EZ Extruder skips

[osr]

Hi everyone. I've had my Rostock max for a month or two now and it's getting close to becoming reliable. The problem I can't seem to solve is with the extruder. I'm printing with blue PLA from Seemecnc at 200C. Every few seconds during a print, it makes a clunking sound. Most of the time, it continues to extrude, but sometimes it doesn't. Sometimes it will restart on it's own after a layer or so, leaving a horizontal seam in the part. I've taken the clear plastic cover off to watch it carefully as it clunks, and it seems to slip off the filament and then turn backwards slightly to correct itself. This backward movement made me suspect the retract settings. The default speed was 30mm/s, which seemed fast, so I lowered it to 10mm/s. There was no decrease in the clunking, so I set retract to 0 to verify that it wasn't the cause. The next thing I checked was the gear itself. It was close, but not perfectly aligned with bearing. It had some plastic stuck to it too, so I cleaned it with a needle and carefully centered it on the bearing/filament. It did seem to improve, but only in that the frequency of clunks decreased from every 10sec to every 20 sec (not that they happen at regular intervals). I noticed that it tends to slip more at higher speeds, so I brought the infill down to 30mm/s from the default 60mm/s. This seemed to help, and dropping all speeds down to 20mm/s gave me almost no slipping. All this makes me think that there's not enough compression on that spring. I've thought about putting some washers under it, but I don't want to break that red arm. One thing I haven't tried adjusting is the stepper voltage. There is enough power to grind away the filament, and the motor doesn't seem very warm. I put a 120mm fan in front of the stepper drivers in case they were getting hot, but didn't notice a difference. Could I have a bad gear? It looks nicer than some of my hobbed bolts. I'm not at all happy with printing at 20mm/s. My Prusa prints nicely at 60mm/s perimeters and 90mm/s infill (I tried 120mm/s for the infill, but it started walking around on the table). I was hoping the bowden tube on the Rostock would let me go faster than that. Is anyone here printing at default speed or greater with an EZ extruder?

[foshon]

Make sure your steps per mm for the extruder are correct. I believe it falls around 96 for the EZ. I had a very similar issue with mine and solved it by lowering the stepper current in the firmware. My thinking is that with increase current, the hobbed extruder has enough arse to tear the filament, which explains the plastic in the bolt. After changing mine I went from having a EZ full of shavings with somewhat constant clunking to nice even extrusions. I believe I ended up with 135 for a current setting ymmv.

[bubbasnow]

I would suspect hot end temps. Try increasing by 5c and try a simple print. I do pla at 215c

[geneb]

The clunk sound is the audio element of the spring back caused by the compression built up in the bowden tube. If the hot end isn't hot enough it can't melt plastic fast enough to keep up with the extruder's feed rate. When it hits a certain point, the filament becomes a spring (in conjunction with the bowden tube) that overcomes the stepper motors ability to move or hold position. The clunk is the stepper motor being forced in reverse for a few steps. Put a flag of tape on the motor shaft and watch it. When you hear the clunk you'll see the tape quickly reverse direction.

g.

[dsnettleton]

PLA is finicky. I assume since you've got a Prusa that you'd know this, but I'll say it anyways. Make sure you have a fan pointed at the shaft of the hotend. Then get your temperature right. Too cold and your extruder skips. Too hot, same thing. The default steps/mm for the EZstruder are 92.4. Default motor current for the extruder is 225. SeeMeCNC just released a new "official" build of repetier firmware, which you can find on their github branch https://github.com/seemecnc/RostockMAX under the firmware directory. The "RepetierMAX" branch has been discontinued.

My recommendation for finding the ideal temperature is to hold that orange lever down and feed it by hand. Start at 165 or so and bump up 5 degrees at a time until you've stopped getting and major resistance. Then use that temp.

Another common cause of extruder skips (for me) is proximity to the build platform. This probably isn't your issue since you're getting skips on intermediate layers, but for the benefit of other board members, I should point it out. My Rambo board inexplicably resets the EEPROM settings to the firmware defaults, changing my max length values without my knowledge or permission. If this happens to you, and the values are close enough, it could go unnoticed. Then you'd be printing too close to the bed, and the extruder won't have the space it needs to push out more filament. Just another thing to keep an eye on. Nowadays, I just use my EEPROM for tweaking values, then reflash my firmware with the new values once I've found what I like.

