Getting Started With the Printrbot Simple Metal

Created by will on Aug. 29, 2014, 6 a.m. Last post by UABMaddog 2 years, 9 months ago.

Norm and I kicked off July by building a 3D printer, the Printrbot Simple Metal It was the third printer we’ve built, and it was interesting building a printer with a metal frame, but once we got it assembled and did a couple of test prints, we didn’t have time to touch it for a month. I’ve spent much of the last week dialing in the printer, figuring out its nuances, and getting decent prints out of it. We’ll do a Tested In-Depth video with it at some point in the future, but in the meantime, here's what I've learned so far.

First, in the time since we finished the build, the instructions for building the kit version of the Printrbot Simple Metal have been updated. The kit’s assembly instructions have been completely revamped, addressing many of the issues we had during the assembly. Along with good pictures, the newest version of the instructions provides written instructions for non-obvious steps.

I love that the Printrbot makes it easy to make slight Z-axis calibration changes in software rather than hardware.

The instructions for calibrating and making the first print are quite good, and I love that the Printrbot makes it easy to make slight Z-axis calibration changes—a common cause of bad prints—in software rather than hardware. It took two or three false starts, but we were able to print a fan shroud that was good enough to work in two or three tries. Because of the way this type of 3D printing works, it sometimes takes a few minutes for failures to become obvious. To give context, when we built our first printer, the original Makerbot Cupcake, it took almost a week of tweaking to get usable prints.

Once you get past the first print, configuring the software gets a little hairy.

Your printer software lets you place objects on the printer’s build platform, then slice those 3D objects into two dimensional layers. Those two dimensional layers are then converted a series of instructions that describe the movement of the print head and the build platform that the printer can understand, called gcode. The software that Printrbot recommends, Repetier also lets you control the stuff you need to do to maintain the printer--move the print head, the build platform, turn fans on or off, and adjust the temperature of the extruder.

Repetier handles the housekeeping, but gives you multiple options to convert your 3D objects into gcode. Printrbot recommends Slic3r for this task. Configuring Slic3r is tricky. Both Slic3r and Repetier are designed to work with many different types of devices, so you need to do a fair amount of configuration to get them to work with the Printrbot. Some of that is handled by configuration files provided by Printrbot (I had the best luck using the Simple Slow Config), but you’ll also need to tell Repetier about your printer’s printable volume.

I was surprised at the lack of profiles for the Simple Metal that work with different vertical resolutions. Switching the vertical resolution reduces the number of layers that you have to print, which lets you print much faster. While I was able to find a very reliable 0.2mm vertical resolution profile the 0.1mm profiles didn’t work particularly well with our printer. They under-extruded, printing a test cube that had a grid of plastic (think Chex cereal) instead of producing a solid layer of plastic. I love having the granular controls over every variable that this setup provides, so I’m sure I’ll eventually have a 0.1mm profile that’s reliable, but I wish there were better configuration files available for fine, medium, and coarse prints.

I also experienced a few technical problems as I started printing. When we were assembling the printer, we hadn’t locked the hot end into the block well enough. When the printer heated up and the extruder pushed filament through it, the hot end slipped out of the extruder block and dragged through the model and across the build platform. I gouged up the platform pretty badly. Before I realized that the hot end was actually loose, I thought the z-axis sensor had slipped out of alignment and spent some time adjusting it, which was undoubtedly a mistake. Luckily, I was able to cover the damage enough to get good, flat-bottomed prints using blue painter’s tape.

While we’re on the subject of blue painter’s tape, this is the first printer I’ve used in several years that didn’t have a heated build platform (there is a $100 upgrade available though). Typically, users recommend applying a layer of blue painter’s tape to the print bed to help your prints stick and also make them easier to remove once the print is done. If a print breaks loose before it’s done, it’s essentially impossible to recover. At first, I just used whatever tape we had laying around the office, but I had problems with that tape breaking free from the platform and causing the prints to warp. After a quick trip to the hardware store, I had six different types of tape, and eventually found that 3M's Scotch Blue Painter's Tape for Multi-Surfaces #2090 worked really well. I still had some slight warping at the edges of very large prints, but for the most part, the tape stayed stuck to the platform, objects stuck to the tape, and I was able to remove the tape from the prints.

If you’re having adhesion problems, the first thing to do is wipe down the build platform with rubbing alcohol, let it dry, apply your blue painter’s tape, then wipe it down with rubbing alcohol too. The alcohol takes off any leftover manufacturing residues and removes your fingerprint oil. It’s best to get in the habit of wiping down your print surface before every print. Not much sucks more than spending hours on a print only to have it break loose after 5 hours.

