- 06/19/2019 at 13:10 • 0 comments
05/13/2019 at 08:33 •
I'm at the point where I am satisfied with the state of my project. Sure, there are still a couple more improvements that can be made, but as long as it prints then I'm happy.
I still had to deal with a couple of problems that seem to have appeared suddenly out of the blue.
One problem I encountered was the motors suddenly started skipping. After weeks of using it, this only just happened now and it kept on happening. I looked into a lot of possible reasons but it ultimately pointed to the actual cause: the motors were turning too fast
Now this boggled my mind at first. I never changed the speeds and it worked perfectly. My hunch is that my motors may have deteriorated slighlty due to constant use that it cannot handle fast speeds anymore. I am not a hundred percent sure with this but things slowly break over time and this is no exception.
To fix this I have updated my firmware and set the maximum feedrates to an amount where there are no more skipping. I've also made sure that the current towards the motors are at a safe amount, around 200mA for axes with no heavy load (like the y axis), and 300-400mA for those that do (like the x and z axis).---------- more ----------
Another mind boggling problem was prints stopping mid print without any indication as to why. This happened multiple times at different points on the same print.
The head just stops at a certain position and does not move at all. If I try to move it from pronsole or pronterface the axes does not move. Turns out the print was still ongoing so pausing will let it move freely.
After lots of debugging I found that when the bug happens the last command that the pronsole sends is never acknowledged. Because there is no acknowledgement, pronsole just continues to wait.
My research says that this may be caused by a bad USB or electromagnetic interference. i think that the second one may be the culprit as my USB cable is all over the place. So i fixed the placement of my cable and the problem went away. Now this may also mean that it may also be a bad USB problem, moving it may have made the USB work better for some reason. So I am not discounting this.
Another problem i dealt with was that my prints were getting slanted as the z axis goes up. This was way more straightforward. My z axis itself was slanted and I fixed it by making sure that it isn't.
With all of the above getting fixed. I'm ready to call to call this project as done. At least, for now. I'll head on to a different project until I decide to come back and do an upgrade or improvement to this project.
Thank you to those who followed along!
05/04/2019 at 15:26 •
I managed to increase my machine's bed size from 35x35x35mm to 40x40x40mm. It may seem small but the 10mm increase in dimension is huge for me. Every millimeter helps!
It all started when I learned that there are stepper motor sliders similar to the ones found on CD-Rom drives but are longer. The screw length of the one below is 90mm, while the ones I found for my printer are only 50mm long.
This is when I realized that if the screw length of my sliders are supposed to be 50mm, why am I only able to print at 35mm?
I investigated my setup and learned that CD drives were designed to have physical endstops to limit the movement of the slider. I'm actually unsure as to the reason for this, my guess is so that the teeth of the slider that comes into contact with the screw would rest at a proper position that would not allow it to misalign. If this were the case, I don't think it would be an issue for me as I don't seem to get any problems even if I move the sliders past their limits.
So I cut off these endstops and the slider can now go way farther effectively making the range of movement up to 40mm.---------- more ----------
As to why just 40mm instead of the full screw length of 50mm, that is because the holder for the slider teeth itself is 10mm (The white part in the picture below). There's no way to get extra length out of this aside from making a slimmer holder, which I'm not so keen on doing at the moment. Even if I do that, the most I might be able to get might be an extra 1 or 2 mm. Which does not seem worth it for the amount of work.
If I want more space I might buy the sliders with the 90mm screw length. I'd have to gut and remove the CD-Rom sliders that I currently have now and replace it with that. It's tempting but it's not going to be easy as I also need to extend the base from where the sliders will be mounted on.
For now I'll be sticking to 40mm until the next time that I yearn for more.
Up next: Not sure yet, but maybe finally get around to improving the spool holder?
05/01/2019 at 11:24 •
I've been printing at a layer height of 0.2mm and it has been giving me good and consistent results. I wanted to find out how high a resolution my machine can reach so I've done some tests to find out.
The picture above shows three test prints. From left to right 0.2mm, 0.175mm and 0.15mm. You would need to look at the object closely to see the differences between the prints. 0.15mm is definitely finer which makes it perfect for small scale objects like the one I designed below:
I tried lowering the layer height to 0.125 but the extruder was not extruding anymore. I reckon that the finer movement required to extrude such a small amount could not be achieved anymore by my cheap knockoff stepper motor. It may also be possible that the retraction distance and strength might be sucking the pressure too much that the extruder could not get the pressure back. I'd definitely be looking into this again in the future. Right now I'm actually quite happy with a 0.15mm layer height.---------- more ----------
Thanks to the improvements that I made before (details in the last project log), my machine can now run reliably with minimal monitoring on my part. Prints form before were failing quite a lot because of various factors. I constantly had to deal with filament getting tangled in the spool, warping, and sliding layers. These problems don't happen anymore and I could now leave the printer alone and come back after it has finished.