[626Pilot]

My recommendation for finding the ideal temperature is to hold that orange lever down and feed it by hand. Start at 165 or so and bump up 5 degrees at a time until you've stopped getting and major resistance. Then use that temp.

This is similar to how I do it. There are three varieties of PLA, each with its own heat range (anywhere from ~170-230) and there are additives they put in for color or translucency or whatever which may also change it. Also, two spools from the same vendor don't necessarily have exactly the same heat range, so you may have to re-do this at the same time as you update the filament diameter.

I like to set the temp to 170, let it stabilize, then set it to 230 and feed filament through by hand as the temperature climbs. This gets me fairly close to the right temperature. It isn't necessarily perfect because the duty cycle on the heater is 100%, which can throw things off. After I notice the feed force has bottomed out and is starting to climb again, I stop there and reduce the temp by 10 degrees. I let that stabilize, then try the filament at that temp. Then I add 10 degrees and test again, then another 10 degrees and test again, each time letting the temperature stabilize. The temperature with the lowest feed pressure wins.

The other thing to do is make sure your heater block is not being washed by any cooling fans. If that happens the heating resistor will have to be on for longer in order to maintain the same apparent temperature on the thermistor. Inside the hot end, the actual temperatuere may be significantly higher, and that means it's either going to jam, or work fine for awhile and then jam (often just after a retract.) Use a fan shroud and make sure that there's no way for air to leak down from the shroud. I like to use thin strips of Kapton tape for this. You can also wrap the hot end in some kind of heat-blocking tape but I forget what it's called. However, you should button up the fan shroud first.

[Eaglezsoar]

It's called self fusing silicone tape.
Nice writeup on how to find the right temperature.
Sounds like it would be a good idea to maintain a spreadsheet of every spool
of filament that you have used and the temperature that worked best for that spool.

[626Pilot]

It's called self fusing silicone tape.
Nice writeup on how to find the right temperature.
Sounds like it would be a good idea to maintain a spreadsheet of every spool
of filament that you have used and the temperature that worked best for that spool.

I asked for a subforum for that but I don't think they did it.

[Eaglezsoar]

It's called self fusing silicone tape.
Nice writeup on how to find the right temperature.
Sounds like it would be a good idea to maintain a spreadsheet of every spool
of filament that you have used and the temperature that worked best for that spool.

I asked for a subforum for that but I don't think they did it.

A subforum where we can post info on the different manufacturers, type, color and temps
would be great if we can get them to create one and if our members would participate.
Consider this an official request for this sub-forum Ye Gods of SeeMeCNC!

[geneb]

There's this weird thing called a "wiki". It could be the perfect spot for stuff like filament test data...if only there was one just laying around somewhere....


g.

[Eaglezsoar]

There's this weird thing called a "wiki". It could be the perfect spot for stuff like filament test data...if only there was one just laying around somewhere....


g.

There's also this weird thing called a "forum". It could be the perfect spot for stuff like filament test data...if only there was one just laying around somewhere....

We don't want to end up like Makergear and have to dance between a dozen sites to find the info you need.

[dpmacri]

There's this weird thing called a "wiki". It could be the perfect spot for stuff like filament test data...if only there was one just laying around somewhere....


g.

There's also this weird thing called a "forum". It could be the perfect spot for stuff like filament test data...if only there was one just laying around somewhere....

We don't want to end up like Makergear and have to dance between a dozen sites to find the info you need.

I think there are benefits to both the forum and the wiki. IMHO, ongoing discussions are best for the forum, whereas tables and organization of information that results from those discussions is better placed in the wiki. Of course that's just my 2c (if it's worth that ). Regardless, I created a wiki page for this: http://wiki.seemecnc.com/Filament_Information

[osr]

Thanks for all of the suggestions. I am aware of the need for a PEEK fan. I have the 25mm fan wired directly to the 12v line from the power supply. I originally had it at 5v, and ruined a pnumatic fitting. I'm not using any other cooling fans. The first thing I tried was the temperature since it was the simplest. I am able to feed the filament by hand at 200c, and going hotter just seemed to give me more strings, but I tried 220c and 230c just to see if it would help. The slipping was unaffected. I am guessing that the PLA that See Me CNC sells is 4043. I usually print 4043 at 190c on the Prusa and set it at 210c for 4032D. Temperature doesn't seem to make a difference, so next I reduced the stepper voltage to 135 as Foshon suggested. The slipping didn't go away, but the clunk noise is much quieter. I'm hoping that reducing it further will do the trick. I am using the Repetier-MAX firmware, and my stepper voltage was set at 195 by default. Why would this setting vary so much?

