Using a single drawing for many processes

[JCL]

Hi there

 

Quite a while ago now, in Nov 2013, I started the Silhouette cutter thread to see what could be done with the machine and to find out whether it could be used by modellers. I was rereading the first few pages the other day after being asked a couple of questions and saw the 6 wheel M&GN passenger brake that I produced as a test.

 

 

 

Unfortunately the coach was scaled incorrectly so I abandoned it. Since then I've gained more experience both in drawing out, and using other technologies such as laser cutting and 3D printing, so I've decided to see how versatile a cutting file can be. I'm looking to produce a master file that can be used by someone:

• as a basis for cutting with a knife, etc
• for using with the Silhouette
• as the input file for a laser priinter
• to use as the start of a 3D print

I'm also looking at the fact that these files can be resized to be used by others modelling in different scales. I expect that the same file can be used for all of these, but each method has its own little foibles. The laser cutter, for example, has its kerf to deal with, and the Silhouette has a problem creating really sharp corners.

 

I want to use the same file with different technologies, so I'll be using Inkscape as opposed to a piece of proprietary software. The main reasons for Inkscape are that there is a tutorial on here by Mike Trice that I can refer to, it produces DXF files that can be used by other software, and it's free, so suits my budget. I can also re-explain a few of the problems that people have converting from Inskscape to Silhouette while I'm at it.

 

I'll be writing the thread in the same way that I did the Blender tutorial, that is, I'll detail my issues and dead ends as well as successes.

 

On that, since starting the Silhouette thread, I've become  a member of the GNR Society, and I've been given some drawings for a Diagram 85E Toilet 1st 6-wheel coach, that is externally almost identical to one that took part in the 1938 RCTS tour behind the Stirling Single No.1. I also have a couple of photographs of this vehicle as well to which I can refer.

 

 

Hopefully there will be something in here that's of interest to some people. A lot of it might be very obvious to many of you, but I hope that I can show how the work that can be put into creating a single file can be reused in new ways, and that we don't need to keep reinventing the Mansard wheel.

 

cheers

 

Jason

[drduncan]

Could you post a link to your blender tutorial?

Thanks

Duncan

[MickRalph]

It's here.

 

I'm hoping to start working through the tutorial when I go to France shortly, so Jason's new thread is well-timed.

 

Mick

[MikeTrice]

...and that we don't need to keep reinventing the Mansard wheel.

 

"Mansell wheel", unless you want to invent a Mansard wheel ;-)

[JCL]

And here's me trying to look clever...

 

Thanks Mick. Here are some other links that I know of that could also be of interest:

 

My Barnum Coach bogie cutting files:

http://www.rmweb.co.uk/community/index.php?/topic/81360-using-inkscape-and-the-silhouette-to-create-coach-bogies/

 

Andy G has some inspirational posts that start with cutting with a knife, and moves onto the Silhouette:

http://www.rmweb.co.uk/community/index.php?/topic/79446-coach-bodging/

 

3D software:

http://www.rmweb.co.uk/community/index.php?/topic/40091-cad-applications-payware-freeware-updates-and-trial-versions/

 

Of course, I'm going to concentrate on coaches, but there's no reason why the work we're going to do can't be used for other projects. Also, for Inkscape read Corel Draw, Serif Draw (at least that's what it was called once), Adobe Illustrator, various CAD programs, and for Blender read Maya, Rhino 3D, etc. A list of software is available via the above link and pinned to the top of the 3D forum.

 

Specific to this project:

 

Mike Trice's chassis building thread:

http://www.rmweb.co.uk/community/index.php?/topic/112237-6-wheel-chassis-for-gnr-coaches-oo/page-2&do=findComment&comment=2371386

 

...and teak painting:

http://www.rmweb.co.uk/community/index.php?/topic/75178-reproducing-varnished-teak-improving-latest-Hornby-thompsons/

 

I'll add to this list as and when I find something else.

