ABS issues, prints are not accurate, wrong size

Hey All,

I have been using my taz 4 for a few months. Got good with it but never really tested the prints. I had someone ask me to print a gear for them and I realized that the prints are not coming out the same size as the files.

I started to check out Calibration methods and downloaded a 20mm cube with 0.5mm thin walls. The 20mm size is close but not perfect, but the wall thickness is 0.84mm. I think if I can fix the wall thickness, the cube would have been the correct size.

I then used the LCD screen to extrude 20mm of ABS into the air. Tested it, and it came out as 0.61mm thick, does that seem right?

I checked the esteps calibration using this guide: https://ohai-kit.alephobjects.com/project/extruder_calibration/

When I do this, I am getting different numbers every time. I can run 100mm at 100mm/min with the default esteps of 842.0 and get different numbers every time I run it. If i adjust it, it still pumps out different numbers so I went back to the default setting since my problem isn’t with esteps. The machine is calibrated so I doubt it is wrong anyway.

Back to the gear that I need to print. The size’s are all wrong. The overall size is to small, the teeth are too fat, the inner whole is too small.

I checked the fliment, numbers are all over the place. I get a lot of 2.95 but it goes up to 3.0 and down to 2.85. Should I just average this stuff together?

I am going to be printing with Bridge Nylon soon, so I want to make sure everything is perfect before I attempt anything with this stuff.

Any help would be great. I am just getting sick of dealing with the settings. haha. I need prints as perfect as possible if I am replacing a gear with a printed part. As far as nylon, is the setting on lulzbot good enough or should I tweak it? I want the highest quality print for these gears.

I use Cura but would learn Slice3r or other programs if I it works better. I have the Taz 4.

what are my next steps in calibration?

Lots of questions in your post!

There is a systematic process for getting correctly sized parts. I have not read the link but here is how it goes:

  1. Calibrate the extruder - this includes calibrating for the specific filament you are using. As you observed, filaments can vary a lot. Measure in 6 places over 12" and take an average for diameter. That should be good enough. It is a good idea to measure the diameter of the extruded plastic if you can. It is tricky since any stretch as it dangles down will affect the measurement. It is normal that it will be larger than your nozzle orifice, that’s called die swelling. Die swelling is affected by extrusion rate (back pressure) so extrude slow - say 10mm/s - for this test.
  2. Next you need to make sure that X, Y, Z steps/mm are calibrated accurately for your printer. The default values are in the ballpark but to take it to the next level of precision, calibrate your printer. You do this with a standard calibration cube. There are several (20mm cube) on the thing sites. This is where it gets a little tricky though - there is a relationship between final parts size, printer X/Y/Z calibration and slicer parameters. For instance, your X/Y/Z calibration could be perfect but parts may be larger or smaller depending on slicing parameters.

What I like to do is use a representative “no frills” slicer configuration (I use KISSlicer so I can’t help on that unless you use KISS too) and use it to calibrate the printer with a well behaved filament. I find ABS much better to use to calibrate than PLA because it has less die swell and the small amount of shrinkage after extrusion seems to compensate for that. Once I’ve calibrated the printer I never touch that. I then print a new part like your gear and measure it. If it is off, I compensate with the slicing parameters. I can usually get it spot on with 1 test print. I write all of this down (see my guide in my link) so the next time I use this filament I can usually get it right with the first print.

NOTE: you can actually calibrate your printer without printing by using a dial indicator mounted so you can measure distances along X movement, Y movement and Z movement. This is how we calibrate CNC milling machines. The same can be used with 3D printers, especially Cartesian printers like the TAZ.
3. Next, I calibrate the single wall thickness with a single wall calibration thing. This helps refine the slicer parameters for the specific filament I’m using.
4. Finally, I use my single layer test object to nail the single layer thickness for the first layer. I do this at least once at the start of every day/print session.

I designed and now manufacture 3D printed fly fishing reels. There are 9 printed parts and two assemblies that must rotate freely without slop. Here is a photo of the most critical:

These parts are “as printed” - no cleanup at all. The white part must have .05mm +/- .01mm clearance on the shaft for best operation. I print these in several dozen brands and colors of PLA and can get the perfect dimensions for all of them. But, some do require a slightly different slicer profile to get these results.

