LennyRhys

Thanks guys. That's me just finished cast #15 and dang, I'm getting tired so I think I'll call it a day and resume again tomorrow morning. Each cast including preparation and cleanup takes about 90 minutes, so it takes me about 8 hours to work through five casts from start to finish (and I'm also looking after my son during the day, so generally it takes a bit longer). It's very repetitive work but it is rewarding, pulling back the sides of the mold to see the newly formed plastic part that was liquid resin not long before. I'm REALLY excited to see one of these buckets on the excavator and that's motivating me to push on. I haven't decided yet how best to sell but I'd prefer to avoid ebay (or e-shylock as I like to call it) because of the ridiculous fees which will bump the price up. Will cross that bridge when I come to it. Cheers again

Thanks guys. The stuff I'm using has a shore hardness of 75D, so it feels very much like the plastic that TLG uses, but it is definitely not as strong because it is not injection molded. In saying that, it's still hard plastic and should last as long as any other Lego part if it's taken care of. I have one bucket (the very first cast) which will be my lab rat for some tests. My initial impression is that the buckets will withstand average play wear, but not excessive strain, especially on the teeth. I'll make sure that all relevant info is supplied when the buckets go on sale. Price-wise, it's hard to say but I expect to charge around £15-20 ($23-30) each as they have been very expensive and time-consuming to produce, and they are a bespoke part. As I have mentioned before, these will only be available in the UK to begin with, and one per person because of the limited quantity. If all goes well with the first batch, I plan to do a larger second run and cater for overseas parties, but it may be some time before that happens because (have I said this already?) this is a lot of work!

Won't these be too big? Not to mention impossible to obtain! :)

So I've been busy casting buckets (and still am - it's a lot of work!) but the results are very good and I'm extremely pleased with the outcome. The buckets pictured are virtually straight out of the mold with no finishing or tidy-up work done, except for the bucket at the bottom left which has been sanded and varnished. My intention is to set up a production line so that all the buckets can go through each stage together. I've ordered 100 boxes for shipping (but I very much doubt I'll have that many buckets, at least to begin with) and I need to drill, sand, varnish and pack each bucket. Suffice to say, this has been a lot of work and there's a lot of work still to do... I really hope it's worth it! I'm just about to pour another cast (#11, for those interested) and will update soon.

I got 42030 (Volvo front loader) from Tesco just over a week ago and the promotion at the time was spend £50+ on Lego and get 1000 extra clubcard points. What specifically is the promotion that you describe, and how does it result in a saving of £75? That sounds overly generous for Tesco.

Some stores had stock available before the official release date. It's been available online for a few days now.

This is amazing. I love your gearboxes and to see this model is just the icing on the cake.

I don't think anybody has sad "I hate that this part was released," nor indeed that niche parts like this rack assembly are a bad thing. All that we're discussing here is whether or not it has limited uses, which a few of us think it does. The only benefit it offers over a manually constructed rack/pinion solution is compactness, but it still requires an external drivetrain to function. Re, Leif's point about using the gear rack in conjunction with a worm gear, that would be a poor solution for high loads. Worm gears are very inefficient (extremely high friction) so putting them under excessive loads will result in powdered plastic from the grinding of the Lego gears.

Looks really nice and is very realistic. There seem to be no non-Lego parts which is quite rare for a model of this size. Looking at the outriggers and their construction, I'm suspicious that some parts have been glued in place to provide structural rigidity, but I may be wrong. If I am, he has concealed the main structure of the functional parts very well indeed.

I think that the idea of using these racks as alternatives to LAs is more than a little ridiculous. Some of the very first Technic models used gear racks for precisely this function, and LAs offer a much better and more compact solution. I agree with OP that these parts are very much in danger of having limited uses, which is inclined to happen with parts that are custom made for a specific model. It's good to see that TLG have found two uses for the part, and I'm sure that the community of Lego enthusiasts will find more uses, but also many limitations too. One thing I do see happening soon with these parts is a small-scale forklift with telescopic mast, although the telescoping part would need extra beams added for this to work (and there's the limitation right there!).

Thanks guys. I'd be able to make other buckets no problem. but I don't think it would be cost-effective to mold and cast them because TLG already has a selection of loader buckets available. My main reason for building the backhoe bucket is that it has been 23 years since TLG produced a new backhoe bucket (2950, released in 1992 with Pneumatic Excavator set 8837). The bucket was not included in a set again until eleven years after its initial release, where it was featured in set 8455 - the only time it was ever molded in yellow. I have to say that I'm still REALLY surprised that TLG didn't create a new mold for set 8043, given how much an appropriate bucket would improve the model's look and functionality. @Karle, I think that initially I will be shipping the bucket with a conversion kit, purely because it keeps things simple for people who want to make one purchase to put the bucket on their excavator (even though it's more work for me). Something occurred to me earlier today: with the money I've spent on this project, I could have bought a Mercedes Arocs set. Maybe once I've sold several buckets, that's what I'll do!!

I notice it's also for sale on Amazon UK, but there are only 4 sets left. Selling like hotcakes!

I need to get a work space sorted out, but I'm going to be back at uni in September so Lego will have to take a back seat unfortunately. I'll take a photo of my current space soon, once I've got my buckets sorted out!

I really like it. Considering the limitations of Lego parts like linear actuators and motors, you've managed well to make the model faithful to the original R9150, which happens to be my favourite mining excavator! Granted, there are some parts which don't look as good as they could, but I think you've done well. Nice work!

Thanks kieran. It's hard to say how many casts I will get from this mold because of the variables. I could get upwards of 30 casts because of the low volume of the bucket (about 40ml), but the mold might start to deteriorate after 20 casts, so I just have to wait and see. I'd really like to get as many as possible, naturally, and if there is sufficient demand for the bucket, then I'll make another mold (possibly with higher grade silicone called "platinum cure" which can cost well over £100 for 5KG) and in theory that will allow me to cast a higher volume of parts before the mold gives up. Waiting for the resin to arrive is a test in itself, but to be honest it's probably good to be having a break from this because it'll get pretty intense again this coming week. I've been looking on bricklink for the parts that I'd need to make kits that I can ship out with each bucket, so hopefully I'll get that organised soon!

Excellent MOC! I like the second render of the drive train and the use of knob wheels. Nice work!

The more I see this, the more I want it... but I also want 42042, and the F40...! Really nice and simple mods allanp - thanks for sharing.

When silicone rubber cures it won't change shape unless there's something acting on it (if thin enough it will flex under its own weight). This is why box molds have so much excess above/below and to the sides of the part - in the case of my mold halves, there's about 1 inch of solid rubber in every direction beyond the internal shape. I have no concerns about the resin parts breaking or deforming... my only worry at this stage is whether or not the part will look good when it comes out of the mold! Seeing how much work (and money ) goes into resin casting I don't think it's something I'd do often, but it has been a lot of fun.

I decided to build a mock-up of the 8043 stick and it turns out I have all the parts that I need (at least to make it representational for the purpose of scale and proportion). I spent some time experimenting with different linkages and it turns out that the greatest (and most realistic) range of movement can be achieved by having 4L liftarms placed 1 hole apart on the stick and bucket. Like I said before, there are MANY ways to mount this bucket, but I think that this is the one I'll settle for. Here's an example of range of movement using the prototype bucket and some rushed phone pics! I'm not sure what kind of force the linear actuators can exert, but this is definitely sturdy enough to do some digging.

Thanks folks. I hope to get organised asap for selling this part but there are a few things I need to do first. I think it'd be better to sell it as a modification kit with all the required parts complete as a set, because set 8043 doesn't have some of the parts that will be required to appropriately fit the bucket with intentional functionality. I don't know how many hours I've put into this, but more than one 14 hour day for sure!

Yes, progress indeed! The molds are finished and I'm about ready to keel over... it was A LOT of work and I'm so glad that it's done (at least for now). I have 2KG of black polyurethane resin on order and I plan to start casting in the next few days. I still need to clean the molds properly before the first use, but other than that they are pretty much ready to go. When the first half of the mold cured I had to flip it over and remove the styrene and clay to prepare for pouring the second half. As you can see, there's a lot of clay there and it's really sticky and difficult to clean off, so this took considerable time. It was important to pack the bucket firmly otherwise it might move and the mould would be spoiled... a potentially expensive mistake! I took a lot of care around the detail parts, especially the teeth. There will be a seam line here but it should be easy to conceal. The pigment in the clay is very strong and transferred onto the part and onto the mold, but I did clean the actual clay out of the mold. And here it is after pouring the second half, with vents and main fill port removed. These holes will be filled with straws to protect the mold from resin, hopefully extending its life somewhat. I brushed the first half with Vaseline to prevent the two halves sticking together (silicone bonds to silicone, and it WILL NOT come apart!). The capability of the silicone is shown here as it actually molded the texture of the brushed Vaseline. LOL. You can also see how clean the detail of the teeth is in the last image. I'm really excited for the first resin cast... fingers crossed!

Some bonkers deals in here. I've had some very good luck in ebay in the past 10 years or so, but it's not nearly as good now as it used to be. Back in 2005/2006 you could get KG of Lego for about £20 (€30) very easily, which is what I did. I'll post a pic once I get all the stuff (it's still in bags in the attic!). My best bargain recently was the following, which I won for £0.99.

