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

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 ) to make it compatible with the high quality idlers sold by E3D (See here: https://e3d-online.com/gates-powergripr-toothed-idler-6mm ).

The Bear design re-uses the 20T idler that ships with the Prusa printers. However, this idler is has a few issues (single bearing, on one side; untoothed), and compatible quality replacement idlers have thus far proved elusive. E3D recently started selling some idlers manufactured with Gates components. These are available in untoothed and toothed (20T) varieties, and by all appearances are a high quality product.

However, the E3D idlers are wider and use a 5mm bore rather than the 3mm bore which the Bear design requires. I have made a few very minor changes to the Bear design to make it compatible with the E3D idlers. 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 have 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 will have to use the special version of this part that I created for this smaller length axle. I have not tested this, and 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.