unwanted rounding for subtractive cylinder

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uwestoehr
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unwanted rounding for subtractive cylinder

Postby uwestoehr » Mon Feb 18, 2019 11:10 am

I have a simple task: a subtractive cylinder. Its radius should be exactly 0.525 mm because my 3D printer has 50 micron accuracy and I need it.

But as you can see in the attached simple example:
Cylinder-rounding-issue.FCStd
(7.85 KiB) Downloaded 9 times
I can set the radius to 0.525 but in the properties I see it is automatically rounded to 0.53.
I use already 3 digits in the FC preferences and also using 4 digits does not solve my problem.

Is there a special setting to avoid the unwanted rounding?

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15860 (Git)
Build type: Release
Branch: master
Hash: 3b708c7f84b0425076b520e1d95627b20fd75fe0
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: German/Germany (de_DE)
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meme2704
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Location: Vosges

Re: unwanted rounding for subtractive cylinder

Postby meme2704 » Mon Feb 18, 2019 12:17 pm

Hi
Do not panic, it shows you 0.53, but if you edit the dimension, it is well preserved at 0.525
Attachments
radius525.PNG
radius525.PNG (45.37 KiB) Viewed 181 times
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uwestoehr
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Re: unwanted rounding for subtractive cylinder

Postby uwestoehr » Mon Feb 18, 2019 12:32 pm

meme2704 wrote:
Mon Feb 18, 2019 12:17 pm
Do not panic, it shows you 0.53, but if you edit the dimension, it is well preserved at 0.525
What have you done to see the 0.525? I don't get the dialog from your screenshot.

Here I get this:
- open the file I attached
- double-click on the second cylinder and see its radius is 0.5300
- now change it to 0.5250 and say OK
- double-click again on the cylinder
result: you see still 0.5300:

FreeCAD_4kQaVQajKH.png
FreeCAD_4kQaVQajKH.png (15.4 KiB) Viewed 179 times

(I know I can use a sketch and then pocket to overcome the issue, nevertheless the cylinder settings should respect my input and not round if I don't want it.)
openBrain
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Re: unwanted rounding for subtractive cylinder

Postby openBrain » Mon Feb 18, 2019 1:28 pm

After setting the Number of decimals to 3 in Preferences -> General -> Units, the 0.525 value is correctly stored.
Just notice you're fighting with 5 µm which is about a tenth of your printer accuracy... I guess it's less than the dimension variation seen between 10 and 25 °C...
Also I can't believe you're printer has a 50 µm accuracy but rather such a resolution. ;)

EDIT :
3decimals.png
3decimals.png (18.38 KiB) Viewed 162 times
chrisb
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Re: unwanted rounding for subtractive cylinder

Postby chrisb » Mon Feb 18, 2019 1:55 pm

It shows, saves, and reloads perfectly. Where did yiu set it in the preferences?

In case something went out of whack you can try to reset the configuration with the button in the preferences. Another possibility is to delete your config files or to move them in case you want to restore them.


OS: Ubuntu 16.04.5 LTS
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15860 (Git)
Build type: Release
Branch: master
Hash: 3b708c7f84b0425076b520e1d95627b20fd75fe0
Python version: 2.7.12
Qt version: 4.8.7
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)
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uwestoehr
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Re: unwanted rounding for subtractive cylinder

Postby uwestoehr » Mon Feb 18, 2019 2:01 pm

openBrain wrote:
Mon Feb 18, 2019 1:28 pm
After setting the Number of decimals to 3 in Preferences -> General -> Units, the 0.525 value is correctly stored.
OK, then it is a bug on my system, because as you have seen, I even used there 4 decimals.
openBrain wrote:
Mon Feb 18, 2019 1:28 pm
Just notice you're fighting with 5 µm which is about a tenth of your printer accuracy...
:D I knew someone would state this. I am building a micro-assembly and friction matters for the hole. I use a photolithographic 3D printer and this one reaches even 27 micron resolution. However I need 1050 microns as hole diameter. The printer allows me to print the diameter reproducibly in steps of 50 microns and 50/2 = 25. And there my value comes from.

OK, so the issue I see is just a display issue. Nevertheless it is confusing (at least it confused me).
openBrain
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Re: unwanted rounding for subtractive cylinder

Postby openBrain » Mon Feb 18, 2019 2:11 pm

uwestoehr wrote:
Mon Feb 18, 2019 2:01 pm
OK, so the issue I see is just a display issue. Nevertheless it is confusing (at least it confused me).
Unfortunately, I believe it's a bug. When I edit the value in "data" tab of combo view, it sets correctly with 3 decimals. But as soon as I edit it in the "tasks" tab (after double-clicking the function in the tree), it permanently rounds to 2 decimals ... :?
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uwestoehr
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Re: unwanted rounding for subtractive cylinder

Postby uwestoehr » Mon Feb 18, 2019 2:21 pm

openBrain wrote:
Mon Feb 18, 2019 2:11 pm
Unfortunately, I believe it's a bug. When I edit the value in "data" tab of combo view, it sets correctly with 3 decimals. But as soon as I edit it in the "tasks" tab (after double-clicking the function in the tree), it permanently rounds to 2 decimals ... :?
This is the same here. I created now issue #3845 for this.

I even deleted my FC user preferences to assure I have a clean setup but the problem persists.
openBrain
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Re: unwanted rounding for subtractive cylinder

Postby openBrain » Mon Feb 18, 2019 2:36 pm

Just notice that it isn't (I believe) just a cosmetic/display issue. As an evidence, the radius will also be rounded to 2 decimals if you display it on a Techdraw page. ;)
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meme2704
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Re: unwanted rounding for subtractive cylinder

Postby meme2704 » Mon Feb 18, 2019 4:09 pm

I have just taken the procedure to zero:
I open your file, I measure your hole, = 0.53mm, including in techdraw
I modify your hole to 0.525mm I measure it (by the two techniques) = 0.525mm, I save, I reopen, I measure = 0.53mm, Damned :mrgreen:
I modify "Preferences" to 4 decimals places, I close Fc, I restart Fc, I redo all the tralala, and .... (roll of drums) .... the hole is to remain at 0.5250mm ...... youpie :lol: :lol:
it should be written on Fc's pediment:
:!: "DO NOT FORGET TO CLOSE Fc FOR CHANGES OF PREFERENCE TO BE TAKEN INTO ACCOUNT" :!: