Problem with the extruder not "rising" far enough, and a few other newbie questions

Hello,

I've finally finished building my first 3D printer (Maker Farm Prusa i3) today. I have adjusted all motors and leveled the bed following the instructions from [reprap.org]. I tried to print the first shape called "Hollow Cube" (attached)... and the results are not pretty at all...

1. First of all, it seems like there's some delay with extrusion. No melted plastic comes out for the first inch or so, and then it starts coming out with a little bit of blob. This blob sometimes gets in the way and knocked down by the extruder later, which results in shifting of the printed object. I can see the extruder gears are moving, however, I just don't see any extrusion of the plastic for the first few seconds...

2. Funny enough, after the printing is done (extruder motor stopped moving), the extruder continues squeeze out the plastic. It's a good inch or two, just like it's trying to compensate the delayed start. Is this normal?

3. What bothers me the most (for the moment) is that it seems like the extruder is not rising high enough during printing.

The inside of the object I'm trying to print, "hollow cube", is not really hollow, but it has some pores rather. To make the inside "hollow", I believe the printer stops and starts extrusion while the extruder is moving back and forth (diagonally) or it weaves some pattern moving the extruder in some kind of zigzag motion, when filling up the inside of the cube. Whether it's doing repetitive stop and go or zigzag pattern, it sure makes a lot of noise.

While it's doing that, I can see that the tip of the hot end is digging into the lower layers. Naturally this gets worse as printing progresses, and later it gets really messy that the bottom of the hot end is totally covered with half melted plastic and it starts knocking the object out of the place.

4. I wonder if it's not really a problem with the extruder not rising far enough necessarily... because the outside wall looks nice and I don't think the upper layer pressing down the lower one there... Having said this, I can think of a couple of reasons;

1) A problem with the extrusion rate or control. Maybe too much plastic is squeezed out while filling the inside?
2) Too much vibration with the extruder. Actually, I can see the extruder motor shaking a lot. Is this normal for the extruder vibrate this much?


Any advice?


Thank you!

I've been checking the cube, and It is hollow.
I Already printed this cube, and was perfect.
The problems you found, may be due to bad configuration of your
software, with which you are working.
Can you report what software are you using?
If you are using the pronterface software with skeinforge, I suggest you choice the 'Starting Point Profile' for your first test prints. I think it could solve the most issues that you described.
Verify the hotend temperature. In major cases of bad prints, it is the "bad guy".
The vibration of the extruder..,well, I did not have this problem. In my printer, the extruder is fixed to the frame and connected to the hotend with Bowden cable.
you can visit my page and see the photos of my printer: [antoniorodriguescom.wix.com]


I hope that this it was useful.

Edited 2 time(s). Last edit at 07/19/2013 10:32AM by novato.

Thank you for your reply.

I am using Pronterface. The shape was sliced using Slic3r into G code, which was loaded to Pronterface and then sent to RAMPS. I used the Slic3r configuration file provided by the vender (Maker Farm), so I think all the parameters should be correct for my specific printer.

I will check the extruder unit later today to see if there are any loose connections which causes the horrible vibration.

Other than the vibration, there are a couple of things I suspect, and one of them is the hot end temperature as you have suggested. I wonder if the hot end temperature setting is too high, which affects the extrusion rate. I can certainly test it out with varying the hot end temperature setting by 5 or 10 degree.

Another thing I am wondering is the software/shape problem, which is another thing you suggested... When yous aid the cube is "hollow", did you mean there's nothing inside of the cube (totally empty) or inside was sparsely filled? I believe it's the latter.. I was able to find a video footage on YouTube, which kinda confirms it: [www.youtube.com]

One thing I notice during my printing process is that... when things start getting messy (when the hot end digging into the lower layer) the printer draws a smaller square - like an internal square for filling, which should go inside of the outer walls (therefore a bit smaller). However, it does not print that smaller square in the center, but against one corner instead. In other words, two sides of this smaller square is on the same line with two sides of the bigger square...

Well, I hope I could explain it a little better.. but what I am thinking is.. if there's something wrong with the slices.. like some of them have wrong coordinates for whatever reason, and they are printed in a wrong place. That would definitely mess up the printing...

Is there a way to check the coordinates of each slice?