Thanks! I didn't manage to pour the mold last night because I was waiting for varnish to dry. Sadly, the varnish was still tacky this morning so I angrily removed it with sandpaper. That's the last time I use that varnish!! Back to business. I started padding out the template with Newplast, and I also filled in the mounting holes just enough so that I could still know where to drill when the cast part is removed. Newplast is great stuff but oh my, is it messy! Registration keys for the mold halves - what else would I use on a project like this?! The box that will contain the two halves of the silicone mold is very simple. It's made from 6mm MDF sheet and I secured it in place with hot glue. Hot glue is ideal in this situation because it's very strong but can also be removed very easily, which I will have to do after the first half of the mold cures. I've also gone round the bucket with Newplast to seal any small gaps, and that was a very laborious process. I'm not looking forward to cleaning that off when the time comes to pour the second half! Adding vents and pour gate. Using straw vents is conveniet because it will help prolong mold life by shielding the silicone from the casting material. I have used ten vents in total, which direct material (and stray air bubbles) away from high points or intersections in the bucket form. Here's the silicone after being mixed with catalyst. I left it to sit for a few minutes so that the air bubbles would rise to the top. I calculated a volume of 1.3L which worked out at just over 1.5kg of silicone for the first half of the mold, so I'm glad I got 5Kg as I'll likely need most of it. And here's the mold box after pouring in the top half. There are a number of pouring techniques which help to minimise trapped air in the silicone, and I used the "high pour" method. I poured the silicone in at one corner and kept it really slow and stringy. It takes quite a long time for the silicone to conform to the shape of the box and its contents, but it's worth it in the long run. It may seem intuitive to pour directly onto the part, but this is a very bad idea as it will just introduce more air into the silicone that will likely ruin the mold. I checked it recently and it's been curing for almost 2 hours now, and it looks really good on top with hardly any air bubbles. I'll be pouring the second half of the silicone tonight and will update this thread either then or in the morning. Fingers crossed that the rest of this project progresses without a hitch. Now I need to buy some resin and get casting!

Two updates - this is moving forward a lot quicker than I anticipated! First: I collected the silicone earlier today so I will (hopefully) be able to start pouring the first half of the mold tonight and finish up the second half of the mold in the morning. It is advised that demolding happens within 24hrs so it'd be good to have that done by tomorrow evening, after which time it is good for the silicone to sit for a while before I start pouring resin through it. And second: I've put significant time into designing the mold and there have been some extremely helpful pointers from a number of professionals (gotta love teh interwebz), so I feel very confident that this will go smoothly. Some further steps towards molding the part: Milliput, used to fill in the small holes/imperfections in the styrene model and also good for sealing/reinforcing seams Starting to create the false mold half which will receive the first pour of silicone. The aperture will be as close in size to the bucket as possible, and remaining gaps will be filled with clay. New blades for accurate cuts. I have 50 of these because I go through them pretty fast, and in my experience they are every bit as sharp as scalpel blades but FAR stronger Done! Test fit before refinement... I need to remove some material so that the teeth sit snug against this border Teeth edge done, and also some bracing added underneath so that the sheet doesn't warp. Now if I cast the part like this, there will be a seam running over that top section of the bucket. I plan to mold this with clay which will hide the seam. So that's it for now. I still have a lot more work to do before I can pour silicone, but that's what holidays are for! Didn't expect to put quite so much work and prep into this, but it'll be worth it for a good quality part.

@ Out of Sight, as far as I know silicone reproduces finish, so I plan to give the styrene a coat of matte spray before making the molds. If the worst comes to the worst, the resin cast parts can easily be sprayed with matte varnish. @ Tommy, Thanks. Most of the bucket is actually made from .06 styrene, which makes it very rigid and strong. I used .04 for some of the details like the teeth and the mounting ears. As for the bucket curve, I just drew it freehand and traced it onto .06 styrene. To cut large curves I always use scissors because as you say the knife isn't good for this. Final smoothing of the curve is done with an emery board or sandpaper; all judgements of accuracy are made by eye and also by running a finger over the curve you can get an idea of how smooth it is. I guess it takes practice to get it just right, and I've been doing it for a few years now! Styrene is very strong and the teeth are pretty big, approx 6mm x 4.5mm, so they won't have any trouble handling moderate stress. I use plastic cement exclusively because it's easier to work with and the bond is extremely strong if the cement is used correctly. CA is good for reinforcing seams but for actual fixing I don't like it, because it sets too fast.