Are 24mm rollers the correct size for the Sovol SV04 build plate?
I recently picked up a used Sovol SV04 printer and have been meticulously inspecting it. When attaching all six build plate rollers, I notice significant resistance in the rolling motion of the build plate bracket.
If I only mount the four corner rollers with the eccentric nuts at their loosest positions, there’s already almost no wobble. The middle rollers, with reversed eccentric nuts, become somewhat offset. Even with all six rollers at their absolute loosest settings, the fit on the aluminum extrusion is quite tight.
This makes me suspect the previous owner may have replaced the rollers with oversized ones. The current rollers measure 24mm (±~.03mm) on digital calipers - are these the correct size?
Alternatively, I am thinking on running this printer with setup with just four rollers. I could also elongate the middle roller mounting holes with my milling machine …
Okay, so the rollers are the correct size. Scratch that idea. That said, I wasn’t entirely clear in my original post. During this troubleshooting, the belt has been disconnected from the build plate bracket, all bearings are in good condition, and all washers are present and accounted for.
In this picture, all eccentric nuts are at their loosest positions, shifting the rollers as far away from the extrusion as possible. However, the middle set of rollers appear shifted slightly to the right, by about a millimeter or so. This creates noticeable tension on the rollers. If my SV04 isn’t malformed, I assume I should feel some resistance when manually moving the bracket back and forth.
In this picture, the holes for the rollers are aligned nicely, so the offset isn’t due to misaligned holes on the bracket.
There are two things about this setup (or its implementation on my printer) that are concerning me:
When I remove the middle set of rollers and set the remaining ones to their loosest positions, the assembly is already perfectly adjusted when mounted to the extrusion—there’s no wobble. This leaves little to no room for further adjustment.
On my Ender 3 S1 Pro, I can adjust the eccentric nuts so the bed moves freely with almost no resistance and zero wobble. In fact, if I tilt the printer with the belt disconnected, gravity alone moves the bed. With the SV04, the middle rollers’ offset creates significant tension, which eliminates wobble but would force the Y-axis motor to work harder to move the bed.
Am I overthinking this, or is this a legitimate concern?
Your initial post was understandable. You may want to ensure that all rollers are in line at the same height in order to fit in the recesses of the 40x20mm profile. This would be require looking at it from the front view perspective instead of the top view.
Visually, they appear vertically aligned. Measuring with calipers, the top of each roller is within 0.07mm, and checks with a square and feeler gauges show similar results.
With the Y belt disconnected, my Ender 3’s bed slides like ice skates on ice, able to coast for some inches under its own inertia. On my SV04, with all six rollers engaged, it’s more like skating in mud—resisted, stopping almost immediately.
Or think of an air hockey table: with the air on, the striker glides under its own inertia—like my Ender 3. My SV04 feels like the air is off, with a magnet dragging the striker. It still moves smoothly because of the fabric underneath, but the lack of air keeps it from floating, and the magnet adds resistance.
How does yours feel?
In my picture, both middle rollers are clearly offset horizontally, which I think is causing the tension and resulting drag.
On my SV04 the Y-axis runs smoothly without significant resistance. Finding the correct settings has taken me quite a while. Using the middle rollers to limit wobble is part of the concept. Is there any dirt, debris or scotch tape on your Y-axis profile?
/R
Bjoern
I ended up (feel free to chastise me) carefully elongating all six holes with a chainsaw file, digital calipers, and a jeweler’s loupe. I never really thought I would mention that particular set of tools in the same sentence.
THEN! Careful as I was, I got too overzealous with the file and spent the next couple of hours shimming the holes back slightly with tiny strips of beer can. Soda would be unprofessional.
After only a little cussing, I FINALLY HAVE THE BED DIALED IN with room to adjust in both directions! All rollers are equally tensioned and the bed assembly has that “just right” feel where it glides nice and smooth with just the slightest hint of resistance from the roller tension. Six rollers is certainly an entirely different animal than four in this respect.
Scotch tape? I guess I can imagine someone shimming this way, but I don’t think I would. That would be janky!
Standard 24mm printing rollers are commonly used in many 3D printers. However, the extreme tightness and friction you are experiencing suggest that 24mm rollers may not be the correct size for the Sovol SV04. It’s possible that the previous owner replaced the original rollers with slightly larger ones. You should verify the correct specifications by checking the printer manual or contacting Sovol directly. If the printer operates smoothly and remains stable with only four Wobble Roller, it could be a workable solution, but it may lead to faster wear on the remaining rollers. While this approach could temporarily address the issue, improper leverage might eventually cause the machine to malfunction. For those with the necessary tools, sourcing slightly smaller rollers (e.g., 23.9mm) could be a practical solution to test if they resolve the problem.
Meh. Yesterday’s news now! I ended up making the holes ever so slightly oblong with a file (see my previous post) and now all rollers are dialed in equally with room to adjust in either direction.
