krtwood Posted February 14 Posted February 14 (edited) It was good timing for this moc with the non-vehicle contest, but being Model Team I can't enter it. But that's okay, at least it fits in with what people are working on! If you don't know, a letterpress is a type of printing press. The functions of the real thing are quite interesting. At the scale I was working at, determined by the size of the largest gear with outward facing teeth (the turntable) I wasn't able to do all of the functions and had to do some of the major functions in different ways. Here is one of the drawings I used for reference. Functions: Drive axle, driven in the model by the flywheel (there would be another pulley on the other side or a treadle in the real thing) turns the large cam gear. On the real thing this gear does three things. 1) Gear reduction 2) Crank for the bed 3) Internal cam drives the platen holding the paper. This platen needs to dwell in the open position so the operator can insert and remove the paper. Since I could not create a cam profile inside the gear, I used a cam on the axle and a rubber band for the return. This cam unfortunately gets in the way of where the lock is supposed to go. The bed, holding the printing block, rocks forward and back The roller arm is connected via a link to the frame which causes it to pivot back and forth from the ink disc and then across the print block. This was the tricky part to get the geometry close enough and so that the rollers don't get caught but still look like they are making contact. I'm really happy with my solution for mounting the rollers. On the real thing, the rollers are mounted on long shafts that are spring loaded to maintain contact with the ink disc and print block. Ink disc rotates. On the real thing, this movement is intermittent driven by a pawl that is activated by the motion of the roller arm. I connected it via a chain and some gears meshing at an angle. Missing Functions: Throw off lever: This should be connected through a complex series of linkages to the shaft that the crank arms attach to and the roller pivots on. The end of this shaft is eccentric, so by rotating the shaft it effectively changes the length of the crank arms and causes the machine to either make a print or just come very close. If the operator can't keep up with the speed of the press to both unload and load a paper in one cycle they can use the throw off lever to unload on one cycle and load on the next. I really would have liked to have the lever at least connected to something but the drive for the ink disc is in the way. Lock: The lock is a frame at the front of the machine that is supposed to be driven by another cam on the left side (where I just have a crank) which causes the lock to tilt in and take the force of the print impression instead of it being transferred to the cam gear. I had to move his down lower than it should be and just make it look like part of the frame. My biggest regret with the design is the way the bed is constructed. There is an inner frame and outer frames and these are only joined by a single pin connection on each side through a 3L liftarm. I was hoping to get another pin connection at the top but I couldn't get it to work out so there are just system parts up against each other with no actual connection. You can see little gaps open up there as it flexes which is annoying. But it is solid enough. If you think it's worthy, you can support it over on Lego Ideas. Edited February 16 by krtwood Fixing links Quote
Divitis Posted February 14 Posted February 14 Fron the first image it looked too pretty to be functional - a really cool and unexpected piece of work! Quote
Toastie Posted February 15 Posted February 15 Wonderful, simply wonderful. You know, I never look at what TLG made out of "Ideas". That is simply too much for me. Gauging the audience, turning an "idea" into a profitable set ... nope. I love to look at and enjoy the original "idea", which is much more than that: It is a so well-thought-out, so well-designed >creation<. Yours is simply beautiful. Thank you very much for sharing (here)! All the best Thorsten Quote
krtwood Posted February 15 Author Posted February 15 6 hours ago, aeh5040 said: Wow, fascinating! Yeah, they are really elegant machines. How the rollers do what they do with just one extra linkage is so clever. 5 hours ago, Divitis said: Fron the first image it looked too pretty to be functional - a really cool and unexpected piece of work! A few system parts makes all the difference! It did start out as a bunch of technic bricks and wasn't much to look at. 2 hours ago, Toastie said: Wonderful, simply wonderful. You know, I never look at what TLG made out of "Ideas". That is simply too much for me. Gauging the audience, turning an "idea" into a profitable set ... nope. I love to look at and enjoy the original "idea", which is much more than that: It is a so well-thought-out, so well-designed >creation<. Yours is simply beautiful. Thank you very much for sharing (here)! All the best Thorsten Well it's up to them to decide if it can be a profitable set. Getting people to actually take action to support it is my task. I think it would be really cool to see what the professionals would do differently. It's the first moc I have done that feels to me like it could be an official set. There's a level of elegance and part usage efficiency that I expect from TLG. Quote
anyUser Posted February 15 Posted February 15 10 hours ago, krtwood said: (don't know why the image won't embed) I think it's because your link originates from a http - Server. Today you most likely you need to run a server that does https - "protocol". Quote
Timewhatistime Posted February 15 Posted February 15 (edited) Great, great, great! So many synchronized motions. There is so much going on that it took me some views to realize each motion - now I got each of them (I hope). My favourite is the rotating ink disc. What is the purpose of the grey axle wihh the no. 1 connector on its top, on the left hand side of the desk? It doesn't move, and it doesn't seem to be an additional "manual" function. Edited February 15 by Timewhatistime Quote
krtwood Posted February 15 Author Posted February 15 8 hours ago, Timewhatistime said: Great, great, great! So many synchronized motions. There is so much going on that it took me some views to realize each motion - now I got each of them (I hope). My favourite is the rotating ink disc. What is the purpose of the grey axle wihh the no. 1 connector on its top, on the left hand side of the desk? It doesn't move, and it doesn't seem to be an additional "manual" function. That's the throw off lever that I talked about in the missing functions. Quote
idlemarvel Posted February 16 Posted February 16 Very clever and deceptively simple. It would make quite a nice small Lego set. Quote
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