3D Printing: The Stepper Conundrum

Today’s conundrum from my 3D printer has vexed me for three days now.

So, an update since the last one.

Last time, I estimated I was at 60% complete with the build and needed to finish that, install the firmware, get the filament, and begin printing. Well… that was almost what I had to do.

I’ve completed the physical build, as much as I can but more on that later. I’ve installed the firmware and tested that it works with the software on my computer. I’ve even attempted to do a test print to start calibrating the settings. Oh, and I got the filament (after ordering the wrong type of plastic the first time).

Filament, just realized that some of you might not know what that is. Filament for 3D printers is basically thread made of plastic. Really thick thread, but it comes on a spool and is fed into the 3D printer like thread into a sewing machine. It comes in two main sizes 3 mm and 1.75 mm. I am using the 1.75 mm, since it has been found to work better than the 3 mm filament. which sometimes overwhelms the heater that melts the plastic.

So anyway, that’s where the problems started.

The trouble presented itself as an inability to push the plastic out to be printed. It comes out like frosting from a cake funnel, or like toothpaste from a tube, and is supposed to be layered up, one on top of the other, until you have a completed object.

At least that’s the idea.

You see, there’s a motor that pushes the filament into the extruder (that’s the toothpaste tube). The motor is a special kind, called a stepper motor. Named that because it can take individual steps of rotation, unlike most DC motors that just spin. Because it can do this, it can push just a little, or a lot, of plastic through the hot end of the extruder in measured amounts.

Mine however, was not doing that.

What it was doing was pushing a little of plastic out, but then reversing direction and pulling the filament back, then pushing it back in or pulling it out more, depending on fate and whimsy. It wasn’t so whimsical for me though. The melted plastic cools very fast, but ends up leaving little spiderweb threads of plastic as it comes out. I went through a fair amount of plastic in the last three days troubleshooting things.

Something said at work today, along with thinking about all of the settings are available finally led me to the solution.

I had tried everything I could think of over the last few days. Switching stepper motors, switching driver circuits, changing the amount of plastic to be extruded. All of those things done one at a time to see the result of the change, and making note of how it improved or made worse the problem. At work yesterday though, one of my co-workers was wrestling with an issue and it was suggested that while he was going through the same process as I was with the 3D printer (it’s a common troubleshooting process for code), that perhaps he had more than just one problem to fix.

This was no surprise to me, having just come off another project where I was tracking down a bug that led to several other bugs being uncovered and needing fixing before I could fix what the client actually wanted fixed. It wasn’t until I got home and looked through the firmware that I realized there was a setting I missed.

Going through the calculations, I realized that the stepping code wasn’t set correctly for my printer. I adjusted that, but still had a problem. It was a bit better, but still would reverse seemingly at random. I switched stepper drivers again, and voila! a working stepper motor.

So long story short, I have a solution for my problem, and as soon as the new stepper driver arrives, I will have a working printer.

I’m keeping the bad driver board for now, to learn from and see if I can eventually fix it. Right now though, with the deck, the secret project, the 3D printer, NaNoWriMo, and HoNoToGroABeMo coming up, I have enough on my plate to last through November!

If any of you have any questions or suggestions about 3D printing, or stepper motors and their drivers specifically, feel free to drop me a line in the comments.

A 3D printer is coming!

Nearly a year ago, I Kickstarted a project called Eventorbot. It seemed a good project, an open source plan by a young man who had come up with a good design for a stable and easy to build 3D printer. It had some good rewards, and after hearing about some Kickstarter horror stories, they didn’t seem overreaching. The creator also had built a machine, and claimed he also owned an import business. Overall, it seemed to be a good deal, so I put my money in.

Well…

It’s been a few months since anyone has heard from the creator, and even Kickstarter can’t get hold of him. His last few posts were telling us that he needed to order some more parts, and then, nothing. The circumstantial evidence points to some bad parts from China, mainly the frames not being square as they should be. A rigid and square frame is essential for precise printing. If that’s the actual case, we don’t know for certain, but it’s the predominant opinion. We’d all be more forgiving if the creator were more communicative, but he’s most likely terrified of the things that he has promised and can’t deliver.

That’s the past, and a lesson about Kickstarter. Take from it what you will.

When I ordered the parts for the Eventorbot, I didn’t get a full printer. I knew I had some of the parts already, and could source some of the rest for less than the full kit price. So for nearly a year I have had rods, stepper motors, a control board, linear bearings, skate bearings, bolts and nuts, just sitting in a box in my basement.

Until a few days ago.

That is when I discovered the Printrbot Simple. I’ve known about Printrbot for a while now. They did a Kickstarter too, but obviously that one went better on deliveries than the one I was in on. They’ve put out several printers from their first, and the Printrbot Simple is their most recent one.

It’s small, a starter printer at an economy size. The print area is 100mm x 100mm x 100mm, about a 4″ cube for those that still prefer the English units. It prints PLA instead of ABS, and doesn’t have a heated bed. That’s actually good in this case, since cost is a factor in the economy printer. For the fully assembled printer, it is only $399. As a kit, $299! It is the cheapest printer I have seen in a while, unless you happen to have access to a laser cutter or someone who can print plastic parts for you already. I don’t, but I do have all those parts laying in a box.

That’s when I saw they offered just the laser cut wood frame for $40! (Total of about $50 with shipping.)

So sometime next week, I will be getting a package of wooden parts in the mail, and hopefully another package from Ebay for the hot ends that I ordered to complete the build. I’m enthusiastic, you would not believe how much. It helps out with my secret project, it lets me actually use the couple hundred dollars in parts that I had ordered, and I’ll have a 3D printer when it’s all done.

So, anyone want anything printed?

For those interested in 3D printing, I wrote a book!

Over the past several months I have been working on something. I’ve touched on it a bit here and there in posts about writing a book. Now I can actually talk about it!

The book is called Instant Slic3r. It is meant to be a beginner to intermediate level introduction to the software Slic3r, which is one piece of software you can use in your 3D printing suite of tools. As part of it being an introduction, and in Packt Publishing’s Instant series of books, it weighs in at around sixty odd pages.

Writing it took some effort, and is one of those things that I mentioned in yesterday’s post where I had to really focus. My workload for the book was 2 pages a day, and juggling that with work, family, commuting, and sleeping I had very little time for anything else.

Over the last few years, I have dug deep into the 3D printing community. Learning about various printers, getting in on a Kickstarter for one of my own, researching how they work and how they can be improved. It’s a big area to explore, and Slic3r is a small, though integral, part of it.

Instant Slic3r front coverThe book comes out soon, hence my ability to talk about it now. I don’t have an exact date, but I am told that it will be out and available in 3-4 weeks from now. When I get more information, like links to the book page itself, I will post them.

I hope if you are interested in 3D printing, you’ll pick up a copy. If you want any more information about the book, let me know in the comments.

Oh! Before I forget, I get to show you the cover too!

 

[UPDATE] The book is now available for purchase from multiple vendors. The main Packt site also links to the other places it is available: http://www.packtpub.com/turn-virtual-model-into-a-physical-object-using-slic3r/book