Ngoc Nguyen Posted January 12 Posted January 12 (edited) INTRODUCTION The collective interest in a Technic backhoe has been around since as far as when I first joined this forum, which was 10 years ago. Such intense interest is understandable: a backhoe is one of the most complex, if not the most complex vehicle for a Technic model, since it has a lot of functions while its main body is rather compact. Hence, as I see it, a backhoe is like an apex of Technic or at least Technic construction machines. Yet there are not many official Technic backhoe. Before this year the most recent iterations were 8069, a medium sized backhoe set released in 2011, and 42004, a mini version released in 2013. That means there was a whole interval of 11 years with no new backhoe. Then this year a backhoe appeared in the lineup, but it turned out to be a mini version, an arguably worse iteration even, given that it has less pieces and functions than the 42003. Even though the full 2025 lineup is not revealed, since there's already a mini backhoe, it's unlikely that there will be another medium sized or flagship sized of the same subject. Therefore I decided to publish my own backhoe this year. DEVELOPMENT The design process for this model actually started in late 2021. Back then I wanted to build a road construction playset that contains a backhoe, a trailer, and a truck from the Heavy duty Tow Truck 42128. I don't have the file for that model with me anymore, but here's a custom digging bucket I built from 42128 parts. At that point I already finalized the digging arms. Its design stay unchanged in the final model. But then for some reasons I lost interest along the way so I stopped working on it. Then last summer there was a Technic Contest that involves building models around the 49.5 tyre. That was when I took that backhoe out of the freezer and combined it with features from my 42157 alternate model. Then I encountered two problems. The first problem is that I've always wanted to build the JCB 3CX Compact. It has to be the 3CX Compact and not 3CX or 4CX because the 3CX Compact has 4 small wheels, which allows more space in the body. In real life there are versions of JCB 3CX Compact that use truck tires like the 49.5, but I think it just looks stupid. I want it to have proper tractor tires. The second problem is that I was stuck at the rear wheel arch. In the real vehicle the arch is yellow with a thin black line. I struggled to recreate that in the small scale. So even though I made quite some progress, I lost interest in the summer and left the model in the freezer again. By that time I got most of the main body done. You can also see an attempt at the wheel arch. Then in November I happened to open this file again, and I felt that I can finish it. I spent a couple of weeks in November on it to finish the preliminary design, then wait for the parts. When I did the test build, most functions turn out fine, except the front loader arms. There will always be something that looks nice on Studio but doesn't actually work and require a redesign. This is how the prelim looks like. I already revealed it in my Technic corner. You can compare it with the first image to see how the front loader arms have changed. In the end I managed to make everything work flawlessly! DESIGN HIGHLIGHTS Since it's a small scale backhoe, most functions are directly driven through knobs, so there's nothing fancy in that regard. However there are other nice things I want to share. Chassis: The whole chassis is nested in side a pair of 3x19 yellow frame. This piece is very usefull as you can form a chassis right away without having to extending it with beams. It is only 5L wide, so I have only 3L in the middle to squeeze 3 functions: drive train, steering, and rotating seat. This is how everything is arranged. Inline 4-engine: I managed to make everything black while giving the piston heads yellow half bushes, so it looks very cool and luxurious. Two-piece hood. In the real 3CX, the lid together with side walls can be lifted up separately from the front grill. In my model I made them openable separately too. I managed to put a fan behind the grill as well. Cabin interior: I managed to replicate some details. In the real cabin there are 3 pedals, two gray ones on the left and one black one on the right. The seat is only rotatable counter clockwise, because there's a control panel on the right side. There are 3 joysticks, and the two in the back are adjustable once you turn the seat around. Sliding digging arm: This is the function I like the most and want to incorporate into the model at all costs. For a compact backhoe, it's very important that it can slide the digging arm to one side to fold it