NathanR

To be honest, the tyres feel very solid and not quite like rubber. They seem dry and dusty, rather than oily. I will give a try with the soapy water and see how I go on.

Sorry if this isn't the right place to ask. I just got an old set with a couple of the large foam tyres (parts 3739, 3740), and the tyres are quite dusty, dirty, and what looks like a couple of cobwebs. Normally, I just wash parts in warm soapy water, scrub a little with a toothbrush, then rinse in cold water. Would that be ok for the foam rubber tyres, or is the soap likely to cause the rubber to start deteriorating?

This is actually a pretty amazing feature of the original pneumatic system. I don't want to be pulling up the pumps manually though - I tried it with one of them and the cylinder's shaft immediately snapped off . This also brings a separate question of what (if any) lubricant can be safely applied to an old-style pneumatic cylinder? Curiously, I have found photos of 8851 boxes suggesting that there were two editions of the set. The box art and photographs consistently show short-stem pumps on the model. However, the moulded plastic insert trays seem to have had a different sized compartment for the pump, according to whether a short-stem or a long-stem pump was included in the box.

Hi all, I just got hold of 8851 Excavator, originally released in 1984 and featuring the original generation of pneumatic elements. Sadly, the set is missing its red pneumatic pump, part 4701c01. I'm trying to find a replacement, but bricklink notes that the pump came in two versions - long stem and short stem - and does not differentiate between the two. There is further complication in that the pump also appears with spring and without. Will any red pump be good enough to work the model? Which is the correct variant for 8851 - short stem or long stem? The box art suggests long stem, but photos online suggest a mix of long stem and short stem, so did the model get issued with both?

Just wanted to say thanks for all the responses! I've been able to successfully clean up all the elements. What I feared was corrosion on the metal rods in the pneumatic cylinders turned out to just be surface dirt. Set now looks like brand new!

I just managed to get hold of one of my grail sets, the 8455 Back-Hoe Loader. It's missing a few pieces, but it's in remarkably good condition given that it looks like it was played with in a sandpit and then forgotten about for years. I'm now trying to figure out how best to clean everything. I've completely dismantled the model. Lego elements that are pure plastic have been washed in warm water with a splash of dish-washing soap, rinsed in cold water, then allowed to air dry. They now look like brand new. However, I'm not sure how best to clean the pneumatic pumps, cylinders, switches, hoses, and the tyres. For the rubber tyres and pneumatic hoses, can I wash them in either water or soapy water without damaging them? If I immerse the rubber pneumatic hoses, how do I fully dry them out again? For the pneumatic cylinders, pumps and switches, how do I clean the outsides without getting any moisture inside them? Also, the metal piston rods of the cylinders are showing traces of dirt and possibly corrosion, so how should I deal with those? Any advice would be much appreciated!

I have two concentric octagons formed from liftarms and the 44224/44225 technic rotation joints. The inner and outer octagon have side lengths of 13 and 18 modules, respectively, from corner to corner. Each side of the outer octagon is 6.0355 modules away from the corresponding side of the inner octagon. If I link them with a 7L liftarm, would the 0.0355 stud offset (about 0.284mm) put too much stress on the pins? The octagons will mounted on their edge, with 6 copies forming a barrel on its side, and this frame will be supporting ~5kg of lego. So I am reluctant of replacing the 7L liftarm with an axle and 32013 to allow a gap to open up.

I recently found my copy of the 8002 Star Wars Destroyer Droid, and some of the black rubber bands have become dry, brittle, and started to crack. Since they are a crucial part of the mechanism, I'd like to get some replacements. However, Lego stopped making the black rubber bands around 2006-7, so any rubber bands I get on bricklink will be at least 15 years old and probably just as fragile as the ones I have now. Are there any non-Lego alternatives that you could recommend? Or at least, detailed specs for the nominal rubber band size for set 8002?

Ok, many thanks for checking. Guess it's back to the drawing board for me.

I have a question on Lego tolerances. When I build a ring using 4L axles and the #3 axle connector (157.5 degrees), Stud.io tells me the resultant 16-sided polygon has a diameter of 500.2 LDU. If I put 1x1 technic bricks with the +-shaped axle holes on four of the sides, can I safely attach them to a single baseplate without stressing the elements? I've done this before with an octagon using 4L axles, #4 axle connector, and the side-to-side diameter was 241.4LDU, which worked (and has appeared in an official lego set) but was a bit tight. Unfortunately I don't have enough #3 connectors to test a hexadecagon.

