Recommended Posts

Posted (edited)

Hello Everyone –

I wanted to share my first MOC in well, several years.  Our beloved Grove GMK6400 crane scaled on the 62.4 mm tire has been an AFOL favorite for years.  I think it is actually one of the largest group-sharing projects we have had on here. 

42108 inspired me to do a similar one, just at a smaller scale and without electronics.  Using 49.5 tires for scale, the below is what I came up with.  There is some inspiration from 42108, to be sure, but so heavily modified that it really is no longer recognized as such.  Also, it is kinda a motley of others’ creations as well.  The outriggers are taken from @M_longer modifications of the set, and a big kudos to him for such a genius solution to fix 42108’s abysmal ones.  Also, as is easily recognized, the boom is a modified version of our fan-favorite Grove GMK6400 at the larger scale.  One of my sources of inspiration was a comment I made a while ago on that thread stating that as beautiful as the model is, I think the boom is undersized.  By my calculations, and looking directly at the blueprints of the real crane, it easily could be increased to 8 studs instead of 6.  @mkbryant assisted with my comments and calculated the following: 

GROVE_GMK6400-Lego%20Scale.png

So, with this in mind I kept the same dimension of the larger version (with undersized boom) and applied to a smaller carrier (at tire size 49.5 instead of 62.4) just slightly shorter.  I think this given the proportions of the crane greater accuracy than our current Grove version at the larger scale. Boom is 7 studs high and the cab is 10, giving the boom 70% of the height of the cab, which is much closer to the real thing.   

Functions in the crane are all the obvious, all steered axles, outriggers deployment and raising/lowering carrier, boom raising/lowering, extending/retracting, hook lower/raise, but I also added superstructure rotation, superstructure cab lifting/lowering, carrier side-mirrors with two way movement, and  lifting vent in cab (superstructure).  Also, all are manual.  No electronics.   Difficult to throw in electronics, motors, etc. at this scale.  I like the manual functions, although they are tedious, especially for raising/lowering, extending/retracting boom.  

125322_small125509_small20210315_140907

Carrier only: 

Carrier_edited20210315_141531

 

I won't bog the thread down with any more pics.  I have a few more on my flickr page.  But here is a youtube video showing it and its functions.  

Comments are all welcome.  This was one of the funner (sp?) projects I have been involved in, I thoroughly enjoyed it.  

Edited by nerdsforprez

Share this post


Link to post
Share on other sites

Wow, that is a really 42108-6400 now! I only started reading the post but have a full understanding that it really is an another coming top-model for several months. There are a lof of cranes here already, by TLG and BY AFOLs, and some of them are true diamonds. But I haven't saw the diamonds in a such scale yet, and never supposed that there is a possibikity to fit all these things into so tiny chassis and boom. :thumbup:

Share this post


Link to post
Share on other sites

Pretty cool model - great job. Especially when it's mostly Technic with just some small portions made with system bricks.

Steering angle on wheels is a bit small though and the rotation on the turntable seems a bit hard, but I get that you couldn't do much at this specific scale in between big turntable you are using and 90 degree arc gear racks.

Anyway really cool mobile crane. I'm going to show off my crane soon at significantly smaller scale - yellow work machines are cool :D

Share this post


Link to post
Share on other sites

Nice to see a top-notch manual model for a change. Looks great, packed with functions - doesn't get much better :pir-love:

Share this post


Link to post
Share on other sites

This is pretty cool! I like it manual too.

But it must be a bit boring to turn some of those manual commands, lots of wheel turns.... maybe you could use an external motor, a bit like an electrical screw driver made out of lego, for the longer operations?

Share this post


Link to post
Share on other sites

Very nice :wub: I remember your idea for tires published nor so long ago.

Share this post


Link to post
Share on other sites
Posted (edited)

Thank you everyone for the kinds comments.  

14 hours ago, SaperPL said:

Pretty cool model - great job. Especially when it's mostly Technic with just some small portions made with system bricks.

Steering angle on wheels is a bit small though and the rotation on the turntable seems a bit hard, but I get that you couldn't do much at this specific scale in between big turntable you are using and 90 degree arc gear racks.

