New build major issues

[edk80]

Hi all,

just built the pro b prusa i3, nothing but major issues.

When i print the first layer is ok kind of (has gaps in lines).. but the 2nd layer the filament SKIPS THE CORNERS OF THE SQUARE (see pics) this is the biggest problem i have... i can live and deal with the gaps.

PICTURES AT BOTTOM OF POST AND VIDEO HERE -> https://youtu.be/SXXeyrCHvJo

i have leveled the bed to a piece of paper under each corner or on the bed touching.

I have calibrated the extruder
the z steps are out but not over, they are under

settings

0.3 nozzle (it is 0.3 nozzle)
1.75mm pla - 1.75 in slicer settings

extruder tmp 205, bed 65

first layer 0.1 layer height 0.1 (also tried 0.2 on both, and 0.05 on layer height)

I also have the z axis issue where if i put the top piece that holds the z axis in place on one side it makes noise and doesnt move.. this has to do with the x belt tightening pulled the z rods together.. i have managed to get this to work with just a little noise every now and then.

Help mostly with the first issue would be great thanks

VIDEO - https://youtu.be/SXXeyrCHvJo

[Gingko]

The Z step seems not correct, it goes up too much so that filament cannot attach together. You can make it move 100mm, then measure how far it actually goes, test for several times, then calibrate the proper Z step/mm.

For other Z-axis issue, please check this post first:
https://www.youtube.com/watch?v=T9vI6DqAcmo&t=335s

[jzero42]

Yep, this is a minor issue.

Correct the z-steps, for me it was around 405. You can do this in the menu and DONT forget to save it (store) to the EEPROM!
By default it's around 2600, way too much.

Layer height can be 0.2 or 0.25 mm (for the 0.3 mm nozzle).

While you are at it, make sure to also calibrate the extruder (e-steps), default is 100, I had to slightly decrease that. Google/youtube on how to do that.

"I also have the z axis issue where if i put the top piece that holds the z axis in place on one side it makes noise and doesnt move.. this has to do with the x belt tightening pulled the z rods together.."

Had the same for me, make sure the Z axis horizontal piece is "wide" enough so that the rods can EASILY rotate and not stuck. Try to adjust it.

[edk80]

Hi thanks for your replies

I did look at the z steps, i made it go up 100mm and it only went up 65mm.. so thats not it right?

also i did calibrate the extruder.. that was out but fine now.

[jzero42]

What is your value for z-steps? Is it around 400?
Is the up-down movement good otherwise, moving well or is it struggling?

[edk80]

I had a quick look last night and it was 2560... ill try 400 tonight thanks

[edk80]

What is your value for z-steps? Is it around 400?
Is the up-down movement good otherwise, moving well or is it struggling?

Hey mate,

I will try 400, but

when measuring from the bed to the extruder.. what part of the extruder? the very top? the nozzle? i measured to the top of the extruder.. top of the fan/heatsink and it was 14cm and a 1/2... after moving it 10cm

Not struggeling but making a little noise which i think i can fix when i get it right.

[Gingko]

What is your value for z-steps? Is it around 400?
Is the up-down movement good otherwise, moving well or is it struggling?

Hey mate,

I will try 400, but

when measuring from the bed to the extruder.. what part of the extruder? the very top? the nozzle? i measured to the top of the extruder.. top of the fan/heatsink and it was 14cm and a 1/2... after moving it 10cm

Not struggeling but making a little noise which i think i can fix when i get it right.

Then the proper Z step=recent z step(2560) * 10 / 14.5=1765

Try to set this value as Z step, then save it!

[jzero42]

I will try 400, but

when measuring from the bed to the extruder.. what part of the extruder? the very top? the nozzle? i measured to the top of the extruder.. top of the fan/heatsink and it was 14cm and a 1/2... after moving it 10cm

Not struggeling but making a little noise which i think i can fix when i get it right.

You are supposed to check the DELTA movement, that is, the difference.
1. Mark or measure where the initial position was
2. Move the head "10 cm up" with controls (or from a PC)
3. Measure the difference.

If all is good, telling the printer to move "10 cm (= 100 mm) up" would move it 10 cm up (= 100 mm). If it moves more, than you have to reduce the z-steps.
Go to youtube and search some "z calibration reprap" or "prusa" videos there, it's the same concept.

[moorebrm]

In 2016 I purchased a Geeetech Acrylic Prusa i3b pro kit - using it while I write this.
Good learning curve and has been a good little printer once you sort out the bugs.

The biggest problem I had initially was z axis jamming (i believe this may also be your problem)

On startup the z-axis stuck at the bottom, the screw threads squeak up and down and the steppers lost steps in travel.
I greased the screw threads but they still squeaked and I was losing level calibration and getting a lousy print.

I determined the problem was excessive run out where the lead screws go into the flexible coupling.
When the flexible couplings are tightened the lead screws are thrown off center and rotate in an orbit rather than turn through their centers.
The problem is magnified at the bottom where its tight and major frictional thrusts between the screw and the 8mm guide rods occur.
The increased friction jams the printer Z drives and they lose steps bed cocks over aggravating the issue.
I spent a day trying to get the lead screws to run through their centers by careful alignment and packing the flexible couplings. I got the problem to almost acceptable - the bed traveled up and down without too much squeaking or sticking but I was still not happy with it.

To correct the problem - (and help resolve z banding issue)
I removed the bronze screw assembly from beneath the metal carriage and placed it on top of the carriage clear of the alignment hole then supported the carriage with Long 20mm screws going up through the carriage hole and into the bronze screw assembly.
(I now use small cable tie straps and springs not the 20mm screws)
The bronze screw assembly is now above a suspended carriage.
I filed a small flat on the flange of the bronze screw assembly to giving them clearance on the metal carriage.
The bronze screw now has a small amount of sideways movement to allow for some screw wobble and is further away from the stepper motor coupling where the run-out wobble is greatest.
This mod requires no drilling or modifications to the frame or bed and I used the existing equipment from the kit in a reconfigured way.

To test if this is an issue - I recommend seriously loosening off the z drive nut screws and test your print again.

Second problem - Incorrect assembly
The x axis rods must be retained on the inside of the carriage with the retaining locks - the retainers need tio be pushed up hard against the carriage supports so the rods prevent the belt tensioner pulling in and bowing the z axis rods.
Be careful of one of the frame screws on the RHS it fouls the RHS carriage as it goes up

Third problem - extruder jamming and erratic flow rate (unlucky on this one )
The teflon tube in the hot end was slightly too long and on heating it expanded into the hot end and acted like a gland nut grabbing the filament and preventing extrusion - the extruder drive slipped or jammed.
It took me a while to sort this one out as it was erratic - changes in heat effected it - sometimes it worked fine other times it jammed solid.
To correct the problem - Once I sorted out what was happening I replace the tube with a new piece and cut it to be the exact length NO longer than the extruder barrel.

I have done a few mods to my printer
Changed it to a bowden drive - all metal J hot end - acme z screw drives but I still think the base kit is a good one to start with.
I am currently assembling/building a more expensive Core-xy printer kit, and I am having to print mods as I go as the kit is not quite right.

regards moorebrm