Bogdan Valceanu

Eurobricks Vassals
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Everything posted by Bogdan Valceanu

  1. 23: 103: 61: 48: 39: 27: 1
  2. Bogdan Valceanu

    Technic General Discussion

    Hi guys, I didn't want to start a new thread regarding this, but after Lego decided to stop allowing custom parts on, we need an alternative. Please help me to convince to start a section for custom parts. See how you can help in this video, spread the word around And the previous video, where I expressed my opinion regarding Lego's decision to stop offering custom Lego parts: Cheers, Bogdan
  3. Hi guys, I’ve been following the forum for some years not, but I’ve been mostly a “lurker in the dark”. But, after 2.5 years designing and building when I had some spare time, I can finally share my 1:20 crawler crane MOC with you. For now it has somewhere around 40.000-60.000 parts (don’t know exactly how many). I’ve tried to build it as close as possible to a real crane in terms of assembly and functionality, with the usual constrains that you have with building out of Lego at this size and scale. As a disclaimer (and as a direct apology to Lego purists), the slewing bearing is not lego, but a cross roller bearing. The drive of the bearing is Lego, using the ¼ gear racks from the 42055 BWE. Took me about 6 monts to find a bearing that fits in size with the internal gearing of the gear racks, so that the driving axles still fit trough. Also, if you look really close, there were some occasions where I got out the Dremel for some adjusting (mainly panels), as I didn’t want to sacrifice strength, or design. Again, sorry to the purists. The crane is powere by 4 BuWizz, one in each central counterweight (between the crawlers), and one in each superstructure counterweights. I love the fact that you can still operate the BuWizz while it’s charging, so I have a power bank battery next to each BuWizz. Like this you get hours and hours of play time even with a large heavy model like this. The drive is as follows: - Each crawler is powered by 4 PF XL Motors (and one BuWizz per crawler) geared down 240:1. The motors don’t drive the ends of the crawler, but 8 sets of 2 gears underneath each of the crawler chassis. Due to weight reasons I used metal axles from Eezo’s Brick Machine Shop from the US. -Slewing is done again by 4 PF XL Motors which sit in the base of the superstructure. - Each winch is driven by a PF L motor. They were powered by 2 PF L motors, but because the winches are worm-driven I had some issues with them not running synchronous and overloading the motors. The winches can be individually taken out from the superstructure for maintenance and use 1mm wax rope. Structurally the main building technique for the crawlers, undercarriage and superstructure is an array of 5x7 technic frames. I’ll come back on another post with some pics of the various building techniques and technical details. Maybe I’ll also do a more detailed video on this sometime soon. The crane is not finished yet. I still need to build the superlift tray and telescope, which will be EV3 controlled so that it self-adjusts, and sadly I need to rebuild all the boom. Until a main boom length of 4.5m everything is ok, but with more than that it starts to bend too much. In the video below I’ve build 4m of boom, because it was pretty windy when we shot the video. The goal would be 7m someday. I want to keep the boom in the main boom+short fixed jib configuration. A luffing jib would be easier to lift (most large Lego cranes that I saw are built in a luffing jib configurations), but as I work in wind turbine assembly, I want to build the boom configuration that we use mostly. Here some pictures from the assembled crane: And here a video about the crane (without wanting to advertise for the channel) As mentioned before, I’ll follow-up with some more pics from the building phase and building techniques. I hope you guys like the crane.
  4. Bogdan Valceanu

    [MOC] [WIP] Crawler crane in 1:20 scale

    A video with some more technical info, mainly about the control of the crane:
  5. Bogdan Valceanu

    [MOC] [WIP] Crawler crane in 1:20 scale

    Continuing with the details, it’s now time for the superstructure and slew drive. As mentioned before, consider the LDD files as being a draft, as I deviated in some details during the build. The superstructure is based, again, on the 5x7 frames in an alternating manner, similar to the building style of the undercarriage. The main structural modules are: the two side frames, the bottom part (which includes the slew drive system) and the paneling. The paneling is split again in left/right and the back and is also used structurally to stiffen the whole superstructure. I had some issued with the slew drive, so I had to disassemble completely the superstructure and building in modules really eased the disassembly work. All 5 winched can be removed for maintenance and improvements. At first they were powered by 2 motors each, bus due to small differences in the rpm’s between the motors and the fact that the winches are driven by worm gears, they ended up in different positions and overloaded the other motor, so for now each winch has a PF L motor in it. In the picture you can also see Mindstorms motors, I changed that later on. As the slew bearing out of Lego would be impossible to build for my target height of the crane (hopefully someday 7m), and still to be rigid enough, I searched for 6 months for a suitable bearing to fit the hole pattern and size of the ¼ round gear racks from the BWE. Not only did the exterior have to match up with the outer diameter of the gear racks, but also the interior diameter was critical, so that the drive axles can fit trough to the internal gearing. If you look one of the pictures with the red circles, you can see how close the holes where the axles pass trough come to the interior wall of the bearing. The bearing is overkill for the crane in terms of its thickness/height, but it was the only one that I could find size-wise, plus as a bonus, it’s heavy enough (around 4.5kg) to act also as a central ballast. The bearing-to-undercarriage connection (on the outer part of the bearing) fit the hole pattern perfectly, but the interior PCD didn’t fit with the superstructure connection, so I had to build an adapter plate for the connection (again, my apologies to purists). The connection plate is a 2-piece aluminum construction, the top part connects to the superstructure using again 5mm thread rods, and the small circular part that fits inside the bearing. I had to build this as a stabilizing part to prevent the drive gears axles from bending and skipping some teeth. I used stainless axles metal gears from Eezo’s Brick Machine Shop just for ease of mind, as reaching this part of the crane for maintenance requires a lot of disassembly. Finally, it turned out that the crane turns so easy and fast that I think plastic gears would have been strong enough for this. Here the dropbox link for the LDD files (including cabin, A-frame and counterweight supports): And pictures of course: 12 13 14 15 15b 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
  6. Bogdan Valceanu

