Pausing Prints – Tech Tips Revealed

We have been getting a lot of feedback that Tech Tuesday is going well, and people like the technical discussion. We have been getting some comments, too. My favorite comment is from Vicky Somma, who said, “Tracy, just out-teched Tom.” I love that sentiment. We have gotten a lot of comments from the slicer and pausing challenge that we had last week. Vicky Somma was the first to write in, and there has been a conversation going back and forth. She has been saying that she pauses prints to insert a mirror and then continues to print to capture that mirror, which is a perfect example of what we were talking about last week.

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Pausing Prints – Tech Tips Revealed

In particular, one of the things I commented on was that I have had problems with certain printers that when you pause it, it doesn’t move the nozzle or the bed down, and your hot nozzle can stay, making a big divot in your print. I think for a lot of printers, it does do that. Vicky said that within Simplify 3D, there is a command, and she can predict this and lower the bed so that doesn’t happen. That’s good news. That was only a part of the puzzle though.

At about the 7 minute mark, Vicky shows how she inserts mirrors into her print. It’s a little different than the way it’s explained in our blog below, but another neat trick to add to your 3D print skill set. Instead of creating a file that prints independently of a computer, she is printing with her computer attached to the printer, using Simplify 3D to print one part of the print at a time, essentially running two different prints as far as the printer is concerned, but starting the second print where the previous one left off. Still, a valid process that will work for many users.

We had another long-time listener write in who loves the show; his name is Brandon Terry. I really appreciate this, Brandon. The reason this is good for Tech Tuesday is that this is not a beginners’ task or user-friendly to do it, but it can be done. The great thing about 3D printers, particularly open-source ones, is that if you use a certain slicing program, you program the printer to do what you want. It’s only limited by the hardware of the machine, but in terms of the programming, it’s only limited by your understanding to manipulate those settings and the code.

Brandon wrote in and said that he doesn’t know of any slicing software that allows you to pause automatically at a certain point. That was something I was saying, too. Vicky was talking about a piece of the puzzle, about having the nozzle stop on your part along the way. But there really isn’t any slicing software that allows you to pause at a very specific point ahead of time.

However, he did say it’s fairly easy to insert a pause into the G-code. He uses Simplify 3D, which is a very good slicing software. We use that as well. What he is saying you have to do is go and slice the model with all its settings to create the print you want to create. Then you open up the G-code. I have done this with some of our prints. There are 16,000 lines of code, which is nuts. How are you going to find anything in there?

What Brandon says is that in the newer Simplify 3D software, they have added layer numbers directly in the G-code. You can preview your print once you have sliced it in Simplify 3D, and you can have a slider bar and it will show you all the layers. You can say that you want to pause the print right here, and as you move that slider, it’s like building the file up layer by layer. So you can see where you’re going to stop it and what layer that is. Once you understand exactly what layer number you want to stop at, then he says you can insert a couple of lines of G-code commands yourself. It’s like a text editor.

I’m having flashbacks to the jacquard machine at RISD where you have to insert blank cards. This is how old I am. Jacquard is when you have a beautiful woven fabric with a design you can feel and touch, where the colors go up and down and in and out, a tapestry-type design. This was usually done on a jacquard loom if it wasn’t done by hand. We used to have to program the code for running that machine because it wasn’t computer-driven. It was run on cards. I would argue that it was one of the first kinds of computers. In order to switch colors, we would have to stop the machine. In order to stop the machine, you had to know exactly when to do it because your threads are so fine; you had to insert a blank card. You had to lay out all the cards, which got laced together, and you’d have to insert the blank card at the right spot where the code was changing based on the same thing. I’m having flashbacks to that. You’re going to give me nightmares because I cut a lot of those cards for you in college.

Back to Brandon’s example. You can search for the layer number within the G-code and add some lines of code. One is a G1 Z100, which moves the nozzle out of the way or lowers the bed. Other commands will do other things. I won’t go into those details right now, but I will put them in the show notes. Not only do I have the specific instructions, but Brandon also gave us some screenshots of him doing this, so we can show you exactly how you might do it.

The caveat is the specific to Simplify 3D. He has a particular printer, a Rep-Rap style printer, and running Repetier firmware. He can’t 100% confirm that it will work for every printer, but he is fairly positive that the commands used in this are recognized by most 3D printer firmwares, if not all. And I think he is right. A lot of them all share similar firmwares.

Not only did he give us some commands to pause the print and move the bed back down so you would resume the print after inserting the part, but he also has provided commands that would cool the nozzle down and heat it back up before resuming. You could change colors, but if you are going to have a period of time where you don’t want to leave the nozzle heated the whole time, that would be helpful.

For his particular printer, in order to resume the print, he has to do something on his printer. He prints from an SD card, so that was another caveat. In order to do this well, you have to print to file, either to an SD card or some type of USB port. If you were printing over USB from Simplify 3D directly, he’s not exactly sure how this would work because he doesn’t do that.

