Inkscape <---> QCAD scaling issues

[Simko]

Can anyone tell me what I am doing wrong. I am sure that there must be a default English/metric setting that I am missing.

Whenever I go from QCAD to Inkscape, I have to readjust the scale by a factor of 25.4 (the number of mm in one inch).

I even scaled the part in QCAD oversized by 25.4 and it shows up in Inkscape the correct size, but when I saved the DXF in Inkscape and posted it here a user reported that it was too small by a factor of 25.4

I have read the posts about working in SVG as Inkscape and SheetCAM really like those files, but it will still need to be converted to DXF to share.

Does anyone have any input on how they go from CAD to Inkscaoe and back?

[acourtjester]

Not sure if this will help but in Inkscape you can change the document properties as to the scale used. I always have mine set to "in"

[Simko]

Thanks Acourt... I do have that set, but there still seems to be some discrepancy. I did a little research and I have some things to try (importing vs opening DXF files in Inkscape) to see how that effects things.

[acourtjester]

post what you find we are all learning

[Capstone]

I open DXF's in QCad from this website and others, but then convert them to ".svg" files and then open them in Inkscape for editing. From then on... I only use .svg in SheetCAM for creating my cut paths and machine-code conversion. The 25:1 scaling seems to be universal, but if I use that specific process, I've had great results with measurements. If you are getting cuts that don't match the measurement in the drawing then that's more to do with kerf width settings and ensuring your steppers are correctly set up.

I would add that I no longer create stuff in DXF. Not saying I never will again, but I have created plenty of both industrial parts based on specific measurements and have yet to feel the need to use QCad for drawings

[acourtjester]

I'm sure you know but just thought I would say when I have Inkscape setup to do inch (doc Props) and then save it in SVG. When bringing it into SheetCam I do a 1 to 1 scaling and the size is correct. As capstone said drawing in Inkscape is quicker for some things. The "Align and Distribute" function really helps getting things positioned in a drawing.

[Simko]

Here is what I have learned so far...

I drew a 1"x1" box in QCAD using the rectangle function, converted it to a polyline and saved as a R27 (2013) DXF. QCAD units were set to inches
- If you OPEN or IMPORT the DXF into Inkscape and scale by 25.4 using the options tab, it shows up as square of dimension 1.011" as a closed entity that can have a fill applied to it
- You must change the Stroke thickness to something small (.001") for it to show the true dimension of 1"
- If you do not convert to a polyline, it will open/import as a bunch of unconnected lines that cannot be filled until the nodes are connected

I drew a 1"x1" box in QCAD using the rectangle function, converted it to a polyline, exported as an SVG using the advanced export (1" = 1")
- You do not need scale it upon opening or importing into Inkscape, but you do need to change the stroke to something very small (.001") for it to show the true dimension of 1" otherwise it shows a dimension of 1.010".
- If you do not convert to a polyline in QCAD, it will open/import as a GROUP in inkscape, but will still be unconnected lines inside the GROUP and will not be able to be filled until the nodes are connected.

So...

- If you are saving a file from QCAD as a DXF, you will need to scale it by 25.4 while opening in Inkscape
- If you export from QCAD as an SVG (1"=1"), it will import into Inkscape at the proper size
- Both ways need to make sure the objects are closed polylines in QCAD before saving or exporting or they will not work well in Inkscape without connecting all the nodes
- Both ways need to have the stroke in Inkscape set to something very small or it will not show the dimension properly due to the stroke width.

How is that for confusing

Image showing where to set units in QCAD to Inches

Image showing where to set scale while importing DXF in Inkscape

Image showing where to set stroke thickness after opeing/importing DXF/SVG in Inkscape

[Capstone]

Just curious... Why are you bothering with QCAD for your initial drawing at all? Unless you're working from an existing DXF files, why not just start with Inkscape? SheetCAM reads .svg files perfectly!

I draw a 1" square using Inkscape and use the Fill & Stroke selections to set my line "weight" to match my kerf (.063 for 45Amp consumables and .043 for 30amp fine cut consumables with my PM45). This allows me to ensure that spacing for making good cuts are good. From there I just work the SheetCAM settings for "Inside/Outside" offsets to the conditions desired. When SheetCAM is finished, I cut a 1" square. Like I said before, I steer clear of DXF/CAD altogether anymore and I get very precise translations. The only issue I currently have is that I'm not using gear reduction so direct-drive steppers on my "Y" are not quite in sync with my "X" so I get some sloppy holes at slower speeds. I manage to avoid all of those conversions between QCAD and Inkscape about 95% of the time.

I'm happy to go through my process via Skype if you like.

[Simko]

Thanks Phil... I havr used AutoCAD for 19 years and get around pretty good in QCAD already.

I think both programs have their benefits. Easier the convert paths to polylines in CAD, easier to simplify the number of nodes in Inkscape.

Fab parts will probably originate in QCAD, artsy stuff will probably be all done in Inkscape.

Plus I am a little OCD when it comes to vector files... Everything must be connected, closed, snapped. I watched some of those Inkscape videos where they remove parts by using the bezier tool but not snapping to anything, just free handing it.

[Capstone]

If you're always starting with CAD because you need precise measurements based on drawings from a customer, I get it. I have a machinist buddy and he's lost in vector-land. I've just learned to adapt to the CAD-side through Inkscape "tricks", but there are limitations, like angled distance measuring on center. The fact that SheetCAM grabs and more importantly quickly recognizes duplicates and inner/outer features for creating cutting operations was the breaking point for my patience. I just want to see what I drew and cut it. The un-tethered nodes made me nuts, and Inkscape saved me from the hundreds of lines and CPU-choking DXF nodes of death. Happy to help anytime you want to delve further into the Inkscape

[jbc28]

Here is what I have learned so far...