I also noticed that the Printrbot is really sensitive to tension on the filament line. If there's any tension in the filament at all, it stops feeding and your print will get messed up. to solve the problem, I put together a simple spindle holder using a couple of pieces of scrap wood and a dowel that I had in my garage, and then printed a couple of filament guides. It solved the problem, but I think I’ll eventually end up making something that holds more than one spindle of filament.

It’s important to note that 3D printing is still in it’s infancy, especially for consumer-priced models like this one. If you’re having other problems, and you will have other problems, this troubleshooting guide will walk you through the most common issues and fixes. In my experience, the most common causes of failed prints are adhesion problems, slicing problems, or poor z-axis calibration. Once you nail those three things, you’ll be able to crank out consistently awesome 3D prints.

I’ve been really pleasantly surprised by what this printer is capable of. It’s $600 assembled or $540 in kit form. After spending a few hours assembling it and a dozen or so hours getting the settings dialed in, I’m getting impressive prints out of it. Best of all, it’s an extensible frame—there are already kits that let you add a heated build platform and upgrade the print head to work with multiple extruders. Because of the way the printer is designed, it wouldn’t even be particularly difficult to upgrade the print volume.

I’ve set up Octoprint on a Raspberry Pi and am now using that to control the printer instead of Repetier. Octoprint is a phenomenal little piece of software that makes the printer essentially standalone—normally, you need to leave a computer hooked up to it while it’s printing. Octoprint lets you control the printer from a browser, check on its progress, and even queue prints. If you have the appropriate camera, you can even watch a live feed of your prints or shoot a timelapse of your build. Next time, I’ll explain how I set up Octoprint and share some timelapses. In the meantime, let us know how you are doing with your 3D printer in the comments below.

Next: Configuring Octoprint and shooting timelapses from the printer's bed.

  • Im working on addressing the Z axis on my conversion by adding backlash to the Z axis threads, if you lift the Z Axis carriage on the stock simple metal you can feel the play in the threads which considering we are all trying to print .1 or .2 is kind of funny

    Ignore my Z axis threaded rod being off centre, but you can see the block has a slot and 2 threaded sections, these can be adjusted by a second screw with a back nut forcing the gap open or closed

  • If I had time and desire to geek out to the extreme level, I would measure the square of everything and deflections of the setup as you move each axis. I been thinking that the Y axis is probably a source of some of the squaring problems with the bed. As the further it extends out the greater the deflection should be. If you add onto it and increase the that axis length I would Imagine it makes it worse. Without something like a counter weight. Same probably goes for the amount of resistance your extruder assembly faces. If you have don't have your spools well centered you can hear it struggle some and probably measure a slight deflection upwards during this.

    I learned long ago that extreme levels of precision and calibration are long processes. They also require attention to detail, and the cheaper something is the less convenient and to tolerance it generally is. If your building something that doesn't matter if your off by 1/16 or 1/8" then it doesn't matter. But when your building something that when your tolerances are off by a hundredth or thousandth, that level of precision makes all the difference in the world.

    Don't forget materials sciences as well, as PLA and ABS both have different shrink and expansion ratios and will naturally be off by a certain amount based on the nature of the material and the tolerances you have accounted for.

  • Just a note...a tangled spool in the middle of the night during an 11 hour print is not a good thing.

  • @chrisfowler99: I ran into that with my abs spools, and the default printrbot filament (though that is unspooled and garbage imo). What I have found is to run my spools vertical instead of horizontal. and make sure that the filament comes from the over the top of the roll and not under. This seems to make up for poorly wound rolls. Which most are kinda hit and miss for winding out of the ones I have used so far. It also helps Counteract the natural twist that the filament seems to get. Which can cause further tangling by itself. Just make sure your axis of rotation for the spool is at the center of gravity and not offset.

    I am tempted to add both a optical sensor to my extruder for when it gets close to running out of filament. As well as an optical encoder to the spool, with a load cell, So I can figure out if the filament is slipping or tangled, and pause the print automatically. Rather than Walk in to spaghetti or nothing.

  • This spool is vertical and running over the top.

    Seems like the only suggestion I've seen to guarantee that there's no tangle is to reroll the filament. Sounds like a pain in the ass.

  • @Malchom: Thanks for the story. I think I just might pull the trigger on a heated platform after reading your experience! The warps are driving me crazy.

  • Hey guys,

    since I'm about to order myself a printrbot simple metal and have nothing to da at work I was just setting up thte software. I found a website with suggested settings for the simple (I guess wood version). In the comments there is a guy who says he has made changes for the metal and i was really confused about the size of his printbed, because its larger than the 150x150x150 buildvolume printrbot suggests.

    http://www.instructables.com/id/How-to-configure-Repetier-settings-for-BEST-Pintrb/?lang=de

    Can anyone confirm those settings because i think they really might work, due to the fact that the printbed doesn't appear to be a sqaure one.