 

cheers

 

Jason

[JCL]

For step-by-step introduction to Inskscape, please see Mike's link as given by Mick. The first few posts will in this thread will be a bit more step by step as I build up the sides and end, but I thought it important to show how I go about things.

 

Note, when I use the term ► it's to denote how to get to items in the menu bar at the top of the screen.

 

For this project, first thing first. Start your new file, then change the default units to mm in File ► Document Properties...

 

I took a whole load of dimensions from the plans any added them to my spreadsheet to find out what they would be in 4mm scale. I do this at the beginning so that I'm not constantly stopping and starting to work out the size of the major parts.

 

Excel Spreadsheet with main dimensions

 

If anyone wants a copy of the spreadsheet please just PM me with your email address and I'll send it on. If you'd like to do it yourself:

• Total Inches in column E is feet*12+inches+fraction, and
• Scaled Measurement in column F is Total Inches *(scaling unit/12)

Next thing to do is to import the image into a layer. Thee are three reasons for using layers. They can be locked so you can't accidentally move things around, they can be hidden, and they can be faded.

Locked - if the image isn't locked, I will invariably move it around from time to time by mistake.

Hidden - sometimes I don't want to see everything at the same time. I might have two different images that overlap for example, or a set of drawing objects that are necessary but are distracting when working on a particular piece.

Opacity - changing the opacity which is the bar at the bottom of the rectangle below will allow me to fade things in and out. This will help me if sizing two overlapping images that need to be the same size, reduce the "power" of a very bold image, or if using a photo, will allow the objects you are drawing to show up better.

 

Anyway, onto the layers.

1. Menu option, Layer ► Layers... if the layer panel isn't displayed.
2. On the right create a new layer with the + button and click on it to give it a name.
3. File ► Import to import your image

Create a second layer, name it, then click on it. Create a rectangle for the body side. In my case, its length is 134.79mm, and height is 46.54mm to the apex of the roof. The body side will be in this second layer. You can always check that things are in the right layer by clicking on the eye next to the padlock against the layer name.

 

So, the rectangle is the actual size of the coach side. You now click on the image to display the sizing arrows, and with the control key pressed you resize it until the body side is the same size as the rectangle. The control key will ensure that the image remains the same shape through the resize.

 

Here's one I did earlier.

 

Sizing the image

 

What I do now is turn on snapping and create guides. From Mike's guide, snapping will ensure that things butt up to each other. in the red rectangle in the image below you can see the buttons that turn different snapping features on and off. The top button shows that snapping is on, and the other buttons are different types of snap - corner, middle of the line, etc. At least to start with, turn click on the buttons highlighted in the image.

 

The idea is that the guides will keep everything lined up and the right size, so making panelling easier. You'll see that there are vertical and horizontal rulers around the drawing. Click on the vertical ruler and drag across to the right to create your guide. Pull the guide with your mouse to the top right corner of the rectangle you created to be your body side, and you will see that it snaps to the corner. Create guides for each corner both horizontally and vertically.

 

Blocking out known shapes

 

Using the spreadsheet for dimensions, I also created a guides layer and drew rectangles to the size of the width of the door and the width of a panel. I also noticed that the height and width of the area between the panels was 0.5mm, so I drew a square that size. I then used these rectangles to created guides, moving them, or copying them about as needed to make sure the guides were all the correct distance apart. Using the snapping I was able to ensure, for example, that the .5x.5mm square would line up perfectly against the panel that is of a known size.

 

Note that rectangles that are going to stay, such as panels of known width, were copied from place to place, and were added to a panels layer. These are red in the image at the bottom of this post. Rectangles that are temporary are blue in the bottom image, and are placed in a guides layer.

 

I do tend to go mad with guides, but by doing this, lining things up is a breeze.

 

Creating the guides

 

The panels that I don't have a measurement for basically took up the slack, but as we are talking fractions of a mm I'm not too concerned about that. In the image below, the red rectangles are of known width, the blue are temporary for lining things up and creating guides, and the green ones are inferred. The great thing is that the guides that were used to create the height of the dimensioned panels will also be used for creating the height of the known panels, and as we know that the panels are .5mm apart, the guides created by the little blue squares will often give us the width of those panels as well.

