Replacement Spool Holder for Qidi Tech Plus 4

Looks like I'm back, yo! This is a little project I had in mind before I even got the printer. The included spool support does work, but right away I knew it could be better. I had a spool of filament running on it and kept hearing a low, pulsed vibration. Turned out to be friction between the spool and the holder. This not only remedies that problem; it allows you to more closely match the spool you're using. If you're using a spool with the common 50mm+ hole diameter, you can use my 50mm diameter sleeve and gain a nice match to hole diameter and a nice bearing effect between support, sleeve and spool, for much less friction in rotation. If you're using an oddball spool with a smaller hole, you can use the bare support or the included 30mm diameter sleeve and maintain a good match while again gaining low friction rotation. Friction is especially reduced if you print this in a slippery filament like PETG or Nylon. I'm using Elegoo Rapid clear PETG in mine and it works great.

Included is the replacement rod holder, the two sleeves, and the rod end spool retainer. A shortened version of the rod is also included if you only ever intend to use common 2 1/2" wide spools and want less droop caused by spool weight. This way you can use what suits you best for your existing filament empire. I have mainly 2 1/2" wide / 50mm hole spools but also a spool of TPU and Taulman 910 alloy that have ridiculously small holes and a wider spool, also some tiny 0.250 kg PETG spools, and this kit covers them all nicely.

The rods themselves are 18mm in outer diameter. The long rod is 104mm of useful length to accommodate big fatty spools like my old Sain Smart 85mm wide spool of TPU. The shorter rod is for spools 70mm wide or less with a useful length of 74mm. The two pairs of sleeves are 70mm and 100mm of useful length respectively, to match the rod lengths, and each have inside diameters of 20mm to give enough slop between sleeve and rod to act as a decently smooth bearing surface. While turning, the spool may slip freely over the sleeve outer surface, or the sleeve inner surface may slip around the outer surface of the rod, or take turns according to friction forces. Think of it as a sort of a friction gearing system and you get the idea.

I strongly suggest you print this in PETG, but Nylon would be great if you can tame it properly. Make sure your printer is up to tight tolerances so that the sleeves can roll freely on the rod, and the rod end spool retainer can slip in and rotate to locked position without unnecessary force needed to rotate it into place. I carefully modeled these parts to fit together just right, but depending on your setup you may need to trim your X/Y compensation (Orca Slicer) or Horizontal Size Compensation (Simplify3D), etc, to get the right fit. Start with printing the rod so that it fits the "Supplies" spool support column properly, THEN print the sleeves to fit the rod, THEN print the rod end spool retainer to fit the rod. The retainer should be nice and snug but not so tight that you have to force it. Note the thread is LEFT HANDED; the spools rotate counter-clockwise during printing, so the if the spool touches the retainer, the retainer is always trying to roll with it to be tighter, not more loose. Don't try to lock the retainer by rotating it clockwise. Lefty-tighty, righty-loosy, see?

Print each piece with its fat end down on the bed, standing tall. In other words, print the rod with the riser attachment end facing down to the bed, rod vertical. Print each sleeve with its end-ring (this prevents spools from rubbing against the attaching end of the rod) facing down, barrel vertical. Print the rod end spool retainer piece with the knob side down, locking side up. You will need no supports anywhere if you do it like this.

See the included pics for my own setup so you can see how it all fits together properly. Enjoy, and have fun with your Plus 4!

Edit: As of 2/4/2025 6:52PM EST I've replaced the rod end spool retainer with a cleaner version. I reworked the insertion end so that it is generally a tighter fit, less wobbly and much more secure. Also thickened the knob portion to 5mm so it feels less bitey and cheap on the fingers.

NightRunner417