Anyway really cool mobile crane. I'm going to show off my crane soon at significantly smaller scale - yellow work machines are cool :D

It does appear that way, yes.  It is actually not that bad.  It is the standard steering angle, as in M_longer's version and 42108.  But, as you noticed, there does seem to be a bit of a lag towards the end of the drive train.  I am afraid this is a product of ABS.  As can be seen here, the axles driving the steering have much to go through. And a lot of friction.  Pic one (left) below shows half of the friction points.  I actually tried also using just one large axle (as much as I could) as I still have some of the very long ones from 42009.  But things were even worse.  I considered using all stainless steel ones, because I also have those, but I wanted to keep things all Lego. 

20210306_0544304steer bypass

I even have to bypass the outriggers (pic on right).  Or at least the first pair.  That is way using a solid axle for that entire length was not possible.  This adds to the lag for as we all know force passing through Lego gears suffers backlash.  But good observation nonetheless.  

 

4 hours ago, vascolp said:

But it must be a bit boring to turn some of those manual commands, lots of wheel turns.... maybe you could use an external motor, a bit like an electrical screw driver made out of lego, for the longer operations?

I have to agree with you on two functions.  Boom raising and lowering and obviously the hook block.  I really like manual functions, agree that the boom extension is tedious...good observation.  this needed a lot of force and therefore geared with worm gears x2.  Extending the boom does take a long time....

Edited by nerdsforprez

Share this post


Link to post
Share on other sites

cool!!

its a nice 49.5 wheel Grove GMK6400!!

good looking and functional :kahuka:

Share this post


Link to post
Share on other sites

It's a huge and detailed model, I like it very much!

Question: did you use some particular rims or are they standard 30.4 x 20mm rims? It looks the tires are somehow compressed on the outside.

Share this post


Link to post
Share on other sites
10 hours ago, mitx2529 said:

cool!!

its a nice 49.5 wheel Grove GMK6400!!

good looking and functional :kahuka:

Thanks!

 

7 hours ago, mpj said:

It's a huge and detailed model, I like it very much!

Question: did you use some particular rims or are they standard 30.4 x 20mm rims? It looks the tires are somehow compressed on the outside.

My bad.... I thought I had shared this.  I think I did in some other thread.... but not here.  

In looking to see if a crane at this scale was possible, in keeping the larger boom to scale, I found indeed it was, with the 49.5 mm tire.   However, although the tires are to scale (more or less) they do appear small.  I believe this is because the side wall seems too thin.  On the real crane the hub is relatively small compared to the side wall.  So, with this rendition of the same tire (because of scale, but using a different rim, it gives the appearance of a bigger sidewall while maintaining the overall diameter of the tire.  Created using Lego parts (4) Technic Wedge Belt Pulley, (2) "....." rubber belt, six gray 2L pins (without friction ridges).  Kinda part heavy for one rim but they work well and solidly hold the tire in place.  Before and after pics below. 

 

 

20201224_064813

 

20201224_064710

 

Here are actual pics with the standard 49.5 rim.  I don't like it as much for the specified reasons..... but nice to compare.  

20210315_13241120210315_132326

 

Share this post


Link to post
Share on other sites

Very ingenious. I understand your task, maybe it's done in a complicated way .

I would have used simply black rims with grey technic wedge belt pulley, but black plastic is different than rubber black.

Share this post


Link to post
Share on other sites
32 minutes ago, mpj said:

Very ingenious. I understand your task, maybe it's done in a complicated way .

I would have used simply black rims with grey technic wedge belt pulley, but black plastic is different than rubber black.

Yea... tried that.  I don't think it looks good at all.  I know it is a common technique used by many to simply place a wedge belt pulley on the outside of a 49.5 rim... but I have never been a fan.   At least in my opinion, this was the best solution for the look I was going for.... 

Share this post


Link to post
Share on other sites

Excellent! I have the large 6400 but this little brother is amazing in design and function!

Share this post


Link to post
Share on other sites
On 5/5/2021 at 5:52 PM, AFOLegofan66 said:

Excellent! I have the large 6400 but this little brother is amazing in design and function!

THxs!  It would be cool to have both and compare them side by side.  Unfortunately, I don't think I will be building the big brother, with the 62 mm wheels anytime soon....

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.