Knuckle Coupler for LGB

thingiverse

Updated Jan 2020: I've included the revised geometry couplings here, which are single-piece parts that require the lock ring to secure them firmly in place within the housings. These components have similar push performance to their two-part counterparts and do interlock, but they're designed to work optimally with my servo-operated coupling, which utilizes the same geometry and features a fully functional knuckle. The revised couplings were originally updated on March 1, 2018, to provide better push performance. I discovered that the original design had a flaw when subjected to strong push forces, causing it to open up. To demonstrate this, I've added an image showcasing four coupled units being pushed together; you can see the left (original) coupling opening while the right (revised) coupling remains in line. The new push versions feature a small additional element on the knuckle that engages with the opposing knuckle during push mode, enhancing their hold. I've also increased the spring strength slightly. This design has been optimized to work seamlessly with LGB and LGB-type models equipped with the "LGB peg." The unusual cutouts in the housings are designed to accommodate these models without requiring any modifications. Once fitted, this coupling sits below the central LGB buffer on coaches but needs to be removed from the larger central buffer on the Stainz loco. This is a press-fit part, so it's fully reversible if you decide to switch back to hook and eye couplers later. This design diverges from Raby's original in that the hook now sits above the tang, making it incompatible with iron bar decoupling. However, the hook-eye is directly connected to the LGB peg on the train model, ensuring efficient load transfer. I've tested one version at approximately 1.5kg of pull and it successfully withstood the force. The coupling has been thoroughly tested for compatibility with the LGB Stainz loco and coaches from the standard starter set. It's also been put through its paces on R1 curves and garden railways, both uphill and downhill. A small hole in the peg portion of the main body allows you to screw a screw into the peg on the coach for added strength if desired. However, I've yet to utilize this feature. The included photos show an earlier prototype with a knob on the end of the spring, which inadvertently limited side-to-side movement. This has been removed in the final version. In the image, the coach and loco are equipped with my electrical connection, which can be found at: http://www.thingiverse.com/thing:1023944 Print Settings: Printer: Mini Kossel Rafts: Yes Supports: Yes Resolution: 0.1 Infill: 35% Notes: This design must be printed in ABS. The main body requires support structures to be printed everywhere, ensuring the overhang prints neatly. Although the upper part of the main body isn't structural, it helps hold the components together during assembly and aligns with the LGB peg on the train/coach when fitting. Be cautious when removing the supports, as they can break off easily. I've found that using a flat head screwdriver to lever out from the sides is the most effective method. The knuckle consists of two parts, which are glued together after printing using Acetone. However, it's unclear whether the additional part is necessary, as the coupling functions adequately without it. Once printed, ream out the eyes of the tang and hook to achieve a secure fit. I use an 8mm rat tail file to gradually advance the eye while rotating the file for an excellent circular fit. Additionally, give the top surface of the main bar section a quick file to ensure smooth sliding between the tang and hook. To assemble, simply slot in the tang first, followed by the knuckle, which should partially engage with the peg in the main body. When assembling it to the coach, the peg will align and hold the coupling in place. How I Designed This Using 123D I designed this coupling using 123D, starting from a Step file of Raby's original design (thank you!). I've added 0.75mm to the face of the tang to make the coupling slightly tighter, but this may be unnecessary.