The print in the picture above, took three and a half hours. The longest print time that I've attempted.so far in this machine. It's a nice feeling to not have to worry too much.
I also salvaged two limit switches from an old inkjet printer. One was an optical switch, the other mechanical. I tried hooking up the optical switch but I could not get it to work. It's possible that it only works with the inkjet's motherboard. I think I broke it though as it caused a spark in my Ramps board. The board is still fine, thankfully.
This leaves me with the mechanical switch above, which works accurate enough from what I could tell. I was not sure how to mount it yet so I just taped it up so I could easily move it to different positions. Will definitely make a better mount for this as soon as I find the best place to put it.
Up next: Improving the current spool.
04/29/2019 at 15:36 •
I was afraid of getting tangles because my filament spool was getting loose, so I decided to fix it by untangling the filament and carefully wrapping around the spool again. Sadly, I wasn't careful enough that I ended up with the mess above. Took me a whole hour (and an aching back) to get the mess sorted out.
I decided to 3D print myself a filament filter to filter out dust and body oils that I have introduced while wrapping the spool. Not sure if it would work but the idea is sound and I needed another thing to print.
I also finally got around to changing the printbed as the old one, seen below, was already a bit worn out.
The new one is cut from thick acrylic which is stronger and is more resistant to burns. It's also red and transparent which makes it stand out from the dull gray and metal motif that I had before. I found out early on that filament is harder to remove because of it's smooth surface so I bought a couple of glue sticks to put on the bed so they can be easier to remove.---------- more ----------
I also cleaned up the wirings as things were getting tangled everywhere especially when I try to move stuff around. I've wrapped wires in heatshrink which I have a lot of. I'm glad that I'm finding more and more use for heatshrinks as I make more projects.
Finally, probably the best improvement that I have done so far was that I ditched the old spool holder that I had in favor of a hard drive bearing. There's nothing much to it aside from the spool resting on top of the plate but it works great. Now my extruder does not have to exert too much effort just to spin the thing.
I'll definitely make something to keep the spool in place. But right now it works so I'll leave it like this for now.
I've done a lot of improvements to the project over the past few days and I'm really happy how things are improving. I have more ideas that I plan to implement but that'll be for next time.
Up next: Pushing for a finer resolution
04/27/2019 at 16:12 •
I have narrowed down the cause of the constant hotend clogging to a loose bowden tube coupling. Because of this the tube eventually gets tugged out of place leaving a gap inside the hotend throat, which then causes a clog.
Thankfully, there's a fully printable replacement which has a better design and fits perfectly to my hotend.---------- more ----------
After this I went nuts with printing.
04/25/2019 at 02:17 •
One problem that became glaringly obvious as soon as I printed a torture test object on my printer is the abundance of strings similar to the one found on my previously printed frog:
I printed a pillar test and found out just how bad it was.
Initially I thought strings are not a big deal as they can easily be cut off. But turns out they can be a huge headache if left unchecked.---------- more ----------
Stringing is caused by filament oozing out while the printer is doing a non-print move. Fixing this should have been as easy as increasing the retraction distance but I'm using a chinese knockoff of a bowden style hotend where too much retraction could lead to a jam.
Jams did happen a lot which forced me to keep the retraction distance at a low number (Not exceeding 5mm) and finding a fix elsewhere.
The retraction speed was the next logical place to check. I slowly increased the speed by small increments starting at 20 mm/s to 100 mm/s. The theory was that the fast retraction would quickly release the pressure in the nozzle causing it to not leak. This did not have a noticeable improvement, but I had the suspicion that it'll work well with other settings so I kept it as is.
I tried lowering the temperature to prevent oozing while idle. This helped reduce the ooze a bit and it also made me realize that I've been printing at a very high temperature before. I've since then reduced my operating temperature from 220 to 190/195. It still not enough though.
I've read somewhere that increasing the non-print speed to an insanely fast number would make it so that the ooze won't have time to spill out. This makes sense but my printer could not handle very high speeds without sacrificing quality.
I tried lowering the extrusion multiplier as I thought it would mean a lower filament flow but this just affected the overall quality of my prints. I left this to my previous setting of 1.
I also tried lifting the nozzle while retracting which was good for fixing blobs that forms on the sides but still did not prevent the oozing.
Fixing this problem took a lot of time and filament. I was ready to throw in the towel but thought of increasing the retraction distance just a tad bit just as a last resort. At this point I was willing to risk another jam, I was all out of options anyway.
And of course, it worked!
There are some strings but they are very thin and barely visible that they can be easily be fixed with a heatgun. I'd consider this a big success!
Up next: Fixing the jamming once and for all.
04/23/2019 at 00:43 •
Since the printer can now print objects properly, the next step is to do advanced calibrations using this guide.
Here's the video of final result after all the calibrations. I never thought I'd reach this level of quality, to be honest.
