Newbie Completely Stuck :( (Prusa I3)

[tricey27]

Hi Everyone,

Completely new to the 3D printer world, I have purchased the Prusa I3 and it has arrived today. Got it all built/ connected up and it seems to be functioning electrically/mechanically. Now I have setup all limit switches and using Pronterface have set it all up. But I followed a youtube vid and it shows you to print a 20mm cube off. Well... Must of tryed 15/20 times now and it wont stick to glass at all. Have tryed some hair spray as seen online and have tryed printing onto paper. The paper was the most successful but still terrible. It just seems to start laying down then gets all clogged around nozzle and just makes a mess. Please could someone tell me there reccommended settings to be setup in Slic3r and see if I can get something made Also how far should I have the nozzle set off the glass as cannot find a figure in the manual at all.

Many thanks in advance

Adam

[Alibert]

Most likely your problem is poor bed levelling.

You should just be able to slide a piece of paper under the nozzle, and still feel some friction. This goes for all parts of the bed (middle and all four corners).

[tricey27]

Thanks for response, I have just re adjusted all corners to the thickness of paper and they are perfect. Gone to run it again and just exactly the same, its not laying the plastic at all. Does any know how to increase flow? Or does anyone know what rate it should be flowing, from what mine is doing to what ive seen videos mine seems to be coming out very minor with a tiny tiny bead so its not setting down very well at all :/ What do you reccomend for all applicable settings? I.e temps, flow etc.

Cheers

[Alibert]

For PLA bed=60, nozzle=200 for first try, for ABS bed=95, nozzle=230.
Layer height 0.2 mm for starters, don't make it too difficult.

Also, not every hairspray is OK. If you can't get the right one, then buy a can of 3DLac. This is guaranteed to work well on glass.

Check that the filament diameter setting in your slicer is the right one., that is don't state 3mm if you are using 1.75mm diameter filament.

If the problem persists, then it might be the extruder steps/mm setting in the firmware. That is how many steps the stepper motor must make to push exactly 1mm of your filament through the nozzle. There are guides on the net on how to do this. A (cheap) digital caliper is a handy tool you should use.

[tricey27]

For PLA bed=60, nozzle=200 for first try, for ABS bed=95, nozzle=230.
Layer height 0.2 mm for starters, don't make it too difficult.

Also, not every hairspray is OK. If you can't get the right one, then buy a can of 3DLac. This is guaranteed to work well on glass.

Check that the filament diameter setting in your slicer is the right one., that is don't state 3mm if you are using 1.75mm diameter filament.

If the problem persists, then it might be the extruder steps/mm setting in the firmware. That is how many steps the stepper motor must make to push exactly 1mm of your filament through the nozzle. There are guides on the net on how to do this. A (cheap) digital caliper is a handy tool you should use.

Thank you for your response, I have set the bed up perfect now and have had a quick play with settings. I was using Pronterface at first to print a 20mm x 20mm cube and this was what the problem. Just before I went out earlier I had a quick play with Cura and started making the "robot". This started laying down the base nicely but had a very poor quality once going further up. I will have a play with some new settings tomorrow and see what the outcome is. What sort of flowrate am I best using? Is there any guide you can recommend for me to use rather that bothering all of you? Many thanks

Adam

[Alibert]

This started laying down the base nicely but had a very poor quality once going further up.

Try lowering your print speed and see if that solves the problem. The stepper motor has to move/accelerate/decelerate the build plate to and fro which is quite some mass. If your print speed is too high, the motor will skip steps and your assumed position is off. When on the critical edge, this will happen when the electronics/elecetrics heat up, aka later during the print.

Or it could be that your z-steps (vertical movement) are off and need re-calibrating.

