NevynPA Posted January 17, 2014 Posted January 17, 2014 Is that a braiding loom, or a Stargate? Quote
Junpei Posted January 17, 2014 Posted January 17, 2014 Wow, Blakbird, your digital building skills are unrivaled! I can't possibly imagine how you have built even this much.. I wonder if it qualifies as a SHIP... Quote
nico71 Posted January 17, 2014 Author Posted January 17, 2014 Wow, that is awesome blakbird ! I am happy that the building instructions of my blog is enough for rebuilt it ! As you can see, the main drum is a bit of geometry, your reconstruction is pretty cool ! If at the end, you have a bill of material, it could be usefull for me ! (and more valuable for future lovers). My work tooks me lot of time, therefore, I do not have the time to make all the computing needed arround my moc. The time I spend is only for building now :) Quote
Blakbird Posted January 17, 2014 Posted January 17, 2014 Is that a braiding loom, or a Stargate? Can't it be both? As you can see, the main drum is a bit of geometry, your reconstruction is pretty cool ! The drum was a lot of fun. By the way, I confirm that it all fits perfectly with no stressing of parts. However, there are some areas elsewhere in the model that stress the parts a little. The yellow diagonal braces on the side of the frame are an example. 9-11-14 is not a right triangle! (but it is close) I couldn't resist posting this picture of the drum and planetary sets. It's fascinating! If at the end, you have a bill of material, it could be usefull for me ! (and more valuable for future lovers). Yes, I will have a BOM soon. I will post the link here when it is available. I'll make the CAD file available as well. I am almost done. Quote
Kumbbl Posted January 18, 2014 Posted January 18, 2014 (edited) it's so cool, man Edited January 18, 2014 by Kumbbl Quote
Blakbird Posted January 19, 2014 Posted January 19, 2014 The Bill of Materials is done. 1929 parts total, with an average Bricklink value of about $225. Note that I did not include any motorization in the file, but you can easily add any of the PF motors to the back where the input crank is. Download the Brickstore BOM here. Quote
nico71 Posted January 19, 2014 Author Posted January 19, 2014 (edited) Many thank to you blackbird !! I have downloaded the BOM in brickstore extension but it is not very usefull for me. Could you give me a normal BOM with just the reference, color and qty in the notepad, like that I can manage it with excel. Or if you can give me a printscreen of the inventory in brickstore, it is the same for me. I only want a picturing BOM :) At the moment, 2 company who manufacture rope machine of weaving machine have contacted me for having a replica in their musuem. As Dornier gmbh at lindau has already made 1 year ago for the loom (also offer a position for me but was already engaged). EDIT : I have made the picturing BOM, all is good :) Edited January 19, 2014 by nico71 Quote
Blakbird Posted January 20, 2014 Posted January 20, 2014 Glad you like it! I am working on synthesizing the string in my model so I can render the whole thing. Should be done by tomorrow. I also wanted to ask you about the thread spools. How do you wind the thread onto the spools in the first place? It seems like this could be quite time consuming. It would be nice to have a small motorized device to wind the thread off of the spool on which it is purchased onto the machine spool. It would also be nice if you could just use purchased spools right on the device. Maybe I'll explore that. What thickness of thread did you use? Looks fairly thick. Quote
Blakbird Posted January 23, 2014 Posted January 23, 2014 I've completed synthesizing all the string. My completed CAD file is available here for anyone who wants to use it so supplement Nico's photographic building instructions. It is not fully stepped, but it has many submodels and steps included which should be pretty helpful. Quote
Blakbird Posted January 27, 2014 Posted January 27, 2014 I've finished building this model and was going to write some observations about how it works, but it looks like this is three posts in a row from me without any responses so maybe there is not any interest. Does anyone want some more information on how this thing works? It's awesome! Quote
legomuppet9 Posted January 27, 2014 Posted January 27, 2014 I'm always interested in how mechanisms work, and this model is a feat of engineering. And is stunningly beautiful Quote
majorna Posted January 27, 2014 Posted January 27, 2014 Yeah, please! More information about this great project! Quote
NevynPA Posted January 27, 2014 Posted January 27, 2014 I'm totally interested! Trying to amass the pieces I need, though...that's tough. 300+ chain links! I have no budgeted money for parts purchases... Quote
Gee Posted January 28, 2014 Posted January 28, 2014 Yeah, me too. For some reason this thread has escaped my notice recently. I love these non-vehicular Technic contraptions. Quote
DrJB Posted January 28, 2014 Posted January 28, 2014 (edited) ... so maybe there is not any interest ... The reason no one has responded is .... Because they're busy building such contraption, following the instructions you provided ... Edited January 28, 2014 by DrJB Quote