The print uses 0.2mm layer height resolution and you can still easily make out the layers. The advanced calibrations went through various factors like optimal temperature and speed, extrusion multiplier, retraction distance, and handling overhangs. It's rather extensive and the results are very noticeable as can be seen below:
The above shows the before and after. If you would look closely the resolution of the second one is better as it uses a 0.2mm layer height. It also printed faster too thanks to the increase in speed. The first one took around an hour while the second one took 20 minutes.---------- more ----------
Here are all the results of the calibrations:
One thing that I had to dial down a whole lot after the calibrations was the speed. While my printer can handle speeds up to 40 mm/s, the motors sometimes skips especially if ran for longer periods of time. Plus, higher speeds might also have a negative effect on the health of the motors.
Aside from software calibrations, I also did improvements to the hardware itself. I cleaned the hotend to prevent filament from oozing, I slapped some heatsinks on the motors, loosened the slack on the bowden tube, and improved the setup and orientation of my spool holder. Each may seem trivial but they also contribute a lot to the overall quality.
Here's an almost perfect calibration cube thanks to all the optimizations above.
Up next: Torture tests!
04/20/2019 at 14:20 •
Behold, the result of countless hours of calibrations, problem solving, and wasted filaments:
It's not perfect yet. But it's the best out of all the tests I've done so far. Look at all the other failed attempts.
I knew going in that calibration would be challenging, especially for a home made 3D printer. I had to go through a lot of options both through firmware and slicing program to get to the result above. It's cumbersome but very enlightening to be forced to understand every bit of the machine you are learning.---------- more ----------
The first lesson that I learned is just how hot the hotend can become. At 200 degrees Celsius it's enough to melt the heatbed and make fingers sore for a few hours. This meant being extra careful around the thing and making sure that it's off when it needs to be off.
The picture above shows the first three prints that does not resemble a string of spaghetti. As you can see I've experimented with a lot of settings each giving me wildly different results. This really taught me just how important understanding what each setting does. I had to do research and tried printing it out so I could compare the results.
I also experienced my hotend clogging up. This forced me to open it up and I got real familiar with how it works and how to properly set it up to avoid future clogging. It has not clogged since. Tip: Depending on the quality of your hotend, the filament might not slide inside quite easily if you feed it through. A better approach is to have the filament already inside the tube when assembling the hotend.
One problem that took a long time for me to figure out was the the infills are getting more filament but only on the second layer onward as shown below. Notice how there's a mound of filament on the top left which the nozzle eventually bumps and ruins the rest of the print.
This had me testing out various settings like extrusion multipliers, layer combining, layer heights. After many failed tests I learned that I was using the incorrect steps per unit for my extruder making it extrude a lot more than it was supposed to.
So the calibration cross that I thought was good was actually overextruded. The correct width of the line was supposed to be thinner like the one on the right. Putting in the correct values solved the issue and actually made all my prints better!
If you would look at the first picture in this post, it's obvious that there's still a lot to be done. One obvious one is the failed placement of the top part of the hollow cube. I think it has something to do with bridging which I think is already a difficult problem to solve. I also need to figure out why some Y layers were displaced resulting in a slightly skewed vertical wall. The hotend also oozes out extra filament which eventually drops onto the print and causing problems.
Having gone through all of the above, I now feel confident that there would be less difficulty in fixing the machine if any problems arise in the future. I guess this is what it feels like to be intimately connected with a machine.
04/17/2019 at 05:04 •
Today I focused my attention on making sure that the printer can properly draw an image onto paper using a pen. I figured that this is an important step that would help weed out problems early. And it did. Lots of them.
One problem that I noticed late was that one of my axes are actually flipped. It was only when I tried printing a word did I notice it.
That's supposed to read "Dianne".
This was easily fixed by changing a setting in firmware that sets if an axis is inverted or not.
You will also notice that there are extra lines that the printer draws to get to one point to the next. These are supposed to be non-print lines where the hotend does not extrude filament. Since I'm using a pen I had to manually add gcode before and after these non-print commands to raise and lower the pen when needed. The solution worked beautifully but is useless once I do use an hotend.---------- more ----------
Another problem I had to deal with was leveling the bed. My design doesn't have a fancy auto leveling system so I'm doing everything manually. This meant checking all four corners by eye with the aid of a magnifying glass, and adjusting nuts and bolts all over just to get the perfect level. It's frustrating but is satisfying when the expected results are met.
It took a lot of time, ink, and paper but it was all worth it. Watch the machine print out "Mahal kita, Dianne", it's Tagalog which translates to "I love you, Dianne" in the video below (Pardon the cheesiness, I want to impress the missus :P)
You will notice though that the printing head moves all over the place. This is because the file I used to make the gcode is not optimized for printing as a 2D image. Will try to look for an optimized image to print next time.
I learned a lot from this step which made me more confident when the time comes that I actually need to use a hotend. Which is what I'll be working on next.