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Using Inkscape to produce cutting files, a worked example

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It is over two years since I created my thread on introducing Inkscape to produce cutting files: http://www.rmweb.co.uk/community/index.php?/topic/80563-introduction-to-using-inkscape-to-produce-cutting-files/


A number of people have said they have found that thread useful, others have asked that I take things further. Going back over what I have written, that does not seem unreasonable, hence this thread has been born.


Inkscape is free to download and install: https://inkscape.org/en/. The latest version 0.91 seems far more stable than the previous version. It describes itself as "a professional vector graphics editor for Windows, Mac OS X and Linux.". I use it for all sorts of things including CAD type 2D drawings even though it is not intended for CAD type applications. It's interface is typical of other commercial industry graphics packages such as Corel Draw and Adobe Illustrator. If you are not familiar with drawing using graphics packages then it is likely to seem strange at first, but stick with it and you will hopefully become more skilled as you use it, as with any software.


As with any scratchbuilt model there has to be a starting point. This usually takes the form of a scale drawing, or quite frequently by reference to original detailed General Arrangements. The more accurate the reference material, the more accurate the finished model. Obviously photographs of your given prototype help as some aspects are not always evident from drawings.


I will certainly start this topic fairly basic but will assume later on that the basics have been mastered. If you have not read my original Inkscape tutorial (http://www.rmweb.co.uk/community/index.php?/topic/80563-introduction-to-using-inkscape-to-produce-cutting-files/) please do, at least for the basics, download and install the software and have a go. Hopefully this thread will help put the theory into practice and inspire you on to other things.


As with all my threads feel free to ask questions, but please keep to topic as it makes things easier for others to follow. May the adventure begin!

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I am sure that this topic, like your introduction, will be of great value to many of us who are unfamiliar with, but recognise the importance of, designing and cutting models in this way.    


It would be sensible for these topics to be pinned.  They are extremely useful and greatly appreciated.



Edited by Edwardian
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For this walkthrough I will be using a 4mm scale drawing as a basis, the subject is a 4 wheel Metropolitan-designed LSWR coach as requested by Edwardian on my other thread. Why this coach and not something simpler? Well he asked, and being based on something other than plain rectangles, is more educational. It is also a prototype outside my sphere of knowledge so will stretch me as well.


Inkscape allows the option of importing a scanned image to incorporate in your design, or in this case provide a convenient method of tracing the design. The drawings is very sparce of dimensions with only a few major ones present so my first task is to do some math to determine what they sould be at 4mm scale. I will produce the cutting files at 4mm but it would be perfectly practical to work to 7mm, or scale the 4mm files later.


The scanned image needs to be square so that verticals and horizontals are really so. Here is the original image with 4mm dimensions annotated:



First task is to open Inkscape:



Now we need to set some drawing properties. Click on the "File" menu then "Document Properties" (in future I will represent this as "File->Document Properties"):



Change "Default units" to "mm" and "Orientation" to "Landscape" (if modelling in 7mm you might want to change the page size to A3 at the same time). To close the dialogue, click on the little red cross on the top right:



We are now going to import our image. Click on "File->Import":



A file open dialogue will appear. Navigate to and select the image you want to use and click on the "Open" button:



You can now change the way the import works. In my case I always leave it with the default settings so just click "OK":



The image now appears somewhere on the page at varying scales. The image is selected (as can be seen by the various manipulation handles around it):



Here I have clicked the centre of the image with the left mouse button and dragged the image up and left to more of less centralise it on the page:



Click "Layer->Layers..." to display the "Layers" toolbar:



Ok, so what are Layers? Image that you are producing your drawing by hand with pen and paper. You can put all your detail on that single piece of paper quite happily, however if you intende to add interior detail and body framing on the same drawing it can start to look complicated. One option is to put a piece of tracing paper over your drawing and add the additional detail to that. The lower piece of paper will show through your tracing, and the new tracing can be put aside so the original detail can be seen uncluttered. Layers are a bit like using multiple sheets of tracing paper over a base drawing with some additional properties that we will make use of.