skriblez Posted January 28, 2014 Posted January 28, 2014 I've finished building this model and was going to write some observations about how it works, but it looks like this is three posts in a row from me without any responses so maybe there is not any interest. Does anyone want some more information on how this thing works? It's awesome! Yes we do! Quote
Blakbird Posted January 28, 2014 Posted January 28, 2014 OK, I guess there is interest after all! Bigger versions of all the pictures on my Bricksafe. This thing was a lot of fun to build. After each step I exercised the mechanism for a few moments to see what changes had been made since the last step. The real marvel of this is that it all works from a single motor or crank! Some observations on functions: The main drum rotates. This rotation is driven in two places. On the rear end, the drum is supported by a turntable. The turntable ring gear is driven with a 11.66:1 ratio with respect to the input crank. On the front end, the drum is supported by a pair of wedge belt tires which rotate while in contact with the outside of the drum. The tires have a ratio of 1.66:1. So why is the ratio 7x different between the front and the back? Because the back rotates the center of the drum directly, while the front rotates against the outer diameter. To get the final ratio at the front we have to consider the drum itself as a pulley and divide out the diameters. The OD of a wedge belt tire is about 76 LDU. The OD of the drum which is constructed of 48 treads rolled backward is about 450 LDU. This means the final drive ratio at the front end is about 9.83:1. You can see that it is not identical to the ratio at the back end which means there will be some minor slippage on the tires. Within the main drum are three thread carriers. Each thread carrier rotates in a direction opposite that of the main drum. This rotation is driven by the rotation of the main drum itself via an epicyclic gear system through a chain. In the image below each green gear is connected a thread carrier. The central black axle rotates clockwise with the drum. The yellow differential is a sun which is driven counterclockwise at a different rate and is connected to the green planet gears by the red chain. The differences in these rates determines the rotation rate of the thread carriers. The drum itself is the planet carrier. Within each thread carrier are three spools. Each spool rotates in the same direction as the thread carrier, opposite the direction of the main drum. This rotation is driven by the rotation of the thread carrier via an epicyclic gear system through a chain, which in turn is driven by another such system as described above. In this system each yellow differential acts as a stationary sun gear. It is locked to the drum via the 16 tooth end. The 24 tooth end drives the read chain. Because each thread spool is rotating, it acts as a planet carrier. The green gears within the planet carrier are driven by the difference between the rotation of the carrier and the stationary sun. (Don't forget to take a moment to appreciate the perfect geometry of the drum core.) Each spool within a carrier contains a different color of thread. Each carrier is the same as the others. So there are a total of three thread colors, each repeated three times. On each thread carrier, the thread is passed through a wedge belt wheel acting as a die. The fact that the spools are rotating faster than the die tends to pre-twist the threads. As the die rotates, it then twists the three threads together. I was surprised to note that the orientation of the chain links is important. When I first build the model there was a lot of binding in this planetary chain. I found that reversing the links so they moved tail end first instead of clip end first solved the problem. Each bundle of three threads then passes through a motorcycle wheel used as a die. This rotates with the main drum and twists the three bundles of three into a bundle of nine. Note that the winding direction of the bundles of three is opposite that of the winding direction of the main bundle. There are some pulleys between the carrier dies and the main die to direct the bundles where they need to go. With all this thread twisting you might think we are done, but there is lots more. How does the thread get drawn out of the spools and further down the machine? This is done with a tractor/tensioning device. A set of 4 driven tires draws the thread through a pair of rollers and a Technic pin hole. A pair of shock absorbers preload the rollers against eachother to provide enough friction to draw the thread. The speed of the tractor wheels compared with the speed of drum rotation determines the pitch of the wind. It is important that the thread spools have enough friction that they do not spin too easily or they can over spin and tangle the thread. The red driving ring at the bottom of the image is used to disengage the tractor device from the drum. The orange crank can then be used to rotate the tires and draw the thread forward during setup of the machine. The shock absorbers can also be compressed during setup to allow the thread to be inserted between the tires. After the completed bundle is drawn through the rollers, it needs to be spooled onto an