 

Creating the inferred panels

 

With regards to the door, I drew all of the rectangles for the door, and then clicked on Object ► Align and Distribute... to turn on the alignment panel, before clicking on the 3rd icon in the top row to align centres vertically. I grouped the objects together (Object ► Grouped), and then made sure that the door rectangles were in the right place as sometimes this causes them to move slightly. You;ll notice in the image above that the green rectangles within the door area don't line up properly with the guides. This is because the guides were a "best guess" and the rectangles are now accurately vertically aligned with the door sides.

 

A quick note about line widths, I always have the fill and stroke panel turned on (Object ► Fill and Stroke...) and my lines are about .1px generally. They are about .35px while doing this so that you can see them. There will be specific instances when I use different widths, and I'll tell you why when we come to that.

[JCL]

 

Just to finish off the panels, the drawing I'm using is slightly different to the diagram for the actual vehicle. The main difference being that some of the panels in the drawing have been split into two separate panels in the diagram for the actual vehicle. I made sure that the panels were in the right position and were the right size as follows:

 

1. Create the single panel as per the drawing.
2. Create the .5mmx.5mm blue square
3. Making sure that the centre snap is turned on (see green arrow), I moved the square to the centre of the panel
4. I drew the guides (not strictly necessary as the inferred rectangles will snap to the blue square)
5. Finally, I drew in the green inferred rectangles and then deleted the first blue panel that's underneath them.

 

[MikeTrice]

A minor word of warning. When creating squares the 0.5mm dimension includes the width of the line stroke so a 0.5mm square with 0.2mm stroke borders would need to be sized to 0.7mm. I tend to work with the border stroke turned off and a fil set so the dimensions are then accurate and only turn them back on at a later time.

 

In hindsight it might be worth raising the issue of line thickness. A line thickness of say 1mm actually cuts along the centre of the line, so in this respect the line thickness is irrelevant. Taking the above example of a 0.7mm square based on a 0.2mm line thickness the resulting cut along the centre of the line should be 0.5mm. Always worth bearing in mind when producing cutting artwork.

[MickRalph]

For step-by-step introduction to Inskscape, please see Mike's link as given by Mick.

Oops - the link I posted was to Jason's tutorial on Blender.  Mike's Inkscape tutorial is here.

 

Mick

[JCL]

Hi Mike

 

I think I work slightly differently. For me, the line thickness doesn't have a bearing on the size of the square as, from what I've seen, the cutter runs along the centre of the line.

 

I choose "Visual boundiing box" in Edit ► Preferences... ►Tools. the different shapes snap to the centre of the lines, not the outside. This can be seen when snapping lines and other shapes together in the image below

 

 

cheers

 

Jason

[MikeTrice]

Having done some experiments it is the other option "Geometric Bounding Box" that allows the stroke width to be set without impacting the size of the item.

 

OK your screen capture seems to confirm it is "Geometric Bounding Box" rather than "Visual Bounding Box".

 

Either way the user needs to be aware of these options and any impact they may have.

[JCL]

I completely agree. And I'm pleased for the help as I'm sure I'll miss things or do things differently to others. Please keep challenging what I'm saying as that'll help us all.

[Edwardian]

"Mansell wheel", unless you want to invent a Mansard wheel ;-)

 

Could be quite hip?

[JCL]

A square, yesterday

 

I've just done an experiment. In Inkscape, I created a square 100 pixels by 100 pixels (equating to 28.22mm) and gave the outline a width of 10 pixels. I then saved it in different file formats as follows:

• svg - Inkscape's native format
• pdf - Adobe's portable document format
• dxf - can be used by many other drawing software such as Silhouette Studio and the Emblaser laser cutter software
• eps - an older format that I think is the basis for the pdf format (I may be wrong)

All of these formats are used for scaleable vector drawings as opposed to pixels as you would see in a photograph. There is some information about this at the beginning of the Silhouette cutter thread (see post #1).

