ZGAP behaviour different in v1.6 vs v1.5

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fboulanger
Posts: 6
Joined: 15 Jul 2017, 22:16

ZGAP behaviour different in v1.6 vs v1.5

Post by fboulanger »

Hi,
I have been trying to control the ZGAP on version 1.6.2 without success.

The 'bubble' says "Currently limited internally to be less than the finest layer thickness".
Does this mean that we have almost no control over it, i.e I cannot set a ZGAP higher than the layer height ?
After comparing the GCODE from version 1.5 vs 1.6 for the same model, it is quite clear that the behavior is very different.

In version 1.5 changing the ZGAP would trigger a SLICE, and would change the distance between the object and the last support layer.
In current version 1.6.2, changing the ZGAP does NOT trigger a SLICE and layer heights are not affected, i.e. no gap between object and support.
So in the model I am using at least, v1.6 does not even apply ZGAP: See Thin Man by Tush in Thingiverse (sitting.stl)

Any help on this will be greatly appreciated.

Thanks,
Francois
3DBastler
Posts: 16
Joined: 09 Sep 2017, 05:23

Re: ZGAP behaviour different in v1.6 vs v1.5

Post by 3DBastler »

Can't help with a solution but can confirm that problem.
I printed a lot of things in the last weeks and wondered why the support is printed at top like a part of the object to print.
It's really hard to remove this support, it's near impossible just to break it away, you have to cut it.
In my eyes it's a bug inside 1,62.
Zgap.jpg
Zgap.jpg (245 KiB) Viewed 1779 times
fboulanger
Posts: 6
Joined: 15 Jul 2017, 22:16

Re: ZGAP behaviour different in v1.6 vs v1.5

Post by fboulanger »

I found in the v1.6rc2 changelog that the maximum ZGAP is internally limited to 0.9x( minimum layer height).
I then tried all possible combinations of values in the screens STYLE and SUPPORT and still could not see any change when I looked at the Paths in Kisslicer: no gap shown, i.e. last support height=10.0mm, next object height= 10.2mm

Then I thought that maybe the way Kiss shows the paths may be 'off' so I decided to look at the paths using a GCode simulator (http://gcodesim.dietzm.de)
Preliminary observations show that Kiss does separate the top of the support with the bottom of the part to a maximum value around 0.18mm (for a layer height of 0.2mm). This seems to corresponds to the internal limit mentioned.

I plan on doing more testing tonight with the simulator and with some prints.
Since using version 1.6.2 I have had some difficulty removing supports: as I usually print in PETG I blamed it on the 'stickiness' of PETG and postponed any further investigation.

It is only when I printed the small 'thin man' object in PLA that I had a real problem: the part would break when trying to pry off the support (it is only 2mm thick). PETG is a lot stickier than PLA so I could not understand.
That's when I started looking into this.

I really think we should be able to override this limitation to allow for different materials/objects. Version 2.0 maybe ???

Francois.
3DBastler
Posts: 16
Joined: 09 Sep 2017, 05:23

Re: ZGAP behaviour different in v1.6 vs v1.5

Post by 3DBastler »

I would like to point to this problem once more.
See the below picture. Red arrows directing to the areas which goes wrong by existing vertical gab limitation (less than than finest layer).
You can see that the support top bakes together with the object. Left and right isn't such good too, but you can see the gabs there.
support_distance_z.jpg
I rotated the object for a better look to the melted areas. Means the bottom of this object is upwards in picture.
This is an good example for showing the problem. BTW, this is printed with ABS, Nozzle and Bed temp as low as possible so object will print and stick on bed. (225° Nozzle and 95° bed).
I don't know why this Zgab is limited as shown in the tooltip inside above post, but I would really like to change the Zgab value. Any chance?
Khayrisill
Posts: 7
Joined: 23 Sep 2017, 16:18

Re: ZGAP behaviour different in v1.6 vs v1.5

Post by Khayrisill »

Hi guys,

Want to add my own note about this, I spend couple of hour setting up the parameters for my supports, and then run a print test. I asked for a Zgap of 0.3 mm but I realized that the slicer ignore this value... It was such a pain to remove the support after all.....

What is the reason behind this?
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