New Printer Troubles

Hi all,

I'm relatively new to this whole printing thing, and having a really hard time getting consistent results out of my Prusa Mendel 2. I'm printing Reprapper brand white PLA on unheated blue tape over glass, using an E3D v5 hotend. I have Marlin firmware on a RAMPS 1.4 board. Control software is Repetier Host, and I'm using Slic3r as my slicing software. Up until I started tweaking things in response to the problems below, I had been having reasonable success with printing my first layer at 225°C and the rest at 220, with a cooling fan on tall parts (not that I've printed many of those).

I have gotten good prints out of the machine in the past, but rarely more than one successful print in a row.

I'm fighting bed adhesion problems: last night I got the best first layer I've seen in a while, then today nothing sticks at all and the extruded material just clumps up on the nozzle of the hotend. To fix this, I've tried to reset the Z 0 height and I raised my first layer temperature 5°C, neither of which helped.

I'm also trying to figure out why my printer keeps skipping steps. It seems to occur on both the X and Y axes, and I don't think I've seen a skip on the first or second layer. It doesn't always skip steps, but it's pretty frequent. I installed a Y-axis belt tensioner of my own design, and it seems to function alright. Now, I think my problem is that my acceleration values in Marlin were too high, since I used the defaults during machine setup. What's a recommended starting point for acceleration values for a flexible machine like this one, and how can you tell if they're too high or too low?

Any ideas anyone? There's so much to consider that I'm pretty overwhelmed at this point.

Thanks in advance,
Klokworker

lets start with the (not so) sticky problem. If its an option for you to get a heated bed: grap it! It is so much easier, its worth the money! Since you have a glass plate you can just put the heated bed under the glass and print without tape or anything. It will stick as hell, I have to let the glass cool down to room temperature in order to get the print of the glass. By the way: I print my PLA on 190-200..

If a heated bed isnt a option you will have to wait for someone else because i bought a heated bed within a few days because i couldnt get my prints to stick.

For the X and Y movement: Its possible the steppers dont get enough current. Move the X or Y ax and try to stop it from moving with one finger. If its easy to stop it, its most likely underpowerd steppers. Ive had the same trouble: print just shifted after a few layers. Its also possible that a belt is rubbing against another part. If there isnt enough current your stepper cant move the ax for a second and everything shifts. Fun fact: Its also possible they get to much current, causing the stepper controller to overheat and reset for a fraction of a second. But if this is the case its very hard to stop the axis from moving with your hand.

If it has something to do with speeds: change it to a low number, lets say 20mm/s (my default for small prints), and try again. You cant go to slow really, only to fast.

Edited 2 time(s). Last edit at 01/30/2015 11:17AM by navyblueboss.