If you intend to produce precision parts with this level of 3D printer it can be done but you need to be systematic about it.

One thing I would like to stress, people always refer to “PLA” (or “ABS” or “Polycarbonate” - whatever the filament) as if it is a single material. It is not! Each filament within a chemical family (like PLA) has different pigments/dyes, plasticizers and even polylactic acid chain lengths and they ALL affect the properties of the filament. The good news is, you don’t have to know the details on what all of these attributes are, you can do a few simple profiling experiments to characterize a given filament so you get reproducible results in your printer.

Some other replies to your post:

Holes can be tricky - not only to print but to measure precisely too. There will almost always be a little “lip” on the first layer due to the smooshed filament on the bed. You need to trim that away with a hobby knife to measure. How you print affects this too. Most slicers allow you to print “inside to out” or “outside to in” and every slicer I’ve used defaults to outside to in. I printer my critical parts outside to in and I slow WAY DOWN on the perimeter print speed - something like 20mm/s for the final, outside perimeter. This is very reproducible (since print speed also affects part dimensions) and results in much better looking exteriors - no blobs from the start of the extrusion, better control over stringing, etc. For parts that have overhangs, it also provides a solid “base” for the perimeter paths to bond against.

Once you have been through this with your ABS filament you will be ready to tackle Nylon systematically.


Hey Mike,

Thanks a lot for the information. I downloaded Kisslicer and will give it a go. I already noticed an abundance of options and tweaks that can be done, many of which I have no idea what they do. I want to set up Kisslicer the best I can and see what the outcome is, then tweak kisslicer till it is perfect.

I don’t know if you can export the settings, but what key settings are you using while printing your parts that you get that accurate? I don’t really know how to tweak settings, I have been using the per-defined settings from Lulzbot on the Cura slicer so I have no real understanding of what each option is. I figure I will learn as I go, but at the same time, it feels over-wheeling since nothing is really documented. Adjusting a certain speed could have any outcome, I might need to extrude less at a slower speed, ect, but I have no understanding of these settings.

Do you know of a good guide for setting up this slicer program? have tips on the best settings for Kisslicer for ABS 3mm. Maybe other tips on how you are printing such great parts? My goal would be to do +/- 0.1mm… Some parts are inside that, but my last gear was a full 1mm smaller on the top and the teeth were 0.5 mm to wide.

Thanks again

Check out the KISSlicertalk forum if you haven’t. A gent is writing a very well done manual that describes al the settings: http://www.kisslicertalk.com/viewtopic.php?f=23&t=332

I can export settings but unfortunately (for now) these are all for my Rostock delta printer with a water cooled Kraken 4 extruder hot end! I just got my KITTAZ assembled last weekend and am working on calibrating and slicing parameters. Once done I will certainly post them.

It is pretty straight forward to go through any slicer’s settings systematically and well worth the effort. You start with the basics - layer height, extrusion width, # shell layers, # perimeter layers. Use a simple object like my test objects (see link in my sig) to practice on without wasting time or filaments. In fact, read my guide if you haven’t!

What do you mean by 1mm smaller on top? That sounds like a non-slicing problem if the part is cone shaped.


Thanks for the help so far. I printed the gear again. I lowered the bed temp down to 80C and fixed the cone issue. I also tweaked the settings and lowered the speed a lot (I am now at 20mm/s for all speeds) with a layer height of 0.20mm (I was told this was a good layer height for a 0.35 nozzle). I might try to drop down to 0.1mm layer height later if I can. Do you know if layer height really impacts anything besides looks? What would you recommend?

Print came out really nice. Size is off by 0.2mm from the original, I will tweak it a little more before I report back. I figure if I tweak one thing at a time, maybe I can find the issue.

Any other advice is great, you have been extremely helpful and I really appreciate it.

Good progress! Yes, layer height can impact dimension precision too. Think about it, make the layers smaller and the material has to go somewhere. The slice compensates for this by extruding less material based on a volume calculation - but there are enough variables that it can’t be exact. Therefore, there could be a dimensional change too.