Thank you.

Having the same problem....

A video of the print would be useful

---

_______________________________________
Waitaki 3D Printer

Registered to reply here. I also recently built a MakerFarm i3 and I think I can help a bit here!

I had the same problem with my Z axis not rising enough. On some prints, they'd finish properly but would be too short (my 25mm cube was 22mm tall). On others, I'd end up with a huge melted blob of plastic on top as the nozzle dragged through the previous layer. Sounds like your exact problem.

I ended up emailing Colin at Makerfarm, and he suggested I go into the RAMPS firmware and change the Z speed to 2 (default is 5) and acceleration to 10 (default is 20). Basically, the motors can't actually achieve the higher speed, so the printer thinks the carriage rose higher than it actually did. If you change these settings, I think you'll immediately see better prints.

Let me know if you need help changing the firmware--I'd be happy to point out the exact setting if you aren't able to find it.

waitaki Wrote:
-------------------------------------------------------
> A video of the print would be useful


Yeah... I actually shot a few video footage but wasn't able to upload them because their size was too big. What would be the best way of sharing video? I've seen some other people posting video on their own blog, but I don't have a setup like that...

DManTech Wrote:
-------------------------------------------------------
> Registered to reply here. I also recently built a
> MakerFarm i3 and I think I can help a bit here!
>
> I had the same problem with my Z axis not rising
> enough. On some prints, they'd finish properly but
> would be too short (my 25mm cube was 22mm tall).
> On others, I'd end up with a huge melted blob of
> plastic on top as the nozzle dragged through the
> previous layer. Sounds like your exact problem.
>
> I ended up emailing Colin at Makerfarm, and he
> suggested I go into the RAMPS firmware and change
> the Z speed to 2 (default is 5) and acceleration
> to 10 (default is 20). Basically, the motors can't
> actually achieve the higher speed, so the printer
> thinks the carriage rose higher than it actually
> did. If you change these settings, I think you'll
> immediately see better prints.
>
> Let me know if you need help changing the
> firmware--I'd be happy to point out the exact
> setting if you aren't able to find it.

Wow... this sounds very promising. Also, I really appreciate that you registered to reply!

To change these settings... I'm guessing I need to change the following lines in Configuration.h file:

from..

#define DEFAULT_MAX_FEEDRATE          {500, 500, 5, 45}   
#define DEFAULT_MAX_ACCELERATION      {9000,9000,20,10000}

to..

#define DEFAULT_MAX_FEEDRATE          {500, 500, 2, 45}   
#define DEFAULT_MAX_ACCELERATION      {9000,9000,10,10000}

And then repeat the same steps I took for uploading the firmware to RAMPS. Is that right?

Wow... that was it! Thank you so much, DManTech!

After reloading the firmware with those two parameters changed now I no longer have the problem with the hot end digging into the lower layer.

A couple of notes on this (for future newbies who may run into the same problem)

1. When I tried to change the Z motor movement settings, I did not know I had to recompile the code. I just changed those values in Configuration.h file and uploaded the firmware, and still had the same problem.

2. After this fix, interestingly enough, I no longer see the printer drawing/printing a "smaller square" any more (which I've mentioned in my July 19, 2013 12:51PM posting in this thread). It's like the hot end was "grabbed" by the lower layer when it dig in, and that grabbing was powerful enough to cause the printer to lose the actual location of the extruder/hot end or something..


I've also tighten up all the bolts and screws used for X axis and the extruder unit - none of them was really loose, but I was still able to give the most of them an extra turn or two before getting too much resistance (it's always hard to know when to stop exactly when you are dealing with screws on wood).

The extruder still vibrates and shakes, but I think it's doing that slightly less than before. When I look at the extruder design, however, I can understand why it would shake this much. The butt end of the motor is sticking out to front, and it's at the furthest point/opposite side of two rods on which the extruder unit ride. As the motor is the heaviest component in the whole unit, there must be quite a bit of gravitational force dragging the extruder unit down even when it's not in motion.

Maybe I can redesign/rebuild this extruder unit as my first real 3D printer project If I can just make the motor's butt end face side way instead of the front, or make it face down (so the butt end would face the sky), I should be able to bring the center of the mass closer to the rods, which should make it less prone to vibration/shaking.