up stay compact while travelling on the road. The sliding is designed like this. You use a long axle to spin the axle connectors on both sides to move the arm. Jackhammer and hose reel: On the right side of the model I put a reel, a pneumatic connector, and a jackhammer. If you have a spare pneumatic tube you can connect the jackhammer to the vehicle. This setup is based on this real life variation of the JCB 3CX Compact. FUNCTIONS I had a lot of fun designing and playing with this model. Most importantly, this model satisfies my burning long-held desire to have a functional Technic backhoe. So if you're like me, you can gather the parts yourself and build this model too! According to Rebrickable, the total costs for the parts are around 150 EUR. I'd say it's a fair price for a 1100 piece Technic set with full of functions and playablity. I tried to minimize the use of rare parts so that it's easy to gather the parts for this. The only uncommon parts that are used are the 3x19 frame in yellow, which can be substituted with the more common 3x19 frame in black if you don't mind the color, and the Bionicle tooth in yellow, which will be available later in 2025 in the Chevrolet set. INSTRUCTION: https://reb.li/m/207516 Edited January 14 by Ngoc Nguyen Quote
Ngoc Nguyen Posted January 12 Author Posted January 12 WOW I got frontpaged I've never thought I could get frontpaged yeahhhhh (Actually I got frontpaged once already but that was for the 42113 Review, not for any MOC) Quote
Krxlion Posted January 13 Posted January 13 Well presented and well deserved frontpage ;) I imagine for a small price and tons of functions, some kids would really beg their parents to have one. :D Great job, and keep up the good work, Ngoc! Quote
Ngoc Nguyen Posted January 13 Author Posted January 13 2 hours ago, Krxlion said: Great job, and keep up the good work, Ngoc! Thanks a lot for the support! Quote
allanp Posted January 13 Posted January 13 Nice job, the proportions look pretty accurate for such a small scale. Quote
EWay Posted January 13 Posted January 13 Looks fantastic, well done for taking matters into your own hands! I've only got 8455 and never really liked it as it always felt too flimsy. This looks nice and sturdy in the video and incredibly packed full of functions, must be great fund to play with! And when you started hammering with the jackhammer it nearly killed me :D One slight criticism is the lack of a HOG, it looks as though it's very difficult to steer. I can imagine it would be very difficult to find anywhere to put it though given how restricted on space the thing is. 11 hours ago, Ngoc Nguyen said: WOW I got frontpaged I've never thought I could get frontpaged yeahhhhh (Actually I got frontpaged once already but that was for the 42113 Review, not for any MOC) I actually find this amazing that your MOCs have never reached the front page! Quote
Ngoc Nguyen Posted January 13 Author Posted January 13 12 minutes ago, EWay said: And when you started hammering with the jackhammer it nearly killed me :D I know right, the jackhammer is very fun to play with 14 minutes ago, EWay said: One slight criticism is the lack of a HOG, it looks as though it's very difficult to steer. The steering is actually very smooth. It's just that my hand is big while the opening is small, and I can only use one hand as the other hand is holding the phone. 15 minutes ago, EWay said: I can imagine it would be very difficult to find anywhere to put it though given how restricted on space the thing is. It is possible to route it to under the rotating seat to transfer motion to the HOG on the roof, but doing so will requires making the seat rotation manual, which is not very desirable as it's hard to reach inside, or removing the seat rotation altogether, which doesn't make sense for a backhoe. So I decided that routing it to the steering wheel is the best solution. Quote
Timewhatistime Posted January 13 Posted January 13 If the backhoe is built like in the digital renders, the two Mini-LAs will work counterwise and so won't operate the bucket. If it's done as shown in the video, they will. Quote
Ngoc Nguyen Posted January 13 Author Posted January 13 6 minutes ago, Timewhatistime said: If the backhoe is built like in the digital renders, the two Mini-LAs will work counterwise and so won't operate the bucket. If it's done as shown in the video, they will. Shoot you're right... Thanks for pointing that out. I've just updated the instruction. As for the renders they took too much time to do so I'll just leave them there. Quote
LEGO Train 12 Volts Posted January 13 Posted January 13 Perfect work of engineering! You have chosen a very complex and not very popular model I have the 8455 set but this one has nothing to envy Quote
