View Full Version : Excavator (rigging for animation)

17-Nov-08, 14:09
I haven't got any experience of Blenders armature or constraint systems so I thought it would be good to have a go at some mechanical rigging. To get a feel for the armature system I am modelling an excavator, the back actor (rear hoe) has enough pistons and a linkage arrangement that should offer more of a challenge than simple piston operated leavers.

I have started by making 2D cut-outs of the parts to set up the armatures and constraints. I will add the 3D models to this when I am happy it does what I need it to.


Link to better Gif Animation (http://rab3d.com)

17-Nov-08, 15:05
Nice grabber.

If you make a tutorial on doing the excavator it would go nice as a tutorial since I have a bearing I could use with it :P.

Excellent work.

17-Nov-08, 16:03
Thanks Terry

This is all new to me, I could do with an in depth tutorial on rigging and constraints my self. The bucket mechanism is probably simple for someone who knows what they are doing but was a struggle for me, still its a good way to learn.

I have progressed a little tonight adding the first arm.


B7 Music Studio
17-Nov-08, 16:14
could you explain what constraints you used? I've gotton stuck on several movements happening here! (Or, could you upload a .blend?? :D)

18-Nov-08, 07:47
@ BonE:

The pistons are simple track to constraints, make sure the object centres are on the rotation point, add an empty at the same location then track the piston to the cylinders empty and the cylinder to the pistons empty.

The bucket required an armature, set up the fulcrum connecting rod and bucket with the object centres as shown in pink.

Snap the cursor to the fulcrum object centre and add an armature, snap the toe of the armature to the connecting rod object centre and Ctrl-N to remove the bone roll. Extrude another bone and snap the toe onto the bucket/con rod joint again Ctrl-N then extrude the final bone and snap the toe to the bucket object centre. Add an IK solver constraint to the last bone with the target as bucket and Use Tail activated. Parent the objects to the bones. When you rotate the 1st bone (fulcrum) the bucket and con rod will follow.

Remember to lock out two of the rotation axis.

B7 Music Studio
18-Nov-08, 10:01
thanks! that makes sense, I didn't use empties for pistons and they ended up tracking one frame to late.

19-Nov-08, 15:21
Added a little bit more with the main arm today.


19-Nov-08, 23:41
Looking good, nice rigging there!

22-Nov-08, 15:03
Thanks Photoguy,

I am progressing slowly with this, the bucket and linkage is now added.

One benefit of modelling from copies of the 2D shapes used to test the rig is that the parts are already parented to the armature. It makes setting up the rig so much easier.


22-Nov-08, 16:32
well happy learning. Every project you seem to start at works out great, and this will be no exception.

What you are trying to get done is very easy to rig metinks, but I haven't time to tinker with it right now.

For this purpose, think of bones as nothing more than pivots to rotate around. The root being the main thing. the tip is more or less just a helper, and the roll of the bone is how the axis for the rotation (localY) is set)
some track to constraints, limit rotation constraints and/or IK with limited rotations and this puppy should fly.
well, if it were a puppy and if puppies could fly anyway.

22-Nov-08, 17:02
the only difficult part i see here is the bucket , connector with the other things

that's gone require some constraint and i hope someone can explain how to do this part - but it should be a nice little mechanical rig to play with

ounce you ahve this one it becomes very easy to do all the other

a good tut should be built with this rig model to make other peoples be able to learn how to and have more fun with blender

great model and happy blendering


24-Nov-08, 14:46
Thanks FreakyDude I have used key framing in previous animations but never played with constraints or armatures. Luckily as with all areas of blender its pretty intuitive, I mean once you have learnt one area of blender the knowledge carries over and helps in others. With regards to rigging, compared to your "Little Fella" this is quite basic and just something to learn from.

well happy learning. Every project you seem to start at works out great, and this will be no exception. That's because I only commit to putting thing in public when I am determined to follow them through. I have got gigabytes of dross and unfinished projects on my PC.
I noticed your link to Metalotherm, does that mean you are also in the chimney / flue business?

RickyBlender: I have about sorted the bucket mechanism as described in post #5 only that gave a fault as you repeatedly animated it everything rolled out of position. I had targeted the IK Solver constraint to the bucket which was parented to the constrained bone. I found you needed an empty on the same location as the bucket centre with the IK targeted to the empty, it works now.


24-Nov-08, 14:50
a diagram with the constaint empty and armature would
definitively clarifiy the riiging!


24-Nov-08, 15:39
@ RickyBlender: When I have finished this project I will probably add a page to my Website seeing it fits with the mechanical theme.

