Rather than using the A1312 hinge mechanism for VESA, I went with the cheaper DIY solution by using a 100 x 100 VESA plate from K&M (model number 19615). This metal adapter plate has 2 “studs” welded to it and comes with 2 nuts. The opening/gap of the A1419 chassis for the iMac stand is big enough for the M6 threaded studs to pass through.
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To secure the VESA plate to the monitor arm, I used screws, washers and nuts. The monitor arm that I purchased from AliExpress came with M4 screws so I only had to purchase the washers and nuts from eBay. I added a layer of 3mm MDF between the chassis and VESA plate (mainly as padding) to prevent the screws from scratching the back of the aluminium enclosure. I also cut a rectangular piece of MDF to “fill in” the gap around the opening of the enclosure to prevent the VESA plate from sliding left and right. Finally, I also added 2 x 25mm M6 washers to increase the surface area that holds the enclosure when the nuts are tighten.
Overall, I am pretty satisfied with the end result especially for the price since the Apple VESA kit for A1419 (used) cost £100+. Initially, I was worried that the 2 x M6 nuts that hold the enclosure might come loose when I adjust the monitor but after few weeks of using it and adjusting the monitor from time to time, the nuts seem to stay tightly secured to the plate. I paid £7.10 (or £12.05 delivered) for the K&M 19615 VESA plate. The washers, nuts and 3mm MDF A4 sheet cost about £10 (or less) in total from eBay.
I have the R9A18 5K driver board connected to an eGPU (RX 580) via 2 x DP1.2. The eGPU is connected to a MBP 15” 2015 via the M.2 SSD slot.
Photo #1: K&M 19615 attached to the enclosure without padding. The cables in the photo are for the iMac speakers, connected to the 5K driver board via a 4-pin header.
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Photo #2: Height of the stud without padding. I used a 3mm MDF board as padding.
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Photo #3: Rear view of the enclosure with VESA plate without padding.
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Photo #4 Interior view of the set up with padding, small rectangular piece of MDF to prevent the plate from sliding left/right and 2 x 25mm M6 washers. If you look through the vents, you will see the screws used to secure the VESA plate to the monitor arm.
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Photo #5 and #6: Exterior views of the set up, attached to a monitor arm.
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