All Inkscape drawings have a "Layer 1" layer defined. When the drawing was imported it was placed on that layer, being the only one present at this point. "Layer 1" is not the best name to call it, so double click with the left mouse button on the name "Layer 1" and type in a replacement name that is more meaningful:



Note: When in edit mode the existing name will change colour:



Type the new name:



When finished press the enter key to stop editing.


I am now going to add a new layer (piece of tracing paper) above the existing drawing. Click on the "+" sign in the "Layers" toolbar:



This layer I am going to use in order to correctly scale the drawing so I have given it the name "Sizing". Click on "Add" on completion:



The new layer appears in the "Layers" toolbar. Note the little padlock symbols next to the layer name. These allow individual layers to be locked from accidental editing. Here I have clicked on the padlock for my "Diagram" layer and locked it:



To be continued....



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Mike...  you are responsible, primarily, for my Son and I starting off on the road to plastic heaven.  We tried the software, we bought the Cameo and the merry chatter, grunt and grind of the cutter is a welcome background to silence.  In the four or five months that we have been cutting away we have achieved an interior kit for a BR Std Brake Van (Slater's kit), the partitions for Mk.1 coaches (Easybuild) and the inevitable coal office.


There are several areas of Inkscape which cause regular gnashing:-


1/ creating and adjusting Bezier curves (think inner surface of 7mm coach sides, not exactly a smooth radius)

2/ inserting round corners into rectangles (think glazing in late build Mk1 partitions)

3/ breaking rectangles apart to enable selective colour choices and / or removing one side of the box (inserting doorways into partitions)

4/ changing the colour of items for reference when cutting from Silhouette (for example, black for guide lines, red for full depth cut, blue / green for cutting to different depths).


If these aspects of Inkscape feature in this topic then I shall be very pleased.


thank you, Graham

Edited by Western Star
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Continuing from earlier it would be useful to enlarge the screen display to just include the drawing. For the purposes of producing screen images for this tutorial I have the Inkscape window set smaller than my screen resolution allows. Occassionally this might look odd.


To enlarge the display I select the magnifying glass in the left hand toolbar then click on the drawing with the left mouse button and drag the mouse down and right then release the mouse button:



With the "Sizing" layer selected, I then click on the rectangle tool in the toolbar, and using the same mouse technique click where I want the rectangle to start then drag the mouse down and to the right and releasing the button:



At this stage I click on the select tool in the toolbar and change the characteristics of the drawn rectangle. Note the little icons along the bottom. Clicking on one of the colours tells the object to fill with, in this case, red. If on the other hand the shift key is pressed and held down when the colour selection is made it affects the border outline. In this instance I have clicked shift and then on the little cross at the left to turn the border (or more accurately its "stroke" to "None". I will cover this aspect in more detail later:



I mentioned earlier that Layers have a number of useful properties. One of these is the "Opacity". If I click the "Opacity" setting for a layer I can make it transparent as I have done here for my rectange:



Now the stroke of the rectangle has been turned off I can now set it to the prototype dimensions calculated earlier, in this instance the dimensions of the plan view (96*32mm). These are entered directly in the top dimensions with the rectangle selected:



To do the next part I have changed Inkscape to go full screen. The imported drawing is now to be scaled to match the 4mm dimensions of the rectangle. The layer settings have been changed so I have locked the "Sizing" layer and unlocked the "Diagram" layer and clicked on the drawing image to select it:



By clicking on one of the sizing handles and dragging it with the mouse the image can be resized. When dragging a corner if the "Ctrl" key is pressed at the same time then the resized image will retain its X/Y aspect ratio:



The image is dragged over the rectangle:



Continued tweaking with the handles will eventually result in the sizing rectangle being in the correct place. Do not assume that keeping the "Ctrl" key pressed when resizing is sufficient. Sometimes the original image is slightly off in one direction so will need tweaking with the horizontal and vertical sizing handles:



It pays to zoom in on the image to better see how the scaling is going. Here it is evident that things are not quite right yet:



Bingo, I do believe I have it. Once happy lock the "Diagram" layer so it cannot be disturbed again:



Now is a good time to save the Inkscape drawing, so select "File->Save As...":



Enter a name for the drawing and click on "Save":



Close Inkscape and breath a sigh of relief!