  • @MadMaxGenius: the build platform for the metal is indeed 150mm x 150mm x 150mm. Because on the left and right of the bed, are dead zones. That the head is not capable of reaching. This is due to the way the bed itself moves, instead of being fixed.

  • @will said:

    @Jerware: Do you have any drafts in your room? Once I aimed the fan away, I was able to print much bigger stuff.

    I noticed the same, and now always print with the window closed and the room basically turned into a sauna. Unfortunately I still get warping with bigger pieces. I've signed up to be notified with the heated build platform is back in stock at Printrbot.

  • My first comment on a tested article! Yay!
  • My printrbot comes in today! I'll be good to have this writeup, and all these comments, to help me tune it in quickly.

  • @Jerware: Have you tried different kinds of tape on your platform? What about cleaning and cooling configs in Slic3r?.

    The first week I had the printer I was basically figuring out how to fight warping without heating the build plate, here a few things you can try. I managed to print rather large stuff with very little warping after a lot of trial and error without heating the platform.

    1. Try different tapes, The best I've found is 3M Blue painters tape I got at a hardware store, it needs to be "papery" and not glossy or plastic
    2. Make sure the tape is laid flat and pressed hard (press several times using a credit card or a paint spatula you can get at the hardware store) to make sure it sticks to the plate. I noticed that the tape sticks a lot better with the heated bed so maybe, if you have a hair dryer, you could blow on it to heat it up and increase adhesion before printing.
    3. Clean the tapes after applying them with Isopropyl alcohol or acetone (nail polish), and repress the tapes flat after you've let it dry a few seconds (clean the tapes before using the hair dryer tip above)
    4. Lower the Z-Axis so the plastic filament can be "forced" onto the tape but not smashed, it's tough to do though, You need to toy around and lower 0.2mm and try a print, then when you start "smooshing" the first layer reup the z-axis in increments of 0.05mm to find a sweet spot. Carefull to not gouge your build plate!!!
    5. I made a large 5.5' cube quickly in 123D Design to test prints and warping, I would start seeing warping at about the 4th or 5th layer on a 0.2mm layer height print.
    6. Make sure your tape strips dont overlap too much, I noticed those little bumps can be like a pee under the mattress for such precise machines as these.
    7. Try turning off the fan for the first layer (or a few more if it's a high quality 0.1mm layer height print)
    8. I also notice warping would be worse on the side of the fan shroud. I theorized that the shroud draft might be lifting/cooling one side unevenly. In another comment on this thread I put a link to another shroud that directs the air flow downwards around the print head rather than to the side

    Of course, it never was 100% perfect for large prints without the heated bed but I was nearly there, just slight lift on corners! TBH I would of been satisfied with the prints I had. I ordered the heated plate for ABS printing and I actually thought I wasn't supposed to heat the platform for PLA as most discussion on the printrbot support site said it wasn't necessary.

    If you do end up getting the heated bed, here's what I do for PLA :

    • I still put down blue tape, clean it and press it hard,
    • Set the bed to 40C temperature,
    • No fan cooling for first layer

    The prints adhere so well to the platform that I am now frustrated that it's sticking so well. One of my prints was so stuck I had to use needle pliers and it just broke.... had to reprint...

    Anyways, I hope this will help you :-)

  • @Malchom: Thanks for the tips. I've tried everything you suggested except the 3M tape. I just ordered the one Will links to in this article, but that will be my last ditch effort before buying the heated platform.

  • @Jerware: You can also try using spray mount for added adhesion. Word of caution don't press down on the bed to hard applying tape as you can create a dip in the middle as the delrin blocks rock a little on the rods. I did this and fixed it by bolting a piece of U Channel along the front to keep the bed level, the bad news is i had already messed with all my settings trying to fix the issue in software before realising it was the bed :(

  • Can you please post a link to the large print in place robot featured in some of your pictures? I bought the Simple Metal kit and after I cleared up an issue with them sending me the wrong coupler twice, I've started to get some very nice prints including the smaller version of the robot.

  • @will: Got it, thanks. Have you shared your printrbot slic3r configs? If not, can you? I'm new to printing and I'm getting decent prints but I think it would be helpful to compare configs.

  • @Thendore said:

    @will: Got it, thanks. Have you shared your printrbot slic3r configs? If not, can you? I'm new to printing and I'm getting decent prints but I think it would be helpful to compare configs.

    yes! Double vote to this. I finally purchased and assembled mine this past week. I'm trying to figure out a lot of little settings, but a comprehensive overview (or Cura/Repetier/Octoprint screenshot dump) would be hugely beneficial!


  • Wish me luck. (luck not actually involved but tons of research was....LOL) Starting the assembly of my Printrbot Simple Metal with heated bed. You guys help me decide on this model with options.

    I plan on using this with my bench top mill (soon to be converted to CNC) to have a blast making and breaking all sorts of RC vehicles!