[MOC REVIEW] Grove GMK6400 Mobile Crane

[afol1969]

I assume you mean 12 tooth bevel gears. The gears in the differential are not a problem. They cannot fall out because the 4L axles with middle stop are used, and they are not breaking. Adding an extra spider gear to the differential does nothing structurally unless it is guided by a pin on the housing.

I suspect that "final" instructions will still take a while, but my draft 3 instructions are already available and are sufficient to build the model, however they don't include any of the improvements we are making to solve specific issues.

I like the submodel callouts you used. I had actually thought of those exact same things but decided to skip them in favor of getting usable instructions as quickly as possible. I'm glad to see that we are thinking of the same types of instruction improvements!

Thanks! Indeed the final instructions take a while, I'm a purist to make perfect instructions. Once more or less the final version available, I'll share it, but I'll make updates in regular times if I find something what needs correction.

Two things: you need to use a PLI substitution to get a complete shock absorber in the parts list instead of a separate cylinder and piston. The belt is also missing from the parts list.

I've seen it, of course I'll make the PLI substitution. Also now I know how to create rubber belts and show them in the part list.

Alex, I highly recommend that you wait a bit before doing any more work because you are working with an old version of the file. The version I am using is different and incorporates some changes I made while building the model to solve problems. I'll give you a copy of the file as soon as I am finished with the changes.

That's ok, so I'll concentrate now to get all the parts to build the model, hope I'll get them within the next week.

This is one of the things I intend to bring up in the review. The superstructure needs more counterweight.

As I've built Jurgens' Ultimate 42009 with the boom from Christophe Moitte, I used an additional battery box and some parts to make the turntable construction more stable. I've not made instructions, but some photos, so if needed, I can send them to you.

Greetings

Alex

Edited September 3, 2014 by afol1969

[jantjeuh]

Is there an up-to-date parts list anywhere (preferably in Rebrickable or BrickStore format)? Curious to see how much I'm missing.

[Blakbird]

Is there an up-to-date parts list anywhere (preferably in Rebrickable or BrickStore format)? Curious to see how much I'm missing.

What counts as up-to-date? There is a Brickstore file posted on my Bricksafe account which is the version I used to buy the parts to build the model, but it doesn't include any changes I made while building. It should be 99% accurate.

[Lakop]

I see you're using some of the older diffs. An epic model you're working on. Cranes etc only get bigger and better. Look forward to the completed model.

H

[Blakbird]

Now I'll talk about the suspension. This model features 12-wheel independent suspension. Each wheel has at least one stiff shock absorber, and the wheels of axle 1 each have both a stiff and a soft shock. Each suspension is of the double wishbone type. Each steerable axle uses the new 5L suspension arms. The non-steered axle just uses beams. The shocks seem to provide plenty of stiffness to support the weight of the crane without tipping. The only issue the lack of lateral stiffness on the arms. Suspension arms are typically called "A-arms" for a reason. They are "A" shaped to provide a wide spacing between the chassis attach points to react thrust and braking forces. Older Technic suspension arms were all 2 studs wide which is still pretty narrow. The wishbone arms from 42000 provide a much wider support. However, these new arms have only one attach point and are really only suitable for small models. This means that they wobble forward and back considerably under load. With 20 of them to distribute the forces it still works well enough, but the engineer in me is bothered by the lack of stiffness. Of course, using the older, wider arms would cost a (another) fortune.

I was surprised to read in the spec sheet for the real Grove GMK6400 that it also features fully independent suspension on each wheel.

The final feature of the carrier is PF lights. The cabin of the model is provisioned for up to 3 sets (6 total) of LED lights. The instructions call for 2 sets, but I only put one set in mine. Use however many you like, keeping in mind that you have to stow the wires somewhere. The wires are activated with a PF switch behind the roof.

[JDC]

Blakbird, there were a couple of posts in the previous topic about making changes to raise the boom higher, and also, you've run across some things while building. Will those types of changes, where the build would be altered from gerger's original, be reflected in your final instructions?

[jantjeuh]

Knowing Blakbird (a bit) he won't rest until the instructions are utterly perfect, so don't worry

[Blakbird]

Blakbird, there were a couple of posts in the previous topic about making changes to raise the boom higher, and also, you've run across some things while building. Will those types of changes, where the build would be altered from gerger's original, be reflected in your final instructions?

Where possible, yes. However, I don't have a solution for everything and this is not my model so I don't want to just start making arbitrary changes. The model will be what Gerger (and others) designed.

Knowing Blakbird (a bit) he won't rest until the instructions are utterly perfect, so don't worry

I never rest.

[CP5670]

This might just push me into getting a 42009. I've been on the fence about getting one since it's similar to the 8421 I have, but this model is awesome. My favorite part is the drivetrain with the transversal differentials and suspension. It's pretty hard to do that on a 15-wide vehicle like this. I do prefer the gearbox in the original model over having separate motors for everything though.

[keroro]

Will you uplaod the MOC on rebrickable?...

It's amazing and very beautiful..!!

[jantjeuh]

Will you uplaod the MOC on rebrickable?...

It's amazing and very beautiful..!!

I'm sure it will be uploaded to Rebrickable once the instructions are finalized

[JDC]

This is from Efferman's Custom Parts topic #803. How would this work for the large lift cylinder seen under the real GMK6400 Boom? 3 Studs wide x 18 Studs of movement.

Edited September 5, 2014 by JDC

[Blakbird]

This is from Efferman's Custom Parts topic #803. How would this work for the large lift cylinder seen under the real GMK6400 Boom? 3 Studs wide x 18 Studs of movement.

It would certainly be interesting (though expensive) to try. There's no doubt that a longer travel actuator would be of great benefit, but it would also have to be very strong.

[nerdsforprez]

I am sure others are already aware of this, but there is a shop on Bricklink that sells large, strong, elongated actuators.....

http://www.bricklink.com/store.asp?p=Eezo

Expensive? Check

Awesome:? Check and Check

[Blakbird]

I am sure others are already aware of this, but there is a shop on Bricklink that sells large, strong, elongated actuators.....

Interesting idea! Too bad it can't be mounted using the regular LA brackets. Figuring out how to mount it would be the hard part.

[JDC]

It would certainly be interesting (though expensive) to try. There's no doubt that a longer travel actuator would be of great benefit, but it would also have to be very strong.

Apparently the white nylon is fairly tough, according to several posts under that topic. If the efferman LA (above) was mounted to the boom, and an L motor mounted to the superstructure to drive it, would the LBG Universal Joint have enough angular travel to drive the boom up to its 80 degree or so angle? Don't know if I asked that properly, but would the U-Joint be able to still operate at that kind of angle?

[Blakbird]

Apparently the white nylon is fairly tough, according to several posts under that topic. If the efferman LA (above) was mounted to the boom, and an L motor mounted to the superstructure to drive it, would the LBG Universal Joint have enough angular travel to drive the boom up to its 80 degree or so angle? Don't know if I asked that properly, but would the U-Joint be able to still operate at that kind of angle?

No, the maximum effective angle of a u-joint is about 45 degrees, but you couldn't use a u-joint anyway. The actuator pivots around a set of set screws at the lower edge which means that whatever axle is coming out of the end will actually swing through space, not just pivot. That's why I said it would be hard to implement. Those actuators are really designed to have a motor hard mounted to them, and there's no way that would fit.

[JDC]

No, the maximum effective angle of a u-joint is about 45 degrees, but you couldn't use a u-joint anyway. The actuator pivots around a set of set screws at the lower edge which means that whatever axle is coming out of the end will actually swing through space, not just pivot. That's why I said it would be hard to implement. Those actuators are really designed to have a motor hard mounted to them, and there's no way that would fit.

Well Blakbird, you've had several minutes to figure this out... Where are the instructions?

[Blakbird]

Well Blakbird, you've had several minutes to figure this out... Where are the instructions?

Part of the problem of existing outside of time is that sometimes others perceive that I get things done really quickly, but other times it appears to take epochs. It's all the same to me.

[Strikeman]

It is unlikely LEGO is ever going to produce a $1000 Technic model, but we can dream. I think this would fall into the same bucket as the Land Rover Defender 110 Cuusoo project. It would have to be so simplified to meet their quality and marketing standards that it would bear no resemblance to this model. In fact, this has already happened and it is called 42009!

1000$ ? Ouch, but seeing as I only need to spend ~100€ to buy the remaining parts (according to that Brickstore file you posted) I need for this MOC, I might actually have a bit too much LEGO ...

This multi-day-stretched review is awesome by the way Blakbird; your renders and explanations are superb!

[efferman]

Interesting idea! Too bad it can't be mounted using the regular LA brackets. Figuring out how to mount it would be the hard part.

The prototype is designed to mount a L motor at the bottom and to use it as mounting point to the uppercarriage. one guy in my german homeforum has ordered it and will test it with a very heavy 4 section boom which cant be lifted with standard actuators. in relation to the success at this test i will think about a different mounting method when it is necessary.

[Blakbird]

The prototype is designed to mount a L motor at the bottom and to use it as mounting point to the uppercarriage. one guy in my german homeforum has ordered it and will test it with a very heavy 4 section boom which cant be lifted with standard actuators. in relation to the success at this test i will think about a different mounting method when it is necessary.

I was referring to the metal actuator linked in a previous post, not your 3D printed actuator. I would be interested to see how it works as well though!

[Technyk32231]

Damn....That's amazing. I love how there is suspension on every axle.

[DrJB]

If one starts with 2 copies of 42009, and assuming one has all the PFs he needs for this project, what are the parts one still needs to get from BL? I know there is a way to figure this and was wondering if anyone has already run this exercise ...

[Kumbbl]

If one starts with 2 copies of 42009, and assuming one has all the PFs he needs for this project, what are the parts one still needs to get from BL? I know there is a way to figure this and was wondering if anyone has already run this exercise ...

This is exactly the question i'm interested too ;-)