hytek
Posts: 2
Joined: Tue Oct 04, 2016 8:09 pm

Size difference from software to print?

Tue Oct 04, 2016 8:27 pm

I'm confused why the size (XYZ) shown in the software differs from the actual print?
Example: I'm printing an Samsung galaxy 4 phone cover. The software size shows X=128.27 Y=65.60 Z=13.70. The actual print came out at X=125.72 Y=63.53 Z=13.75. I've since done 2 other prints and the results are pretty close.
How can I adjust the software size to match the finished product size?
Any advised would be greatly appreciated.
newbie with QIDI 2 extruders.

wirlybird
Posts: 1221
Joined: Sun Jul 17, 2016 1:32 pm

Re: Size difference from software to print?

Wed Oct 05, 2016 12:43 pm

First question is what profile did you pick for the QIDI?

Second thing is you can scale the object in S3D. You can double click the object in the preview window to open the scaling-positioning window. Maybe that is where you got the size from. So, if the size is ok there then it's most likely settings.

hytek
Posts: 2
Joined: Tue Oct 04, 2016 8:09 pm

Re: Size difference from software to print?

Wed Oct 05, 2016 9:31 pm

wirlybird wrote:First question is what profile did you pick for the QIDI?

Second thing is you can scale the object in S3D. You can double click the object in the preview window to open the scaling-positioning window. Maybe that is where you got the size from. So, if the size is ok there then it's most likely settings.
Thanks for the response,
1) Replicator 1 - duel extruder

2) Yes, I did the scaling correctly.

Build volume / Origin offset maybe?

This QIDI prints really well but just noticed the size issue. And in this build....Size Matters....

zemlin
Posts: 266
Joined: Mon Feb 01, 2016 11:36 am

Re: Size difference from software to print?

Fri Oct 07, 2016 1:58 pm

Material, color, extrusion multiplier, layer thickness, extrusion width, extruder temperature, print speed, etc. can all impact the dimensional accuracy of your print. There are two settings that can impact the size of the final part, and they both need to be tweaked when you adjust your print settings.

I designed a 'Calibration Cross" that I use which includes large and small dimensions with both inside and outside measurements. I print one of these parts scaled to 100% with no horizontal offset. I then measure the printed part and use the attached spreadsheet to dial in my numbers for X & Y scale factors and horizontal offset.

See next reply for STL file and zipped EXCEL file.
Calcross2.JPG
calcross1.JPG
calcrossXL.JPG
calcrossXL.JPG (58.6 KiB) Viewed 3588 times

zemlin
Posts: 266
Joined: Mon Feb 01, 2016 11:36 am

Re: Size difference from software to print?

Fri Oct 07, 2016 1:59 pm

Additional attachments - the ZIP file is the Excel sheet only.

Make sure you part has cooled to room temperature before taking measurements. If the part is still warm it will skew your results.

First I find the horizontal offset that gives me closes to 10 in the boxes in the lower right.
Then I adjust the scaling factors to get the numbers in the blue DIFF columns as close to zero as possible. Some will be a little above and some a little below, but in general I can get everything within less than .1mm of nominal - usually half that.

Anytime I make a significant change in my print settings I will run off one of these crosses and figure up new scale and offset factors to guarantee a print that is as close as possible to the nominal dimensions.
Attachments
calibration-cross.zip
(9.89 KiB) Downloaded 214 times
calibration-cross.stl
(130.55 KiB) Downloaded 322 times

curious aardvark
Posts: 50
Joined: Wed Oct 01, 2014 10:02 am

Re: Size difference from software to print?

Sat Oct 08, 2016 10:02 am

are you using abs ?

This shrinks by 1-2% depending on brand, colour etc.

So with abs you ned to upscale by 1% or so before printing.

zemlin
Posts: 266
Joined: Mon Feb 01, 2016 11:36 am

Re: Size difference from software to print?

Mon Mar 06, 2017 8:51 pm

Update.:
I've added a few useful fields to the spreadsheet, and also added a Z-Axis calibration. I have attached an updated drawing, the latest spreadsheet, and the STL file for the Z-Axis scaling.
Attachments
Calibration-Cross.zip
Updated PDF drawing, Excel sheet, and STL file for Z-Axis calibration.
(63.83 KiB) Downloaded 173 times

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