This is an extended Y-Belt Idler that has 3 608ZZ bearings instead of the standard 2. The purpose of this is to prevent the belt from dragging on the lower (or upper) portion of the idler when you have Y belt motor modifications, such as anti-vibration damper, lowered gear, modified tensioner, modified anchor, etc... really any reason that your belt might be contacting the idler housing instead of the 608zz bearings is reason to use this.
While this idler can be used with a stock setup, it also has a hole for Piercets Externally Accessible Y-Belt tensioning system. (https://www.thingiverse.com/thing:1656341) To use that, you can download his parts and replace the Y-Belt Idler with this one.
To use this you will need:
3x 608zz bearings (reuse the 2 that are stock)
1x M8 40mm bolt (stock is slightly too short, but you might be able to make it work)
1x M8 Nylock nut (you can use the same one you have now)
4x M8 washers
4x M3 35mm bolts
4x M3 washers
4x M3 Nyloc nuts
4x 7mm OD plastic standoff (at least 20mm long)
1x 15mm M4 bolt (do NOT use a bolt longer than 15mm, or it will protrude in to the belt/608zz bearings)
Optionally (if you are using the external tensioning system):
1x M4 heatset insert
1x M4 Nyloc nut
You can choose if you want to use a Nyloc nut or a heatset insert. I prefer the insert - if you choose to use the insert version, be sure you install the insert from the front of the idler housing (where the 608zz bearings go) and not the back (where it mates to the Taz front Y Plate). Put the heatset insert in the hole and push down until it stops against the M4 sized hole. The heatset insert should NOT be flush with the face of the part. It should be inset by about 3mm.
Once you've printed out this part, and optionally Piercets external tensioning parts, remove the current idler and take the 608zz bearings out.
Add the additional 608zz bearing, put a washer between each bearing and on the top and the bottom of the stack. Slide the M3 bolts in the Taz plate and then hang the new idler on the 4 bolts. Slide the stand offs in the 4 corners of the idler (you may have to drill out the holes to get a smooth slide), attach an M3 washer and an M3 Nyloc nut to each M3 bolt and tighten down until secure.
The idler will still be loose and wobble a bit, you will need to take the M4 bolt and slide it through the newly drilled hole in your front Y-Axis plate (use the template from Piercets project to drill the hole). Engage the M4 bolt with the heatset insert or the nut (whichever version you used) and slowly tighten down.
If you are NOT using the external tensioning system, tighten the M4 bolt all the way down and then tension your belt as you normally would.
If you ARE using the external tensioning system, slowly tighten down the M4 bolt until the belt is tight, like a bass guitar string.
Congrats, now you have a lot more room to slide the belt up and down, giving you more options for how to mount your motor or make other modifications to the Y-Axis!