Sunday, January 31, 2021

Getting Started with my 3D Printer - One Step at a Time

Ten days ago, I posted about getting my 3D printer going.  Within a couple of days, I had assembled the printer, checked and double checked, then started working on the steps I need to get past to start using it.  I still haven't done anything useful with it. 

One of the essential steps to learn to do is to make the printer's bed, the surface prints are made on, both level so that the movement of the print head either in X or Y is always perpendicular to the Z axis (up down).  The movement in a 3D printer is different from that in a CNC mill.  The printer head is mounted to the X-axis, and the Z axis moves the X-axis up and down.  The Y axis moves the print bed forward and backward in the frame.   I can see why they do it this way, it's just... different from what I'm used to. 

The system controller is that little box on the right.  It has a nice little LCD, but it takes some getting used to.  I'm used to a 17" LCD monitor on a PC so much more information can be displayed and the keyboard allows more input options than the little knob at the bottom of the box.  On my PC, in whatever CNC program I'm using I can do immediate commands, like type "G01 Z2.00 F35"; which is telling it to move the Z axis to 2.00 inches (could be up or down depending on where it starts from) and go at 35 inches per minute.  On this little box, I scroll through menu selections, find "Move", find Z, spin the knob to 2.0 and click the little knob inward.  Say I send the mill to 2" but I wanted it at 3" instead.  I can hit a key that gets that entire command back, change the 2 to 3 and hit return.  On this box, I go back to Z and then crank from 0 to 3 instead of 2 to 3.  A minor thing, but their user interface could be easier to use. 

The print bed is that horizontal surface down around the bottom of the clear space in the printer's frame.  If you look at the front (closest to the camera), on the right, just below that print bed and above the blue knob, you'll see a large disk-like object.  That's the adjustment to level the front right side of the bed.  The one for the left front is visible below the left corner of the bed but it's a crowded image.  There are two identical such knobs in the back.  There is not an overall adjustment, say in the middle of the bed to lift the whole thing up and down.  On You Tube, you'll find at least a dozen videos on leveling a print bed; I ended up preferring this one.  Like learning to fall off a bike, you'll get lots of practice doing this. 

In that post 10 days ago, I mentioned learning to use a slicer program and described how it's the equivalent to CAM software for a printer.  After reviewing another handful of videos and websites, I decided to use the Cura slicer software by a printer manufacturer called Ultimaker.  They give away a home version of the software and charge for business use.  I found it relatively easy to use, but it still does some things that surprise me.  Here's a look at Cura's interface with a test design in it. 

Conceptually, leveling the bed is like tramming a mill, except I get the implication it has to be done regularly, while tramming is likely good for a long time.  The file in Cura is from that video channel I linked to before and the idea is you test your printer by printing a few passes around in that file.  You lightly rub the filament with a fingertip (the printer bed is 50C, or about 125F - hot but you're not really leaving your finger on it). This is a pass on my printer this afternoon.

On the lower right side you can see some gaps in the print.  It's my understanding that's from having the print head just a little too close to the bed and the fact it's in the front right says to lower that a little.  I did that and it did get better but I'm a bit cautious about chasing that around the system.  More tests are definitely coming.  I don't really understand how I could have two areas of thin printing, extending most of the way across in X, in two different places in Y, given how everything is adjusted.

While studying up on this printer, I find that one of the features some higher end printers are starting to come with is auto leveling.  This guy shows how to add it to my printer.  The system is called BLTouch, and it doesn't mess with those adjustment knobs, it does the correction in software.  The system measures the offset of the printer from level around the bed and then adjusts the extruder height during the print.  Given my years of designing control loops, this appeals to me, and adding this to the printer for about $50 sounds good. 

All this said, I haven't printed anything useful yet.  I had a little adapter for an experiment I want to try on my Webster engine that I designed and ported over to Cura to slice.  That's ready to print and Cura says it will take 12 minutes.  It might even print properly, since it's a small thing, 1-1/2 by 1/2" and 1/8" thick. 