24-Nov-08, 15:59
I noticed your link to Metalotherm, does that mean you are also in the chimney / flue business?

yes I am, though I'm no engineer or something. I just make all the pretty pictures, folders, and documentation. I do get to know a little about it because I work there, and I've just finised renovating my own chimney and fireplace last week. which is cool. But I'm not an engineer like you. They make drawings in inventor/autocad/mechanical desktop, and I remodel them in blender to make pretty pictures.

The good thing about using armatures instead of plain old parenting and keyframing is that you can easily reset the pose and store poses, and you don't have to worry that clearing a loc/rot/scale will bork up the pivot points for all your preciously placed parts.
If your model isn't all to complex (like this) I would just join everything into one object and weight paint all the seperate parts to bones. Leaves you with a much cleaner end rig. One mesh, one armature, and possibly an empty with widgets (bone display objects) parented to it.

try not to use empties, use another "dummy" bone instead. the reason for this is that you will have a refresh issue with the constaints that depend on them where you will have to skip a frame to refresh the new pose. This is because the empties are taken into account after the armature object has done it's "calculations" in pose mode.

Back to Blending life...

25-Nov-08, 14:30
try not to use empties, use another "dummy" bone instead. the reason for this is that you will have a refresh issue with the constaints that depend on them where you will have to skip a frame to refresh the new pose. This is because the empties are taken into account after the armature object has done it's "calculations" in pose mode.

It's little snippets of information like this that are pure gold dust.

26-Nov-08, 15:45
I have added the first part of the rear pivot today, though I think it needs a higher vertex count on the cylindrical pivots.

Just the rest of the tractor unit to model.

27-Nov-08, 00:09
Hey there, great work.

I really like the concept and the idea of getting it all rigged to work properly.

I was wondering if you could post some wires of the latest image. I am working on a project with similar style parts (squares with round ends) and I am having some trouble keeping it clean and I would like to see how you accomplished this; if you don't mind.

Thanks in advance.

Keep up the good work,

27-Nov-08, 12:53
@ HJ05
Not the prettiest of wires but this is a small part of a big model that wont be seen close up.

27-Nov-08, 13:54
Thank you for that. It really helps give me some ideas.

01-Dec-08, 07:22
I have now added the tractor mount. The Back Actor rotate cylinder works well with a front pivot point.

01-Dec-08, 14:54
Found time to add a little more this evening.


02-Dec-08, 12:18
The tyres have proved to be a bit more tricky than I thought they would be, but they have turned out OK.

02-Dec-08, 15:01
Wow, great modeling!
No crits..I sat and tried to find some ;-)

05-Dec-08, 15:38
Thanks Photoguy

I am beginning to struggle with this because my plans are so pore (screen grabs from the product brochure). I only have a side and back view, it would be so much easier with good reference material. I will have to see if I can find one working locally and go and photograph it for all the missing details. This is the progress so far.

05-Dec-08, 17:07
What kind of Excavator is it? I live in a housing development and those for up the street from me every once and awhile. I may be able to take some detailed pics if it is the same kind of excavator.

-Nick :) :) :)

06-Dec-08, 19:03
Man, that's some great piece of work! I'm a fan of your site, and this is definitely one of the best works I've seen you do. Hopefully a tutorial will come up on this, if it's not too much to ask for (which, I think it is...). Anyways, keep it up, it's great! :)

12-Dec-08, 13:36
@ AtomicDingo its based roughly on a JCB 3CX, thanks for the offer of photos, I have now managed to find some good reference images and started to make progress again.

@ techwielder thanks for the encouragement, I don't think a tutorial will come out of this, but I am thinking of adding a projects section to my site so I may add some mini tutorials in the project ares.

12-Dec-08, 15:54
Wow, robbur, that's getting better and better! I can't wait to see how this project ends up. And I actually think that adding that projects section to your site is the best solution thing you could add to your site right now!

Richard :)

12-Dec-08, 18:11
That's a pretty awesome model and it really looks like you've payed attention to the fine details. I cant find any technical inaccuracies off of the pictures you've posted.

I do have one question though. It looks like you put a fillet on some of the edges in your wireframe at the bottom of the first page. How did you do this in Blender?

13-Dec-08, 07:43
Thanks techwielder a projects page will give me something to do in the new year.

@ Sharper, thanks for the comments. There are a lot of differences between the model and the real thing, but getting it spot on would require a lot more time than the odd half hour in my lunch break and the limited time at home.

I haven't chamfered any edges on this but I always try and make the edges chamfer friendly by extruding and scaling edge loops into a flat surface before filling them with Shift-F. To add bevels later it just needs you to select the edge in edge select mode and hit W Bevel. Moving the mouse will then add the chamfer on the selected edge.

14-Dec-08, 06:08
Its starting to look a bit like a tractor now. I am still struggling to find images of the steering mechanism, but I will carry on with everything else and add that last.

