Do i need to calibrate Z axis ?

If it was imperial rods we would all be having the problem. Attached pic of part i was printing..i have stock rods.

 

Can u give me more detailed instruction on changes in firmware ?
i know how to flash it, dont know what to change and where

 

Dont change it yet...its not your problem. The belts are too loose!

 

I just want to see what values i have in my printer before i even think about changing them.
Is there a way to do it ?

 

When you load up repetier, it'll tell you what steps per mm it is currently set to when you connect to it in the log.

Race, it's not the belts if it is the same "bulge" on all sides. Here's a question for you. How many microsteps does the firmware have to send to the steppers if your layer height is set to 0.1058mm and your using the default of 2269.472 steps per mm and your trying to get to 1mm exactly?
The answer isn't as simple as it looks.

The problem is, three fold:

1) I don't know if you've actually used the reprap calculator, but plug in 1mm in the layer height. Huh, it says it needs 141.74344436569808 steps to get there for the imperial coarse rods that the robo uses. Multiply that by 16 microsteps and you get 2267.89510985116928 steps per mm. The problem is that even the most-accurate number of steps doesn't match the firmware values.
2) The firmware only handles a few decimal places. Otherwise it ROUNDS UP/DOWN.
3) Steppers can't handle microsteps as accurately as half-steps, so your steppers may suddenly round up/down a few microsteps as it is stepping. Also, the Z axis steppers aren't kept energized, which means vibrations could rotate your Z rods as it is printing. I'm sure you've noticed that you can manually turn the z axis while it's printing.

In light of all of these factors I'm using 141.5 steps per mm. this equates to 2264 microsteps. It's damn close to 1mm, it uses whole/half steps so its damn accurate. And it doesn't have a ton of decimals to "round up/down". Granted it will still have decimals, but less variables is way better then more variables.
Here's my print before I made my steps per mm tweak. This is a Pyramid shaped roof your looking at.
http://farm8.staticflickr.com/7357/11731754703_98ece667b5_h.jpg

If it was the belts, the banding would be inconsistent, non-repeating patterns. AND I think it would be a straight offset of a certain layer, rather then a consistent outside "bulge".

 

What do u mean, i need repetier for that ?
Where do i look for that info once its connected ?

 

Tony, I noticed in the calculator linked by polylac that the G code M92 will override the steps/mm default for the print. You can try his value easily just by putting:

M92 Z2264​

in your printer settings\custom G code\start G code . This will temporally override the firmware value without having to reflash. If you try it let us know if it makes a difference.

 

1st cube was printed with M92 Z2264
Second without.
Third at slow speed.
Any thoughts ?

 

Wait. Could it be filament ?
I remove the part and hit print again after changing filament.
Blue is 2 times the price of white.
Similar results

 

so fore me the problem is like this one, so it has to be something with the imperial rods

http://forums.robo3dprinter.com/index.php?threads/upgraded-to-metric-rods.1525/

found this in the article, if the settings are like this by default there would be almost no change if you calculate it to 2268 and go to 2264...
// Robo3D Default // #define DEFAULT_AXIS_STEPS_PER_UNIT {80.69,80.69,2269.472,747.626} // default steps per unit for Ultimaker

bit anyway I'm a bit confused, closest to 8mm metric rods, would be 3/16'' imperial. but they have 1.270mm per rotation and not 1.4111
if you have 3/16'' imperial, the setting should be more like 2520...

how are the dimensions in general? if you print a part 10mm height is it 10mm? or more like 9mm?

 

If it were imperial rods...everyone with imperial rods would have the problem. Some of the most accurate cnc machines around still have imperial based machined. Its a non issue...the stock settings for this printer exceed the precision a 3d printer is capable of by design.

Have you ever even checked the belts? I can loosen mine and replicate those results. The grub screws on the belt pulleys will do the same. At least tighten it all up so you can get good base line. Then check and make sure extruder assembly doesnt wobble...with loose bolts it can.

 

@racegrafix: possible, assuming that all printer have identical hard- and software.
And some in the forum fixed theyr problem with differenz layer heights or diffrent steps per mm.

 

That's true...i am assuming we have same hardware and standard software settings.

Because if so....math is math.You could use wood screws if your math is right..lol.

 

Hmm. Strange that it's not working for you with the M92 command. The only other change I've done was print out one of those reinforced z axis smoothrod holders, but my before/after testing didn't show a marked improvement with that... I wonder if it has something to do with the steps per mm for the x/y axis that I've tweaked as well. I'll check when I get home and see exactly what I have all the axis set to.


I think I sorta encountered nothing happening when I ran the M92 commands when I first was testing stepper values, so I just went with a full firmware flash each time. I'm not sure if the firmware does "calculations" based on the values set in the firmware or not. I'll redo a test print and then post the results.

 

Ok i think i finaly got some more tests and findings.
Looking at the picture below i see that front left corner is ALWAYS warped no matter what i do.
Front Right corner is slightly warped.
Back and its corners are perfect. (Picture below)


So if Back side and its corners are perfect, then i only have 2 corners that get messed up all the time. That is
FR-L and FR-R. Looking from the top i would see (Picture Above RIGHT)

The M92 Z2264 had no effect on the print, i tried and nothing. Layers are the same.
10x10x100 checked out perfect from left to right and back to front except for Z=99.65mm tall.
Only problem i see is those 2 front corners at the base for about 4.5mm high only at the front and then its normal. (Back side is perfect from layer 1 all the way to the top.)

Here is another picture from the top. I sliced the print with blade with front facing toward me. The Front Right inner corner is where nozzle lifts up for next layer, thats why it looks like that.

What does all that mean ?

 

How many layers for the bottom and it it solid? You have probably seen that for ABS the opposite can happen with a thick solid bottom box where all that material shrinks and pulls in for the first layers. So perhaps this is the reverse? Also where is you fan or fans? Are you using your dual left/right fan setup? I'm thinking airflow relative to the bulge. Also where is your slicer starting each layer? Random or one corner? If one corner then extra could build up and that on top of the base layer's extra material or swelling could add up to this. Wouldn't affect the bulge I don't think but did you see the calibration constant changes in the newest firmware?

 

Layer height 0.3
Bottom /Top 2 layers thick
Wall is 2 layers thick
Fans are ON.
The last picture above shows and i explained that it builds layers from same corner, but that corner has little to no warping, its the one on the left, not the one on the right from which it starts each layer. The corner from which it starts each layer does have extra filament as u can see but its not creating too much of a problem. Biggest problem is the left front (look at the picture that marks directions) corner.

calibration constant changes in the newest firmware ? Dont know anything about it.
Do u have a link ?

 

Yes thinking about it further, the calibration constants won't affect this.

Here's the link anyways: http://forums.robo3dprinter.com/index.php?threads/marlin-firmware-update-2-6-14.1725/#post-13298
. This will affect your exact dimensions though.

 

So my belts are tight as can be with out stressing the motors and I am using the newest firmware with no extra g code stuff that I have been reading on this thread. and here is what I get. Not sure what I have to do next to make better. .3 is the layer height on repeiter and slicer