RepRap calibrating

First RepRap....coming right along. Just got movement yesterday - and control. Waiting on final parts (hobbed bolt, heated build plate, ect) to be able to finalize it.
Im having a tough time trying to find exactly where I can control the x.,y,and z calibrations. Is it in the Sprinter FW? is it in the Pronterface?
I found Spacexulas tutorial on setting up the extruder on yotube, but I cant seem to find anything on setting up the axis' to make sure 1mm actually equals 1mm printed. i want to make sure my circles arent ovals, center of the bed is actually the center, and so on.
Thanks!
Jeff

hey jeff,

inside sprinter you will find a chunk of code

float axis_steps_per_unit[] = {80, 80, 3200/1.25,700};

this is where you calibrate the {x, y, z, e}

tell pronterface to move the axis 100mm and then measure the actual mm moved. now divide the 2 numbers and multiply it to the number in the firmware.

heres an example for X:

[100 mm (desired movement)/ 45mm(actual movement)] x 80 = 177.777 so i would input this into where the x value is in the code above and replace it and repeat the step.

Edited 2 time(s). Last edit at 10/13/2011 01:54PM by ECSuyu.

Thanks!
Working on the x&y now!!
But im confused on the equation for the z....

For a metric Prusa, the M8 threaded rod for the Z axis has 1.25 mm pitch, so one full revolution of the Z-axis steppers produces 1.25 mm movement. Standard steppers have 200 steps per revolution, and if you are using 16 micro-steps you get (200 x 16) = 3,200 micro-steps per revolution gives 1.25 mm movement of the Z axis.
Hope this helps!

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Follow my Mendel Prusa build here: [julianh72.blogspot.com]

ok - I understand - Mines a sae so im using 5/16 threaded rod. not sure of the pitch - standard thread - 18 I believe.
I measured it - close but not perfect. which measurement do I change? and is there an equation for that?
thanks!
Jeff

I've calibrated Z with trying to use the steps to pitch ratio and I've also calibrated with the same method as X and Y. I prefer to calibrate the Z the same way as the other 2. What i did was

took 3200/1.25 = 2560

and just did the same thing as X any Y, set it to move 100mm and divide it by the actual steps moved. and then multiply it to 2560.

I prefer this way over finding out pitch and step if you dont know it. But if the info is the step/pitch works well

Great!!
That worked guys!! Thanks for all the help! Now I have some sort of clue whats going on with how to adjust the measurements.
I have everything set to within .1 mm tolerence. Hopefully that will be close enough. Just waiting for my hobbed bolt to get here and I can calibrate the "E" axis and finish assembing the extruder.
Im excited for my first print!
Let me ask this - how much tweaking of the settings is there after the first print?
Jeff

the sky is the limit to the last question regarding tweaking. What I find is you'll probably get it to print reliably first at a certain layer height. After that you might want to look at possibly decreasing the layer height so you can get a finer resolution. The rest of the tweaking is really understanding SF and what parameters in there does to the print

To be sure you've calibrated your printer correctly have a look at this video: [www.youtube.com]

It was an eye-opener for me.

Ok!!
So I calibrated the printer via all the info here, and got my hot end finalized as well as my heated build plate. Was able to do a test print about 11pm last night. It turned out GREAT for a first print!! I used the mustache ring for a test. Thanks to all for the help!!
However, I am going to need some "advanced" printer calibrating help now. I printed the hinged extruder idler bracket, and it came out ok, but it seems kinda skewed as the build went along on the one side - a couple gaps in the print as well. The bridging was good, but the inner corners looked bulged in...Ill attach some pics.
After that I tried the penny bottle opener, and it got about 80% done and it lifted off the build plate. How can this happen? I thought Thats what the heated build plate is supposed to rectify. I have it set up according to Prusas blog : Heated build plate
So any recommended advice/videos for the above issues?
Thanks!
Jeff

Hi


I did calibrate my prusa but still have a print problem. My prusa prints first layer perfect but the others goes randomly every where. I will appreciate any help.

Thanks
Marwan

Do you have any pictures so we can see what is happening?

jakowisp Wrote:
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> Do you have any pictures so we can see what is
> happening?


I appreciate your fast response. Here is the video of what is happening with me:

http://youtu.be/1ViYHLwiGkA

Thanks a lot
Marwan

It seems you have a problem with your extruder calibration.

I assume you already have adjusted the extruder so 10mm are fed every time 10mm are requested on you gcode. Did you?

What about hotend temperature? Have you monitor the extruder temperature while printing? (Sometimes a loose thermistor may cause your firmware to shut down the heat).

Your slicer software (skeinforge or Slic3r) needs to be tuned to your filament width and your nozzle too (if not the gcode generated won't work ok).

@Marwan: Looks like you're losing steps, it's a different problem. Try lowering your acceleration and oiling your rods.