  1. I don't know how I missed your last post, but congratulations on finally get your printer and assembled.

  2. Possible explanation for the thin spots, the print bed may not be exactly flat.

    It could also be something bumping the bed up in those spots on on the Y axis.

    Have a look at the rail and the v rollers.

    1. Either CHEP or DrVax talked about those rollers being loose, so I took a rough look at that, just that I couldn't move the Y-axis by hand. I'll look closer.

      The bed is that carborundum (coated, I assume) glass that they did as an upgrade. Glass that's flat to within a mil over that size isn't exactly exotic tech.

    2. If you can't move the bed by hand when it's off, then it is definitely way to tight.

      You should be able to move any of the axis by hand. The z will move slowly because of the lead screw but even it should be movable.

    3. As to the flatness of the glass.

      No it's not exotic tech, but don't expect perfect QC on a subcontracted part. Trust, but verify.

      Also the aluminum bed could be warped.

      Just a quick note, my printer arrived with a huge high spot right in the middle of the bed.

      It was so bad that I was trying to get a replacement.

      It turned out to be a air bubble under the generic BuildTak sticker that was applied at the factory.

      Of course I have one of the second or maybe third batch of original Ender 3s made so the QC has improved dramatically since then.

    4. Also, I think I might have misunderstood you on the roller tightness.

    5. Oh, everything moves easily when the motors are off. I think these are NEMA17 motors, and are relatively weak compared to the ones on my micro mill that are NEMA23 and 125 in-oz torque. Of course, cutting forces pushing against the motor just aren't there with a printer.

      The Y axis doesn't noticeably wobble side to side, but that's just a start. I'll go play with it.

      Is it possible my belt tensioner isn't tight enough?

    6. Maybe, but it shouldn't be too tight.

      You'll stretch them out and they will need to be replaced sooner than necessary.

    7. But for right now, unless you plan on using the whole bed, I think you are close enough to start printing a bunch of stuff to get some experience with it.

      Get over to Thingiverse and find something interesting to print.

      Maybe you could use this highly technical engineering tool.


    8. And apparently Prusa has a it's own version of thingiverse.

      Here's what I was looking for earlier,

      a decent little, but useable, print that doesn't take a long time to print, should take about twenty minutes per side.

    9. That cable spool does look pretty worthwhile.

      This one might be very handy around my shop:

    10. It is. I got off of thingiverse when it was still available there.

      It's a nice little 3d printed gift to give out. It prints relatively fast without using a bunch of filament and it's usable by almost everyone.

    11. Yes SiG, there's a lot of useful shop/workbench infrastructure prints that wouldn't be worth the time making if you had to do it any other way.

  3. On the interface, you can hook it up to a PC with a USB cable and use Pronterface to control it. Even print with it.

    But the reason why all printers are now standalone is because of failed prints due PC OS/USB issues.

    But most of the time you can just move everything around manually if you have the steppers "disabled" (ie. Not actively printing something.)

  4. J. Greely, over at dotclue-dot-org, has been spending some time now on his 3D printer and has listed a number of things he's run into. Using tape to hold down items to keep them from curling during the printing process is one.
    He's recently experimented with nozzle diameters.
    He also does some software modification, as well as creating his own, for some of the things he's printed out.

    1. Depends on the filament material, ABS is known for this. Most of the people who still use it normally put their printers in heated enclosures to reduce it.

      Another thing is using an supplemental adhesion coating.

      There's a whole bunch of expensive 3d printer specific ones, but most can't beat plain old PVA glue stick.

      Oh, SiG I forgot to tell you to pick some up. The Elmer's purple ones work just fine. Get the large ones, I think a three pack was around $3-ish at Walmart.

  5. As for the need to frequently level the print bed.

    Unless you adjust something or remove the print surface, you shouldn't need to relevel.