output drum. This is one of the most marvelous mechanisms of the whole system. The red drum is the final spool for the braided bundle. It rotates to draw the bundle from the tractor. The blue device acts as a guide which rotates on a turntable. As the bundle is drawn onto the drum, the guide gradually translates across the width of the drum using a worm gear. It is important for the relative speeds to be right. The drum needs to rotate at the right speed to draw the thread from the tractor. The guide needs to translate at the right speed to allow about one width of thread bundle per drum revolution to be spooled. Perhaps most importantly, the guide needs to change direction when it reaches the edge of the drum. The 40 tooth gear on the lower part of the image is geared to the drum. The blue connector pushes against a bush which drives a spring loaded crank. When the crank passes over center, it translates the drive axle at the top of the image, also pivoting the red lever. This alters which tan bevel gear drives the 20 tooth double bevel, thus reversing the guide direction. It is important that these be synchronized so that the reversal happens at the right time. You can also see the translating spline joint with allows the drive axle to translate 1 stud. Finally, the dark gray pin connector acts as a clutch so you can manually crank the drum if you wish. This is important because the speed of the drum is initially not quite right. Because the effective diameter of the drum changes as it fills with thread, the speed at which it rotates technically needs to change in order to keep pace with the tractor. During the first layer of drum winding, it turns too slow and you have to turn the crank occasionally to avoid slack in the system. Once you get to the second layer, everything is nicely synchronized. Once you are done making your braid, I've noticed that there is no good way to remove it from the machine. I remove the white clutch gear in the previous image which allows me to rotate the drum freely and simply pull of the braid. The braid is very sturdy and does not tend to unravel. There is a fair amount of wasted thread due to setup, and a bit more waste at the end if the threads are not all exactly the same length. I am using 10 yard lengths in my machine, and the machine can make the entire braid in only a few minutes. One thing I hadn't thought about prior to building was how I was going to get the thread onto the spools to begin with. This turns out to be quite tedious. I ended up using the XL motor as a spool winder. I would remove each spool from the machine, plug it into the motor, and then guide the string with my fingers as it wound onto the spool. This thing is incredibly fun and in my opinion is a pure expression of what Technic is all about. It does not need to be all vehicles or things with wheels. This type of machinery is fascinating and teaches the builder as much or more about mechanics than a vehicle. It is likewise just as playable. However, setting it up and troubleshooting it would not be suitable for younger builders, or even older builders without a strong mechanical aptitude. Thank you Nico71 for this wonderful contraption! Feel free to download the CAD file which will allow you to take a closer look at all these mechanisms and understand them much better than with just a static picture. Better yet, build it! You don't even need a motor to see it operate. However, a motor is much nicer. I highly recommend the 9V train regulator. This allows you to adjust the speed and power the system from a transformer instead of batteries. Batteries will not last long. You'll need a 9V to PF adapter/extension to hook it up to the old regulator. Alternatively, you can get speed control from the PF rechargeable battery. Quote
DrJB Posted January 28, 2014 Posted January 28, 2014 Nicely done Blakbird ... you've done it, and now I want to build it. Placing an order for chain links as I'm not sure I have enough ... Quote
Blakbird Posted January 28, 2014 Posted January 28, 2014 Nicely done Blakbird ... you've done it, and now I want to build it. Placing an order for chain links as I'm not sure I have enough ... If you are in the USA, Lego Education is the way to go. I ordered 200 chain links, 120 treads, 50 24-tooth gears, and 50 wedge belt wheels from them for way under BL prices. Here are a couple of views of the mechanical internals to make it easier to see what's going on. Quote
ArcspacE Posted January 29, 2014 Posted January 29, 2014 That's quite remarkable indeed Blakbird - out of interest, what software do you use for the renderings? Quote
Gee Posted January 29, 2014 Posted January 29, 2014 Man, I' beginning to get a sense of what a feat of engineering this is. Mind-blowing! Super write up Blakbird, makes it all (fairly) easy to understand. Quote
skriblez Posted January 29, 2014 Posted January 29, 2014 Brilliant write up Blackbird. Really helps me understand the concept and complexity of the moc :) Might have to build this one day. Thank you Nico71 for the creation of this moc Quote
Balrog Posted January 29, 2014 Posted January 29, 2014 Thanks Blackbird for this thorough insight. Thanks Nico for such a great machine! Quote
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