jorgeopesi Posted January 13 Posted January 13 Very nice looking MOC we are very similar making videos, manual MOCs are a nightmare to show... and we have similar breathing too . Quote
bruh Posted January 14 Posted January 14 Wow what an insane MOC!! This is SO packed with functions. Great job, much better than I could do. Quote
Ngoc Nguyen Posted January 14 Author Posted January 14 16 hours ago, Ngoc Nguyen said: As for the renders they took too much time to do so I'll just leave them there. I realized it didnt actually take much time so I actually went back and redid all the renders. 17 hours ago, allanp said: Nice job, the proportions look pretty accurate for such a small scale. Thank you! 8 hours ago, LEGO Train 12 Volts said: Perfect work of engineering! You have chosen a very complex and not very popular model I have the 8455 set but this one has nothing to envy Thanks a lot! 4 hours ago, bruh said: Wow what an insane MOC!! This is SO packed with functions. Great job, much better than I could do. Thanks for the support! 5 hours ago, jorgeopesi said: Very nice looking MOC we are very similar making videos, manual MOCs are a nightmare to show... and we have similar breathing too . What do you mean similar breathing Quote
1gor Posted January 14 Posted January 14 6 hours ago, jorgeopesi said: Very nice looking MOC we are very similar making videos, manual MOCs are a nightmare to show... and we have similar breathing too . Wow and you both have 5 fingers...yes this MOC is great, but manual functions are pain in the a... Quote
MCD Posted January 14 Posted January 14 (edited) This is amazing! I've been tyre kicking #8455 and #8069 for some time now, but neither are accurate enough! But this! Dam!! Its stunning! I will certainly be downloading instructions and building this beauty! Top work. (Can you confirm - is this 15 stud wide? Think ive visually measured right?) Edited January 14 by MCD Quote
Jundis Posted January 14 Posted January 14 Impressive functions for such a small size! Also the presentation is spot on, well deserved front-paging ;-) Quote
Ngoc Nguyen Posted January 14 Author Posted January 14 35 minutes ago, MCD said: This is amazing! I've been tyre kicking #8455 and #8069 for some time now, but neither are accurate enough! But this! Dam!! Its stunning! I will certainly be downloading instructions and building this beauty! Top work. (Can you confirm - is this 15 stud wide? Think ive visually measured right?) Thanks a lot! Please try it out, it's very fun to build and play. The whole model fits perfectly into a 17 stud width. 43 minutes ago, Jundis said: Impressive functions for such a small size! Also the presentation is spot on, well deserved front-paging ;-) Thanks a lot! Quote
NV Lego technic Posted January 14 Posted January 14 The presentation is just awesome! I like how you tell us about the history and building process, and the "back of the box" renders are very cool too! Quote
suffocation Posted January 14 Posted January 14 Brilliant build and awesome presentation. Bloody well done, mate Quote
Timewhatistime Posted January 14 Posted January 14 Is the reel able to turn in order to wind/rewind the jackhammer's hose? On the one hand, the reel seems to be fixed to the black connector; on the other hand, it looks as if connected to the mini-LA's axle... Quote
Ngoc Nguyen Posted January 14 Author Posted January 14 (edited) 7 minutes ago, Timewhatistime said: Is the reel able to turn in order to wind/rewind the jackhammer's hose? On the one hand, the reel seems to be fixed to the black connector; on the other hand, it looks as if connected to the mini-LA's axle... The reel is fixed. There's no space in that area to make a functioning rotating reel. Hence the jackhammer's hose is connected to the DBG hose connector behind it. The mini LAs are connected through a 12L axle that extends only to the left side (the other side of the model) and can be driven only from there. The hose is connected to the black connector through a black 2L axle with notched. Edited January 14 by Ngoc Nguyen Quote
Timewhatistime Posted January 14 Posted January 14 Now I see, thank you. Did not expect a black 2L axle. Quote
Ngoc Nguyen Posted January 15 Author Posted January 15 19 hours ago, NV Lego technic said: The presentation is just awesome! I like how you tell us about the history and building process, and the "back of the box" renders are very cool too! I love those renders too! Even though they are a pain to make, the final results are totally worth it. 19 hours ago, suffocation said: Brilliant build and awesome presentation. Bloody well done, mate Thanks mate Quote
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