doug72

Thanks it’s taken quite awhile to get it sorted. Each side of the boom has two 5x11 & two 5 x 11 taper panels so panel boom Is now a bit longer. Now tested OK on test rig with three motors. Once dipper arm re-built to test again before replacing Mk 1 boom. I might have to add more counterweights to balance the rotating structure.

Revised Main Boom / Dipper Arm hinge gearing:- Finally achieved the desired swing range for Dipper arm from horizontal to vertical without any gear clash problems.

 Achieved by using 3 x 7 bent beams which enabled the dipper arm to reach the vertical position, when main boom is fully raised.

 New dipper arm to build and attach.
Note: M motor only shown for testing the drive to the four claw grab or clam shell grab.
 Once section shown is connected to lower part of main boom drive shafting to dipper arm actuator and the drive to the attachment to devise.

Thanks for that info. Not many available in the UK and then most dealers only have 1 or 2. I was thinking of using them for a vertical lift and then tip when they reach the top. I have one of the hockey return to centre spring unit in orange.

Can anyone identify this part - I think is Lego and is a helmet of same kind, approx 4 x 3 x 3L with one pin hole & one axle hole. There are no markings on it. Potential use for a GBC lift I have in mind and able to hold two balls.

Thanks yes it works very well. I modified it slightly in how it is connected on the boom by using 2L pins with axle. To change the attachment I just push the 5L axle though the #1 connector to release it and then twist the other #1 connector enough to release & pull the grab out. New grab fitted and push 5L axle back into place.

Panelled Boom:
 After many attempts using panels for the main boom I have failed to replicate the range of movement of the Mk 1 main boom which used beams only. Drive through the hinge point between main boom & dipper arm works OK but so far unable to get the swing range required for the dipper arm due to limited mounting points on the 5 x 11 panels to get the right angle for the linear actuator to push the dipper arm from the vertical position to fully raised position without fouling the drive to the grab attachment.
 Tried a system using worm drive & crank but same lack of success and does unable to fit within the boom panels. Does anyone have suggestions ?
 If not will stay with Mk 1 boom & dipper arm.
 Meanwhile started work on a crawler under carriage. 
 


You can download instructions from Lego,s website

Built a test rig to see if the main boom could be made using panels.
 Taper panels required each end, with taper on underside, to allow for drive axle paths and to let the dipper arm fully retract to hang vertically.
 Test successful using a L motor and able to raise / lower the boom with full weight of dipper arm plus the grab.
 Dipper arm to improve and will probably still use beams each end with a 3 x 11 panels in the centre. Drive shafts to dipper arm actuator & grab to sort out on the test rig before installing the finished boom. Boom raised: 
 Boom lowered: 
 Improved drive to grab through hinge point between main boom & dipper arm: 


Many thanks, I have downloaded the file OK and will use that to build a grab unit for my MOC which aslo based on Sennebogen products. I like the way you interchange the two grabs, which I will use, much easier then my method. Update:- Now built your design and its works great, had to modify the end of the dipper arm to attach it and also modify the 4 claw grab to be interchangable. Clam shell bucket fitted:- Linear clutch removed due to the drive slipping. 
 Four claw grab fitted: 
 Many thanks again for the design & building instructions. Doug

Thanks for your suggestions. At the moment the stroke of the linear actuator is only 1.5 to open or close buckets which is too short The grey 5L horizontal beams connecting the buckets to the L.A ram tilts which causes one bucket to move before the other due to a friction free tan 3L pin used. A re-design required The problem with GBC balls:

Many thanks for your comments. There will be further adaptions for this build:- Mount onto a crawler under carriage & change main boom to a version using panels instead of open beams. Getting close to that looking & working OK - to test before installing. Improve clam shell bucket grab.

Help:- I am having trouble getting the ball loading to work correctly - any tips on how to set the gears up please ? Should the 14/24 diff body be free to rotate slightly or should it be fixed so it doesn,t move ? Found best if use a speed controller instead of a basic controller.

Many thanks for comments, it’s been a very enjoyable build solving the various problems. Still room for improvement, so it’s an on going process. However I need to find a better driver !,

MOC complete: see video for demonstration of functions etc. Very pleased with how this went and how smooth all the functions are - the secret being the use of a stable turnatble system. First section shows the undercarriage drive and steering, second section the upper rotating unit in action picking up Lego boulders. Tested using the 4 arm claw grab OK with boulders but the clamshell bucket grab was not successful when trying to pick up Lego balls, which made it jam. 

Tried bird seed and same problem - one bucket closes but the other does not spilling the contents, so back to the drawing board on that for now. I plan to mount this on a crawler undercarriage later and I am still working on a panelled boom version if can sort out the section between Main Boom & Dipper arm.


