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doug72

Eurobricks Dukes
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Everything posted by doug72

  1. doug72
    Thanks for the comment, I hope to make it a bit more compact and try to get rid of the little bit of slack. Can you provide the links to the two you mention. Can,t seem to locate them. Now found.
  2. doug72
    Thanks' I came across that video when looking for ideas on Google. Also found a three leg Geneva mech. but I am after 180 deg. indexing. Only way at present is to use 1:2 step up gears so a 90 deg. step gives 180 deg out. There is a little bit of slack causing a slight jolt as the locking comes into operation. Looking for away damping it.. The gearshift solution might possible work with a reciprocating arm to move the gear lever back & forth but not sure how much it power it would have to could rotate if used on the Ballkirk lift. Found and downloaded the LXX file - so will give it a try. Doug.
  3. doug72
    For some time I have been trying to develop a mechanism to allow intermittent rotation for various GBC modules I have built or plan to build. A Geneva mechanism would be ideal but its not easy to build using Lego, and some solutions are quite large. I have developed a fairly small version which uses a rotating arm to intermittently turn the black gear with 4 rollers. Indexing is acheived by using a 24T gear with four blue pin/axles. As the wheel rotates and drive arm disengages the 24T gear & wheel is held stationary by an arm kept in contact with two of the blue pins by a shock absorber with a soft spring. I tried using knob gears but due to them being slighty smaller diameter the indexing is no longer exactly 0, 90, 180, 270, degs. The two black 36T gears are only used to hold the rollers and drive arm as along with the 24T gear as they are the only lego parts which 4 equally space holes in line with the axle hole. At the moment the output axle stops every 90 degs but could be made to stop at 180 degs if use a 12T gear meshed the the 24T indexing gear to give a1:2 step up. (An alternative would be to use a 20T meshing with a 40T gear holding the drive rollers.) Hope that makes sense. Timings should be adjustable via varying the drive input / output gear ratios and choice of PF motors. Video will make it clearer how it works. Next step to try and make it more compact and see if I can use it for my build of DaFokka's Ballkirk Wheel GBC Lift.
  4. doug72
    Progress and success: Both rotating arms now built and linked together. Friction device for the differential is now working well but found that if too tight then the wheel jerks when retarding arm releases. The optimum tension seeems to be to allow friction wheel to rotate at the same rotation speed of the Wheel lift meaning the internal geasrs in the differential do not move and diff. rotates a one unit. Friction device consist of a large 32mm pulley with 2mm elastic cord in the groove around it for 180 degs. - cord tension tension is adjustable. Housing for this friction wheel has to be robust. Although it is possible to have a single motor system I have opted to use a two motor system as this allows the trip drum timing to be adjusted as found it absorbes too much powewr from the Wheel lift drive motor Next step is to build the ball gondolas, once parts on order from Lego arrive. New video:
  5. doug72
    Re Z60 Turntables: Received and installed six new turntables and as the build progresses it has become harder and harder for the "L" motor to rotate the lift wheel. At first I thought this was due to the eight 20T double bevel gears linking the t/t's keeping them in sync, rubbing on the support structure as wheel rotates. While trying to eliminate these by using new gear sync. arrangement I found that the 5 x 7L frames can catch on the bevel side of the Z60 gear ring which is slightly proud and the cause of the grating sounds as wheel rotates. This is causing rotation to slow down and also effect timing of the retarding arm release. Have split a turntable apart and lightly sanded the bevel side of gear ring on fine sandpaper placed on flat surface. Turntable now rotates without any grating. Five more to fix.
  6. doug72
    Here's the video, in the end the trip drive drive mechanism used is identical to the previous. The "L" motor drives the worm gear which drives the differential and also meshes with a 24T gear which then drives the trip drum via a right angle drive. The friction system seems to be working well and can be increased if required. Slight binding as wheel arm rotates and a bit more tweaking required, very slight jolt as retarding arem release the wheel. Rotation speed about right and can be control via the PF remote. PS. the noise near the end of the video is my chair squeaking !!!!
  7. doug72
    Re Video - once I get the trip drum functioning. Re One motor, could use output from "L" motor via reduction gearing to the trip drum - might need to change to an XL" motor for more power. Will see what I can come up with. There is plenty of room in the structure to accomodate something and locate the trip drum at a lower level .