My rule of thumb is start with 50% of the nozzle diameter for the layer height. Some say you can go as high as 80% and if you know what you are doing and have a well tuned machine, you can. But try to limit to 60% unless you have good reason for thicker layers. For thinner layers, “go as low as you can go” as they say! It really is more a matter of machine capabilities, bed levelness, etc. Of course, much longer print times will result. But, the extra strength is sometimes needed. For instance, I printed that reel with a .4mm nozzle and .2mm layer height. The white click check (gear) is printed at .15mm layer height to get stronger teeth. I did have to compensate a bit for the diametrical shrinkage when I did this.

And good job - tweak one thing at a time and hold the others constant is the way to go!

“Once I’ve calibrated the printer I never touch that. I then print a new part like your gear and measure it. If it is off, I compensate with the slicing parameters. I can usually get it spot on with 1 test print. I write all of this down (see my guide in my link) so the next time I use this filament I can usually get it right with the first print.”

Micheal, how are you compensating for these things with slicing parameters, can you elaborate? Do you mean that you tweak the G-code that slic3r puts out? I find I can vary results by changing some of the generated values for width etc. in the generated G-Code…

I might as well ask this in this thread also, but is there a way to set the number for the extruder on the LCD panel of the TAZ? I’m talking about the number that you set in pronterface to calibrate the extruder, M92 e9xx or whatever?

I’ve finally setup my LCD so I’m working unteathered now, so havn’t been setting this calibration number for different filaments yet.

JonathanB, there are 2 ways to compensate for sizing variations in the slicer.

The first is to tweak extrusion width. I’ll do this if the delta between printed part and actual is small (say < .05mm) or if the part has internal features like holes and both the external dimension is too large and the holes are too small (think about it, this indicates that the extrusion width is probably too high as filament is flowing into the open area).

The second, and more common adjustment, is to use the slicer’s scale feature. In KISSlicer this is called “scaling factor” and is under the All Models menu. You calculate the scaling factor like this:

scaling factor = actual dimension/measured dimension

So, if a 50mm diameter part prints at 49.3mm, scale - 50/49.3 = 1.014

You can very accurately adjust the printed object’s size simply by making 1 test print. And, if you keep notes on these things, the next time you print with that filament you can usually nail it the first time.

Oh for sure, I’ve been doing the test print method, but then I actually go and change the CAD file to get it to where I want…basically comes out to the same thing, but I will try adjust those other two settings next time within the actually slicer program…I’m using slic3r though, I don’t think it has a scaling feature… :frowning:

As far as extrusion width, I’ve definitely played around with that in the generated G-Code, it makes a difference, I guess I was on the right track.

You can do that too, especially if you find a systemic delta across a variety of filaments. But, once you are in the ballpark, tweaking the slicer scale is more efficient to adjust for differences between filaments. And by keeping records, you have these scaling factors ready when you use a particular filament again.

The other advantage to using the scaling factor is for the cases where you don’t have the source CAD files.

Slic3r does support scaling. Its under the Object menu -> Scale. You can even scale each direction independently if you need to.

Lol, I’ve been printing with this thing for a few months, noticed the scale, rotate features etc. before, just never clued into them. Probably because I never used them…hmmm…could be really handy. I’m not seeing how each individual dimension could be scaled though…just gives me 100% scaling.

**Side note, I’m sure others know this, but it’s new to me, searching through a few windows in Slic3r, just noticed there’s an option that will let you customize the layer height along the print…pretty cool actually.

Slic3r version 1.2:
Screen Shot 2015-03-06 at 8.40.24 AM.png
This goes back a few versions too. The button on the window only does uniform scaling (which is what you want most of the time anyway).

The Rotate feature is your friend! It can be used to debug problems - see a strange print artifact that you can’t sort out? Rotate the part and see if the issue follows the part or stays in place relative to the printer. You can also orient the first/last shell layers to get the orientation you want.

This problem of printing plastic to fine detail is so troubling, it might be worth getting a few sample cogs printed in metal from shapeways. Its about $30 American without postage for a little cog to be printed in stainless steel.

Wow this is great info - thank you so much for sharing this!!