Also, check your slicer settings (Cura now?). The slicer needs to know all dimensions to make the right gcode file. The printer itself is just a dumb machine that does more or less exactly what the gcode file instructs it to do. The printer specific part you need to be aware of is that the gcode file generated by the slicer specifies movement in mm, and that the firmware 'knows' how many steps to pulse the motors to achieve that movement in mm. Therefore you may need to calibrate the firmware settings with a guide from the net. It is not uncommon for a chinese printer to come with firmware settings based on a particular hardware setup, but that they forgot to adjust those settings when exchanging some hardware for cheaper alternatives....

If you want to check if this is the problem, use the firmware movement controls. First home and go to the build plate (z=0) at the front edge. Then manually move the z-position to 150mm or whatever the max height is and measure with a digital caliper the distance between the tip of the nozzle and your build plate. If that measurment is significantly off compared to the z-pos you manually enteredand moved to, then you need to recalibrate.

[tricey27]

Thanks for reply again Alibert. I have had a read up earlier on updating firmware on the Geeetech GT2560 board. This looks fairly simple to do. How do I go about calibrating all the axis so I know for definite that they are correct? I had quick look at a few guides earlier on but they all seem very complex. Do any of you recommend a simplish guide to get me going? Are my limits right in that they have the Y axis has the limit at the back. The X axis has the limit on the left. And the Z axis has the limit on the bottom of printer. Just want to see if print something half successful. Does anyone have any recommended settings to try on the Cura robot to see if I can get it to print?

[Geoff]

Thanks for response, I have just re adjusted all corners to the thickness of paper and they are perfect. Gone to run it again and just exactly the same, its not laying the plastic at all. Does any know how to increase flow? Or does anyone know what rate it should be flowing, from what mine is doing to what ive seen videos mine seems to be coming out very minor with a tiny tiny bead so its not setting down very well at all :/ What do you reccomend for all applicable settings? I.e temps, flow etc.

Cheers

Most likely you will need to add a compensation for the Z position.

Get the nozzle to within the papers width off the platform, run an M114 command and see where it thinks the nozzle is, use that measurement in Slicer, in extruder settings for the Z-offset.

If pronterface thinks your nozzle is 3mm away from the build plate when its in fact touching it, you need to deduct that from the offset, so in that case it would be -3mm but ideally you shouldn't need to adjust that low, my prusa is like at -0.4mm its close but still I need to put a Z offset in to compensate because I built a new extruder for it, which threw it out a little.

[Alibert]

The x- and y- axis are the easiest. Design a 150x150 mm square line, print it, and then measure it. If it comes out at 150x150 mm those settings are OK. If not, then you can recalculate the steps/mm. Look up the current setting in the firmware, multiply those steps/mm by 150 to get the number of steps the firmware sent the motor to achieve the assumed 150mm. Divide the number of steps you calculated by the actual size and you have the true steps/mm for that axis.

Example: the firmware has 100 steps/mm and you wanted to print 150 mm in x-direction. That means the stepper was moved 100*150=15000 steps. The measured size of the printed object is 144.2 mm. So the actual steps/mm is 15000/144.2=104 steps/mm. Change this in the firmware and your printer will print true in the x direction. Same for Y.

The z-axis is a bit different as you also need to take into account the z-axis zero with respect to the build plate as Geoff pointed out. Calibrate the z-axis zero first. You can do this with an offset value in software, or you can fiddle your z-axis endstop and re-adjust the springs leveling the build plate (my personal preference as the springs have a decent amount of play).

You can then move the nozzle to z=0 at the front of the plate, manually go to z=150 and measure the actual distance between nozzle tip and plate with calipers. Alternatively you can print a cube tower of for example 100mm high and measure that. Calculate the actual steps/mm in the same way as for the x- and y-axis.

[cjalas]

If you're still having issues with the filament not sticking to the bed, and you are using glass, I highly suggest trying to use Elmer's Glue sticks (the purple non toxic super strength kind). Using the stick, make one pass up and down across the glass making sure to cover all the surface evenly, then do a second pass left to right across your first layer of glue. Don't overdo it, but make sure the glass bed is "foggy" with glue. Then try printing.