I prefer to print to file, too, so this makes sense to me. We have found more consistencies this way; there can be issues with translation and communication through the port. With a lot of open-source printers, we have had issues with the print stuttering and intermittently stopping when it’s not supposed to, and it’s because the lines of code are being streamed from the USB to the printer, and a lot of times the USB ports on these printers are not operating fast enough in order for that code to be getting there faster. The machine stops when it doesn’t have instructions. So I prefer to print from a stand-alone or to-file from a USB or an SD card.

He said in order to resume on his printer, he has to go through the menus on the OCD panel and tell it to resume that way. That’s a bit of a manual process, but I prefer that than automatically.

Pausing Prints Tip from Chris Thompson

We got a great tip in our inbox from listener Chris Thompson that we wanted to share with you all:

“I want to share an encapsulated part that I designed and printed successfully on a reprap. The design called for a clear window in a lid. I designed a C channel in the frame and an acrylic window with a bit of clearance on the edges and on top. After slicing the 3D model, I viewed it in http://gcode.ws/ to see what layer was the first that would cover the edge of the window. I noted what layer and Z height that was, and the hardest part, I edited the Gcode manually to insert a host command. In Repetier host and printrun you can add commands in the gcode that only control the host software. The commands I added were Gcode to move the nozzle away from the print, and a pause command for the machine.”

 

 

“Then I quickly placed in the acrylic window and resumed the print. The small amount of nozzle ooze wasn’t a problem. Then the print went on as normal. I did need to test print it a few times. If you don’t leave enough Z clearance, the nozzle drags on the surface of the window, the same collision you described on the show. If you don’t leave enough XY clearance, you can’t fit the window in when it comes time. It was a successful print and a great design tool for me.”

 

Pausing 3D Prints… Not for Beginners

I want to step back for a minute. I’m so glad that Vicky and Brandon helped get us further with this. We did put a feeler out to MatterHackers, but they have not yet responded. If they do respond, we will add their comments into the show notes. If you are using that, if there is a possibility for that to happen, we will let you know. Check that.

But I also want to say that this might be too technical or advanced for your skillsets. Think about this seriously. Think about the ideas of making two parts, inserting parts, changing colors. There is going to be a design possibility that you would want to do this in the future. Bookmark this, remember it, and come back to it. It’s definitely something that as you will be designing and coming up with these ideas, sometimes we overcomplicate our design process when we do this. We think, Oh my gosh, 3D printers can only print things once, so I should. Sometimes you don’t need to though. Sometimes it’s okay for you to do things separately, and you should take it more simply. That’s okay now. But the next step might be to do that all in one. There might be a good reason for it, the way it needs to be inserted and captured. You don’t want to see lines and other reasons. But it’s okay for you not to do this more complicated method in the beginning.

At the same time, if it’s important enough to you, you can note this information. Create yourself a Word doc that has these codes in it. You don’t even have to remember every time what these commands mean or what they do. You could just have something that when you find the right layer height, you hit copy and paste, and you know how to operate your machine while it does this. Then you can do it over and over again. You don’t have to become a technician to a super high level to do this. It’s more a matter of how do I want to do what I want to do and do it well.

Reach Out to Your 3D Print Community for Answers

The other lesson I want to send everybody away with is that there are people out there who are more than willing to help, like Brandon and Vicky. I know there are lots of you out there who make suggestions all the time like this. There is a community out there that probably someone in it has figured out what you want to do. This is where you go. Use your forums and Twitter and whatever else you need to go seek out the information. If you want to do something special, someone out there is willing to help you. Or you reach out to us, and we will broadcast it to all of our listeners. That seems to be working. We are communicating back and forth much more with our listeners, which we are thrilled about. It’s making doing this podcast all that much more fun.

One more thing I just want to mention is that we want to talk to our friends at MakerBot and help them realize that it would be great if they could put a way to predict and pause a print like this in their software. Even MatterHackers, too. Anybody that is creating their own software so you don’t have to do this G-code hack if you will. The MakerBot is already doing a lot of pieces of the puzzle. You can already pause at any point, but you cannot be entirely certain about what line you are on or layer you’re at. They already move the bed down and move the extruder away from the part so you have room to put in another part. And it resumes really well on command. I can’t say that it’s at this layer height.

I hope we are catalysts for making some of these things happen. Not everyone thinks about these features and needs them to happen. People do some complex things with their 3D printers, and they have hacked them to do these things. But some of these features, to try to weigh and understand if they are a high level of need for designing something or if there are multiple reasons why you might need this feature. Being able to communicate that to these 3D printer companies is valuable.

If you guys send us information and we find that there is a consolidated effort, that many people need to know exactly where they are pausing their printer, that’s great information for these companies to incorporate. They want to know what to do next based on what people need. I think our audience will hear next week from our Ask Us Anything event we did with MatterHackers. They have a list of requests that is significantly long. Maybe we can help bump some of these items higher, especially if we can show that there is a bigger audience that needs these features. That’s the point.

If you have specific information or anything you want to add about ways you have paused printers, the best way to do that is include it in the comments. Then it will be there for others to see.

Important Links

• Simplify 3D
• G Code Analyzer
• Repetier Firmware

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