RE: VFA Artifacts on X+Y Straight Edges
Just so I'm clear, ideally the belt will sit and run halfway down the toothed part of the pulley, so touching neither the top or the bottom of the toothed part?
Also, I guess I should loosen the belts first, adjust the pulley, then re-tension the belts?
That would be ideal, but I don't see how that state could be guaranteed. The only thing which holds the belt at a certain height (or height range) are the flanges of the pulleys and idlers. So the best you can hope for is a belt which lightly touches some of the flanges, or wanders up and down between touching the upper and lower flange.
The only thing you can avoid is a belt which is always rubbing, somewhat forcefully, against the same flange somewhere. But you can't make sure that the belt is and stays centered, not touching any flanges on any pulley or idler.
RE: VFA Artifacts on X+Y Straight Edges
The only thing you can avoid is a belt which is always rubbing, somewhat forcefully, against the same flange somewhere. But you can't make sure that the belt is and stays centered, not touching any flanges on any pulley or idler.
True, you can't completely avoid it. It's about avoiding extremes. Like, for example, further up in the post, where you can already see belt wear in the printer.
RE: VFA Artifacts on X+Y Straight Edges
Just so I'm clear, ideally the belt will sit and run halfway down the toothed part of the pulley, so touching neither the top or the bottom of the toothed part?
Also, I guess I should loosen the belts first, adjust the pulley, then re-tension the belts?That would be ideal, but I don't see how that state could be guaranteed. The only thing which holds the belt at a certain height (or height range) are the flanges of the pulleys and idlers. So the best you can hope for is a belt which lightly touches some of the flanges, or wanders up and down between touching the upper and lower flange.
The only thing you can avoid is a belt which is always rubbing, somewhat forcefully, against the same flange somewhere. But you can't make sure that the belt is and stays centered, not touching any flanges on any pulley or idler.
Cool, that makes sense.
Where can I find this VFA test print that everyone seems to be using for reference?...anyone?
RE: VFA Artifacts on X+Y Straight Edges
https://www.printables.com/model/1189256-vfa-test-prusa-core-one
RE: VFA Artifacts on X+Y Straight Edges
OK, so I'll caveat this by saying ignore the horrific general print quality...this is the cheapest, crappiest filament I've ever bought, its old, I've never even attempted to dial it in, it's never been dried and sitting on a shelf in the open absorbing all manner of things for about a year but its the shiniest filament I own so great for showing up VFAs
I had to create my own quick VFA test as this filament is PETG and (I think) the VFA test linked above is for PLA.
The bottom one is before adjusting the idler, the top one is after adjusting the idler.
note: the horizontal banding that can be seen on the top model isn't there on the part or the original image, there must be some alteration of the image when posting to the forum...but the VFAs are literally gone on the top model.
RE: VFA Artifacts on X+Y Straight Edges
The bottom one is before adjusting the idler, the top one is after adjusting the idler.
Congratulations, that's quite the difference! 👍
By "adjusting the idler", do you mean adjusting the toothed pulley right on the stepper motor? If so, did you adjust it to the nominal height (as defined by the multi-purpose tool included with the kit), or try to center the belt on some neighboring idler wheel? (Which one?)
RE: VFA Artifacts on X+Y Straight Edges
The bottom one is before adjusting the idler, the top one is after adjusting the idler.
Congratulations, that's quite the difference! 👍
By "adjusting the idler", do you mean adjusting the toothed pulley right on the stepper motor? If so, did you adjust it to the nominal height (as defined by the multi-purpose tool included with the kit), or try to center the belt on some neighboring idler wheel? (Which one?)
I've edited my post mate I was mistakenly typing idler instead of pulley....I haven't adjusted any idlers.
All I did was loosen off the 2 grub screws on the pulley shaft, gently persuaded the pulley up maybe 1mm, enough so I could see the toothed part above and below the belt, then retightened the grub screws...not exactly scientific I know 😂
Here's a picture of the pulley after adjustment: you can just make out the toothed part of the pulley being visible both above and below the belt. Before adjustment the teeth were not visible above the belt:
Not sure if it's significant, but I did notice the uneven marking on the pulley to the left as I was making the adjustment. (the bottom of the pulley is much shinier than the top)
RE: VFA Artifacts on X+Y Straight Edges
I had to create my own quick VFA test as this filament is PETG and (I think) the VFA test linked above is for PLA.
https://www.printables.com/model/1256267-vfa-test-prusa-core-one-petg
RE: VFA Artifacts on X+Y Straight Edges
The result here gives me great confidence that a definite cause will be found, and subsequent remedy/procedure to eliminate the VFAs altogether (or to a generally acceptable standard) will be introduced....although it's slightly disheartening that the push towards this is being driven by the community and not the manufacturer, all we get from them is 'it doesn't happen on the machines here'.
