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Hi, 

as a crane fans, i'm happy to introduce my lastest building

GROVE GMK5250L in scale 1:20 

it's a revise version to my last crane project

more accurate appearance and gear functions are more effective

the 6 panel boom max can reach around 140 cm after extendend, and the crane high is 165-170 cm

The angle of rise can reach 82 degrees, just like the real crane

the counterweight is datchable 

 

Thanks for viewing and appreciate any feedback!

07/08/2021 the video added

09/09/2021 the instruction is available on rebrickable

https://rebrickable.com/mocs/MOC-86030/mitx2529/grove-gmk-5250l-mobile-crane

 

 

 

GROVE GMK5250L-00

 

GMK5250L

 

 

 

 

GMK5250L

 

GMK5250L separate

 

GROVE GMK5250L

 

GROVE GMK5250L

 

GROVE GMK5250L

 

GROVE GMK5250L

 

GROVE GMK5250L

 

GROVE GMK5250L

 

GROVE GMK5250L

 

 

GROVE GMK5250L counterweight

 

GROVE GMK5250L counterweight

 

Edited by mitx2529
07/08/2021 the video added, 09/09/2021 the instruction is available

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Hi! Does it drive and steer? Any video will be appreciated!

I like the cabin most of all - so smooth and accurate indeed!

 

Also I think that 1 BB is too little for the counterweight.

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Great build! I agree... smooth, clean and accurate build.  You also got the angle at which the boom can be lifted correct, which does not always happen.  Great job.  

A video of seeing this thing in action would be really nice....

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On 7/6/2021 at 8:50 PM, Aleh said:

Hi! Does it drive and steer? Any video will be appreciated!

I like the cabin most of all - so smooth and accurate indeed!

 

Also I think that 1 BB is too little for the counterweight.

thnaks, the video would be add later, it drive and steer like u42009

I though the counterweight size is ok, but you remind me of the idea that I can add two little counterweight on both side

 

On 7/6/2021 at 9:55 PM, nerdsforprez said:

Great build! I agree... smooth, clean and accurate build.  You also got the angle at which the boom can be lifted correct, which does not always happen.  Great job.  

A video of seeing this thing in action would be really nice....

thanks! i wll add a video later

On 7/7/2021 at 12:30 AM, mic8per_ said:

Very realistic, I like the the boom.

thanks, I also like the boom, it has a better-looking and work well

Edited by mitx2529

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7 hours ago, suffocation said:

Awesome work!

thanks you!!:laugh:

7 hours ago, GerritvdG said:

Thanks for the video, impressive!

thanks you!!:laugh:

4 hours ago, onzenuub said:

Would be great to build, are there gonna be building instructions?

thanks you!!:laugh:

3 hours ago, nerdsforprez said:

Beautiful crane.  Functions well.  Great job.  

thanks you!!:laugh:

Edited by mitx2529

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After seen the video:

Crane looks very accurate, recognizable and perfect scaled, but I see several problems here:
- counterweight is too light, as I have already said

- slewing is not smooth I assume - some rollers would become very helpful to fix it. 

- one driveing axle can't cope with the weight of the crane. The torgue is enough, but the wheels on the axle are sleeping. It needs more load.

 

Sorry if I'm wrong here or there, just imho.

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1 hour ago, Aleh said:

After seen the video:

Crane looks very accurate, recognizable and perfect scaled, but I see several problems here:
- counterweight is too light, as I have already said

- slewing is not smooth I assume - some rollers would become very helpful to fix it. 

- one driveing axle can't cope with the weight of the crane. The torgue is enough, but the wheels on the axle are sleeping. It needs more load.

 

Sorry if I'm wrong here or there, just imho.

thanks for your comment, yes, all problem are exist

the 1st and 2nd are the same problem, but I think it's not serious

it's all about center of gravity,

in the real crane, the boom set up behind the turntable, so did my brick crane.

when the boom is in the high angle, the counterweight can balance center of gravity (even with the light counterweight)

on the other hand, low angle(under 70 degree) must with a heavier counterweight to balance center of gravity

and unbalance center of gravity could resulting in the superstructure would't slew well

in this case I had already keep some spaces to add weight :head_back:

in addition, the lego turntable 48452 was too small to handle the superstructure, the lego 24121 is too big to fit in 17 studs (I think we need the new turntable part)

I didn't solve the problem though I had add rollers around the turntable already

 

 

the 3rd problem is the chaissis problem, it driven by only 1 axle(just like u42009), to solve it is add more driven axle 

maybe I would build my chassis version in the future

sincerely.

 

 

 

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Thank you very much for the adequate responce! Good luck in further building!

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16 hours ago, Aleh said:

Thank you very much for the adequate responce! Good luck in further building!

thank you, sir!! :grin:

Edited by mitx2529

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That is a really nice looking crane.  I don't see any signs of a gear rack so I guess the boom lift and extension is all being done with string?  You must have a pretty solid mechanism to pull in the string lifting the boom, that will take quite a bit of force.  It seems to work really well in the video so great job and it definitely makes a very clean looking model.  I will experiment with that idea next time I want a large actuator.

Trying to balance the weight to get smooth slewing is always a problem.  Lego simply can't do what can be done with metal bearings on a real machine, even using the large bearing solution like on 42082.  At least not when working at any normal scale.  I think my next crane will be some kind of crawler with variable counterweight positioning, that's one sure way to solve the problem.

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On 7/10/2021 at 7:06 AM, mdemerchant said:

That is a really nice looking crane.  I don't see any signs of a gear rack so I guess the boom lift and extension is all being done with string?  You must have a pretty solid mechanism to pull in the string lifting the boom, that will take quite a bit of force.  It seems to work really well in the video so great job and it definitely makes a very clean looking model.  I will experiment with that idea next time I want a large actuator.

Trying to balance the weight to get smooth slewing is always a problem.  Lego simply can't do what can be done with metal bearings on a real machine, even using the large bearing solution like on 42082.  At least not when working at any normal scale.  I think my next crane will be some kind of crawler with variable counterweight positioning, that's one sure way to solve the problem.

thnaks!

yes, the boom lift and extend works with string,I got the ideas from brickshelf and modified to my moc, but I thought the most difficult issue is putting motors and gear in 3 studs space.

I had spent so much time to overcome the problem.

you mention that variable counterweight positioning sounds awesome and challenged, i had no idea how does it work *huh*

I can't wait for the final result :head_back:

 

 

Edited by mitx2529

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THis is a good reason to bump the topic.  

Great crane.  I have several other projects at the moment, but one-day I would like to give this build a chance.  Great job...

 

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11 hours ago, nerdsforprez said:

THis is a good reason to bump the topic.  

Great crane.  I have several other projects at the moment, but one-day I would like to give this build a chance.  Great job...

 

thanks you, I put my whole heart in to this crane, I'm glad you like it

 

10 hours ago, efgen86 said:

Cool job. I like how neatly the cockpit and the whole model are made.

the cabin was really hard to build, I tried numerous methods catching the curve

thank you!

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