Thanks @ColletArrow & @Aventador2004 After an intensive search I found another yellow 5 x 11 panel and checked to see if feasible to to build a boom with a 5 x 5 cross section using panels only - so far partial success but quite a struggle to route the two drives to the head & dipper arm actuator due to less pin holes in the right places ! The head of the boom also proving to be a problem to get desired swing range in & out for the dipper arm and drive through the pivot. So a completely panelled boom not worth continuing with. Doug.

Following comments ansd suggestions improvements made to cabin and the taper section has been replaced by an air cooler intake for the hydraulics.
 Cabin rebuilt and has added more weight requiring some balance weights at the rear of the body to counteract the front dipping despite use of the 13L turntable system. Slewing is still OK. Don’t think this MOC would be feasible just using a Z60 turntable. Cabin in lowered position: Cabin in raised position: Main boom side with panels:
 Due to increased overhanging weight of the main boom with panels and lack of 5 x 11 yellow panels I have decided against this. It would also require a complete re-build & re-locatiion of drive shafts & U-joints to the two actuators. Re Lego Technic Figures: I have one which moves from MOC 2 MOC !!! Also have a Meccano figure which is about same size and these I believe are still available. Just a few more cosmetic bits to add before making a video which may take me a while to complete.

Thanks for the comments and suggestions. Re cabin, see previous post. Re taper panels - idea was to represent air intakes but not really happy with the way it looked. The taper panels match the boom shape at top and bottom. I have had to rob my Bucket Wheel Trencher for the yellow panels - they seem to be very scarce at the moment from both Lego and on-line. Doug

Thanks for your comments - agree cabin not good Width available for cabin is very tight unless extend it sideways. see photo I had thought of extending a platform out for a bigger cabin with access ladder at rear. P re panels on the boom - I now have some 3 x 11 yellow panels and a few taper wings but will add even more weight ! I'll give a try

Parts finally received after postman struggled though deep snow !! Build almost completed, just need to improve the operators cabin and fit access ladders & guard rails etc. PF receivers and battery box installed and body work completed. Battery switch can be accessed by opening the left side curve panel. All functions tested OK both for the under carriage and rotating structure and booms. Weight of the model is 2.2 kgs. Action video to make in next few days. General views:- Elevating Cabin:- Decided to just have it raised & lowered by hand, friction pins are used at pivot points to keep in any desired position.

Many thanks for the excellent instructions,

Thanks Sawyer for an amazing Mini GBC module - which I am now building. Had to rob a Lego train for the spacer ! Mine will be multi coloured due to a limited range of parts. Built as per instructions but gears slip / drop as arm rotates back down to collect the next ball. I may have found the reason. There is a possible error in the instructions at page 27. Sea photo At page 28 Instructions show the link arm with the bachkpack spacer attaching BELOW the axle for the swinging 24T gear whereas the photo shows it is ABOVE the axle. Which is correct ? Tried in both positions with & without spacer and seems best with spacer and ABOVE axle and now appears to be working OK when tested by hand.

Tried a white clutch gear but it requires a lot of force before it slips and module pulled apart ! With elastic cord the degree of friction is easy to adjust, and the dwell time at top and bottom is set by gearing on the reversing unit. Also other outputs from reversing unit can run other GBC modules.

This is how I used a reversing module and elastic coard to control a single car lift - could be adapted for two cars by using a normal cord between cars over the upper pulley and elastic cord between the two cars and around the lower reversing drive pully. When cars hit end stops the elastic cord slips until drive is reversed, takes bit of trial & error to get elastic cord tension OK. Tested for a few hours and performed OK. Reversing unit is on the right thand side of green baseplate. Doug

Thanks for your comments and concerns. Both attachments can reach the ground OK see images showing boom & dipper at various maximum & minimum positions. It’s a compromise as the Lego large linear actuator does not have enough travel.
 The real machine it has long reach hydraulic cylinders and main boom is able to be lowered to almost parallel with the ground for transport. I am happy with the range of movement for the main boom & dipper arm, but when I later mount it on a crawler base I will see if I can improve it. The MOC is now getting quite heavy but it still balances and slews OK. Elevating Cabin:-
 Started the hardest part of the build the aesthetics - something I am not good at !!
 At the moment elevation is by hand with friction pins in the linkage to keep it at desired position, a hand operated geared system will later be fitted later. 

Next step is to complete the body work once parts arrived - delayed by the “Beast from the East” snow storm we are having at the moment.
 Twisting of attachments:-
 When the attachment small actuator reaches its end stops it twists the grab up untill the LA internal clutch works - see photo.
 Using a linear clutch has lessened this but not entirely eliminated it and prevents u-joints from being broken.

Clamshell bucket grab:-

 Proved harder than envisaged to mount this on the dipper arm and make it interchangeable with a four claw grab.

 To remove Clamshell attachments the two Green Pins are removed, extension axle removed and fittings for four arm claw grab installed. A linear clutch inserted into the drive to these attachments to protect the U-joints, relying on the mini actuator internal clutch is not enough to prevent the attachment from twisting when they reach full travel open or shut.