    [MOC] [WIP] Crawler crane in 1:20 scale

    Sure. I'm from Romania (I've update my profile now, I forgot to put it in) The counterweights have 0.5mm lead sheets cut into stacks, and also the BuWizz controllers with a powerbank battery for each controller. The total counterweight is around 15-16kg I will give some more details when I post the details about that.
  7. Bogdan Valceanu

    [MOC] [WIP] Crawler crane in 1:20 scale

    Yeah I know, already saw this. I was happy to meet Ian Webb in person, I've been following him for years. You can also watch my video about the Modelshow Europe. This is just the preview, the full episode will be online in the weekend:
  8. Bogdan Valceanu

    [MOC] [WIP] Crawler crane in 1:20 scale

    With a small delay due to us attending the Modelshow Europe in the Netherlands this weekend, I want to start posting some more technical info about the crane. I will also post the LDD files, but these are partially drafts, I did deviate a little during the build, so please take them more as a “suggestion” and to see some of the building techniques. First, the undercarriage. As most of the structural part of the crane, this uses a loooot of 5x7 frames. These are set up an interlocking and alternating manner, so in the end the piece is almost “solid”. This gives excellent stiffness and strength in all directions, without too many “slack points”. It took 5 designs and 2 builds to get a satisfying stiffness. As mentioned also in the first post, the slew bearing is not Lego, but I wanted to use the ¼ gear racks to drive the slewing motion. I searched for almost 6 months to find a bearing that fits over the gear racks and matches up with the hole pattern, and still be able to pass the axles trough to drive the gears (more detail in a later post). The bearing plays a structural role, as it stiffens up the undercarriage, and it’s held to it using 5mm thread rods that are fixed on the underside of the undercarriage. Where they get fixed I used some of Brick Machine Shop’s aluminum liftarms as “load spreaders” so that the forces are not concentrated just where the nuts are located. Link for the LDD file: Photos:
  9. Bogdan Valceanu

    [MOC] [WIP] Crawler crane in 1:20 scale

    Thanks for the wonderful feedback from all of you, this means a lot to me to get this kind words on my first MOC from the forum that I've been following for years. I want to start the series of technical and build details with the most important question of them all : " Why is the crane operator called Alfredo? " When building the crane cab, I stumbled on a 5L liftarm with an "Alfredo" sticker on it. It came like this from a Bricklink order and went unnoticed until building the cab. So, I carefully pealed the sticker off and used it on the dashboard of the crane cab. When researching where the sticker came from, it turned out that it was on the 2009 8264 Hauler ( ).
  10. Bogdan Valceanu

    Question about gears and chains

    It will work. The small chain and small tracks work with 16t, 24t, 40t gears, and even with 8t, but the 8t gear is pretty small.
  11. Bogdan Valceanu

    Lego Technic Figures

    Meet Alfonso (found a sticker with that name on a 5L liftarm) and used it on the instrument panel. He's my crane operator in my WIP 1:20 crawler crane MOC
  12. Bogdan Valceanu

    Linear actuator in LDD

    Here another build proposal of the retracted small LA, using the 1L "liftarm"
  13. Hi all, This is my first post, and maybe the admin will consider this off-topic, but talking about the PF 2.0 I would like to have a feedback from you guys. I am working on a large 1:20 crawler crane (4 x XL Motors per crawler side, 4 x XL motors for the slewing, etc) so this will use up a lot of current, and drain batteries fast. So, as I didn't want RC accu-packs visible, I started working on a custom battery pack with 2600mAh and 5200 mAh capacity Li-Ion (the crane would have multiple of these) with integrated charging management and selectable output voltage (9-10.8V) /amperage (1-2-3A). So you can use it with normal IR receivers, but also with the Sbrick. The size of the casing would be 5x9x11 studs for the 2600 mAh (so just slightly larger then the PF Battery box) and 7x9x11 studs for the 5200 mAh. I was playing with the ideea to start a Kickstarter/Indigogo campaign to manufacture these, but I kinda decided to wait what the PF 2.0 will deliver, also in terms of connectors (if they will be the same) and separated/integrated receiver. Would you be interesed in this? and if yes, feedback would be nice. BTW...I voted for separated receiver, obviously for the above mentioned custom battery pack. Thanks, Bogdan