Help refining the A0-100

I’m Caleb Kraft, formerly of Hackaday, now focusing on

Jebba and the lulzbot team donated an A0-100 to the cause, to help make custom gaming controllers for people with physical disabilities. It has been quite helpful.

Since I’ve had this I’ve had a few annoying issues that have been a thorn in my side.

  1. dimensional inaccuracies.
  • holes aren’t ever quite the right size. Gears are always a tiny bit oversized. Stuff never quite fits right. I have to drill out any holes for screws.
  1. vertical shift.
  • when printing something that is supposed to be perfectly vertical, it will actually get wider as it goes. the 100mm cross for calibration will be vertical on 3 axis, but get wider on one leg. (jebba says possibly hairspray issues?)
  1. sloppy bumpy messy mess sometimes
    — adding a fan really helped this, but with a .25 nozzle, models can sometimes be bumpy all over. Not positive if this is the model or not because I printed a perfectly smooth model yesterday.

  2. stripping

  • the fillament really likes to strip during a print. I clean the hobbed gear thoroughly with the pick and load new fillament each time. (too hot maybe?)

I have no idea if this is important or not, but with the .25 nozzle my layers end up with all these little rough bits.
like this (right click and choose “view image”)

pardon my dirty print bed, I’m doing test after test and it is a pain to get totally clean. I’ve compared with and without this mess and that makes no difference.

Hello Caleb,

I too own an AO-100.

You’ve left out some useful information: do you use ABS or PLA? What temperature and on what surface do you print on? You mentioned hairspray, are you printing on bare glass? I printed that way for a time until I found out that the lower layers were shrinking. Now I print on PET tape with lulzjuice (ABS + acetone solution) and it works quite well. My parts’ outer dimensions are now quite good, but printed holes remain smaller than the 3D model.

My guess is your nozzle is a little clogged. See this topic:

When starting a print, I used to start heating up the nozzle and the bed at the same time. But since the nozzle is a lot quicker to reach its printing temperature, it would sit iddle for at least 10 minutes while the bed was reaching its temp. I think it’s the reason at some point I started having trouble. Now I first start to heat the bed, and only when it has reached about 90 degrees do I start to heat the hot end. I haven’t had more trouble since.

Nevermind the uncleanlyness of your bed, the picture quality is not good enough to see what the problem is. Can you zoom in on the printed part with better focus?

Hi there. Hopefully I can help a little bit, as I’ve had a few of those issues myself, and have managed to get some of them resolved. I’m sure others here may know more about the subject, but here are a few tips and pointers to address a few of the issues you mention.

  1. Dimensional accuracy:
    I can’t see all of your machine, but there are a couple of fixes out there that can make a world of difference. First off, if you don’t already have them, the X end clamp 2.0 with the lower pillow block bearing is a must do upgrade. That relocates one of the pillow blocks from the upper segment and moves it down as far as possible. Since I see you have a newer X carriage on your machine, i’m guessing they already installed one, but if not, here it is: Please note that you don’t have to print the lowered Z motor mount to make those fit, but you will have to modify your Z axis end stop or print the new one, and you may have to lower the threaded rod coupler. It sounds like alot of work, but if you don’t already have that, it helps a huge amount. Z-stop holder:

Next, take a look at the X and Y motor, do you have a small aluminum 16 tooth belt pully, or the larger black plastic and brass pulley? If you have the plastic and brass one you will want to swap that out. A firmware change will be required, but it eliminates most shifting and step skips. Proceedure is described here:

The other required fixes are the X and Y belt tensioners. Circles that aren’t fully round is a sign of low belt tension, and I find you can’t get a high enough belt tension by just pulling on the belts manually. There is a Lulzbbot specific upgrade part for the Y belt, and

For the X tensioner, There isn’t a lulzbot specific part yet, but I adapted this one to fit fairly easily:
xtensioner.stl (57.4 KB)
If the circles are out of round only one direction, thats the direction you need to tighten.

  1. vertical shift can be due to lifting. I only know ABS printing, so assuming you are printing with ABS, the best anti lifting method I found was to set the printbed to 112 degrees. I still get occasional lifting, but it’s maybe one in every 40 parts now. I tried the hairspray trick and it didn’t work for me. Also tried the lulzjuice acetone solution, that helps, but the temperature seems to help more. You could also be getting layer skip due to the black plastic and brass pulleys.

