Tag: 3dprint

These issues are easiest to identify on square parts. If you have mysterious blobbing on organic shapes, maybe try a cube test print to see if your printer has one of these issues on the corners. If you do end up with issues on your corners, and your printer has no other problems with printing, pressure advance (Klipper firmware) or linear advance (Marlin firmware) may solve your issue. Although they accomplish the task in different ways, both solutions solve the problem of issues with corners in 3d printing.

As a side note, when I am attempting to determine how accurate my machine is or to calibrate it, I first print a cube that I designed that has very large corner radii so that corner issues won’t bias my calibration.

If you spend any time reading through 3d printer help forums, it won’t be long before you see someone post about a problem that they are experiencing, to which someone else replies “you need to level your bed better.” But how good is good enough?

When it comes to 3d printer beds, I typically run into two variations:

  • 5 point bed level. This is a bed configuration that comes standard with many different firmware packages. It’s simple to set up and will give you pretty good results. The downside is that it doesn’t provide any flexibility in case your bed is warped in between the points. In doing some testing on this version, it seems like I started to have problems if my bed variance exceeded 0.05mm. Increasing my first layer height somewhat mitigated the problem, but didn’t solve it completely.
  • Mesh bed level. For this experiment, I used a 25 point (5×5 grid) mesh bed level. I allowed my bed variance to get close to twice my layer height, so for a 0.1mm layer height my bed variance was nearly 0.2mm. Then I set up my mesh bed level. I was able to see a slight difference in print quality near the base as the bed variance was increased, but it wasn’t significant. However, the differences that I observed were pretty minor and I believe that, in most cases, the resulting print would be considered “fit for use.”

Here is my recommendation. Get your bed as physically flat as you possibly can. See if you can get it to 0.05mm flatness. In most cases, this is possible as long as you have decent springs holding the bed up. Then run a mesh bed level to compensate for the variance that still exists. For most materials, I’m able to run prints without any hairspray, glue, tape, or anything else to hold the print onto the bed by following this methodology.

Some 3d printers end up with rough top layers. One thing that you can check if this happens to you is the rate of filament flow. Filament flow is affected by a couple of things, the most common issues are:

  • Flow rate setting in slicer. I normally set my flow rate to 105% – 110% for the first few layers, then turn it down to 100%. If this is set too high then your printer is adding more filament than you might need, resulting in a rough surface.
  • Extruder calibration. Run a simple extruder calibration to double check that you are extruding the amount that you think you are. If you are overextruding, you might be causing problems for yourself.

Although there are a couple of things that can cause parts to curl, I have found that it is usually related to the environment that the printer is in. If your parts initially print good layers, and then the print curls up away from the bed I would initially start to investigate whether the printer is in line with an HVAC vent or in a very drafty area. Ideally, put it in an enclosure.

I saw on a forum someone who was having problems with their mesh bed level. The advice that they were given was to disable the feature and use the screws tilt adjust features in the firmware. Here is what each of those features do.

Screws tilt adjust, in most firmware packages, allows you to set the distance between the bed and the nozzle. It does this in each of the four corners of the bed and in the center of the bed. The benefit of doing it this way is that it’s pretty simple to get started and the results are typically decent. No need to fix it if it ain’t broke. The downside of this method is that it assumes a pretty flat bed in between those points. If it isn’t, the firmware won’t be able to account for the variations simply because they haven’t been compensated. This was my situation. After replacing a warped bed a number of times I decided that it was time to do something different.

Mesh bed level. This method is more work to get set up, but it does account for a warped bed. To set up a mesh bed level, the firmware will allow the user to select a grid, usually 3×3 or 5×5. This grid is used to compensate for any warpage that may be present in the bed.

My typical approach is to mechanically make the bed as flat as possible. By adjusting the clamping pressure on each corner of the bed you can manipulate it to flex more. For now, don’t worry about the orientation, we’ll deal with that later. Once you get a bed that’s pretty flat, let’s go ahead and adjust the bed screws manually. Run the function to adjust the bed screws and make sure that your orientation is as good as you can make it. Next, adjust your mesh bed level. Some people do this before each print, I don’t. My environment is pretty stable so I just leave mine set up and run a mesh bed level from time to time.

A lot of times I’ll see someone asking for help online that goes something like this:

“I just changed the bed on my 3d printer to XYZ, bought a new extruder from LMNOP brand, updated my retraction, temperature, and speed settings, and now nothing works. How do I fix it?”

My advice to these folks is almost always to back it up a bit. What ends up happening is that they change so many things all at once that it’s impossible to tell which configuration change or setting change was the one that threw everything off.

I recently turned on and homed my 3d printer, only to find it grinding against the side shortly afterwards. Here is what I found. I did a quick check of my limit switches (seems to be a common cause) and found out that they are good. It turned out not to be necessary for me, but I could also have checked the voltage to the motors.

What it turned out to be was that the cable that provides power to the hotend fell down in front of the limit switch. Then when I homed it, the axis wasn’t able to reach the limit switch. The fix involved a quick zip tie of the cable harness to make sure it didn’t happen again.

Each 3d printer owner buys their printer for their own reason. Some of the most common reasons are that they enjoy making models or that they like to tinker and invent. I do both. I picked up a ceiling fan for $10. It was listed so cheap because it was missing a piece. A small plastic piece. Ha! I thought, this is perfect. I’m teaching my two boys about design, drafting (on paper) and cad drafting. This was a perfect real-world opportunity to have them put their skills to use. We looked up the OEM piece online, took some measurements on our parts to get the sizes right, sketched out some ideas on paper, then created some cad files. Bing bang boom! For about $0.05 we now have a working fan, but the lessons that they learned are worth so much.

After a while, things wear out on your printer. One item that is often overlooked is the connection on either end of a Bowden tube. If the teeth that hold the tube in place aren’t doing their job correctly, the tube can move back and forth as the extruder extrudes and retracts filament. The result of this is that you can end up with zits and voids in your final print.

To fix this, replace the fittings on either end first. If it still happens, replace the tube too.

Just like checking your oil and your tire pressure on your car every once in a while, you should run a quick check on the overall health of your printer from time to time, as well.

My preferred way to do this is to print a Benchy model. There are other torture tests, but once you know what you are looking for with this model, it can tell you a whole lot. It is not a diagnostic tool, in the sense that it will tell you what adjustments to make, but it does tell you if there is a problem so that you can do some additional investigation, if needed. Benchy features include, bridging, holes of all types and angles, retraction, fine details, etc.