Edited by MikeTrice
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Before going much further consideration needs to be given to how the coach sides are going to be produced, or more specifically how many layers.


A quick experiment colouring in the drawing suggests that 5 layers of 10thou would be correct as shown here:



Green: Waist beading

White: Main beading

Yellow: Main side

Light blue: Window rebates

Red: Door droplights


In practice it might be practical to combine the Light Blue and Red layers however I suspect the extra depth to the droplight will look better. At least if I am proved wrong it will be very easy to revise.





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Before going much further consideration needs to be given to how the coach sides are going to be produced, or more specifically how many layers.


A quick experiment colouring in the drawing suggests that 5 layers of 10thou would be correct as shown here:



Green: Waist beading

White: Main beading

Yellow: Main side

Light blue: Window rebates

Red: Door droplights


In practice it might be practical to combine the Light Blue and Red layers however I suspect the extra depth to the droplight will look better. At least if I am proved wrong it will be very easy to revise.


First, Mike, let me say how good it is of you to do this and so quickly.  I hope to start going through your topic posts thus far over the weekend and attempt to emulate them.  I am suffering from acute deadlines at work at the moment, which might slow me down.  One thing I must do is work out how to import the drawing in the first place.  Thus far I have imported a jpeg.  The drawings exist as pdfs (my current printer won't scan as an image file).  The Memsahib tells me that in Illustrator she can convert a pdf to an image file, so I am going to try to catch her in a forgiving mood and ask her to do that!


Second, for what it's worth I agree concerning the droplights; they are generally recessed beyond any other part of the side of a coach.  I know you have considered the picture below.  It shows a Third, so the compartments are narrower, hence no vertical panels between the quarter lights, but otherwise it is the same style as the 1st/2nd Composite in the drawing.  Looking at the base of the quarter lights and drop lights, I notice how much more deeply the latter appears to be set. 


The photograph is taken by me from the Weddell volume and shows a detail of one of the pictures he reproduced.  This is the clearest view I have seen of the panelling of these coaches and it might be useful for others following your topic, as they can relate it to the drawing.  The volume concerned is LSWR Carriages Volume 1 1838-1900 by G R Weddell, published by Wild Swan, 1992.  The picture from which my detailed picture was taken is credited to F Moore.


Edited by Edwardian
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Moving on, a practice I follow is to copy and version number the Inkscape svg files at various points during the model's development. The svg previously saved is copied and given a "2" suffix before being opened in Inkscape:



There are many ways to achieve our final cutting file. I tend to start by roughing out various guidelines before continuing.


Here the visibility of the "Sizing" layer has been turned off by clicking on the little eye symbol. Alternatively the layer can be deleted:



Click on the "+" button to create a new layer and name it "Rough" or some other suitable name:





The thinnest strip that the Silhouette can cope with is in the region of 0.5mm so I add horizontal and vertical lines over the drawing to act as guidelines. Start by selecting the line tool, clicking with the left mouse button and then whilst holding down the "Ctrl" key click the left mouse button again to the right of the first point then press the return key to finish. This will create a horizontal line:



To set the line thickness we need access to the Fill and Stroke dialogue. To display it either select "Object -> Fill and Stroke..."



or right click on the selected line



Click on "Stroke style" and set the line width to 0.5mm:



Click on a suitable colour in the lower pallette whilst holding down the Shift key to change the line colour:



Move the horizontal line by dragging it with the mouse to act as a guide for the upper beading:



As can be seen from this close up the drawing suggests that the upper beading at this point can be 0.5mm without a problem:



Duplicate the first line by selecting "Ctrl" and "D" then drag the duplicated line up to the upper edge. Here I have increased the line width to 0.9mm to match the drawing:



Additional lines can be added as required to act as guides in whatever colour suits you. Here I have added one to denote the lower edge of the windows and door droplights:



Vertical lines are added as required to match including centre lines for the doors:



Likewise I have roughed out the end panelling, ignoring the curve to the outer beading at this point:


Edited by MikeTrice
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Saving the above and creating a version "3" of the file I decided to add rectangles representing the doors (in this instance the drawing indicates that the out doors should be 2'0" wide so the rectangle is sized to 8mm width). As before the rectangle only has a fill:



The new door outline tends to obscure the horizontal lines added previously so I moved them to the back of the image, e.g. behind the horizontal lines, by selecting "Object -> Lower to Bottom"





The first door is duplicated ("Ctrl/D") and the duplicates width changed to 8.33mm to match the prototypes first class door and dragged into position then "Lowered to Bottom":



The remaining doors are populated and centre lines added (by eye at this point in time):



Lock the "Rough" layer and save the file.



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With the "Sizing" layer selected, I then click on the rectangle tool in the toolbar, and using the same mouse technique click where I want the rectangle to start then drag the mouse down and to the right and releasing the button:

I've been using Guidelines for sizing drawings. I set them for almost every known dimension, so when I'm resizing I can match lots of different lines and points on the drawing. I've often found inaccuracies in the drawing and it helps me to get the best compromise, and see how accurate the drawing is. I know you've already straightened this drawing, but the Guidelines also help me to use Inkscape to do any further straightening that's needed.


I've tried it your way, and now I'm going to try it mine!

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Using Guidelines on every known dimension, I'm much happier that I've sized it correctly, as I had more lines and points to match it to. I also spotted that the rotation was 0.5 degrees out, and corrected it. It seems to be one of the most accurate drawings I've come across so far, but as the only height dimension is the buffers, that could be out if the width of the plan view is wrong. I'm doing it in 7mm scale on an A3 sheet in case the position of the Guidelines cause confusion!



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Unfortunately at this point I need to divert into some theory.


Here I have drawn a simple line from point A to point B and given it a thickness of 5mm:



If I switch to node editing mode the individual nodes are displayed each end of the line and as expected there are two of them:



Cutting machines on the other hand do not recognise the line width so they see things as a simple a line from point A to point B:



Here are three different widths of line, however cutters see them as identical in terms of cutting:



Here I again have a single line which has a width of 10mm. In node editing mode the two start and end nodes can be seen:



Something really useful happens if I click on "Path->Stroke to Path":



If I switch to node editing mode I now have four node points visible. What has happened is the Stroke to Path command has effectively replaced the original line by tracing a line around its perimeter including its stroke width:



At this point it does not look any different from my original line:



However I can turn the fill off, select a line colour and thickness and end up with this:



What I have ended up with is a rectange which will cut 10mm wide.


Although you may be wondering what use this can be, bear with me and all will be revealed.

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Continuing the digression.


Here I have a simple rectangle:



When I switch to node editing mode note that the top right hand corner of the rectangle appears as a little circle:



If I now drag it downwards with the mouse it curves the corners of the rectangle evenly:



Back in selection mode I can increase the stroke width:



If I now select "Path->Stroke to Path: and then go back into node editing mode I now have more nodes than I started with and my original rounded corner rectangle has effectively been replaced with inner and outer strokes:



If I now turn off the fill and set a stroke width the final result can be seen:



If this was sent to a cutter a rounded rectangular frame would be cut.


So a very quick application of this technique.


I start with a rectangle (I have added a line to act as a measure for adding a horizontal line below it::



Additional vertical lines have been added. Most of these lines are as the recommended minimum width of 0.5mm:



Corners are now rounded. Look familiar?



Selecting all the objects (after deleting the spacer) and you can see how the various lines overlap the window frame slightly:



Will everything selected click on "Path->Stroke to Path":



If I remove the fill and set the stroke width you can see more clearly how things stand:



Ensuring all objects are selected click on "Path->Union":



The result is a basic BR window frame overlay that was fitted to Mk1 coaches to battle rust around the windows:



Again this could be sent to a cutter and a window frame produced.

Edited by MikeTrice
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Last one for the moment, taking the earlier concept forward and being more practical for the coach side in question.


As before I have started with a rectangle that has had the corners rounded:



If I grab the other circular handle and drag it to the left I can change to characteristics of the curve:



Back in selection mode providing the little buttons on the toolbar above are turned off I can stretch or shorten my object without impacting the curves set. Here I have made it taller:



After selecting "Path->Object to Path" and entering node edit mode I can now see that my original shape has been broken converted to a path complete with various node editing handles:



Here I am selecting the two lowest nodes. I can do this by lassoing them with the mouse or clicking on each in turn while keeping the shift key pressed. When selected they do change colour but it is not easy to see on these screen shots:



Clicking on the node delete button on the previous screen shot results in the selected nodes being deleted:



The bottom two nodes now show bezier curve handles which I will ignore for now (covered shortly). As before select the nodes themselves and click on the convert to line tool above:



The bottom edge now magically straightens:



If I want to change the height of the resulting object I now have to select the bottom two nodes then drag them up with the mouse whilst holding down the Ctrl key:



At this point I still have a simple path and I can change the stroke's width as I desire:



When I am happy with the result I can select "Path->Stroke to Path":



Now the fill is turned off and the individual stroke set:



Converting a Stroke to a Path is a very useful technique as it provides a way of producing parallel lines that to my knowledge Inkcape cannot do otherwise. Coupled with the ability to set the width of the initial stroke the parallel lines will be precisely the correct distance apart for sending to the cutter.




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As ever this is really good stuff.  I think it was Jason (JCL) who said that cutting right angles was better done using a series of lines so the blade lifts and turns before continuing rather than asking it to run round a rectangle in one sweep.  Can your file be adjusted to work with this requirement.

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As ever this is really good stuff.  I think it was Jason (JCL) who said that cutting right angles was better done using a series of lines so the blade lifts and turns before continuing rather than asking it to run round a rectangle in one sweep.  Can your file be adjusted to work with this requirement.

It could but I have never found it necessary.

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Enough digressions, let's get back to producing a cutting file.


In order to be able to see the actual drawing I have changed the colour of the door markers on the "Rough" layer to yellow, and now created a new layer "Master":



Zooming in to the right hand door I have drawn a simple rectangle to represent the droplight aperture. The observant ones might notice that I have brought it down too low which I only realised later:



The same rectangle was then duplicated and moved up to represent the surround around the door vent. Any moving with the mouse was done with the Ctrl key pressed to maintain vertical alignment with the droplight (although in hindsight it would not have mattered too much is alignment was out a little):



Another rectangle was added to represent the outline of the door vent and sized and positioned by eye:



The droplight window was now added. At this point I noticed the incorrect aperture and have corrected it:



The moulding on the door has been added. This will eventually be processed later, but for now it is a simple rectangle with a 0.5mm stroke:



Note how the various edges etc are aligned to the guidelines from the "Rough" layer, simple to achieve manually by zooming in on them.


The door frame has been added. The width on the prototype is 8mm so to allow for a 0.1mm style outline the width needs to be 8.1mm:



Selecting "Object->Align and Distribute" displays the appropriate dialogue. I have unlocked the "Rough" layer then selected all my door items by lassoing them with the mouse and then clicking on the centre line from the lower layer whilst holding the shift key down. Once happy I clicked on the "centre" icon in the dialogue:



The difference is subtle but has had an impact. The "Rough" layer can now be locked again:



The central door moulding has been duplicated and moved to the left. This can either be down by dragging with the mouse and holding down the Ctrl key, or using the "<-" key. Difficult to judge the gap between its right hand side and the door opening but it looks as if it should be different than the distance to the door panel:



For reasons that will become obvious later I have added a short line to act as a spacer and set its thickness accordingly:



Now to put to use one of the digressions from earlier. A rectangle is added to represent the upper beading recess (to easy visualising alignment I have also reduced the opacity of the "Master" layer:



In node edit mode the top right hand handle is dragged down vertically to round off the edges:



As before a spacer has been added to assist in setting out the gap between the door frame and the panel recess:




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Using another of my digressions, I can now attempt one of the quarterlights.


Draw a rectangle:



OK that's odd, it seems to be trying to draw a ready curved object. Simply click on the right angle button on the toolbar (highlighted on previous screen) to reset:



I decided to make the rectangle taller. A stroke thickness of 0.38mm seems about right and the outer edges aligned to the top and side guidelines:



In node edit mode the first circular handle is dragged down:



And the second it dragged left:



At this stage playing with the two handles I could not get a curve I was happy with so when a stage further and selected "Path:-Object to Path". Now in node editing mode I see the following:



The right hand node's handle was selected and dragged up whilst holding the Ctrl key down until the curve looked better:



I then had to repeat the process for the left hand node:



A quick word of explanation. When the "Path:-Object to Path" command was invoked the behaviour of the rectangle changed so that the resulting path resulted in 4 corners and 4 sides.


The bottom two handles are selected by lassoing them, then the "-" button in the toolbar clicked:



The remaining two lower handles were then selected and converted to a straight line segment by clicking on the relevant button on the toolbar:



Whilst both lower nodes were selected they were then dragged up by the mouse while pressing Ctrl to align with the guideline for the bottom of the window.





So step back and admire the work to date (save and create a new version number for the drawing):



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As ever this is really good stuff.  I think it was Jason (JCL) who said that cutting right angles was better done using a series of lines so the blade lifts and turns before continuing rather than asking it to run round a rectangle in one sweep.  Can your file be adjusted to work with this requirement.

I once did a test in styrene of squares cut as squares and others cut as a series of vertical lines and then horizontal lines. Each pair were different sizes to see how small I could go. The squares tended not to look as good as the separated horizontal and vertical lines, which had sharper corners. It was a long time ago now, and I can't remember if a photo of the results went up on the Silhouette thread.

Edited by JCL
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Thinking how to complete the first door I decided that I could really do with the centre line from the "Rough" layer so I locked the "Master" layer, unlocked the "Rough" layer and selected it:



Duplicate the line by "Ctrl/D" then right click on it with the mouse and select "Move to Layer...":



Select the "Master" layer and click "Move":



Just to prove I now have a copy of the centre line on the "Master" layer I have switched off visibility of the other layers:



Now I select the centre line and the objects to the side of the door that I want to mirror:



It is not necessary but might be easier if the objects are grouped via "Object>-Group". This allows them to be treated as a single object rather than many:



The way the objects appear when selected now reflects a single group. Duplicate the group (Ctrl/D) then click on the horizontal mirror icon on the toolbar:





Move the duplicated door items so they align with the previous door items about their centre line:



Select all the door items by lassoing them with the mouse:



"Object->Group" them into a single object. I have switch back the visibility of the other layers:



Rather than draw everything from scratch again I am going to try and duplicate the current 3rd class door to form the basis of the 1st class one. Duplicate it (Ctrl/D) and move it left to match the other door's position (using Ctrl key to restrict movement horizontally):



You might be tempted to simply stretch the new door to its new width which would not really achieve the results we need. I have done it here just as an illustration but have not saved it in this condition:


















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Hi Mike

I'm following with great interest thank you for providing the step-by-step details. It may tempt me to actually purchase a machine !


As a general question of interest, do you are any of the other listeners following your tutorials have a finished example of this please.




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