Delta callibration problems

Hello everybody,

2 weeks ago I finished my delta printer with the following specs:

-Taurino power
-ramps 1.4
-A4988 motor drivers
-nema 17 motors
-gt2 timing belts with 20 teeth pulleys
-mechanical endstops
-LCD smart controller
-onyx heated bed
-bulldog lite extruder

At first I ran into a lot of problems, mainly because I really wanted to finish it and made some mistakes. At first my vertical extrusions weren't perpendicular to the bed and my diagonal rods weren't the exact same length. Now that I solved this it prints well... sometimes. The main problems I now have, and I can't solve myself, is that I have to recallibrate every time a print is done. Sometimes there is a difference of +/- 1 mm in buildheight. Sometimes I even have to change the horizontal radius! Because it's bowed OR cupped. And last but not least, I have a problem with over-extrusion, is this simply solved with a lesser flow rate?
I know these are a lot of questions and even more variables, but even some suggestions would help a lot. Callibrating before every print starts to be very annoying.
Thanks,
Beerend

Have you calibrated the stepper drivers yet?

[reprap.org]

I did in the beginning of the build. But, since then I installed a fan blowing across all of the heatsinks. Is it safe to give them a bit more power when they're cooled correctly? My motors feel cool to the touch en the heatsinks are warm, but touchable.
Beerend

What host are you using (pronterface, repetier, etc.)? When you calibrate are using the M666 code or are you making your changes in the firmware? If you are using the M666 code, are you saving your changes with the M500 code? Upon each start of the printer, run the M666L command to see the printers calibration specs. Write them down and make sure that you have your specs correct and as a baseline to recheck every time at startup. Also make sure that EEPROM settings are off or turned to 0 in the firmware so bad settings are not kept, and so that new changes are not overridden by what was previously changed.

You say that your machines calibration changes every time: were you able to do multiple tower calibrations and center calibration and come up with the same numbers every time, or did the numbers change (x tower, y tower, z tower, center)? If it changed every time then either something is loose, enstop, hotend, etc.. Horizontal radius, I believe you mean delta radius or (R). Deltas inherently have a bowl or rise, after you change either the delta smooth rod offset or just change the delta radius in the M666 code (M666 R[whatever number you choose] e.g. M666 R120.2) you can eliminate the bowl. After all changes are made save your settings with M500.

Extruder should be calibrated with a caliper to make sure that if you tell it to extrude 40mm you actually get 40mm of filament. Use the extruder calibration guide: [richrap.com]. Or [reprap.org] (scroll down to extruder section).

Edited 2 time(s). Last edit at 08/17/2014 12:42PM by Wildcard.

Ok,
So I found a lot of things which weren't correct. First of all my bed was crooked, VERY crooked. I screwed it down to hard and clamped my glass on top. I loosened it all and used half of the clamps. This works a lot, but not quite there yet. I'm now printing spacers on which I can mount some plywood and made some springs to push the bed and the glass against it from underneath. Hope this will do the trick. I'm also printing a thing which can measure if my vertical beams are perpendicular in the horizontal plane (to the center of the bed). All my stepper drivers were correct and all my belts are tighter then ever. Also I found I was printing WAY to slow, all of the extruded plastic kept oozing and formed little mountains on which the printer crashed.
Thanks for the help so far.
Still, there is one problem I still can't figure out. My extruder motor is still missing steps. I calibrated the steps per mm and still i have to keep the flow rate at about 85 % so it won't make a lot of stuttering noises. I'm using repetier firmware with repetier host software.
And to answer the last questions, I use the EEPROM endstop offset to level the bed. I used bolts in the first place, but found they were a pain to get correct.

Thanks
Beerend

Edited 1 time(s). Last edit at 08/21/2014 08:59AM by Beerend.

Try upping your temp 5 or 10degress and see if it stops the extruder from skipping so much.

Temps are only a reference, each machine and filament is different, so what temp works for your machine will not always work for others.