Tag: 3dprinting

If you 3d print for any length of time, things will eventually start to get loose. One of the things that people often have questions about is how to tighten up the print head. It’s a pretty straightforward process, once you know how it’s put together. The roller bearings that most manufacturers use have an off-center hole. This is done intentionally, so that the bearing can be rotated to tighten or loosen. 

The process is to loosen the bearing(s) slightly, then rotate it until you have a snug fit between it and the rail that it rides on. Then tighten it back up. I typically check my bearings for fit when there is a significant weather change, when I have a crash, or if something just feels “off.”

Sometimes, the extruder will start clicking and the filament will stop feeding. This can be a couple of things, I usually start my diagnosis on the hotend, as that is most often where I have found the problem(s) to lie. In my experience, it usually means that I have some type of clog on the hotend side that needs to be cleared.

To clear things up and get printing again, I usually do a cold pull. Then I snip off the first 25mm or so of the filament to make sure that I’m not reintroducing some contamination to the hotend. Then I heat the hotend up to about 20 degrees hotter than my print temperature and make sure that I heat tighten all of the hotend components to make sure that there aren’t any gaps anywhere.

I had a fun project that I did a little while ago. I made a jewelry box for my wife. I bought some wood PLA. After a little bit of testing, I decided that I wanted it to have that wood grain look and so I did some research into finding out how to do that. I found a script on Thingiverse that varies the hotend temperature within a range while it is extruding. This had the effect of turning the filament darker at higher temps and lighter at lower temps, giving my jewelry box a woodgrain appearance. Give it a try if you have any wood projects coming up.

https://www.thingiverse.com/thing:49276

I relearned something important over the Christmas break that I had forgotten. The word “At.” All of your settings only apply at specific temperature, retract settings, etc.

I increased my temperature, but didn’t change anything else. I know better, but I did it anyway. Oh well. Sometimes it takes a few times to learn a lesson. My print started stringing like crazy. The science of what was happening is simple in hindsight. I had all of my retraction set up for a particular printing speed, specific extrusion values, temperatures, retraction settings, etc. When I increased the temperature, it created a situation where my filament became more molten so it was oozing out of the nozzle and stringing everywhere.

I needed to tune my printer to the new settings. Live and (re)learn.

In the help forums, I see a lot of people asking about supports. How close they should allow them to come to their main print structure, speeds, etc. I don’t have a standard answer for this question. I’m usually most concerned with cosmetics when I’m printing figurines for my boys. The underlying issue is that supports that are too close (or touching) the main print will cause surface imperfections. This isn’t something that I’m normally concerned with when I’m making some type of prototype of something as much as when I’m making figurines.

For figurines, I usually make sure that my machine is really dialed in. A temperature tower and a retraction tower don’t take a lot of filament or time. Making sure that I have a solid bed level and printing out a test print to make sure I have a good solid bed level are pretty quick too and save a lot of headaches later. Once I’ve done that, I usually work with around 0.5mm clearance for X and Y axes and 0.25mm for Z. Your results may vary.

I was reminded recently that temperature and retraction are closely related. I had run a retraction tower and dialed in my settings. Then I ran an actual part in Cura and kept getting stringing. Turns out that I needed to run a temperature tower, then rerun my retraction tower. It’s an iterative process. Setting retraction, but then increasing the temperature (like I did) will cause the filament to ooze out of the nozzle and give you stringing, despite having the proper retraction settings.

 

If you do much with a 3d printer, at some point you will need to head out of the house but still want to monitor your printer’s progress. There are a few ways to do it. I’ll tell you how I have my printer set up for this.

A few years ago I tried Octoprint on a Raspberry Pi, which was configured and connected to my printer with an attached camera. I used Octoprint to manage my printer and all of my gcode. It did a fine job, to be honest, and I don’t really have any complaints except that Octoprint feels “heavy” and sluggish.

At some point I found out about Klipper. I set it up one day to give it a try and I’ve stayed with Klipper ever since. It provides all of the tools that I need to monitor my printer and to manage my printer. It also provides me with an upgraded firmware that seems to give me better print results.

I’ve only been able to get Klipper to work on my home network, so I wasn’t really able to monitor my printer if I had to run to the grocery store for a minute. I found a telegram plugin that allows me to communicate with the printer from my cell phone, even if I’m not home. 

I’ve seen too many printers pulling up pieces of their bed along with their print when they go to remove it. There isn’t much you can do about the damaged bed, but you can prevent it from happening again in the future. I have found that such aggressive bed adhesion often is the result of too much “squish” in the first layer, temperatures being too high, or a scored bed surface.

  • Wait until the part and bed are completely cool before attempting to remove. Don’t do what I did when I first got my printer and take a spatula and try to force it under the print to remove it as soon as it says “printing 100% complete.” After the part and bed are cool, if it still doesn’t come off easily, I use compressed air sprayed at the base of the part. It is cold enough coming out of the can that it causes the part to shrink away from the bed and separate.
  • Adjust your temperatures. 
  • Take good care of your bed surface. Use isopropyl alcohol to clean it with lint free cloth.

I talk a lot about getting the most out of your 3d printer. But, how do you know if your 3d printer is capable of doing the job? Sure, if you are making a Christmas tree ornament, who cares if it’s an extra 0.5mm too thick? What if you are making a functional assembly? Or, what if you are building a prototype for a component that needs to fit inside of a housing? Is your machine capable?

One way to know for sure is to do a quick tolerance analysis. Rather than looking at the machine capabilities only, you can now design with certain tolerances in mind. Based on what you know about your machine variability, you can design components so that, even with the variability from your process, you can still make parts that will fit. Or, you can know if your machine is incapable of making the parts you need, in which case you need to come up with an alternative manufacturing process.

Have you ever looked at your 3d print and wondered what those little patterns are in the sides of your print? It’s possible that they are artifacts from resonance in your X and Y axes. Resonance, meaning that your axis is vibrating, which means that your nozzle, which rides on the axis, is also vibrating, which means that you are transferring those vibrations to your print.

There are a few things you can adjust.

Most printers have off center holes in the bearings that the axes ride. This is done intentionally, so that you can adjust the tension. Make sure that your bearings are tight. Make sure that your belts are tight too. Try wiggling the motors, the print head, the bed, and the vertical supports. 

What does this have to do with resonance compensation? I’m a believer that you can’t solve a mechanical problem with software. If something is loose, don’t try to apply compensation, fix the problem.

Even after you have a mechanically solid machine, however, you will still have some resonance remaining in the system. I believe that this is what resonance compensation is for, not to mask underlying mechanical problems.