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.
- 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: http://www.thingiverse.com/thing:32900 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: http://download.lulzbot.com/AO-101/hardware/printed_parts/stl/z_stop_holder_v2.stl
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: https://www.lulzbot.com/?q=blog/upgrade-your-ao-100
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, http://download.lulzbot.com/AO-101/hardware/printed_parts/stl/Y-Idler-mount_1_copy.stl and http://download.lulzbot.com/AO-101/hardware/printed_parts/stl/Y-Idler-tensioner_1_copy.stl
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.
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.
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.
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!