RE: VFA Artifacts on X+Y Straight Edges
I'm not wildly surprised that they didn't find the issue, especially if they have been testing on perfect printers. "Everything is fine on our perfectly assembled printer" of course it is! It'll be interesting to see how their testing goes with the RTB printers they are getting back.
I've got some obnoxiously shiny PLA on hand so I'll try to get some testing in tonight using your fix. Looking at the right hand side (RHS) gear it is much like yours would have been. I can't see the other side of the LHS gear but from the side I can see it is pushed hard against the other side.
- Before adjustments. I'll get pictures of both toothed gears to show nominal position (I think you can only see part of the left hand pulley).
- Adjust the RHS pulley to have clear space above and below belt. Confirm with manual movement of extruder that it runs true and remains central. Photograph gear. Reprint VFA test.
- Adjust LHS pulley so that it has the same clearance as is visible on the RHS pulley. Confirm belt runs true and photograph gear. Confirm RHS pulley is still true. Reprint VFA test.
The result here gives me great confidence that a definite cause will be found, and subsequent remedy/procedure to eliminate the VFAs altogether (or to a generally acceptable standard) will be introduced....although it's slightly disheartening that the push towards this is being driven by the community and not the manufacturer, all we get from them is 'it doesn't happen on the machines here'.
RE:
Today i installed toothed idlers, result: none.
RE: VFA Artifacts on X+Y Straight Edges
Today i installed toothed idlers, result: none.
Meaning no VFAs or no effect on VFAs?
RE: VFA Artifacts on X+Y Straight Edges
I'm not wildly surprised that they didn't find the issue, especially if they have been testing on perfect printers. "Everything is fine on our perfectly assembled printer" of course it is! It'll be interesting to see how their testing goes with the RTB printers they are getting back.
I've got some obnoxiously shiny PLA on hand so I'll try to get some testing in tonight using your fix. Looking at the right hand side (RHS) gear it is much like yours would have been. I can't see the other side of the LHS gear but from the side I can see it is pushed hard against the other side.
- Before adjustments. I'll get pictures of both toothed gears to show nominal position (I think you can only see part of the left hand pulley).
- Adjust the RHS pulley to have clear space above and below belt. Confirm with manual movement of extruder that it runs true and remains central. Photograph gear. Reprint VFA test.
- Adjust LHS pulley so that it has the same clearance as is visible on the RHS pulley. Confirm belt runs true and photograph gear. Confirm RHS pulley is still true. Reprint VFA test.
The result here gives me great confidence that a definite cause will be found, and subsequent remedy/procedure to eliminate the VFAs altogether (or to a generally acceptable standard) will be introduced....although it's slightly disheartening that the push towards this is being driven by the community and not the manufacturer, all we get from them is 'it doesn't happen on the machines here'.
Yeah your results should be interesting.
I'm kind of hesitant to go any further as if such a small tweak like adjusting a pulley by 1mm can make such a stark difference, it makes me think that the overall cause and remedy could be a lot simpler than I first feared...I don't want to go stripping the entire gantry down if the fix doesn't require that level of interference.
As I mentioned earlier, the adjustment I made was by no means measured or scientific...so I might just stick where I am now and see what Prusa come up with, I'm increasingly confident that a suitable remedy will be found, and apart from this issue I'm really pleased with the printer.
RE: VFA Artifacts on X+Y Straight Edges
I'm not wildly surprised that they didn't find the issue, especially if they have been testing on perfect printers. "Everything is fine on our perfectly assembled printer" of course it is! It'll be interesting to see how their testing goes with the RTB printers they are getting back.
I've got some obnoxiously shiny PLA on hand so I'll try to get some testing in tonight using your fix. Looking at the right hand side (RHS) gear it is much like yours would have been. I can't see the other side of the LHS gear but from the side I can see it is pushed hard against the other side.
- Before adjustments. I'll get pictures of both toothed gears to show nominal position (I think you can only see part of the left hand pulley).
- Adjust the RHS pulley to have clear space above and below belt. Confirm with manual movement of extruder that it runs true and remains central. Photograph gear. Reprint VFA test.
- Adjust LHS pulley so that it has the same clearance as is visible on the RHS pulley. Confirm belt runs true and photograph gear. Confirm RHS pulley is still true. Reprint VFA test.
The result here gives me great confidence that a definite cause will be found, and subsequent remedy/procedure to eliminate the VFAs altogether (or to a generally acceptable standard) will be introduced....although it's slightly disheartening that the push towards this is being driven by the community and not the manufacturer, all we get from them is 'it doesn't happen on the machines here'.
Yeah your results should be interesting.
I'm kind of hesitant to go any further as if such a small tweak like adjusting a pulley by 1mm can make such a stark difference, it makes me think that the overall cause and remedy could be a lot simpler than I first feared...I don't want to go stripping the entire gantry down if the fix doesn't require that level of interference.As I mentioned earlier, the adjustment I made was by no means measured or scientific...so I might just stick where I am now and see what Prusa come up with, I'm increasingly confident that a suitable remedy will be found, and apart from this issue I'm really pleased with the printer.
Im in a similar spot. 245 hours of printing since I got it and no realy issues apart from trying to squeeze perfection out of it. It's why I got a prusa (solid foundation). But I also got in early knowing full well that new releases with prusa can be challenging.
I dont really have a boat in the vfa race. I don't care if it does them or not, but I love a project.
I also can see that something like an over constrained belt would cause a subtle defect like vfa so I'll do the change on mine to see the impact.
RE: VFA Artifacts on X+Y Straight Edges
I'm not wildly surprised that they didn't find the issue, especially if they have been testing on perfect printers. "Everything is fine on our perfectly assembled printer" of course it is! It'll be interesting to see how their testing goes with the RTB printers they are getting back.
I've got some obnoxiously shiny PLA on hand so I'll try to get some testing in tonight using your fix. Looking at the right hand side (RHS) gear it is much like yours would have been. I can't see the other side of the LHS gear but from the side I can see it is pushed hard against the other side.
- Before adjustments. I'll get pictures of both toothed gears to show nominal position (I think you can only see part of the left hand pulley).
- Adjust the RHS pulley to have clear space above and below belt. Confirm with manual movement of extruder that it runs true and remains central. Photograph gear. Reprint VFA test.
- Adjust LHS pulley so that it has the same clearance as is visible on the RHS pulley. Confirm belt runs true and photograph gear. Confirm RHS pulley is still true. Reprint VFA test.
The result here gives me great confidence that a definite cause will be found, and subsequent remedy/procedure to eliminate the VFAs altogether (or to a generally acceptable standard) will be introduced....although it's slightly disheartening that the push towards this is being driven by the community and not the manufacturer, all we get from them is 'it doesn't happen on the machines here'.
Maybe take video, because I know the belt rides up and down in the pulley depending on where the print head is at.
RE: VFA Artifacts on X+Y Straight Edges
The first test is done and there is definite vfa. Seems to chill out at a point, but the filament also goes slightly matte so possibly a temperature related issue. I only noticed halfway through it was sliced for the hf nozzle. Im running again with the hf nozzle. Im going to also swap from the overture radiant rainbow I've got to eryone dual colour purple/black silk pla and do another stock check and then get to the mods.
Changing the filament for consistency in the colour.
RE: VFA Artifacts on X+Y Straight Edges
Maybe take video, because I know the belt rides up and down in the pulley depending on where the print head is at.
That's been the case for me. When distanced with Prusa tool as per assembly manual, the belt rides against the flange constantly (towards the motor, visually up). Correcting it doesn't center the belt tho, it just makes the belt ride up and down constantly. So it still rubs, just not 100% of the time.
Also, I have seen no improvement whatsoever by correcting this.
RE: VFA Artifacts on X+Y Straight Edges
On mine, looking at the right-side gantry idler, the belt centers itself when the extruder is up against the right side, and rides back down to the bottom flange of the idler when it moves out away from it. Seems like it starts touching the idler flange when the extruder is not quite halfway back to the left. The left-hand idler shows the belt doing the exact opposite and riding up to the top of the idler when the extruder moves to the right. This almost suggests the idler blocks are out of tram/square with the X gantry, though I could be misinterpreting that.
RE: VFA Artifacts on X+Y Straight Edges
I've long since returned my Prusa Core One printer for a refund minus the time and effort for debugging for them but it seemed like most of the assembled models were still giving VFAs, so presumably both pulleys would need adjusting for this to reduce it this much.
Still, it's poor that they claimed they couldn't solve this after I sent it back. They should set these positions in a more robust way.
If anyone who's fixed this, could you try my gcode from the original post and check it for vfas.
https://drive.google.com/file/d/1T7X2J3Gm2UYetzKfY6ZBBM5pxz3wiFaG/view?usp=drivesdk
RE: VFA Artifacts on X+Y Straight Edges
Looking like some good progress here. Reading on with interest and hopefully more positive advances.
Thanks to everyone, just hoping my printer doesn't suffer too badly when it's finished being built. 😊
Scott