Printer prints always 0.5 mm more

Hi,

Everything I print is almost exactly 0.5 mm too big in X and Y directions.
For example, a 4 mm hole will be only 3.5 mm in diameter. The length of an object will be 100.5 instead of 100mm.

I't not caused by miscalibrated X and Y travel because the error is constant. I believe it's caused by the amount of PLA I print.
But if I reduce the amount of PLA applied, the object will not stick to itself / will not be stable. There will be too much space between the PLA strings.

Is there anything one can do against this?

MendelMax 1.5
JHead MK4b 0.5 mm
Sanguinololu 1.3a
recent Marlin firmware from git (self built)
Slic3er 1.0.1
Pronterface 2014.04.06

thanks,

Jan

Most timing belt pulleys are pretty good but they do have a small amount of tolerance you still have to go in and calibrate steps per millimeter. As to holes depending on the slicing software most print the holes a little small and is not much you can do about it calibrate by outside dimension. Calibrate your extruder very accurately first to best way to do calibration of the X and Y is use a dial indicator but most people do not have this

Edited 2 time(s). Last edit at 05/09/2014 08:24AM by cnc dick.

I'm pretty sure that's nearly universal. If you look at production part STL files in a design program, measure the holes of a part and they're almost always designed .5mm bigger than the actual desired dimensions. Like dick said, part of it could be extruder calibration, but that's just how these printers are. Especially if your first layer is lower than the rest of the layers, then that first layer will almost always stick out ~.5mm from the rest.

Part of 3D printing isn't just calibration, but also designing parts. You have to design parts in such a way that they will come out to satisfaction based on the printers capabilities. Lots of trial and error.

This should be the job of the slicer. Since the slicer knows about the target printer.
Designing parts is about avoiding bridges etc and should not include using modified dimensions in order to fix problems like this.

Maybe I get in touch with the author of slic3er... have to report another bug.

Yeah, trial and error describes reprap printing very good. Had a lot of it already, parts are becoming better and better
eg. my first layer was wider than the others, but I fixed this already.

Thanks for your answers. In understand there is no official way to solve this problem.

Why you ask question you know the answer to??

Don't you know Sesame_Street ? In german the theme song says "Wer nicht fragt bleibt dumm" -> "Anyone who does not ask remains stupid".
And that means I always question my knowledge: I wanted to know if there is something I missed.
If I abused your time, I am sorry.

Edited 1 time(s). Last edit at 05/10/2014 03:31AM by JPT.

Quote
JPT
Don't you know Sesame_Street ? In german the theme song says "Wer nicht fragt bleibt dumm" -> "Anyone who does not ask remains stupid".

Just as an aside, you may want to question the accuracy of the sub-titles you're watching on TV. The theme song (in its original Klingon) is:

http://www.lyricsondemand.com/tvthemes/sesamestreetlyrics.html

Sunny Day
Sweepin' the clouds away
On my way to where the air is sweet

Can you tell me how to get,
How to get to Sesame Street

Come and play
Everything's A-OK
Friendly neighbors there
That's where we meet

Can you tell me how to get
How to get to Sesame Street

It's a magic carpet ride
Every door will open wide
To Happy people like you--
Happy people like
What a beautiful

Sunny Day
Sweepin' the clouds away
On my way to where the air is sweet

Can you tell me how to get,
How to get to Sesame street...
How to get to Sesame Street
How to get to...

Quote
JPT
This should be the job of the slicer. Since the slicer knows about the target printer.
Designing parts is about avoiding bridges etc and should not include using modified dimensions in order to fix problems like this.

Maybe I get in touch with the author of slic3er... have to report another bug.

Yeah, trial and error describes reprap printing very good. Had a lot of it already, parts are becoming better and better
eg. my first layer was wider than the others, but I fixed this already.

Thanks for your answers. In understand there is no official way to solve this problem.

Its more likely your machine is inaccurate rather than a slicing problem.

---

_______________________________________
Waitaki 3D Printer