RE BED SHAPE

My printer's bed is 335x305 BUT I have a small hotbed 200x200 with origin located at 50, 70.
My question is, should I set the BED SHAPE in PRINTER SETTINGS to:

size: x:335 y: 305
origin x: 50 y: 70

or
size: x:200 y: 200
origin x: 50 y: 70

Obviously, when I am using the full bed I set it to
size: x:335 y: 305
origin x: 0 y: 0

If the bed is unevenly heated, which can not be prevented in your case, you will get a hugely varying temperature at the surface and chances are the bed will buckle unevenly.
Imho you will not be able to print with high print bed temperatures (50°C - 110°C) due to this and you will have big problems with small layer heights.
In any case, adhesion will be best in the center, where the temperature is closest to the target and where, hopefully, the warping is the least.
You should start planning on getting a heater that matches the printplate, or the other way around.

---

[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

thx Srek --- but that wasn't the question and my bed is not unevenly heated
- I just have a smaller build plate when using the hotbed.

there is a Bed Shape option in the Slic3r config.
when i am using the hotbed i tell Slic3r with the Bed Shape entries so that it slices it on the hotbed.

I could ignore that for 2 reasons:
1. My hotbed is in the center of the full bed and Slic3r always defaults to positioning the model in the center of the bed
2. I could manually poisition the model b4 slicing

But if I try to slice something bigger than the hotbed build plate it would do it without that config

Also when I do reposition the model, it is easier if I can see the area in question w/o counting lines.
SO, to do that I need to configure Bed Shape.

with the dimensions given I think the answer is:
size: x:250 y: 270
origin x: 50 y: 70

The origin and bed size is referenced from the printer home position, which does not change.

Edited 1 time(s). Last edit at 11/10/2015 09:50AM by ruggb.

This may not be possible with your setup, but it might be easiest to position one corner of your heated bed at x0,y0 then define it as square and 200x200. Otherwise you'll have to manually position objects as you mentioned above.

In order to use a smaller square bed on top of a larger square one you'd need to define some sort of offset I'm not sure how to do that.

Edited 2 time(s). Last edit at 11/11/2015 04:34AM by DjDemonD.

well the above seems to work
it is setting the origin at the 0,0 of the hotbed and setting the top rt limit to the top rt corner of the hotbed.
it results in the model being sliced dead center of the hotbed if i do not manually chg it.
of course, this is also dead center of the full bed so i can't say which Slic3r is setting it at.
I guess I could chg the upper limit and see if it moves it.

OK - I would say I have no idea what if anything Slic3r uses that for.
It ends up placing in the center of the bed as defined in Repetier.