Anyway, once again thank you DManTech and everyone else who commented on my posting and responded! To show my appreciation, I've attached some pictures of the cube I just printed. Yes, my first (not counting the failed attempts) 3D shape! I am pretty sure there are a lot of things I can/should improveme, but getting this far still was a very significant achievement for me.

Have a nice day!

Awesome! Glad that worked. I was really frustrated when it was happening to me too, and I thought the fix was going to be a lot more complex than it was.

Your bottom layer looks pretty thick--how much distance do you have between the nozzle and the bed?

I'm still new to this as well, but tweaking the settings is really fun in my opinion. I like your idea about changing the extruder so the motor doesn't stick out as far; I'll be interested in seeing what you and others come up with to reduce the stress that adds to the system.

Have fun printing!

Quote
Yamster
Yeah... I actually shot a few video footage but wasn't able to upload them because their size was too big. What would be the best way of sharing video? I've seen some other people posting video on their own blog, but I don't have a setup like that...

Ever heard of YouTube?

You upload it to YouTube (you need an account) and can then embed it in a post (or simply post the URL to the video).

---

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Yamster Wrote:
-------------------------------------------------------
> DManTech Wrote:
> --------------------------------------------------
> -----
> > Registered to reply here. I also recently built
> a
> > MakerFarm i3 and I think I can help a bit here!
> >
> > I had the same problem with my Z axis not
> rising
> > enough. On some prints, they'd finish properly
> but
> > would be too short (my 25mm cube was 22mm
> tall).
> > On others, I'd end up with a huge melted blob
> of
> > plastic on top as the nozzle dragged through
> the
> > previous layer. Sounds like your exact problem.
> >
> > I ended up emailing Colin at Makerfarm, and he
> > suggested I go into the RAMPS firmware and
> change
> > the Z speed to 2 (default is 5) and
> acceleration
> > to 10 (default is 20). Basically, the motors
> can't
> > actually achieve the higher speed, so the
> printer
> > thinks the carriage rose higher than it
> actually
> > did. If you change these settings, I think
> you'll
> > immediately see better prints.
> >
> > Let me know if you need help changing the
> > firmware--I'd be happy to point out the exact
> > setting if you aren't able to find it.
>
> Wow... this sounds very promising. Also, I really
> appreciate that you registered to reply!
>
> To change these settings... I'm guessing I need to
> change the following lines in Configuration.h
> file:
>
> from..
>

> #define DEFAULT_MAX_FEEDRATE          {500, 500,
> 5, 45}   
> #define DEFAULT_MAX_ACCELERATION     
> {9000,9000,20,10000}
>

>
> to..
>

> #define DEFAULT_MAX_FEEDRATE          {500, 500,
> 2, 45}   
> #define DEFAULT_MAX_ACCELERATION     
> {9000,9000,10,10000}
>

>
> And then repeat the same steps I took for
> uploading the firmware to RAMPS. Is that right?

Well.. I don't understand..
my configuration.h has:
#define DEFAULT_MAX_ACCELERATION
> {9000,9000,100,10000}
It is a big difference, and not have these problems.

ya mine has 100 also (latest marlin) .. i put it at 10 and will print somthign smalll , then back to 100 and print again and possably do 200 and see the differances .. because it's a MAX i dont think it will make a differance , it think thats just to limit the unit from hurting it's self .. i also have a prusa and marlin is setup for ultimaker when you just grab the code and changing a ton of stuff isnt new to me.

Edited 1 time(s). Last edit at 08/06/2013 01:13AM by lucindrea.

Hi, i´m also new to the 3d printer bussiness. I build a makerfarm prusa i3 since last week.

But i think i have an answer for the shifting layer problem, or motors that did not move enough. You solved it by lowering the acceleration, that is one way. But i think the problem is that you have to increase the current to that particular motor. Just a little bit. By lowering the acceleration, you need less current.
I had the problem that after a few layers the layer shifted 20 to 30mm in the +x direction. I just increased the current a little bit after this no problem with this.

These settings can be measered: [www.solidoodle.com]

I hope i helped a little bit.
I´m learning a lot from these forums

This thread has been dead for months, I doubt anybody is still looking for a solution. You probably will get better traction with a new thread.