[Eaglezsoar]

Thanks for all of the suggestions. I am aware of the need for a PEEK fan. I have the 25mm fan wired directly to the 12v line from the power supply. I originally had it at 5v, and ruined a pnumatic fitting. I'm not using any other cooling fans. The first thing I tried was the temperature since it was the simplest. I am able to feed the filament by hand at 200c, and going hotter just seemed to give me more strings, but I tried 220c and 230c just to see if it would help. The slipping was unaffected. I am guessing that the PLA that See Me CNC sells is 4043. I usually print 4043 at 190c on the Prusa and set it at 210c for 4032D. Temperature doesn't seem to make a difference, so next I reduced the stepper voltage to 135 as Foshon suggested. The slipping didn't go away, but the clunk noise is much quieter. I'm hoping that reducing it further will do the trick. I am using the Repetier-MAX firmware, and my stepper voltage was set at 195 by default. Why would this setting vary so much?

First let's get the terminology correct. You are not adjusting voltage, you are adjusting current going to the stepper.
Actually the setting doesn't vary that much. The settings as defaulted from the basic firmware are all set to 195 for
all the axis steppers and the extruders. That works fine in most cases but was done that way originally to support the
Steve's extruder. Now that we have the direct extruder the stepper for it does not require that much current but most
people leave it set at 195 because it does not cause them any problems. In your case you did experience problems so
you needed to turn the current down to 135. 135 should be where the current defaults to now that we are using direct
extruders but no one has changed the release and most have not changed it when they swapped out the old Steve's
extruder. The stepper should run quieter and cooler at 135 or even 125. I don't think I would go below 125 because
there is no benefit after that and it could cause the stepper to starve for current.

[osr]

Now that I think about it, the voltage shouldn't have to be changed. It's probably set in the middle of the acceptable voltage range of for the stepper motors. By lowering it, I dampened the clunking noise, which is a good thing. You don't really hear it over the motor noise anymore, and hopefully I won't have to explain to people why it's making all that racket so often. Next I adjusted the rest of the motor voltages a bit lower and brought the clunking sound back in to focus, but lessened the overall noise from the machine. The other effect of less extrusion power was that the quieter skips leave more filament out of the print. The frequency of skips is proportional to speed, so if my infill happens faster than my perimeters, the beads there are thinner than those in the perimeter. I set all printing to happen at the same speed, lied about the filament diameter to compensate for the skips, and got a pretty solid print at 30mm/sec. I guess that is the fix. So why is it skipping? I'm fairly certain it's lack of pressure between the bearing and the filament. If I pull up on the red lever, pushing the bearing harder on the filament, I can get it to stop. The only way I can imagine adding force is by putting a spacer under the spring, but the arm already bends when I pull on it. I don't see it getting any better. Am I the only one who's had this experience with the EZ extruder?

[osr]

Missed your last post. I meant to say the current.

[Eaglezsoar]

Missed your last post. I meant to say the current.

I wonder if you have a bad roll of filament?

[osr]

I'm almost to the end of my second spool with this machine, and it's been skipping since the beginning. I'm more familiar with the situation now, but I don't remember the first spool being much better than this one. It would be great if it just stops when I put in the next spool, but this one seems fairly accurate. My calipers say + or - .05mm.

[Eaglezsoar]

I'm almost to the end of my second spool with this machine, and it's been skipping since the beginning. I'm more familiar with the situation now, but I don't remember the first spool being much better than this one. It would be great if it just stops when I put in the next spool, but this one seems fairly accurate. My calipers say + or - .05mm.

