2LegoOrNot2Lego... Posted October 10, 2015 Posted October 10, 2015 Nice build, thanks for sharing so much info!!! Quote
doug72 Posted October 13, 2015 Author Posted October 13, 2015 (edited) Update: Mechanics of my crane build now finally sorted with all functions running smoothly. Slewing gear driving the turntable is back to the offset position with the two UJ’s located near base of the tower. Winding house and operators cabin now all in yellow with stickers applied. Not sure wether to clad the counterweight in yellow - I have the right colour sticky back plastic film to do this. One thing I find awkward is mating studded technic with studless technic due to the different spacings. I have endeavoured to hide the holes in the technic beams where possible using flat plates and tiles. Next step - make a new video. Two photos show the results IMG_2621 by Doug Ridgway, on Flickr IMG_2621 by Doug Ridgway, on Flickr IMG_2622 by Doug Ridgway, on Flickr Edited October 26, 2015 by Doug72 Quote
Cumulonimbus Posted October 13, 2015 Posted October 13, 2015 I like your crane, the stickers look as if they were meant for this model. The "angle-o-meter" on the boom is a nice touch.The only thing which lets the model down a bit (for me) is the brick built cabine and its position. For a Technic creations I like to see a Technic cabine as well. I feel that the cabine should be lower and further forward as well, for example: Good luck with your entry Quote
doug72 Posted October 13, 2015 Author Posted October 13, 2015 For a Technic creations I like to see a Technic cabine as well. I feel that the cabine should be lower and further forward as well, for example: Thanks for your comment and suggestion - I will see if I can support to cabin further forward and lower. Re Technic Cabin: at the scale I'm using (Minifig) use of Studdless Technic parts I feel would be too chunky. Aso I like the angle glazed front similar to a real cabin. Have a Lego Train part with a curved front that may suit. Doug72 Quote
doug72 Posted October 13, 2015 Author Posted October 13, 2015 (edited) Operators cab now rebuilt and located on the correct side of the Terex Crane !! Floodlights (non working) also added. Curved front idea didn't work as could not get a proper connection. IMG_2626 by Doug Ridgway, on Flickr Edited October 13, 2015 by Doug72 Quote
doug72 Posted October 17, 2015 Author Posted October 17, 2015 (edited) Jib luffing system improved and side panels altered to suit new arrangment. The model is now complete. IMG_2653 by Doug Ridgway, on Flickr Edited October 17, 2015 by Doug72 Quote
doug72 Posted October 23, 2015 Author Posted October 23, 2015 (edited) The real tower crane my MOC is based on has a jib with a triangular cross section. At present my MOC has a square cross section jib. I have now made a new jib to try and replicate a triangular cross section jib but cannot make my mind up which is the best jib to use. I have also managed to eliminate the two gray "I" frames from the jib structure. Your opinions appreciated. Square Cross section jib: IMG_2667 by Doug Ridgway, on Flickr Triangular cross section jib IMG_2666 by Doug Ridgway, on Flickr Edited October 23, 2015 by Doug72 Quote
MaxSupercars Posted October 23, 2015 Posted October 23, 2015 (edited) Yes... I like the triangular version very much to... maybe I use it sometimes... ;) Max... Edited October 23, 2015 by MaxSupercars Quote
allanp Posted October 23, 2015 Posted October 23, 2015 Triangular is better and also more your own design. Quote
doug72 Posted October 23, 2015 Author Posted October 23, 2015 Triangular it is - thanks for the comments. My MOC of a horizontal jib tower crane uses a version of this design of jib with track for the hoist trolley. Quote
doug72 Posted October 23, 2015 Author Posted October 23, 2015 (edited) imho, square seems more solid :) More solid but prone to racking or twisting along its length. A triangular shape resists this. The whole jib is a series of triangles. Also the jib is lighter as there is one less corner beam to make and allows for lifting a slightly heavier load on the hook. The key is getting the top rib of the jib that forms the apex of the triangular cross section in tension with good connections between the main 15L beams. Simple 2L connections are not enough - 4L thin plates are used with 2L red axles at each end through the X holes with two half pins with stud used in the plain holes (One pushed in form each side to connect with the 15L beams) making it a 4 pin connection. The protruding stud allows for 4L x 1L flat plate with "Technic" to cover the connection. (not shown in photo) The angle braces between lower & upper beams again form triangles making it strong, light and straight. Could be lighter if 9L thin liftarms were available. Old square jib now consigned to my parts boxes forother projects. Edited October 23, 2015 by Doug72 Quote
