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How to set to proper Idler tension of the i3MK3S+?  

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prusanewuser
(@prusanewuser)
Prominent Member
How to set to proper Idler tension of the i3MK3S+?

Hi, I am still trying to fix the extruder not extruding any filament in the middle of the print while producing strange sound issue. I read that too tight or too loose is not good. Is there a good way to tell if it has been properly adjusted?

https://help.prusa3d.com/article/extruder-noises_2013

Posted : 18/09/2022 8:12 pm
jsw
 jsw
(@jsw)
Famed Member
RE: How to set to proper Idler tension of the i3MK3S+?
Posted by: @prusanewuser

Hi, I am still trying to fix the extruder not extruding any filament in the middle of the print while producing strange sound issue. I read that too tight or too loose is not good. Is there a good way to tell if it has been properly adjusted?

https://help.prusa3d.com/article/extruder-noises_2013

The Party Line is that the screw head should be 'just about flush' with the edge of the extruder case.

Mine is just under the edge, but close enough to call it 'just about flush' in any case.

I would say that if you are grinding filament and that the idler tension screw is 'just about flush', it's probably something else that's causing the issue.

Posted : 19/09/2022 12:34 am
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE: How to set to proper Idler tension of the i3MK3S+?

That is what I had when I tried to fix the problem. However, still failed. What else could be the problem? It printed PLA in an enclosure with a fan. I have tried printing at 215c and 205c (E3D told me to lower the temperature by 5-10C when using the Revo as I got some leaking problem during the 49-point calibration). It is strange that failure always happened after printing for 6-8 hours. Before that, everything looked fine.

Posted : 19/09/2022 12:51 am
mechedd
(@mechedd)
Eminent Member
RE: How to set to proper Idler tension of the i3MK3S+?

Is this happening with a certain filament, or all filaments? What filament are you using? 

Is the sound coming from the motor or the gears? Do you see the gears spinning, or not spinning at all?

Posted : 19/09/2022 12:59 am
mechedd
(@mechedd)
Eminent Member
RE: How to set to proper Idler tension of the i3MK3S+?

Just about flush works for me with PLA and PETG. I've been printing mostly TPU recently so keep the tension light. Had to print a few PETG scrapers yesterday, didn't change the tension and it worked fine, so I seem to have found a sweet spot at least for the moment.

Posted : 19/09/2022 1:02 am
jsw
 jsw
(@jsw)
Famed Member
RE: How to set to proper Idler tension of the i3MK3S+?

I'm assuming that when you say 'leaking' in this context, you mean oozing out of the nozzle orifice and not a filament leak around the heatblock, which would be a Bad Thing (tm) and needs to be taken care of pronto.

I'm also assuming that the 'strange sound' you hear is an intermittent clicking noise.

Clicking and/or grinding filament can be caused by several things.  One is bad idler tension, which can be a simple misadjustment or even something like a tension spring that's damaged or out of tolerance.  Maybe there's debris compressing the spring more than intended, causing too high tension.

Misalignment of the hobbed gears or friction of the idler gear can cause it.  Filament dust or residue in the hobbed gears can cause it as well.  I've had to clean mine with a dental explorer on occasion.

Any blockage or constriction in the hot end can also cause it.  A good sanity check is to release the idler tension, heat the nozzle up to filament temperature, and manually push some filament into the extruder and watch it come out of the nozzle.  It should flow out of the nozzle, straight down, with modest pressure on your part.

If you really have to press to get any extruded filament, something is wrong.

If the bead out of the nozzle veers to one side, you probably have a partially clogged nozzle.  In that case a so-called cold pull and/or needling will usually cure it.

I had an issue (with my other printer, not Prusa, but Ultimaker) where I found scorched filament remnants blocking the nozzle, and both needling and cold pulls were ineffective.  I had to remove the clip-in hot assembly, remove the nozzle, and use a drill bit to clean out the hardened scorched filament remains.  I then reassembled it, heated it using a bench supply, and sanity checked that manually pushing filament into it resulted in a good straight-down flow.

I've also heard of a bent heatbreak causing friction and then jamming as well.

 

Posted : 19/09/2022 1:17 am
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE:

Thanks.

By ‘leaking’, I meant when the nozzle was dipping to the heat bed during 49-point calibration, it left a small ball of filament at each point and thin line along the path. It happened twice times immediately after I installed the Revo. After leaving the printer alone for awhile, that problem disappeared by itself. However, sometimes before the printer starts making the prints, a small bit of filament hangs down from the nozzle.

By ‘strange sound’, it sounds like ‘ka ka ka ka ka….’

One thing I don’t understand is that if there is some mechanical problems with the printer, why not failing during the first few hours of printing but always fail after printing for 6+ hours?

 

How to check If there is a bad idler tension due to misadjustment or even something like a tension spring that's damaged or out of tolerance?

