Tag: 3dprinting

Every once in a while, I am asked by someone about what their acceleration should be set at. My answer, as in so many cases, is “it varies.”

If you go too low, you won’t necessarily hurt anything, but your prints will take forever. If you set acceleration too high your belts will jerk abruptly each time the axis changes direction and you risk skipping teeth on the belts and getting layer shift.

I’ve run tuning test towers, and I know that my printer starts to have problems around 2,500 or 3,000 mm/s². It skips teeth and my layers end up all over the place.

Unless you want to do a tuning tower for each print (not practical) you are better off doing a little educated guessing based on what you are printing. 

For small, intricate, parts I set my acceleration low. Somewhere around 500 mm/s². For larger parts that don’t have a lot of detail, I might set at 2,000 or 2,500.

Maybe this is an unpopular opinion, but I don’t think it matters a whole lot for small parts. When you do a 3-point turn in your car, your acceleration doesn’t matter much. You are changing direction too frequently for it to even matter. I don’t have scientific data to back this up, but I would guess that it takes a Ferrari about the same amount of time to do a 3-point turn as my Dodge Dakota. If someone has a Ferrari they want to let me borrow to do that test, I’m game. The same is true on your 3d printer when you print small parts, so your acceleration doesn’t matter a whole lot.

As the temperature outside gets lower, I’m seeing an increased number of asking on forums why their prints aren’t sticking to the bed properly. In addition to all the normal reasons why your print might not stick to the bed, cold weather presents a few additional challenges.

 

For starters, most homes aren’t airtight and many have drafts. A sudden burst of unexpected cold air on your print can cause it to shrink away from the bed and lift off. 

 

Be careful of where you have placed your printer. Is it in front of a HVAC vent?

 

Your heater has to work harder to get up to temperature and maintain temperature. Make sure you have done your PID tuning and I usually increase my temperatures by a couple of degrees.

 

As a more generic principle, consider how you might be able to keep more heat in. I usually put my enclosure around my printer this time of year. It’s not terribly complicated and doesn’t need to be watertight. I found some brackets on Thingiverse and printed them, then connected them to make a frame with 2×2’s. I bought some acrylic and hinges to make a door and I have an enclosure. It’s not the most beautiful enclosure on the planet, but it works well enough.

I switched filaments. I’ve been meaning to change my nozzle, so while I was in there I did that too. When I printed a test print to make sure everything was good my first layer had holes in it.

Here is what I had to do to fix it.

  • my new nozzle doesn’t necessarily have the same height as my old one, so I releveled the bed and reestablished my mesh bed leveling.
  • my new nozzle probably doesn’t have the same heating characteristics as the one that I replaced, so I tuned PID.
  • my new filament may not feed in quite the same way as the old one, so I updated my e-steps.

Sometimes, you just can’t get the part quality that you want. For whatever reason, your machine just is not capable. Whether it is because your overhangs cause you to have to use a lot of supports which leave ugly marks on the surface, or your machine just doesn’t have the resolution to leave a good finish. There are a few things you can do.

  • Tune your machine. Make sure that 25mm commanded in the gcode results in 25mm of material printed.
  • Split your model into pieces. I print a lot of figurines for my kids. The hands and arms prove to be particularly difficult, as they need to be supported and they are small. When I cut the arms off and print them separately, I have much better results, then I just glue the arms onto the model.
  • Primer/paint. A little paint covers a multitude of imperfections. 

The final intent of the part is going to drive a lot of decisions in the 3d printing process. 3d printed parts have become very useful in improving prototyping and developing new products. However, as the cost of 3d printers has come down significantly over the past decade, or so, many hobbyists (like me) have also started buying 3d printers. I’m sure I’m not alone in this, but I use my 3d printer for all kinds of stuff. I make figurines for my kids’ games. My wife wants a new decoration for her curtains and can’t find any that she likes in the store, 3d printer to the rescue. I also use if for functional parts.

