mescalinum

I've done a similar design of spherical wrist, but using the big turntable as I don't own those small turntables (but I should definitely get some they look very useful!) all the motor are attached outside the structure. soon I will post some preliminary video of the whole 6 axis arm NXT controlled

how about using plastic wheels instead of balls? Like shown here or also here:

Hi I need a strong turntable for a robot arm. I've seen strong turntables made with the very expensive droid wheel: I was wondering if it is possible to do it with the lime wheel as well: can anyone confirm?

I never thought he had all of his creations assembled at the same time!

well, have a look at the blueprint and find out

that wishbone alone means nothing to turning radius. the radius depends both on the maximum steering angle and the wheelbase (and marginally could depend on axle track, if you do not build a ackermann steering to calculate the turning point, you intersect the front wheel axis with the rear wheel axis as shown in figure: (the 4 axes intersect only in the case of ackermann steering)

I often found myself needing this part - the right one, which is the converse of the left one: hey someone should track all those unexistent pieces somewhere… like a gallery of broken dreams if I remember, this topic already appeared in the past

great! this is the piece I'd love most. just one side note, given that it's about designing a new part, I would avoid using the 6542 , because it introduces backlash. using ordinary LEGO pieces, I avoid that by using a differential for passing the second coaxial function thru the turntable. that would need to be a whole piece (not meant for disassembling into its component parts). also, extending your design, there could even be a 3-coaxial thing, for passing 4 functions thru turntable

all piled up… doesn't take up much space: nxt box #1 bottom: nxt box #1 top: nxt box #2 bottom: nxt box #2 top: bricks: bricks & misc: panels: pneumatics (still needs a proper box): 25 meters of silicone tubing: liftarms: wheels: gears: connectors & small parts: pins: axles: misc: even more stuff that doesn't fit previous boxes: nxt battery chargers:

nice and original GBC, very good! I hope to see more from you, I like your technique

just a few days ago I assembled most of my sets (8455, 8070, 8466, 8258, 8043, 8263): but this morning I just received the 3 x 9797, a 9398 and a 8110 , so it's gonna take a while to design a new organization system. will post photos when finished

But what's the point of making another crawler [using the very same parts as 9398], when 9398 has just been released? Using different tires (larger, smaller) could suggest TLG to make a new tire, if not resurrecting some old part.

99.999% for parts I often find myself checking inventories on BrickLink to decide buying a set or not. key aspects to me are rare parts, part count, color palette (I'm sick of red pieces , I'd prefer to have only VLBG, LBG, DBG, black and yellow parts) models are nice to study, but live up to few hours, then become just parts for my MOCs

according to the printed pattern on the rechargeable nxt battery: it is a 7.4V battery, which is rather unusual. Using 6 rechargeable batteries you'd get 1.2V * 6 = 7.2V, so you get an extra 0.2V however I do not understand this choice by LEGO engineers, since with alkaline batteries you get 9V, they could have put one or two more cells, resulting in 8.4V or 9.6V which is closer...

Hello, I'm seeing the WeDo USB Hub 9581 (img) and I'm wondering if it can work with the new PF Servo motor (img) By work I mean if it can be proportionally controlled. Also, not knowing well that WeDo part, I wonder what alternative do you have for controlling it other than what LEGO offers you. In Mindstorms NXT for example, if you don't like NXT-G, there are alternative firmwares like RobotC, leJOS, … How does the WeDo thing work?

I can find 8547 new boxed for around 230~240 EUR incl. fees (and including the seller's profit!) for 330 EUR I can get new Education NXT base (9797) which has WAY more parts than NXT 2.0 but it depends also on the country. consider visiting Ebay to get an idea. speaking about used, the 8547 I own, I bought it second hand (MISB) for 180 EUR incl fees

yes, the sequencing was OK, and when lifted from the ground, it behave fine the problem was a weakness in the structure, that can be seen in the following photo. each leg is attached to only one liftarm, causing it to bend btw, I tried another implementation of the walker, this time pneumatic only, and it is again a failure. once again it works in no-gravity, but in the real usage test, the pneumatic cylinders can't withstand the weight of the structure (and it's even lighter than before!) and the tubings continuously pop. check the video for details:

it's pretty basic. it's the following mechanism serially repeated (3 times in my case). synchronizing the opening and closing time of all the valves might require some patience :)

here it is: unfortunately, crushed by hypergravity, it can't even stand on its own legs (it was designed on anotherplanet hehe) seriously, after putting the sequencer, the motor, the battery pack, the structure that holds the joints it's just too thin, and now it doesn't walk properly (needs improvement)

I think I have solved it! (I'm afraid the video is a bit dark) tomorrow I'll put all the pieces together

yes, I happen to have one 8547 (and planning to buy another one or two!) but the point is that this little thing would be much cooler if with the same single PF motor pumps air and does the sequence, don't you think? ;)

hmm that's an interesting idea. in that case the extra cylinder would rise at the end of each state, so it should trigger a state transition. we'll see… :)

hi all (long time no speak!) I'm building a pneumatic walker, and I need now to make it move in some automatic way, but I cannot commute the pneumatic switches by the pneumatic actuator themselves, cause the construction is too crowded. what could be an alternative to sequence the pneumatic switches states? I have 3 switches to sequence, A, B, and C, and I figured out I need this sequence of states, for each time step t: t | A B C --------- 1 | 1 0 1 2 | 1 0 0 3 | 1 1 0 4 | 0 1 0 5 | 0 0 0 6 | 0 0 1 (where I indicated with 0 switch to the left, and with 1 switch to the right; switch is never in middle position) now the easy thing is that all 3 switches have the same period although with different phase offsets (so they can be actuated by some rotating gear + lever). the complication is that switches B and C have a duty cycle of 33%, i.e. they stay in one state 1/3 of the cycle, then stay in the other state 2/3 of the cycle. can you figure out a linkage that would achieve the above sequence? Actually, I think the sequence can be simplified a bit, by doing 2 state at once, becoming: t | A B C --------- 1 | 1 0 1 2 | 1 0 0 3 | 0 1 0 4 | 0 0 0 I was thinking to some linkage seen in akiyuki creations (like in ), but apart from taking quite some space, I fear it would not be strong enough to actuate pneumatic switches…ideas?

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=477330 EDIT: oops, I just realized the topic is about return-to-center valves, so this is slightly OT

there was a trick in order to install NXT software on Windows 7 Started (I installed it on my netbook) it involved changing the setup.ini file. if you google around probably you find it I googled that for you: from http://messageboards.lego.com/en-US/showpost.aspx?PostID=3204252