E3D 20T Idler compatible mount for Y-Axis on Prusa MK3 with Bear Upgrade

thingiverse

This is a remix of the Y-axis idler mount for the Bear upgrade kit for the Prusa Mk3 printer (see details here: https://github.com/gregsaun/prusa_i3_bear_upgrade ). The goal is to make it compatible with high-quality idlers sold by E3D (see here: https://e3d-online.com/gates-powergripr-toothed-idler-6mm ). The Bear design reuses the 20T idler that ships with Prusa printers. However, this idler has some issues - single bearing on one side; untoothed - and compatible quality replacement idlers have thus far been elusive. E3D recently started selling idlers manufactured with Gates components. These are available in untoothed and toothed (20T) varieties, and by all appearances, they're a high-quality product. The E3D idlers are wider and use a 5mm bore instead of the 3mm bore required by the Bear design. To make it compatible, I've made some minor changes to the Bear design. For the axle, here are some options: * 4.95mm drill rod from McMaster Carr, cut to length ( https://www.mcmaster.com/2900a299 ) * Go plug gauge - these have a very precise diameter, so you can get 4.99mm which is a perfect fit, but if that isn't available, I've tested sizes down to 4.95 and they work well ( https://www.amazon.com/dp/B002710PAU/ref=cm_sw_em_r_mt_dp_U_.aizCb7JR6AEH ) * Go / No-go plug gauges from McMaster Carr, cut to length. Here is one that is 4.97mm. With stated tolerance, this should work (but untested) ( https://www.mcmaster.com/2281a2 ) You can choose whether or not to cut these to length. Currently, the axle is held in place by friction only (as opposed to the screw used in the original design). If this turns out to be an issue, I will modify the design to add a retention mechanism. All3dmakers sells a 15.8 mm length, 4.95mm diameter dowel pin. To use this, you'll have to use the special version of this part that I created for this smaller length axle. I haven't tested this, and I have some concerns about the thinness of the plastic that supports the axle, but feel free to try it if one of the other options isn't available to you ( https://all3dmakers.com/products/bear-x-axis-dowel-pin-for-e3d-gates-5mm-bore-idler ). The original version, which was designed for a 23mm or longer axle, is named y_idler_23.stl, and the version for the 15.8mm axle is named y_idler_15.8.stl. The two Fusion 360 archives are identical with the exception of the configured axle length parameter. If you're looking for a CAD model of the E3D 20T idler, you can find one here. Note: I patterned the tooth profile after the Gates belt, so it's probably not an exact match for the actual idler.