doug72 Posted October 26, 2015 Author Posted October 26, 2015 Final tweaking of my tower crane MOC before posting on Entry Topic once the video re-shot. Slewing problem resolved whereby the 12T double bevel gear driving the turntable was catching on the corners of the winding house base 5 x 7 frame as it rotated, causing jerky rotation. No Lego parts were harmed during this modification. Its all in the balance of the rotating structure. The slewing drive to the turntable has reverted to a straight drive using a short UJ section to give 1-1/2 L spacing to get 12T gear correctly meshed with turntable gear ring without off-set. IMG_2676 by Doug Ridgway, on Flickr Quote
A Gallifreyan Cat Posted October 26, 2015 Posted October 26, 2015 Looks really good! I'm having a lot of fun looking at people's great entries. Quote
Milan Posted October 27, 2015 Posted October 27, 2015 Looking very good. I enjoyed observing its developmentg process. Well done! Quote
doug72 Posted October 27, 2015 Author Posted October 27, 2015 Looking very good. I enjoyed observing its developmentg process. Well done! Thanks for your comments. The main problem has been getting the turntable revolving smoothly as there is a lot balanced on top of it and no room to use a wider base. Tried both the new Z60 & old Z56 turntables each of which have their own quirks and raising the revolving structure above the slewing gear ring but finally after a lot of experimenting kept to the Z60 TT. Quote
lcvisser Posted October 28, 2015 Posted October 28, 2015 This entry is really great! I just noticed in the entry topic that it is operated by the technic control center; must be a lot of fun to play with! Quote
doug72 Posted October 28, 2015 Author Posted October 28, 2015 (edited) It was a Christmas gift to my eldest grandson many years ago - who no longer uses it - so it was returned for me to use. Needs adaptor leads to control PF motors and works OK. re Entry video" I need to upload this again to Flika as the last appears not to upload OK video's longer than 2m 30s. Edited October 28, 2015 by Doug72 Quote
doug72 Posted October 28, 2015 Author Posted October 28, 2015 (edited) Re Slewing being jerky: Now concluded that this is being caused by the long drive shaft up the side of the tower - 64L to universla joints. The axles are acting as a torsion spring (twisting) and building up force then releasing it, resulting in jerky rotaion. Have tested this therory by making a temporary worm reduction unit at top of tower just below the slewing drive gear and then using a M motor coupled directly to it the slewing motion is now steady and smooth. Now have to re-design the drive so that all the gear reduction is done near the top of the tower. Probably will be a 2 stage worm drive giving 64:1 ratio. Edited October 28, 2015 by Doug72 Quote
Samer Posted October 29, 2015 Posted October 29, 2015 Liked. This seemed to me like a LEGO set, simple and functional. Quote
doug72 Posted October 30, 2015 Author Posted October 30, 2015 (edited) Slewing problem is due to intermittent contact between the 12T double bevel gear and the bottom edge of the corners on the 5 x 7 frame on which the top structure is built on. The 12T double bevel gear is 1L thick same as the turntable gear ring, see close up image. New drive unit for slewing the crane now designed, installed and rotation is now much smoother. Upper unit has a 8:1 worm gear reduction with a 1:1 right angle drive up to the 12T slewing gear. Installing this onto the side of the tower was a challange. Lower unit has a 8:1 worm gear reduction then a step up stage 20:12 gears. Overall gear ratio - 8 x 8 x 5 x 20/12 = 192:1 Side view showing new transmission for slewing:- IMG_2701 by Doug Ridgway, on Flickr Close up view showing contact point between 12T double bevel gear and corner of the 5 x 7 frame:- IMG_2698 by Doug Ridgway, on Flickr Upper reduction worm gear unit and right angle drive:- (8:1) IMG_2699 by Doug Ridgway, on Flickr Lower worm gear reduction and step up gears: (4.8:1) IMG_2700 by Doug Ridgway, on Flickr Hopefully I will have time to remake to the entry contest video. Edited October 30, 2015 by Doug72 Quote
Zerobricks Posted October 30, 2015 Posted October 30, 2015 What bout using a bewel 12 tooth gear? Maybe that will fix your slewing problems? Quote
doug72 Posted October 30, 2015 Author Posted October 30, 2015 (edited) What bout using a bewel 12 tooth gear? Maybe that will fix your slewing problems? Tried that but a thin 12T bevel gear only engages with the bevel part of the Z60 turntable gear ring and has very poor meshing. What is needed is a 12T parallel gear with same profile as the latest 8T gear. With a thinned down gear works fine. Note: only for testing - contest entry uses a standard 12T double bevel gear - just have to ensure that the rotating part is balanced so the bottom of the 5 x 7 frame is level and not tilted one way or the other. Edited October 30, 2015 by Doug72 Quote
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