn how to upload them on here. i printed the track tighteners and power wheel stabilizers before i saw the cutouts, so i'll make the cutouts with a dremel too. i kind of thought there might be washers in the slip rings but i couldn't tell for sure. good idea! did you also use the center shaft for the ground conductor? or is there four washers stacked up?
so far i have the arm built up (need to make new linkages, with tighter tolerances) and am controlling it with arduino joystick shield.
i used #0-80 x 1 1/8" screws for track pins, from http://mcmastercarr.commcmastercarr.com (you have to ask for them, about $20 for 100 screws)

the center shaft is ground... 4 stacks would be too high. An hydraulic system would be cool, but expensive, yea. So I only used servos.


Anyone got alternatives to the gears ? it was like 50 euros total with shipping for a 6 euro kit of gears :/

I used these gears, because my print results are not good enough...
Maybe you can print some gears...

I will try ;) going to print this thing this weekend. its awesome!

Absolutely amazing! Adding this to my "Gotta Make It!" list.

Do you have some pictures of how this went together? especially the track sections.

I uploaded 2 pics of the put together of the tracks but they are not displayed correctly (tried png and jpg). The best advice is to download freecad from http://sourceforge.net/projects/free-cad/http://sourceforge.net/project... and load the sources... there you can display and remove every part by pressing spacebar to see how it is assembled...

Now you can see them... funny

OK... Sun was coming out => the sand is not frozen anymore
So I uploaded: work.avi

I'm not sure how the global rotation is designed, but this thing may help to build a very rigid system: http://www.thingiverse.com/thing:37320http://www.thingiverse.com/thi....
Just use a larger thrust bearing...

Okay, that is absolutely fantastic. Anyone else want to motorise it... blinkblinks Wait, it !Is! motorized... that is even more than fantastic, that's downright epic.

Agreed! Need some video!
And some more instructions please. This an Awesome thing

Very nice! I can really appreciate the amount of time and effort that went into this project. Can't wait to see what else you'll make in the future.

Very impressive! I've always dreamed of such toy...

totally cool project!

Needs me a video of this bad boy in action!

Very nice! Could you post FreeCAD source? Would love to tweak for some of the servos and electronics I have.

nice..what software did you model it in?

updated the name... thank you

the software was/is FreeCAD: http://sourceforge.net/apps/mediawiki/free-cad/index.php?title=Main_Pagehttp://sourceforge.net/apps/me...
and blender for editing the tracks