New user frustration: Calibration issues?

Hi!

I got my Taz5 yesterday.
I followed the manual, but it stopped after bed leveling, so i assumed that’s all i have to do. (it better be for the price of a car :neutral_face: )
then i went and printed http://www.thingiverse.com/thing:34778 with ABS at 240/110 C as recommended by https://www.lulzbot.com/taz-cura-profiles. Result is: won’t fit. http://i.imgur.com/da78dpy.png No amount of force will make that snap.

So i thought, maybe its just me being a noob, and i went and print a 30x30x3 cube. It turned out to be 30x30x3.3, except on the edges where there’s significant overspill to 30.6mm. http://i.imgur.com/2XIRP9s.png So that’s why the gear model won’t fit at the snap-in thingies.

Some googling suggests i need to set flow lower. So i tried with 50% for the sake of showing the difference. http://i.imgur.com/oB9JK9R.png It’s 29.6 now, except at the edges where it overflows to 30.1. At 80% fow i get 29.9 and 30.4… etc.

uuuh… what do i do? The machine doesn’t … look bad, so i guess it’s a software thing that is supposed to make sure it stays less at the corners maybe? Doesn’t happen with other printers.

thanks!

3D printing isn’t like normal printing (plug in USB cable and print). The next thing is, the transmission model will need a perfectly tuned printer and some experience of yourself to fit as expected. I suggest to print some easy models first until you are familiar with all the options and functions, then proceed to the next step.

For your specific problem, your are quite heavily over extruding. Stay at 100% flow, but calibrate your esteps. See this Howto or if you need more pictures this one.
One important thing, don’t do the test at 100mm/min but stick to 40mm/min. This will give you a much better result.

The calibration should reduce or eleminate your fitting problem, also the corners will be much nicer after it. A little bit “overshoot” at the edges is unavoidable by the way.

That transmission model is pretty complex for a first print…

Looking at the first photo of your print, there is significant overextrusion. 3D printers seem to come set that way to make it easier to get acceptable prints, but it does cause dimensional accuracy to go down a little. On my Mini, I found I need to go down to about 70% flow before I get rid of the overextrusion. Another option is to change the esteps value in the firmware, Sebastian covered that. I’ll likely do that soon.

If you’re willing to do a lot of test prints, you can get most of the issues you mentioned adjusted out. There will always be a some inaccuracy though. For example, if you print a design with a 5mm hole, you will likely get a 4.9x mm hole.

Another suggestion for test/calibration prints… Use a few different types of parts. A calibration cube is great, but doesn’t tell you how your settings work on a tall skinny bit, for example.

A few test prints I like… There’s not really one true way, they all test different things.

http://www.thingiverse.com/thing:24238
http://www.thingiverse.com/thing:1023717
http://www.thingiverse.com/thing:1278865

There’s another thread about this on the front page called getting prints to the right size or something similar. There’s some very useful tips in there.

I have been trying similar, I’ve never needed high tolerances until now so originally set the printer up to get a reasonable print and left it be.

Now I’ve set my target to get within a tenth of a millimetre accuracy in both height and width, I don’t know if that’s a tight tolerance for a 3D printer or not, whilst I’ve had my printer the best part of a year, for what ive printed until now simple adjustments to get reasonable but consistent prints have been enough.

I’ve managed to get my esteps absolutely bang on. Ive measured, remeasured, and triple measured filaments at lots of different points. I also bought a dial gauge and got the four corners spot on, although mentioned in another thread I have a .1mm sag in the centre (that’s with the whole print head carriage removed and the dial gauge and its bracket don’t even weigh a fraction of the former, so it doesn’t account for x axis sag which I haven’t measured).

I’ve spent the last two days attempting to fine tune the z axis stop, and tiny changes in height make massive differences. I’ve managed to get to within .3mm horizontal and vertical accuracy printing a small 4.4mm W x 4mm H part at all four corners and the centre, with the z set at .11mm above the centre of the print bed. I don’t know if that would be considered high or low but a piece of paper will slide effortlessly under the nozzle at that height. It has also brought the best results print quality wise that I have managed so far. The prints are coming out slightly wider and taller than they should be. I think that points at overextrusion.

I’m sure all this has been discussed in detail many times previously, but using Google throws up thousands of results, pretty much all of which ive looked at refer to the paper method. When set to a piece of paper, my nozzle always eventually ends up rubbing into a part of the print and causes chaos.

I’m also beginning to wonder if the z axis wants to be changed to match whatever layer height you’re printing at, which is something I’m going to look at tomorrow. Is there a reason the first and top layers are set to be smaller than the rest in the lulzbot cura profiles? Or is it good practice to set every layer at the same height?

Assuming you’re using Cura, switch to Expert mode. Then adjust the flow % (last setting on the “Basic” tab) to 95% (going down to 90% if you have more overlap set). That should counteract the overextrusiong which is why parts aren’t fitting together… openings slightly smaller and parts slightly bigger.

Unfortunately, different filament (and colors from the same manufacturer) may require different flow rates to account for fillers. Adjusting the flow rate is the quickest way to account for this factor when switching filament brands or colors…