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[Solved] Problem printing with drawing-unit=INCH

Posted: Tue Nov 05, 2019 3:44 pm
by johnnyd
Hi,
I try to print a file with a simple 2D design, with drawing-unit=Inch.
I added a line of 5" to check scale.
The line length on paper is good, but other things are too small.
I searched in forum and people suggest to change the scale,
but when I change the scale, all lines become very thick.
I need to print this in accurate scale per millimeter.

See attached images,
The DXF is from here: https://grabcad.com/library/fender-stra ... -11-hole-1

Thanks for your help,
JD.

Re: Problem printing with drawing-unit=INCH

Posted: Tue Nov 05, 2019 7:31 pm
by Husky
Hi,
so far I don't quit understand what you trying to do. I'm sure that is just me ... :wink:

Your drawing is in inch,
you will print it 1:1,
it has no dimensions what means if you print it 1:1 it doesn't matter how you call the unit on paper. 5" is printed as 127 mm.
So, when the 5" test measurement is ok where is the problem within a 1:1 print?
johnnyd wrote:
Tue Nov 05, 2019 3:44 pm
I searched in forum and people suggest to change the scale,
but when I change the scale, all lines become very thick.
I need to print this in accurate scale per millimeter.
If you change the unit within the Drawing Preferences you only change the name of the unit! A 5" line is then called a 5 mm line. More to that when I understood your task ...

Re: Problem printing with drawing-unit=INCH

Posted: Wed Nov 06, 2019 12:44 am
by CVH
Changing Edit / Drawing Preferences (Crtl.+I) to mm only changes the actual unit of the drawing at hand.
Anything drew 2inch will now be considered as 2mm.

We don't know at what state you added the 5 inch line.

The lines of the draft you point at in the second picture have a lineweight of 0.15mm.
They look thin on an inch grid from what they originated considered the piece is 7.6 units high.
And they will look 25.4 times fatter on a mm grid. :wink:

Took the test, viewed zoomed in inch one would say the lineweight is about 0.006 units in relation to the grid.
0.006 inch turns out to be a pritty good guess: its 0.1524mm. :P

To scale a drawing made in mm to inch use:
Edit / Convert Drawing Unit (CU) e_geek
The conversion parameters pop up left high.

Why your lineweight is metric I can't explain at this point.

Your next hurdle will be print scale, lineweight and type scaling.
And the problem isn't the scaling, that's pure math.
But to have an overview and get the whole picture.
Kind of a mindset.
Just do tryout some things and it won't take long to become clear.

!! Remark: :!: :?:
I see multiple contours even at circles.
As if it is drew as point perspective.

Regards,
CVH

Re: Problem printing with drawing-unit=INCH

Posted: Wed Nov 06, 2019 7:05 pm
by johnnyd
First thanks for your help!

> so far I don't quit understand what you trying to do. I'm sure that is just me ... :wink:

This is my first time using DXF file and/or QCAD, so I hope I'm using the correct terminology.
I will try to explain my problem again.

The DXF contains a 2D drawing of an object.
This object has a standard size in the real world (see "Fender Startocaster Pickguard")m
but when I've printed it, it came out much smaller then expected.

For example let's it was a drawing of a golf ball.
You go to wikipedia, you see the standard diameter of a golf ball is "has a diameter not less than 1.680 in (42.67 mm)".
Now you download a DXF of a golf ball, you print as 1:1, and the result on paper is only 30 mm, way too small.
at first I thought the problem is with the scale of printing, and maybe inch/mm,
but based on your answers, maybe the problem is in the DXF file itself,
namely it doesnt contain the correct dimensions ?

Re: Problem printing with drawing-unit=INCH

Posted: Wed Nov 06, 2019 7:48 pm
by Husky
johnnyd wrote:
Wed Nov 06, 2019 7:05 pm

The DXF contains a 2D drawing of an object.
This object has a standard size in the real world (see "Fender Startocaster Pickguard")m
but when I've printed it, it came out much smaller then expected.
Thanks - I think I understand know the issue. I'm going to briefly explain it to you what is going on but first I need the "real world" measurement confirmation.

1. Would you say this could be the real world measurement in inch? If not - what should be the dimension.
2. What is the idea behind the unit change from inch to mm?
Husky-2019.11.06-01.png
Husky-2019.11.06-01.png (32.78 KiB) Viewed 1138 times

Re: Problem printing with drawing-unit=INCH

Posted: Wed Nov 06, 2019 10:18 pm
by johnnyd
> Thanks - I think I understand know the issue.
I should thank you ! (-:

> 1. Would you say this could be the real world measurement in inch? If not - what should be the dimension.
No, 7.58" is too small, it should be around 9".

> 2. What is the idea behind the unit change from inch to mm?
When I printed it, it came out too small,
so I thought there is some issue with the scale and it will fix the issue of scale.
(because I have another DXF in mm, that printed in correct size)
I dont care to convert it, as long it will be printed in correct size.

Re: Problem printing with drawing-unit=INCH

Posted: Wed Nov 06, 2019 11:26 pm
by Husky
Ok, now we are talking .... :wink:

Compared with the provided photo and the 9 inch guess the drawing is drawn to small!
I think more accurate would be 8.62" instead of 9". BTW - we can stick to inch!

Regarding to this findings I scaled the drawing with the QCAD "Scale" tool. You can find the tool below Menu/Modify/Scale
Just select the whole drawing and launch the scale tool. I think the dialog is then self-explaining.

If we then launch the QCAD Preview for printing then we can see that this Workpiece doesn't fits on an "ANSI A" page. So far I don't know if that is a problem (maybe you are only looking for the drill pattern) or you're going to print on a larger paper size.

Husky-2019.11.06-04.png
Husky-2019.11.06-04.png (42.32 KiB) Viewed 1134 times

Howsoever - when you print the workpiece it has to be a 1:1 print scale.


Husky-2019.11.06-05.png
Husky-2019.11.06-05.png (38.31 KiB) Viewed 1134 times

Please check this modified dxf and tell me how it works for your project ....
Strat Pickguard 11 holes_mod.DXF
(161.76 KiB) Downloaded 60 times

Re: Problem printing with drawing-unit=INCH

Posted: Wed Nov 06, 2019 11:34 pm
by CVH
I urge you to investigate the contours in your drawing.
Added layers, set all lineweights and types to Default/By Layer
Superimpose the picture, this only works at your side if the png is in the same folder as the dxf.
I added 4 perspective lines from 4 opposing circles + arcs.
These do meet with that accuracy that I can tell this draft originated from a point perpective.

Revision attached.

Regards,
CVH

Re: Problem printing with drawing-unit=INCH

Posted: Thu Nov 07, 2019 4:02 pm
by johnnyd
Thanks for your help !

@Husky, yes it is the correct scale now. I'm very surprised the DXF was not in correct scale, because the whole point,
is to download a template with correct placements for the screws,
so one can print/make this design without need to drill again holes in the wood.
But I've checked on grabcad, and the original versions there were SLDPRT and STEP, so maybe it was missed during conversion,
when later they uploaded the DXF version.
Any way, now I know that I should fix scale and not mess with print issues.

@CVH, thanks a lot for your comments and notes, I will check these.

Thanks again for both !!