  8. doug72
    New differential looks promising - rotation of wheel arm was slightly jerky at first due twisting of the differential frame between the two Z56 turntables. Strengthen it by using two "H" beams and rotation now much smoother. Differential is driven by an "L" motor via worm drive giving 56:1 ratio giving approx. 5 secs per 180 deg. rotation. Friction can be adjusted by using 2, 3, 4 or 5 16T gears. (image shows 3 in use with friction pins.) Next step is to sort out the retarding mechanism. Will probably use a seperate "M" motor to drive the trip drum which allows for easy timing adjustment to release lift wheel arm. To get required trip drum speed with a single motor would required multi stage gear box.
  9. doug72
    Thanks for the comment - I was almost on the point of giving up !! You are right about hign torque - can only just hold the axle friction with my fingers as lift wheel rotates ! The differential is the one shown in "Sariels" guide book on page 93 - 2nd edition, will need to reduce output RPM more. I will use the Z60 turntable as can use stronger double bevel gears to rotate it. Z56 turntable with worm gear drive gives a good rotation speed without need for other gear reduction. Uusing an "L" motor = 10 secs. per revolution - XL motor gives 20 secs per revolution. The wheel lift support tower / gearbox will need to be re-designed to accommodate it. Precise stopping the wheel lift is OK, its the jerk that happens when friction is too much. Toying with an idea using driving rings & clutches to change drive between the lift wheel and trip drum, getting the timing right might be a problem.
  10. doug72
    This build is proving to be very challanging to get a mechanical retarding system to function reliably, smoothly and still drive the wheel lift. So far have built both sides of the lift wheel but not yet the gondolas. As build progesses more and more friction is required to ensure the differential transfers power to rotate the wheel lift untill the retarding arm stops rotation. When lift wheel rotation stops the motor and differential gearbox are strained ending up with worm gear forcing the gearbox apart. I am surprised that the 12T single bevel gears in the diff. have not failed with the strain ! I have re-built the gearbox with the worm gear inside a 5 x 7L frame to prevent this. Having another try using a braking system used on incline railway haulage, using a large brake wheel with rope passing around 270 degs with a weighted lever to apply force. Elastic cord is used and has good grip and self adjusting. See image. IMG_4446 by Doug Ridgway, on Flickr Next step is to build a differential using knob gears but will take up a lot of space. If that fails then I will have run out of ideas.
  11. doug72
    Having now installed both sides of the wheel lift, and I tried again with my original version using white 24T clutch gears and initially works OK but then starts to puase rotation before contact with retarding arm. This happens in a relatively short period of constant running. Tried 1, 2 3 24T clutch gears in parallel using the newer gears to see if it would help but results are still the same. So but to the drawing board using a 16/24T differential plus another friction system and find a way to stop the jerk as retarding arm releases the wheel lift !! Doug
  12. doug72
    Problem solving: two steps forward - one step back !! New Z60 turntables recieved and build continues. Raised lift wheel axis by 3L to give enough clearance for the lift gates as the wheel rotates. At same time re-built the gearbox tower and improved the connection to the centre turntable. A new problem has now emerged. When the lift wheel is stopped by the retarding arm the 24/16T differential transfers the drive to the 16T gears with friction pins. When retarding arm releases the lift wheel there is an initial jolt which then settles down to a smooth rotation again. This happens every cycle and It is even worse if use 8/24/8T gearing for the friction and caused the gearbox to spring apart. Determine this is due to Torsion in the Lift Wheel axle between differential and the point where motion is transferred to the rotating lift arm. i.e the axle twists slightly and then un-twists as retarding arm release the lift wheel causing the jolt as it starts to rotate again. Solution: 1/. Make the axle stiffer between diff. and lift wheel drive. 2/. Shorten length of axle that is subject to torsion by positioning the differrential closer to the axle drive for lift wheel. Should be able to place the diff. partly within the turntable to shorten section of axle subject to torsion. =================================================================================== Jim / Milan: Should I continue to update progess on this build here or start a new thread ? Doug72 Update: Well that theory failed ! Have now tried the alterations as above but the jolt is still present - anyone got ideas how to prevent this ?
  13. doug72

    Older Than Dirt!

    doug72 replied to Andy D's topic in Community

    How do I get my badge ? Doug72
  14. doug72
    Still waiting for new Z60 turntables, so I have robbed two from my Fowler Gyrotiller MOC, so as to be able to complete the side of the lift wheel that has the retarding arm. Retarding device works well BUT now have an issue in that it will foul the ball unloading gates as the lift rotates !!!!! Possible solutions: 1/. re-locate the retarding arm to a new position so it doesn't foul anything as lift rotates. 2/. raise the lift rotation axis higher to allow unloading ball gates to pass clear of the retarding arm but still stop the lift every 180 degs. 3/. re-locate ball gates onto the gondola's. Loading ball gate will still be OK as its will be on the other arm. 4/. turn gondola's 90 degs. and re-arrange ball loading & unloading (least preferred). Options 1 & 2 seem the best solutions. Another boat lift that would work well as a GBC is the Anderton Boat Lift, which I visited it last year and took a trip on it. It to uses guillotine gates at each end of the cassions. Its hydraulic, so maybe a pnuematic version or gear racks to raise and lower the the side by side cassions.
  15. doug72
    Spotted this on facebook. Can't see much use for Technic builds.
  16. doug72
    At the moment the amount of friction is OK. Re 42T gear, I think you mean an 8T / 24T / 8T combination. I am satisfied with the latest arrangement and will be using an L motor. More support framing now installed for the gearbox unit. Z60 Turntables are in the post and due to arrive soon, so I can start to build the rotating arms & gondolas etc. I think it is possible to incline the ball run on each gondola so won't have to tilt the whole unit to give an incline. Using a slope of 1/3L over 16L still allows balls to pass through t/t centre when using 1 x 2 tile slopes, only have a few to test this so another parts order required. I may try using flat tiles for the gondola ball runs. I am working from your excellent notes, video and photos in your first posting. So far not have not got to grip with the Stud.io app. Is there a away to get it show a building guide as per LDD or even better pdf. instructions ? Doug.
  17. doug72
    Now tested and works well using a single XL motor. Trip drum now has two pins and gives a dwell time of approx. 2.5 secs. When the build progresses I may have to alter the trip levers system once the larger turntables are installed. Owen, thanks for the tip about using differentials instead of white 24T clutch gear, two 16T gears on friction pins is OK but possible to add more if required. Photos of latest gearbox:
  18. doug72
    The two motor solution allows for trip timings to be easilly changed You must have read my mind as I have been working on a one XL motor solution tonight and to get enough friction I have use three 16T gears. When the lift arm stops, the diff. drives the centre gear which drives the other two which have friction pins. New gearbox will be more compact and will be testing tomorrow to get the right gear ratios for the trip drum. Once I get the turntables I have on order I will be able to commence building the remaining parts. Doug
  19. doug72
    Partial success BUT as soon as trip drum releases the lift arm, the trip drum drive stops and doesn't allow the trip arm to re-set to catch the lift arm next time. Tried various combinations of gears and friction pins without success. Solution: Use two motors !! The XL motor drives a 24/16T differential, one output driving the lift arm - the other drives a 24T gear meshing with an 8t gear mounted on a friction pin. As lift arm rotates and hits the stop the drive to the lift arm stops and transfers to the other output with friction gear allowing the XL motor to continue running OK but with lift arm remaining stationary. The second M motor drives the trip drum continuously and by using suitable gearing and PF controlller this can be set to give the required intervals to release the stop arm allowing time to load and un-load balls. This 2nd motor could also be used to drive the inlet hopper ball pusher. See video below showing final arrangement, M motor has 24:1 worm gear reduction to the trip drum and speed can be adjusted using the PF controller.
  20. doug72
    Yes, it had crossed my mind ! For the amount of time I would run this GBC it would probably be OK, but for longer GBC running times you could either use two white 24T gears ( as per BWE). or I think I have an idea using a 24/16T differential to alternately turn the Lift wheel until the normaly down trip arm stops wheel rotation and then drives the trip drum until it releases the lift wheel. Trip drum would probably need some resistance to rotation to allow lift wheel to rotate again. I have a try later to see if feasible using an XL motor and worm drive. Doug
  21. doug72
    Thanks: I have added a prawl to stop the arm kicking back when the white clutch gear overcomes internal resistance. Also prevents the wheel rotating the wrong way. IMG_4437 by Doug Ridgway, on Flickr Dwell time can be decreased if use 20 / 12 step up gears in the right angle drive to the trip drum but occassionly the arm missing stopping as trip has not re-set quick enough. Have six Z60 Turntables on order and will be building this with some mods to suit my requirements. Sorting out what other parts I am short of.
  22. doug72
    PV Productions now have instructions for a C model LEGO GBC 15 – 7 Modules – 42055. Looks good. http://pv-productions.com/product/lego-gbc-15-42055-building-instructions/
  23. doug72
    Think I do but it takes up a lot of space and complicated. Meanwhile I have tidied up my idea for a trip operated stop/start system, Using an XL motor the dwell time is 4 secs. with an M motor dwell is 3 secs. allowing plenty of time for balls to load & unload. Trip drum has only one peg and stops wheel rotation every 180 degs. There is a slight kick back of the wheel due to the internals of the white clutch gear. Anti kick back device now added. Video of improved trip system.
  24. doug72
    Yes I did see this thread: Model now dismantled.
  25. doug72
    Can you explain how that works and what each axle is doing ?
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