WINSINN GT2 Idler Pulley - 20 Toothless, 5mm Bore, for 10mm Width Timing Belt, Aluminum - Ideal for 3D Printers, CNC Machines (5-Pack)

I used these WINSINN GT2 idler pulleys as part of a custom CNC printer project, and they worked out better than expected. The aluminum feels solid and well-machined, and the 20-tooth profile lined up perfectly with my 6mm timing belts. Installation was quick—everything fit snugly on the 5mm shaft, and the movement stayed smooth without any wobble or noise. I’d definitely use them again on future builds. If you're working on a 3D printer or CNC system, this will do the trick. Reliable, clean finish, and no headaches.

Winsinn consistently makes great products. Does not matter the product. All well-made and work perfectly.

It idles fine I guess, and the dimensions were good. I did find that it spun better after I added a few drops of machine oil and let it soak into the bearing.

Installed on my monoprice maker select v2 instead of the smooth idler pulleys that come from the factory. Correct size.

Good set of idler pulleys. Used for my 3d printer to make my z axes belt driven.

As far as I can tell, they are all perfectly round, and the bearings are decent. NB: it's really hard to get good 3mm bearings in an idler - if they even exist, that is - but these seem to be made well.

The toothed belt running over the smooth idler bearings on the Stock Ender 5 Plus belt tensioners was causing patterns in my prints with any speed over 20mms. No one makes an after market set of belt tensioners that use these toothed idlers, so I made my own. I was instantly able to more than double print speed. After dialing in the belt tension I am now able to print at 90mms. That’s 350% faster because the idlers now mesh perfectly with the toothed belts. I’d say they are worth it

I busted some other ones I had, so these come to the rescue, the bearing has been working reliably enough.