  6. Ratus beat me to it on several items, and answered a couple of questions I had.

    1. If you have questions, I'm pretty sure SiG wouldn't mind you asking them here.

      I've only owned a 3d printer since September of 2016, but I have learned a lot though trial and error.

      And from a bunch of 3d printer YouTube channels and printer specific subreddits.

    2. I've been following 3D printing since I got back into R/C cars. One of the forums I frequent has a whole 3D printer section, as people are producing all kinds of custom parts these days. I was looking in to buying a printer, and then realized I could spend more time than available learning how to use it. I tried several software packages, and forget which one I liked.

      It's extremely interesting, and I understand most of it, but it's just not for me. I have too many projects now!

    3. "I could spend more time than available learning how to use it. "

      Actually, it's a easier now then even a couple of years ago.

      I won't say it's as simple as a paper printer, but it's getting very close.

      Once you get it setup, the most you when you are printing is making sure your first layer is adhered then you can go back to whatever you were doing.

      That's the best part, you don't have to be there operating it.

      You can even automate that part if you want with a raspberry pi with a camera running OctoPrint.

    4. "...the most you are doing when you are printing..."

  7. In regards to the BLtouch, it's a good bit of kit.

    Mesh bed leveling has been around for awhile now, but it does slow down your ability to get a print started because it does it every time.

    One you get a good bed leveling, you can start very quickly.

    Especially if you have some kind of adhesion issue at the start of a print.

    For example, you start a print and either the hotend isn't as primed as it should be, so you have an underextrusion failure. You stop the print, push a bunch of filament through the extruder manually and go to start the print again.

    If you have mesh leveling on it has to do it all over again.

    It's nice feature to have, but it's not necessary for good prints.

  8. It's the software that I have the most difficulty getting my mind around.
    Everything done on a conventional mill requires that the ways be tighten to the correct point, the vise must aligned with the long axis of the mill table, and if adjustable, the mill's head must be trammed to a high degree of accuracy.
    If I understand this correctly, an auto leveling 3D printer head of sufficient sophistication would be able to print accuracy on a skewed printer bed. Or a moving bed or something I cannot even think of.

    This is all really interesting.

    1. It's part of the firmware, not hardware.

      The only hardware difference between a printer with and without mesh bed leveling is a probe/sensor.

      The firmware takes the measurements of the bed and creates model of the print surface, then raises and lowers the print head to compensate for the unlevel surface during printing.

    2. "If I understand this correctly, an auto leveling 3D printer head of sufficient sophistication would be able to print accuracy on a skewed printer bed. Or a moving bed or something I cannot even think of."

      Also, yes.

      The company that came with the the code for the auto leveling, Prusa Research, has had printers that compensate for skewed and warped print beds since 2016.

      They are very good, but double to three times as much as a Ender 3.

      The current price for a i3 mk3s kit is $750+shipping from the Czech Republic.

      But they released their code as open source, it's part of the Marlin firmware that nearly all printers use.

    3. One of those things that will mess your mind up is that there is no equivalent of gibs on the axes. Everything moves easily by hand when the steppers are off. When power is applied all stepper motors lock up and typically have their highest torque at stall or when they're just barely moving.

      The vise isn't needed because the machine doesn't go to a place where you tell it go and start cutting whatever it finds (and whose vise on a CNC machine doesn't have a ding or two on it?); the machine goes to where there's nothing and puts something there.

      The printer has microswitches for automatically homing, and the first thing it does is home itself to set (0,0,0). That's a "luxury" add-on that none of my three CNC tools has.

  9. On slicers, Cura is very good.

    I've been using it since they changed the version numbering.

    It's gotten better with almost every revision.

    As CHEP says, the current stock profiles are very good.

    But don't limit yourself to Cura.

    Prusaslicer is also very good and has a bunch of cool options like variable later hight and infill density in the same print.

    It also has profiles for most common printers too.