I drew a 1"x1" box in QCAD using the rectangle function, converted it to a polyline and saved as a R27 (2013) DXF. QCAD units were set to inches
- If you OPEN or IMPORT the DXF into Inkscape and scale by 25.4 using the options tab, it shows up as square of dimension 1.011" as a closed entity that can have a fill applied to it
- You must change the Stroke thickness to something small (.001") for it to show the true dimension of 1"
- If you do not convert to a polyline, it will open/import as a bunch of unconnected lines that cannot be filled until the nodes are connected

I drew a 1"x1" box in QCAD using the rectangle function, converted it to a polyline, exported as an SVG using the advanced export (1" = 1")
- You do not need scale it upon opening or importing into Inkscape, but you do need to change the stroke to something very small (.001") for it to show the true dimension of 1" otherwise it shows a dimension of 1.010".
- If you do not convert to a polyline in QCAD, it will open/import as a GROUP in inkscape, but will still be unconnected lines inside the GROUP and will not be able to be filled until the nodes are connected.

So...

- If you are saving a file from QCAD as a DXF, you will need to scale it by 25.4 while opening in Inkscape
- If you export from QCAD as an SVG (1"=1"), it will import into Inkscape at the proper size
- Both ways need to make sure the objects are closed polylines in QCAD before saving or exporting or they will not work well in Inkscape without connecting all the nodes
- Both ways need to have the stroke in Inkscape set to something very small or it will not show the dimension properly due to the stroke width.

.....................

Can someone explain how to do this in qcad? I tried exporting a dxf to svg and Inkscape slowly opened a glob of a drawing. I think this may be my problem. Thanks.

[acourtjester]

Capstone thanks for the kerf weight note I had not used that I just used the narrow stroke so I could see it on the screen

[Simko]

Can someone explain how to do this in qcad? I tried exporting a dxf to svg and Inkscape slowly opened a glob of a drawing. I think this may be my problem. Thanks.

If you are getting a blob of a drawing in Inkscape it is most likely being imported too small.

After you click on the export SVG (advanced) in QCAD you will get a dialog box. The only thing that I set is the scale, set it to 1"=1"

If you have done that and you still have a blob of a drawing in Inkscape, go up to the top bar in Inkscape and click View -> DisplayMode -> Outline. This will remove all of the stroke widths and fills. If your drawing looks normal now, you need to change the stroke width to something smaller. Once the stroke is something more manageable go back to the top View -> DisplayMode -> Normal to see the drawing with the stroke width again.

Making a polyline in QCAD is the same as making a closed path in Inkscape. I am not at the computer right now (iPad) but if the above doesn't fix your problem, I will post how to convert a series of lines to a single closed polyline.

[jbc28]

Thanks for the response. I will give that a try.

[jbc28]

Can someone explain how to do this in qcad? I tried exporting a dxf to svg and Inkscape slowly opened a glob of a drawing. I think this may be my problem. Thanks.

If you are getting a blob of a drawing in Inkscape it is most likely being imported too small.

After you click on the export SVG (advanced) in QCAD you will get a dialog box. The only thing that I set is the scale, set it to 1"=1"

If you have done that and you still have a blob of a drawing in Inkscape, go up to the top bar in Inkscape and click View -> DisplayMode -> Outline. This will remove all of the stroke widths and fills. If your drawing looks normal now, you need to change the stroke width to something smaller. Once the stroke is something more manageable go back to the top View -> DisplayMode -> Normal to see the drawing with the stroke width again.

Making a polyline in QCAD is the same as making a closed path in Inkscape. I am not at the computer right now (iPad) but if the above doesn't fix your problem, I will post how to convert a series of lines to a single closed polyline.

I followed your advice, and now I can see the SVG. But it is still very slow to work with because it is literally made of thousands of nodes. Is there a way to remove these and create arcs or something?

[Simko]

Can you post up the DXF and SVG? You may need to put the SVG in a zip file in order to post it.

Another thing to try in the meantime is to highlight the whole drawing in Inkscape and go up at the top bar Path -> Simplify

You can change the Simplify sensitivity in the Application Settings if it doesn't simplify enough or simplifies too much.

[jbc28]

I'll give that i try tomorrow. Thanks

[jbc28]

Here is the file that I am testing.

I tried to simplify, but I don't see any difference. This file was opened in qcad and converted to svg with 1:1. There are so many nodes that it just bogs down inkscape.

[Simko]

It took me a little bit to figure it out, but I think this is what you are looking for. i put together a quick list of what I did to get it to this point, I would recommend going through it yourself. Hope it helps.

Open the file in Inkscape
- View -> DisplayMode -> Outline so you don't bog down the computer with strokes
- Resize to 24x13 INCHES rather than PIXELS as it currently is saved
- Set stroke width to .001"
- Save file as SVG

Open file in QCAD
- Select the whole image
- Draw -> Polyline -> Create from selected entities (this took my computer about 60-80 seconds)
- Export as SVG Advanced 1"-1"

Open file in Inkscape
- Right click image and select UNGROUP
- Select the whole image with the selection tool PATH -> SIMPLIFY (this took about 30 seconds)

Oval Insert 8_test_QCAD.svg

(26.13 KiB) Downloaded 101 times

[jbc28]

Thanks. I will try that today.

[Capstone]

I never did manage to get the 413K file open in Inkscape, even after using QCAD Pro to convert it to .svg. Your PC and memory must be pretty beefy.