Make sure that the drive pulley is aligned as close as possible to the center of the bearing. I would not fool with trying to increase spring pressure, you'll just increase chances of
breakage of the plastic parts. Ensure that there are no plastic bits in the teeth of the drive pulley and take a q-tip with some alcohol to clean off any oils that may be present.
You have already tried increasing temperatures so you are running out of options. My next step would be to replace the drive pulley. I think they are called Mark 7 drive pulleys
if you need to find one. A new one may have sharper "teeth" and grab better. I know that should not be necessary but I am just putting out ideas.

[osr]

I picked the plastic bits out of the teeth before I started testing today, but maybe a cleaning with alcohol will improve things. It has been shaving the filament for a while now and the edges could be gummed up. I know I have a magnifying glass somewhere. Thanks.

[foshon]

You could always try something crazy, like lowering the current. just saying.

[osr]

I have tried other current settings besides 135, down to the point where it won't extrude at all. It's a trade off between how much noise the skips make, and how much filament is left out of the print. I cleaned the gear with alcohol, and it skipped less for a while, until chunks of plastic built up on the gear again. I've got it printing better than it used to by entering a smaller than actual filament diameter. The problem with this is that it causes it to extrude faster and skip more. Through many hours of trial and error, I can now get solid prints at 30 mm/sec, and not terribly loud clunking during the skips. I'm not really happy with this though, and I intend to replace the EZ extruder with something else. I thought about replacing the gear, but I'd rather spend the time and money on a better design. My first thought is to go with a Greg Wade's, since I'm already familiar with making them work well, but there's not a good place to mount one. I've been looking at the airtripper design, and it seems to be a big improvement over the EZ extruder. I would just have to move the mounting tabs to work with the SeemeCNC bracket. I was about to get started on that, but it occurred to me that all the extra clamping force of the airtripper design would put more stress on the bearings in the stepper, which seems like a bad idea to me. This brought me back to the Greg Wade's extruder. I could probably get it mounted to that hanging bracket too, but I haven't thought of an elegant way to do so. I could mount it to the top plate, but I'd have to cut and drill the top to do it, and build a new spool holder. I think the best option would be to use the original side mounted extruder bracket. Does SeemeCNC still sell those? Why did they switch? It seems like the bends in the bowden tube would be much less severe with that setup. I could also put bearings on the spool holder, instead of just resting it on a piece of wood.

[geneb]

See the problem here isn't with the extruder, it's with your hot end. It's either too cold for the material you're pushing or you've got a partial clog in the nozzle.

The _only_ time the extruder will skip is if the back-pressure from the filament is too much for the stepper to overcome and the spring action provided by the extra filament in the bowden tube forces the extruder to rotate in reverse for few steps.

You can go ahead and replace the EZStruder with one that supplies more force, but that will only solve your problem until the constant high back-pressure causes one of the press-fit connectors holding the bowden tube to fail.

The way I see it, you've got four flat tires and you want to install a bigger engine because the stock engine can't make you go fast enough.

g.

[dpmacri]

The way I see it, you've got four flat tires and you want to install a bigger engine because the stock engine can't make you go fast enough.

g.

Wait, didn't someone tell me once, "Don't force it! Use a bigger hammer!"

I love your analogy Gene

[osr]

I thought my hot end troubles were over, but that could certainly be the problem. Soon after I first started printing with the Rostock Max, the pneumatic fitting on top of the hot end clogged with plastic. This was because I had the PEEK fan running on 5v instead of 12v. I have 5v fans on my other printers and incorrectly assumed that all tiny fans run on 5v. Soon after I got that fitting replaced, I had another clog because the PTFE tube inside of the hot end had apparently overheated and swollen up without appropriate cooling. I think the first replacement tube was a little too long and was being compressed, because it was difficult to feed the filament by hand. After carefully cutting a piece of tubing to the right length, I can feed the filament by hand pretty easily. The bowden tube offers some resistance, but when feeding filament directly into the top of the hot end, it feels similar to my jheads. I checked the tube again for any swelling, but it looks just like it did when I put it in there. Your four flat tires analogy describes exactly how I'm feeling about this printer at the moment. I would prefer not to replace the extruder or the hot end, but I feel like I'm out of options. Could the PTFE tube still be too long? I cut it so that the nozzle just touches it when fully screwed in. The back pressure doesn't seem excessive to me, but I don't have a feel for how much there should be.