  2. sloppy bumpy mess is a problem that I run into as well. I suspect its due to overextrusion because I don’t have the filliament set 100 correctly in the printing software. Basically, you are supposed to measure the actual filliament diameter and input that for each filliament you use. it can change over the length of the filliament too I’ve found. measure it in a few places, then input that measurement in the settings. you’ll also want to check that your extruder is extruding exactly how much it thinks it is. I saw a brillliant idea on how to measure this on the fly that I haven’t implemented yet. put some 1cm marks on the filliament guide tube, then place a mark ont he filliament itself. Extrude 10mm and meausre if the filliament mark actually moved 10mm. I’m still trying to get this all the way dialed in though myself so there may be better methods. The root cause is probably slight overextrusion though, which you can either experement with turning down slightly, or slow printing.

  3. The filliament stripping issue is one that I struggled with for a while. It ended up being a combination of things. Check the small gear on the NEMA motor and make sure the set screw is tight. Next you’ll want to dissassemble the extruder and really clean out all those plastic shavings and put some bearing oil on the main bearing. In my case, the shavings had built up in one of the bearings and were jamming it, causing the idler bolt to bind up and strip the filliament. The initial problem was mainly due to the loose gear and my not haivng the springs tightened correctly, but even after I corrected that, the volume of plastic shavings caused problems until I cleaned them out all the way.

Hope that helps some!

Thanks for all the great ideas to pursue.
I’ve already got the smaller pulleys.

I’m printing the new X endclamps now. If I recall correctly they bump against the brackets that mount the steppers to the threaded rod right?

I’ll also print the tensioners and come back after all that.

There is just enough clearance to get the X end clamps in there. They’ll hit the Z endstop if you don’t either thin it down, or print the replacement one, and they’ll probably hit your rod clamps until you move them lower, but they will fit without too much trouble. You should end up with about 4-5mm clearance between the bottom of the end clamp and the top of the rod clamp when you are done. There is a set of lower z axis motor mounts that give you more clearance. Those definitely make it an easier swap, but it’s two more large things to print. That’s about the only A0-101 upgrade I haven’t printed at this point. Oh, the AO-101 filliament guide is also worth printing

Here’s what the basic layout of the replacement parts for the x end clamp should look like. My printer wasn’t homed in these shots, so ignore that part, but the other pieces of it should give you an idea of how things fit. In particular look at the Nema motor shaft and how far down the coupler is now compared to where it started. You can also see how the replacement Z endstop fits where the original one won’t without surgery

I have upgraded the following from stock:

  • x carriage
  • z axis stepper mounts
  • x endclamps
  • smaller gears (and updated code)
  • filament tube mount
  • Z endstop mount
  • box fan pointing at it.

The difference is considerable. I actually printed a part where the little nut actually fit in the nut shaped hole!

Congratulations! Glad it’s working better for you now.

The 0.25mm nozzle is really small. Going to 0.35mm speeds up the prints quite a bit and is more reliable. It’s hard to blow air through 0.25mm. That said, there are places where people may want to use it. It may be overkill (=more work) on a game controller. Just a thought. :slight_smile:


There’s new TAZ ends for AOs too. It’s all pretty early stage, but it will be interesting to see if it works better.


Yeah, I have high hopes for project A0-TAZ I think i’ve got things about where they need to be on it, but the threaded insert installing bit is throwing me for a loop so far. I’ve got some press fit ones on the way that should work, but the threaded ones so far have not. That, and the spring tension itself on the plastic spring are about the last hurdles on it I think. That and whether the ACME nut fits this time I suppose heh. It’s getting there though.

I’d be careful with press-fit inserts, they’re usually meant to expand as you thread into them, and this causes some nasty delamination in a lot of printed parts. I prefer heat set inserts, they install with a standard soldering iron and the melting of the plastic around the insert creates a super strong joint.

I get them from mcmaster (, they’re pretty handy to keep a stock of for misc projects.

Thats what I ended up using in the final parts. I have some hilarious blooper springs from the attempts with the press fit ones, and they did not go well at all. The heat set ones worked great though!