This post was modified 1 year ago by prusanewuser
Posted : 19/09/2022 2:15 am
Diem
 Diem
(@diem)
Illustrious Member

it left a small ball of filament at each point and thin line along the path

This can be symptom of damp filament.

why not failing during the first few hours of printing but always fail after printing for 6+ hours?

Filament can absorb significant moisture within that time.

it sounds like ‘ka ka ka ka ka….’

That's the sound @jsw was writing about; see his advice.

Cheerio,

 

 

Posted : 19/09/2022 6:18 am
Lichtjaeger
(@lichtjaeger)
Noble Member
RE: How to set to proper Idler tension of the i3MK3S+?

Posted : 19/09/2022 7:20 am
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE: How to set to proper Idler tension of the i3MK3S+?

 

Posted by: @diem

it left a small ball of filament at each point and thin line along the path

This can be symptom of damp filament.

why not failing during the first few hours of printing but always fail after printing for 6+ hours?

Filament can absorb significant moisture within that time.

it sounds like ‘ka ka ka ka ka….’

That's the sound @jsw was writing about; see his advice.

Cheerio,

 

 

OK. Do you know how to check a bad idler tension due to mis-adjustment and tension spring that's damaged or out of tolerance?

Posted : 19/09/2022 5:49 pm
jsw
 jsw
(@jsw)
Famed Member
RE: How to set to proper Idler tension of the i3MK3S+?

If the spring is the stock one that came with the machine, and you have not abused it, it's probably fine.  The test would be to use a new known-good one.

If it happens over time, and consistently, I'm wondering if you might have something with the machine that occurs when it's been running for a long time, such as a droop in the nozzle temperature, or maybe an undervolt or something.

It may even be something like scorched filament residue in the nozzle, where a piece breaks off and partly obstructs the nozzle after it's been good and hot for a while.

It could even be some slight dimensional changes in the extruder due to temperature, such as the extruder stepper getting warm and the extruder friction increasing, thus loading down the stepper and causing it to skip.

My gut says it's something with the hot end in your case.

If this were mine, I would take the steps to deal with a partial clog first, such as one or more so-called cold pulls, maybe combined with a good needling.  If that does not take care of it, I would probably disassemble the whole extruder and hot end and carefully inspect it to be sure that there's no friction involving the hobbed gears, no obstruction in the heatbreak or nozzle.

I know I've written in this forum about a frustrating filament flow issue I had with my other printer (Ultimaker), which uses a clip-in nozzle and heat sink assembly.  One of them had a low flow and cold pulls and needling did nothing to help.  After a few minutes of printing with that one, the flow reduced significantly and the print failed at that point.

I eventually disassembled that hot end assembly and found that the nozzle was filled with scorched filament crud which the cold pulls did not remove.  I had to clean the nozzle out with a drill bit to fix it.

Posted : 19/09/2022 7:11 pm
Diem
 Diem
(@diem)
Illustrious Member
RE: How to set to proper Idler tension of the i3MK3S+?

I doubt the spring is critical.  Show us the head of the tensioning screw if you're doubtful.

You will have a lot of filament powder in the bowden gears 'though, it must be cleaned out or it makes things worse.

Cheerio,

Posted : 20/09/2022 12:19 am
jsw
 jsw
(@jsw)
Famed Member
RE: How to set to proper Idler tension of the i3MK3S+?

I've seen so much filament residue in the Bowden gears that they are almost smooth, and they still pull filament through almost normally, that is until they don't.

I use a dental explorer to remove it, and disperse it with canned air (I really don't know a better way of doing that).

I know there are countless other things that are like that, meaning that they continue to (appear to) work under marginal conditions, until they don't.

Posted : 20/09/2022 12:26 am
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE:

 

Here are photos of the tensioning screw. I followed the guide and stop tightening it when the extruder was able to load the filament.

[img] [/img]

[img] [/img]

 

I am concerned about the invisible PTFE tube. Is it supposed to be visible? E3D suggested 10mm from the top of the V6 (the aluminum not the collet) as shown in Step. 11. 

Revo Six Prusa (MK3S+) upgrade guide – E3D Help Centre (zendesk.com)

How to improve the quality of your 3D prints on the Original Prusa i3 MK3? - YouTube (at 2:29, the one came with the original V6 is visible)

[img] [/img]

 

Somebody mentioned that he thinks he read somewhere that the short PTFE tube caused clicking sound.

This post was modified 1 year ago by prusanewuser
Posted : 20/09/2022 2:14 pm
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE: How to set to proper Idler tension of the i3MK3S+?

I noticed that several times right after I chose "Load filament" and pressed the knob on the control panel, I heard the clicking noise once. If I recall correctly, same for unloading.