Edit: added the front end and radiator.


15-Dec-08, 06:49
Rigging the linkage for the front bucket looks a bit tricky? thoug I think I can make it work.

15-Dec-08, 15:15
I thought I had the rig for the front bucket sussed out for this, but it wont work the way I would like. The linkage onto the top cylinders is there to stop the bucket tipping back when the arms are raise. I can make the linkage work OK but with a track to constraint on the cylinder the cylinder compresses as the arms are raised rather than the bucket rotating to stay level. It means I will need to animate the bucket rotation as the arms are raised. If anyone has any ideas or tips how to rig this movement it would be much appreciated.



15-Dec-08, 15:39
this is awesome!
if you textured it and plopped it in a construction site picture, i'd think it was real!

17-Dec-08, 15:04
If anyone has any ideas or tips how to rig this movement it would be much appreciated.

a screen or two of your rig would help :P

17-Dec-08, 18:24
Hey there, you're making some great progress! I rigged something similar a while ago. The front bucket is a bit tricky, but it can be done.Here's the blend.


To operate the bucket, rotate downLever.L rotating liftArm.L will move the whole front mechanism. If you hit play, you'll see it all moving, just enable script links to activate the wheel turning (and ignore the windscreen wiper). It's still a W.I.P., so it's a bit messy, but it should help with rigging ideas. :)

18-Dec-08, 14:26
a screen or two of your rig would help :P.

Hopefully this will explain what I am trying to achieve.

Picture 1 is the rig: Armature A,B,C ends with an IK Solver targeted at an empty on point 1. When you rotate Bone A the arm lifts and Linkage B and C rotate correctly. The piston is a simple track to set-up.

The problem is (Picture 2) rather than the piston and cylinder remaining at the same length, they compress and the bucket follows the arms rotation.

The bucket should only rotate about 1/2 the rotation as in picture 3.

I still also need to be able to separately rotate the buckets tipping movement.

Is there a better way to rig this?

@ Fatfinger
Thanks for your Blend I will have a look now, hopefully it will solve my problem.

18-Dec-08, 14:34
Besides struggling with the rigging I have also made some more progress with the model.

21-Dec-08, 05:57
@ Fatfinger: That's a really impressive model and rig you posted. I haven't yet worked out how to apply the techniques to the front bucket of my excavator. What you have shown is much more advanced than my level of rigging.

If anyone has any suggestions on rigging the front arm and bucket, it would be really appreciated.

In the mean time I have continued adding detail to the Tractors Cab.

21-Dec-08, 19:23
--oops. Double post. Sorry--

21-Dec-08, 19:32
Cheers, thanks Rob. I can't take credit for the model though, I got that off a Lightwave site. It needed a lot of separating of bits etc, (which turned out to be only slightly more difficult than modelling from scratch :).

I'll have a look at my rig later and see if I can explain it better. It looks complex, but, if I can do it. . . ;)

P.S. model's looking great !

22-Dec-08, 14:44
@ fatfinger: Thanks for the reply and the offer to look deeper into this, however I managed to crack the rig at lunchtime today.

It turned out to be much simpler than I imagined, the diagram below is the armature set-up.

Bones A, B and C make the red pivot arm operate correctly when Bone A is rotated in Pose Mode.

Bone D keeps the correct distance between the red pivot and bucket linkage.

Bones F and G have a IK solver constraint to empties on their pivots. To make the bucket tip you just need to scale Bone D.

"Edit: After a bit more testing I found this doesn't work correctly, so I am still searching for a solution,"

22-Dec-08, 15:47
it's beginning to look very nice almost real!

would you be able to upload a sample file for this part of the rig
for the front bucket it looks a little complicated
just looking at the pic here
would be easier to study it and be able to reuse it for other type of machine too

also if you could make a nice tut on this rig it would great for pelple to learn about riggning machines in general

Keep up the good work


23-Dec-08, 23:21
That's great you got it working. It's looking good.

I really liked your 608 bearing tutorial, too b.t.w.

I uploaded a similar rigged model. You can check it out in the meantime if you want. P.M. me if you have questions etc.

27-Dec-08, 06:05
Thanks fatfinger, I was a little premature saying I had cracked the front rig. Scaling the bone and having more than 1 IK solver caused a few problems with the linkage moving off it's pivot points. For now I will have to key frame the bucket/arm linkage movement.

I have got the basics of the model completed, though a lot more detail is needed, hydraulic pipes and hoses etc. I am still not sure if I will be able to get the front bucket rigged the way I would like.

For now I have uploaded a turntable video (http://www.vimeo.com/2642683) with the bucket and back actor animated to Vimeo.

@ RickyBlender: If I manage to get this rigged and working the way I want it to, I will definately add a tutorial to my site.

