[MOC] Mini 42215 - Volvo EC500 Hybrid Excavator

[Ngoc Nguyen]

I tried to participate in TC25, 26, 27, 28, but I only managed to finish my entry in TC25. And that was like 5 days before the deadline. For other contests I was either too ambitious with my idea, or I just got bored.

This time I'll just go for something quick and dirty just for fun. I'll use the 42121 as a base and modify it into a mini 42215.

Rear lights:

 

As for the model, I just did some quick work on the undercarriage of 42120. I mostly extended it to make it fit the scale of the EC500. Interestingly, the width of the base of this model should be 14 studs, and the width of the base of 42120 is also 14 studs, so there's no need to work on that dimension. The sprocket technique is taken directly from the new City excavator 60420.

 

Edited Tuesday at 01:30 PM by Ngoc Nguyen

[NV Lego technic]

You just had to shrink Down a set didn't ya;) it looks pretty good 

[Ngoc Nguyen]

The scale would be based the track width of 3. Based on that the uppercarriage's width should be 12, but there's no such thing as an even width Technic model, so I'll go with 11. Boom will be 3 studs wide, same as that in 42121, and two sides will be 4 studs wide.

Edited February 14 by Ngoc Nguyen

[Timewhatistime]

42120 is a hovercraft.

[Ngoc Nguyen]

1 minute ago, Timewhatistime said:

42120 is a hovercraft.

I mean 42121

[Ngoc Nguyen]

I took the bucket curling linkage from my JCB 3CX and did some modification. Since the official 42215 has the tool swap function, I made the bucket removable as well. It's not gonna be motorized or use some fancy gears like in the official set since there is no space. You just fix or remove the bucket with the two 4L axles with stop.

Edited February 14 by Ngoc Nguyen

[mpj]

This sounds very good! Looking forward to see the progress 

[Ngoc Nguyen]

On 5/20/2025 at 5:15 PM, NV Lego technic said:

You just had to shrink Down a set didn't ya;) it looks pretty good 

If not for shrinking I would have nothing to do 

 

On 5/21/2025 at 1:30 PM, mpj said:

This sounds very good! Looking forward to see the progress 

Thank you! 

I just did some quick parts for the cabin. At first I tried to go for an openable door like the EC230 but that means I'll have to do the curved hose twice, and that looks ugly, so I decided no door.

 

Edited February 14 by Ngoc Nguyen

[Jundis]

Nice effort so far!

Are you going for rubber wheels as sprocket+idler? Wouldn't the tread get off without side support?

[Ngoc Nguyen]

On 5/22/2025 at 2:10 AM, Jundis said:

Are you going for rubber wheels as sprocket+idler? Wouldn't the tread get off without side support?

Thanks a lot for catching that problem. I totally didnt think of that. I went back and change the sprocket into black 24z gears.

Edited February 14 by Ngoc Nguyen

[mpj]

Test the tracks in real life to check if they are too tensioned.

[Ngoc Nguyen]

Since the official 42215 has a breaker, I created one for this model too. It has the same interface as the bucket, which is two pin holes 3L apart, so the tools can be swapped.

Edited February 14 by Ngoc Nguyen

[Ngoc Nguyen]

I also did some quick work on the appearance of the other side of the superstructure. Since there's no diagram for this side I took some creative liberty.

 

 

Edited February 14 by Ngoc Nguyen

[Ngoc Nguyen]

Just realized that the hand rails are supposed to be taller than the cab, so this is more accurate.

 

Edited February 14 by Ngoc Nguyen

[Ngoc Nguyen]

I spent a whole evening sculpting the boom and the arm. Since this creation is designed after a real machine, I want the boom to look accurate too, instead of using the solutions in the stock 42121. I'm very happy of how it turns out in the end. 

 

[Ngoc Nguyen]

I redid the breaker so that it has a more consistent color scheme and form.

 

As for the main model, the only big task left is to fill the inside with the the knobs for the two functions as well as supporting structures.

 

I hope to finalize the design by the end of this week or next week the latest, so that I can order the parts. Optimistically the parts should take one month to arrive, and I can do a real build before July 28th arrives.

[Jundis]

Nice effort :-)

What I think is way out of scale are the orange steps on the undercarriage. Even the original model has only small bars. 

Sadly, no telephone handle is available in orange...

[Ngoc Nguyen]

12 minutes ago, Jundis said:

Even the original model has only small bars. 

The small bars is for the older version of the EC500. At first  I also put small bars there, then I did some searches and saw that new gen of EC500 has the orange box now.

[Ngoc Nguyen]

Life happened and more than a month went by with no progress. Fortunately, I finally got the time and energy to finalize the design. It's too late for the contest but it will be published later.

[Ngoc Nguyen]

On 6/11/2025 at 6:06 PM, Jundis said:

Nice effort :-)

What I think is way out of scale are the orange steps on the undercarriage. Even the original model has only small bars. 

Sadly, no telephone handle is available in orange...

For some reasons I randomly thought about your comment, and my mind ran through a couple of possible alternative builds, until voila! I found the perfect solution. Does it look better now?

[Ngoc Nguyen]

It's finally available!

 

Very basic functions.

Bucket can be swapped with breaker.

 

Free instruction available: https://reb.li/m/255817

Edited Tuesday at 02:07 PM by Ngoc Nguyen

[mpj]

Very cool!

[Jundis]

At first glance you can't even make out it is a smaller scale!

Impressive :-)