Posted : 20/09/2022 2:22 pm
jsw
 jsw
(@jsw)
Famed Member
RE: How to set to proper Idler tension of the i3MK3S+?
Posted by: @prusanewuser

I noticed that several times right after I chose "Load filament" and pressed the knob on the control panel, I heard the clicking noise once. If I recall correctly, same for unloading.

I've never heard the clicking when unloading.

However, when I load a filament and previously had a higher temperature filament in there, such as loading PLA after printing with ABS, and I don't remember to preheat to the higher temperature, I will occasionally get some clicking and hesitation.

When I change filament, I always preheat to the temperature range of the higher of the two, and be sure to purge a few times so that the correct filament is in there all the way to the nozzle opening and will be what is printed on the prime line and first layer of the print.

Posted : 20/09/2022 3:15 pm
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE:

I just print PLA in an enclosure with a fan connected to a window. After I took the photos, I put back the tensioning screw. This time no click sound during Loading and Unloading.

>Maybe there's debris compressing the spring more than intended, causing too high tension.

The spring is clean. I didn't see debris nor abused it.

>Misalignment of the hobbed gears or friction of the idler gear can cause it.  Filament dust or residue in the hobbed gears can cause it as well.  I've had to clean mine >with a dental explorer on occasion.

The hobbed gears seem OK and clean. How to check friction of the idler gear?

>Any blockage or constriction in the hot end can also cause it.  A good sanity check is to release the idler tension, heat the nozzle up to filament temperature, and >manually push some filament into the extruder and watch it come out of the nozzle.  It should flow out of the nozzle, straight down, with modest pressure on your >part.

>If you really have to press to get any extruded filament, something is wrong.

I did not have to press to get the filament extruded. It did it by itself. Just tried to load again. With the Revo, even I cleaned the nozzle with a soft cloth just before I loaded the filament, short filament still came out from the nozzle. This caused the filament to form a loop before dropping straight down to the build plate. Tried it a few times. Same for all trials. 

 

>If the bead out of the nozzle veers to one side, you probably have a partially clogged nozzle.  In that case a so-called cold pull and/or needling will usually cure it.

So should I do a cold pull? Previously, I already used needle at 270c. 2-3 breads of filament came out with one popping sound. Also used nozzle cleaning filament to clean it several times. However, after cleaning, the printer still failed in long print jobs again.

The PTFE tube is always clean. I am a bit concerned of the shorter length (not being visible when I had the door opened) could cause issue. However, I could push filament straight down and the print jobs were working for a few hours before they failed, not right after I changed filament.

What should I check next? Shall I get a new PTFE tube but this time cut it at about 13mm long?

This post was modified 1 year ago by prusanewuser
Posted : 20/09/2022 4:02 pm
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE:

I got a reply from E3D in regard to failure in long prints and their suggested 10mm PTFE length in their upgrade guide. Are they telling the truth? I told them to give me a refund if they still could not solve my problems. Initially it took them about 2.5 weeks to reply for the issue of leaking during 49-point test. For the past few weeks, they made the Tech Support chat line unavailable.

Note that I installed the tube while on chat with them. I even sent them a photo to confirm proper installation (in this case, PTFE tube not being seen) and the same guy told me that I installed correctly. Not sure what "requested print test" they were talking about.

 

 

"Issues with print failure several hours into a print are very unlikely to be mechanical in nature like the PTFE tubing but more likely to be caused by buildup of temperature in the coldside of the hotend, also known as heat creep. This is why previous steps in troubleshooting have focused on the print temperature as lowering the print temperature will reduce the likelihood of heat creep. Could you please share the results of the requested print tests at the lower temperatures. Are there pictures from those tests that may help us determine the type of failure?  Can you provide the gcode from the print so we can look further into the settings and how things may have changed at the higher layer heights? As for the positioning of the PTFE tubing, the close you can get it to the gears without it being touched by the gears the better feedpath you'll have, however a tight feedpath like that should only effect the ability to print flexibles."

This post was modified 1 year ago 2 times by prusanewuser
Posted : 21/09/2022 1:06 pm
prusanewuser
(@prusanewuser)
Prominent Member
Topic starter answered:
RE:

In regard to leaking during 49-point calibration (the extruder left a small ball of filament at each dip down the heat bed. It also left filament along the trace of the moving path) , he wrote:

"the likely cause for the issues is just a little too much heat. Definitely make sure a PID tune is done, this helps adjust for the difference in how the the heater/thermistor cycle respond to changes in temperature.  As for the leaking during the 49 point leveling and the jamming, this is likely due to a little bit too much heat in the hotend.  The Revo is more compact and more efficient at heating the filament so you may need to lower your melt temperatures slightly (5-10C). This also explains the variation in it happening sometimes and not others.  "

This post was modified 1 year ago 2 times by prusanewuser
Posted : 21/09/2022 1:13 pm
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