End use drives many decisions, such as:

  • material selection: for functional parts, I tend to use ABS. For the figurines that I create for my kids or decorative items that I make for my wife, I tend to use PLA
  • layer height: for decorative parts especially, I like to use a very small layer height to allow my components to be as smooth as possible in the Z direction. If I’m just creating a quick prototype and don’t care if there are obvious stair steps on the model, I might increase the layer height
  • speed: in my experience, higher speed = more vibrations, and more vibrations = lower part quality. There are a few things that you can do to dampen vibrations in your printer, but you will need to adjust your speed based on the final use of the part

 

 

I’ve run across a couple of posts where people are having trouble with different things. Upon digging into it a little bit, I have found that they are using the wrong temperatures for the materials that they are trying to print with.

My post today is pretty simple, use the temperatures for the filament that you are using. If you are using PLA, use temperatures in the PLA temperature range. If you are using ABS, use temperatures in the ABS temperature range. Most manufacturers provide their recommended temperatures on the side of each roll of filament.

The optimal temperature will vary some and will depend upon your setup and your ambient environment, but you can’t run PLA at 260 degrees and expect a successful print.

“Dad, the fence is down again!”

We live in a rural area and have animals. As anyone with animals can tell you, there is always something breaking, always something to do. Whenever possible, I like to have my boys (ages 10 and 13) fix it. I think it teaches them responsibility and gives them problem-solving skills. 

In this particular case, a fence bracket had broken. I could easily have gone to the store to pick one up for a few dollars. But miss out on this great opportunity to teach my boys something? Nah, not me. I had been looking for an opportunity like this. Something that needed to be custom made. A part that was pretty straightforward, but did need to be a certain size for it to function properly. This bracket needs to fit right, but it would also be forgiving. After all, it’s just a fence.

My boys had tinkered in Fusion 360 before, but it had always been just to create random toys and things that didn’t have a specific function.

“Go get my calipers from my toolbox and meet me outside.” We talked about how to measure parts to make sure they fit together and how to make sure that you have gathered enough dimensions. Then I turned it over to them to design. After many trips outside to confirm measurements, we had a design. Then we 3d printed one. It worked, the very first part off of the printer worked.

Whether they end up as engineers or not, these boys will have some valuable skills.

For Christmas, I’m making the famous leg lamp from “A Christmas Story” for one of my family members. He’s always been a big fan of the movie and the leg lamp has become a running gag between us. 

However, making the lamp does pose a few unique problems. One issue is that I will need to run an electrical wire through the leg itself to provide power to the led light that I will put in it. I figure I have two options, I can either put a hole through the leg in the cad and then print it that way, or I can change the print settings. What I’m trying first is to create the leg with 0% infill, but I’m increasing the number of exterior walls to compensate. Hopefully this provides a leg that is still structurally sound, but allows me to put the wire through the inside of the leg.

For those using Klipper, they just released a pretty major change in the way that they store files. When I updated to the latest version all of my config files disappeared. As I looked into it, there seemed to be a lot of other people experiencing the same issue. It turns out that my files did not disappear at all. They were still there, they just had the incorrect file permissions. Here is how I was able to fix it after some Googling.

First, ssh into your pi and take a look in ~/printer_data/configand ~/klipper_config.

If your files are in one of those places, then you should be fine. If neither of those folders has your config files, then that is a separate issue entirely and you should reinstall moonraker and klipper. If you were able to see the config files in your ssh session, but not from your web access, then run the following commands in ssh.

cd ~/moonraker
git pull
./scripts/data-path-fix.sh

I recently stumbled across MobileRaker on the iPhone app store. If you are using Klipper, MobileRaker makes things so easy for you. I would encourage you to use it. And if you aren’t using Klipper, I would encourage you to check it out. I’ve noticed a significant improvement in both the quality of my prints and the speed at which they print. Usually, those two things work against one another, but Klipper has managed to accomplish both.