27-Dec-08, 07:37
The glass IOR doesn't look right in animation. Other than that, it seems great.

27-Dec-08, 12:11
Nice work robbur.

I guess one would need the game engine to lift the wheels off the ground like this....

28-Dec-08, 05:11
I guess one would need the game engine to lift the wheels off the ground like this....
Not now it's rigged, this is a quick pose from the JCB dancing diggers (http://uk.youtube.com/watch?v=uFBAzRc5vXE&feature=related)

28-Dec-08, 12:49
Not now it's rigged, this is a quick pose from the JCB dancing diggers (http://uk.youtube.com/watch?v=uFBAzRc5vXE&feature=related)

That is awesome! :evilgrin:

Proficient operators, of these real machines, can move the whole rig sideways by using the bucket arm (pivoting off the front scoop).

It would be sweet to set your model up w/ some actuators and try to flip it over and stuff.

28-Dec-08, 13:03
This would be cool to model.

28-Dec-08, 13:09

Robbur, I was curious how long that took to render? I guess thats blender internal w/ AO enabled. What is your vert count?

28-Dec-08, 13:37
Robbur, I was curious how long that took to render? I guess thats blender internal w/ AO enabled. What is your vert count?

So far the model is at about 150,000 vert's and its all done in blender. The 800 x 500 pix images take about 4 mins to render on my old athlon PC with AO set at 6 samples and 3 area lights at 4 samples each.

28-Dec-08, 16:25
Very good work pretty details:eyebrowlift: Congratulations

28-Dec-08, 16:28
Nicole Kidman and Hugh Jackman making a bet in german TV-Show on two guys who are trying to move in a harbor on the water with only the use of the bucket of a excavator like being in venice.
Afterwards some digeridoo play of Miss Kidman ... and something hilarious.

02-Jan-09, 05:51
I have started adding the pipework and hoses to the cylinders. Simple hoses deform well using curves with a bev object and a hook at one end. Some of the more complicated ones will need an armature to get them to flex correctly.

02-Jan-09, 08:56
interesting subject - moving tubes

what is available to rig theses tubes

1 - mesh then add armature to it

2 - can we put an armature on curves with texture

3 - can we use nurbs curves then add armatures with texture?

i like the idea of having a tube that can bend following a constaint i guess

Happy Blendering Thanks

05-Jan-09, 15:54
I have finally found time to complete the front arm pipes and hoses. I am pleased that all of them deform quite well just using bezier curves and hooks, it's made setting up the hoses much easier than using armatures.

06-Jan-09, 08:00
Wow, that's looking great! The only crit is that the black parts are a bit too dark (at least in my monitor) and can't be really appreciated; maybe you could increase their material value. Other than that, it's perfect. :)

10-Jan-09, 16:32
Thanks techwielder: I have lightened up the black colours which looks better.

I have also reworked the back hoe pivot mechanism to use 2 hydraulic rams and give a full 180 degrees of rotation. It animates well but the hose deformation isn't very good yet.

Here is a short test animation (http://www.vimeo.com/2783143).


17-Jan-09, 05:11
I have finally managed to work out how to animate the hoses using curves and still keep good end tangency of the hoses. The method would also work well for other situations such as electric cables and tubing.

I have added another test video on Vimeo (http://www.vimeo.com/2858113)


17-Jan-09, 09:49
can you show an example of whah you did for theses flexible cables

it's interesting for futur project


18-Jan-09, 12:34
not much to say other than this is progressing at a nice pace. You certainly got the hang of rigging by now. And it just looks plain cool...

26-Jan-09, 19:20
I have enjoyed following this thread....any new updates Robbur? How's the project coming along?

27-Jan-09, 13:52
Thanks for the comments.

I haven't been able to progress this over the last week or so because I was away from my computer at a meeting in Lanzarote and used my spare time to explore the island. I have started a page on my website to document the techniques I have learnt, I just need the time to fill in the details. Now I am back in England I'll hopefully get the project rolling again.


31-Jan-09, 14:04
Well I have finally got all the hydraulic cylinders and hoses finished and they all work and deform really well. That's about it for the modelling, the next thing is to set up the materials and add it to a scene for a small video.


31-Jan-09, 19:39
Looks great, very detailed what are you planning to do, animation or sell the model?

03-Feb-09, 07:25
Thanks Cativo: I suppose my long term intention is to have enough quality material to put together a demo-reel.

Before I build a scene for this, I thought it wood be good to see how it looks in a studio type shot.


10-Feb-09, 13:06
Very nice! The rab3d.com plate is a nice touch too. I love this model. I had an opportunity to dig about a 20 foot long and 3 feet deep trench w/ a backhoe, a few years ago, for a septic system.