I am super excited for these space sets! 42179 will be an incredibly novel departure from the usual technic lineup. I imagine 42178 ahs 42181 are designed to work together, based on the common "LT" number. Also, neat reference to the founding years of technic...

Not strictly a technic question, but I thought maybe someone with experience of GBCs might be able to help. I'm trying to build a working hourglass sand timer out of Lego bricks, with pairs of 67950 3x6x6 half cylinders for each chamber and a 2x2 square opening between the top and bottom halves of the hourglass. I would have thought that any 1x1 element would fall freely through this setup, but everything just locks together in the top half of the hourglass and refuses to drain out. I've tried 1x1 round plates, 1x1 round tiles, 32606 flower, 11609 star tile, 30153 jewel, and even technic 1/2 bushes (which worked well the first 2-3 tries, then they all started automatically stacking up into columns). Will these elements mesh together and block up anyway, no matter what size aperture? If the aperture is too small, then what size NxN hole is needed to ensure smooth flow of 1x1 particles? (Also, are there any smaller Lego elements that I could try to use as "sand"?)

Hi all, it's me again, still working on the Atlas model. I'm trying to create a thin, C-shaped bracket - basically an octagon with a few sides removed - but the top of the bracket needs to be rigid as it will carries some weight. Can something like this work? It seems valid in Stud.io, but is it actually "in system"? Do the click hinges have a pivot point that matches the centre of a technic pin hole?

Thanks for all the advice, it's reassuring to know that pins aren't that fragile. I considered that, but then I would need an odd-sized technic brick to fill the gap. And there just aren't enough pin holes available to hold the beams together and slot them into a brick. Oh dear, I grabbed an older render, I was just trying to show the overall structure that frame has to support. I have five octagonal frames, a 4L wide one that uses the 3L pin with bush, and four other frames that sue the 3L pin with stop. My new solution is to add in a few 1x2 bricks with 2 holes, and 1x2 plates with pin hole. This feels a bit wrong, somehow, like there should be a more elegant way to do it, but it uses every available pin hole: You make a good point, the click hinges are the main thing holding the shape, and I will have a total of six hinges distributed along the length of the barrel. However, I have more planned. The reason I use a pair of 7L beams for each side of the octagon, instead of a single 15L beam, is that the diameter of the ring is 41.04 studs. That's close enough to be in system. You may have spotted some radial beams on the render, these are connected to an axle passing through the hole in the click hinges. The axle should bisect the octagon corner, at 67.5 degrees, but if I move them to 67.4 degrees then the radial beam forms the hypotenuse of a 5-12-13 Pythagorean triple. I use half this due to lack of space, so it's really a 2.5-6-6.5 triangle. At 6.5 studs from the pin hole in the click hinges, I can link a pair of the radial beams with a 13L beam. 13L is another magic number, as an octagon with side length 12 modules (or 13 pin holes) will be 28.97 studs across. So by mirroring the base section at the top of the barrel, I will get (Pythagorean triple + octagon + Pythagorean triple) = (6 + 28.97 + 6) = 40.97, almost perfectly matching the outer octagon. The smaller octagon doesn't need to use click hinges, I can use part 79846 which conveniently has a pin hole at the corner, reinforce it with plates and brackets so it cannot be compressed, and that should be strong enough to lock the outer ring in place, and transmit all the weight directly down into the base block.

You're right, of course, but I just don't see how to add additional connections points... It's awkward because I have transition from odd-based studless technic to even-based Lego system. The 7kg comes from what's on top. This is a prototype render, with only three of the octagon frames - the central ones are are C-shaped brackets, the outer two are full O-shaped rings. An inner octagon rings, built using the new 79846 bent plate will provide some extra support, but ultimately all the weight goes down to the technic beams on the bottom of the barrel. More blue blocks (muon chambers) will be suspended from the 3x3 cylinders running the length of the model (the toroid magnet coils). Then there will be an entire separate cylinder unit inserted in the centre, housing the calorimeters and inner detector: