RE: Tension pulley broken
Agreed
But in no way should anyone have trusted that man. it's just a shame that he took others with him. Sorry for going off topic.
RE: Tension pulley broken
Thankfully I don't do a ton of ABS/ASA printing. My MK4S's had most parts printed in ABS just because I liked the lime green ABS color, not for temperature tolerance purposes. For this initial conversion I'm just leaving things the way they are but later I might do some color mods to spruce things up. If thing have to be CF that's going to cut down on the options. I suppose I could just spray paint the metal frame bits and leave the other parts alone. At one point I had done a nice multi-color lcd cover print but that went away when I went to the MK4S. I've had these two smaller machine since MK3S and it's been fun printing non-standard colors for the parts.
At one point I had done decepticon purple for once and autobot blue for the other.
But functional printers are more important at this point.
Much as I’d love to, having just watched the Netflix documentary, I’m going to resist the temptation to take this discussion way off topic 🤣
I think the difference here is that CF is likely overkill in our application - its stiffness is its main benefit for maintaining belt tension, rather than its outright tensile strength. I already know that ABS can withstand the tension, but will it retain its shape, and hence the belt tension, after a few hours of 55 degrees chamber temperature?
I’ll have some idea by the morning.
RE: Tension pulley broken
I replaced my tension pulleys yesterday with Chris design. My originals were still in good working shape with no sign of galling so this was preventive maintenance before introducing the new tensioning procedure. I reassembled with new brass screws and a bit of Prusa grease on the threads. Despite my original threads where in good shape tensioning adjustment is very noticeable smother with the longer threads, there is no need to apply force tuning belts. The swap takes minutes if done preventative instead of waiting for galling to freeze things up, highly recommended.
/Anders
RE:
@Chris I modded your mod (mod^^2 ?) to make the surface entrance parallel and to fit heat inserts I had (M3*5D*6L). I could not fit them easily in your mod.
Also I simplified the "garnishings/labels" so my poor little MK3 could print it with minimal mess (I used PA-CF). I attach the STL.
RE: Tension pulley broken
I replaced my tension pulleys yesterday with Chris design. My originals were still in good working shape with no sign of galling so this was preventive maintenance before introducing the new tensioning procedure. I reassembled with new brass screws and a bit of Prusa grease on the threads. Despite my original threads where in good shape tensioning adjustment is very noticeable smother with the longer threads, there is no need to apply force tuning belts. The swap takes minutes if done preventative instead of waiting for galling to freeze things up, highly recommended.
Thanks for the feedback Anders. In my opinion the right time to replace these is exactly as you've done - when you have an opportunity and before you have a problem. It's really a disproportionate amount of bother to replace them if the nut seizes, and not everyone will have a Dremel or bolt croppers to hand. If someone doesn't want to go to the lengths of replacing them, a little bit of lubrication should be considered essential preventative maintenance. Don't touch them until they need adjusting, but as soon as they do need adjustment, release the tension gradually and evenly on both sides, apply a little lubrication (to the threads only, keep the head clean and dry), and then re-tension, gradually and evenly.
RE: Tension pulley broken
@Chris I modded your mod (mod^^2 ?) to make the surface entrance parallel and to fit heat inserts I had (M3*5D*6L). I could not fit them easily in your mod.
Also I simplified the "garnishings/labels" so my poor little MK3 could print it with minimal mess (I used PA-CF). I attach the STL.
Thanks @musokestrain - I guess those inserts are a fraction bigger than the ones I used. I know there are various sizes out there - I just used the ones I had to hand.
I'm curious what software you used to tidy up the lettering. I notice that you've removed the bearing and spindle screw spacers - did the extra play in the lateral movement of the bearing cause any issues?
For anyone else using inserts that don't fit my STL, note that I supplied the OpenSCAD script with my model, so that it's straightforward to change the insert dimensions. The dimensions are parameterised at the top of the script:
//heat-set insert dimensions - slightly oversize for an easy fit heatset_shoulder_depth = 1.5; heatset_insert_length = 6; heatset_insert_nose_diam = 4.2; heatset_insert_body_diam = 4.8;
If you're not an OpenSCAD user, I'll be happy to make additional STLs for anyone who messages me.
RE: Tension pulley broken
My printer did a 5hr 30min ABS print overnight, and the chamber temperature will have been in the mid 50s for most of that time. This morning I checked the belt tension to see how my ABS tensioners had held up. The tension is still spot-on - no change at all. This was after an earlier shorter print, after which I did have to re-tighten the belts, but I think that's normal even with the PC-CF parts.
I haven't inspected the ABS parts, because I don't want to disturb the tension and have to go through that tension 'shakedown' again, but I'll leave them in for now and monitor the tension occasionally.
I guess another VFA tower would be in order, to make sure the ABS hasn't changed the resonant response of the belt system.
RE: Tension pulley broken
My printer did a 5hr 30min ABS print overnight, and the chamber temperature will have been in the mid 50s for most of that time. This morning I checked the belt tension to see how my ABS tensioners had held up. The tension is still spot-on - no change at all. This was after an earlier shorter print, after which I did have to re-tighten the belts, but I think that's normal even with the PC-CF parts.
I haven't inspected the ABS parts, because I don't want to disturb the tension and have to go through that tension 'shakedown' again, but I'll leave them in for now and monitor the tension occasionally.
I guess another VFA tower would be in order, to make sure the ABS hasn't changed the resonant response of the belt system.
ABS-GF it is then 😂
RE: Tension pulley broken
@Chris I modded your mod (mod^^2 ?) to make the surface entrance parallel and to fit heat inserts I had (M3*5D*6L). I could not fit them easily in your mod.
Also I simplified the "garnishings/labels" so my poor little MK3 could print it with minimal mess (I used PA-CF). I attach the STL.
The STL apparently did not make it through. Could you try again please, or put it on Printables? Many thanks!
RE:
where do I get the inserts to do this?
I am new ish to the prusa world and never dealt with these inserts before, no idea where to buy them.
I had already my first run at replacing this stupid part, resulting in 2+ weeks of having a dead printer, I need to replace this part with something better.
RE: Tension pulley broken
where do I get the inserts to do this?
The threaded brass insert: https://www.amazon.com/dp/B0CTMSXDYW?th=1
RE: Tension pulley broken
I'd never used OpenSCAD before this but found it easy enough to use to adjust for the inserts I got. Spares now printed - both original design and updated for inserts as I plan to first take the risky approach of trying anti-seize alone and evaluate over time. If nothing self-destructs on disassembly I'll continue with the original pulleys with added lubrication. I'll be using the messy stuff made for spark plugs.
RE: Tension pulley broken
So far I don't have an issue with binding but I'm doing preventative maintenance tonight. Will print out replacements with PCCF.
Interesting though, wasn't this the same (or similar) setup on the MK4? I don't recall reading about that when I had the MK4 and later MK4S.
RE: Tension pulley broken
I'd never used OpenSCAD before this but found it easy enough to use to adjust for the inserts I got. Spares now printed - both original design and updated for inserts as I plan to first take the risky approach of trying anti-seize alone and evaluate over time. If nothing self-destructs on disassembly I'll continue with the original pulleys with added lubrication. I'll be using the messy stuff made for spark plugs.
OpenSCAD is my go-to 3D modelling software now - it appeals to the programmer in me, and it naturally leads to parametric designs. The range of basic operations is quite limited, hence easy to learn, so the fun comes in using those operations in creative ways to achieve the end result.
If the insert you used is a common size and you've found a set of dimensions that work, I'd be happy to add this as an STL variant to the model.
RE: Tension pulley broken
As a software developer myself I agree. I should get more comfortable using than I am. I've done some basic stuff with it and it's pretty slick. I need a good IDE for it though.
I'd never used OpenSCAD before this but found it easy enough to use to adjust for the inserts I got. Spares now printed - both original design and updated for inserts as I plan to first take the risky approach of trying anti-seize alone and evaluate over time. If nothing self-destructs on disassembly I'll continue with the original pulleys with added lubrication. I'll be using the messy stuff made for spark plugs.
OpenSCAD is my go-to 3D modelling software now - it appeals to the programmer in me, and it naturally leads to parametric designs. The range of basic operations is quite limited, hence easy to learn, so the fun comes in using those operations in creative ways to achieve the end result.
If the insert you used is a common size and you've found a set of dimensions that work, I'd be happy to add this as an STL variant to the model.
RE: Tension pulley broken
I learned 3d modeling in Alias Wavefront and Maya... but writing code is part of my job now so it's in the skillset. Not going to be my first choice of tools still.
I pulled the tensioner screws on my Core One today and inspected - no sign of wear, stretching, cross-threading, or any other damage... they came out smoothly. I've had to retension 5-7 times if I'm remembering (first few prints each needed some attention after, at least once after starting to work with ASA and higher temps, and at least once somewhat randomly in the middle. Belts (new method) were at 81t/70l when I checked before pulling the screws, and seem to have printed my spare pulleys without issue - I've suspected they were low though as it's occasionally done the head-banging of late.
Reinstalled original screws and pulleys + proper anti-seize (holy cow do I hate that stuff, it gets on everything!) and tensioned with the web tuner. Slightly fiddly stepping up to tension and keeping the gantry square but I think I got it. Have to pick something to print later and verify.
Based on this experience I wonder if it's just a bit too easy to cross-thread these. Nearly every image I can remember seeing of damaged tensioner screws has all shown signs of cross-threading. The brass inserts option will still help here as it'll be a whole lot more obvious (plus a handful of other benefits).
RE: Tension pulley broken
dhl just delivered my replacement tensioners and pulleys. Hopefully I can get things back together today and get through calibration without the damned red screen of death.
RE: Tension pulley broken
4.5mm d1, 3.9mm d2, 6mm h STL attached
First insert I went a bit too far and the brass is flush with the edge; I suspect it may still hold so whenever I get to needing/using these I'll give it a try and verify. For now I'll be testing original hardware + antiseize till I have a bunch of tension adjustments with that setup.
RE:
well this is disappointing. Got things back together. Gantry is square as far as I can tell. x and y belts have been tuned to 98 and 92 respectively. It still won't pass x and y calibration.
It moves to the far right then does a series of homing motions that that front right corner. It does this for a minute or two before the machine resets and it gets the red screen of death. On the bright side, the lubricated screws in new parts seem ok... I'm really not sure what's wrong.
RE: Tension pulley broken
well this is disappointing. Got things back together. Gantry is square as far as I can tell. x and y belts have been tuned to 98 and 92 respectively. It still won't pass x and y calibration.
It moves to the far right then does a series of homing motions that that front right corner. It does this for a minute or two before the machine resets and it gets the red screen of death. On the bright side, the lubricated screws in new parts seem ok... I'm really not sure what's wrong.
How annoying. Was the gantry square before you started tensioning? Is the firmware up to date? I’ve read reports that the latest version improves the headbanging.