On opening the compatible files with the Cut2D software that comes with the laser cutter I found the following:

• pdf - two nested squares, inner 28.22mm, outer 31.397mm
• dxf - 1 square 28.22mm on each side
• eps - an uneditable white square

Silhouette Studio has limited importing ability. OK, the fee one can only import:

• dxf - one square, 28.22mm

With the pdf file, when I saw the two squares, I expected one to be the inside of the stroke, and the other the outside, but it seems that the inner square equates to the centre of the stroke and the outer one is the outside edge of the stroke..

 

The above results were the same for both the visual bounding box and geometric bounding box.

 

Separately, I opened the 100px square.svg file in Adobe Illustrator. Strangely I found that it had shrunk to 80px square. I resized it back to 100px square and save it as square2.svg. I then opened both files, and both showed squares 100px square. Very odd.

 

Software versions used:

• Windows 10
• Inkscape 0.91
• Adobe Illustrator cc 2015.3.0
• Cut 2D 8.024
• Silhouette Studio 3.8.64.ss

[raymw]

I think it is best to draw the original at actual size, (dimensions in imperial or metric). Line  thickness is irrelevant (except from the point of view of seeing the line, or emphasis). Then scale the drawing to the final scale needed  (1:48, 1:76, whatever). Other measurements, pixels, dpi, whatever will depend on the display device you are using - vdu/printer, and will be device dependent.

 

Machines, such as laser, other digital cutters, cnc mills, extrusion type 3d printers, use either an internal code, such as g-code or hpgl or similar, and those codes are dimensionless. However, internally the machines will be set to so many steps per mm, or steps per inch. e.g. a line given by, say, from the origin to x5, y0 will be 5 inches long in an imperial machine, or 5mm in a metric machine. Pixels, and dpi are meaningless to those type of machines. this is probably the cause of what you see as odd. Don't worry about it, don't use pixels (or dpi).

 

Of course, you will find that you will need to remove detail from the full size drawing as the size of the final object goes down, which may be helped by assigning finer details in the original drawing to different layers (or colours), and ignoring those layers for the smaller models.

 

Best wishes,

 

Ray

[Dazzler Fan]

JCL -

Went back to your original posting on the Silhouette Machine.
Your Crossing Gates look nice, any chance of buying a pair?

 

Noel

[chris p bacon]

JCL -

 

Went back to your original posting on the Silhouette Machine.

Your Crossing Gates look nice, any chance of buying a pair?

 

Noel

Here

 

http://www.shapeways.com/product/BRYYXF9E8/dual-track-crossing-gates-4mm-scale?optionId=59620147

 

Plus other GN goodies here

 

http://www.shapeways.com/search?q=GNR&type=

[JCL]

Thanks for that Dave, I PM'd Noel.

[chris p bacon]

Thanks for that Dave, I PM'd Noel.

You could have put something in the post..........Oh hang on ...you want it to turn up...

[JCL]

Sorry for the delay, this has been open on my desk for a week, but work took over.

 

Beading

Obviously beading is thin, especially in 4mm scale, and it will be difficult to cut to the correct dimensions at that scale. Mike has mentioned to me that GNR beading is 1⁵/₈” on the lower panels and 1¹/₂“ on the upper panels.

 

Any cutting we do will have to take into account the materials and processes used. For example, the Silhouette can cut a beading strip out of styrene of about .25mm. My laser cutter beam is about .15mm thick, so that thickness would have to be taken into account if I’m using it to cut out the parts.

 

One of the important parts of creating beading is to get it a uniform width across the whole vehicle. Mike Trice explained to me the best way of doing this.

 

Setting up the beading

1. Set the boundary box to “Visual” (see above) and ensure that snap is on (including the 5^th button down in the snap toolbox, see top arrow above).
2. Create the guides so that they are around the outside of the beading.
3. Draw your rectangle.
4. Draw the horizontal line halfway or partway up the rectangle. It needs to be the same width as the rectangle, so the guides help here.
5. Change the stroke width to be the width of the beading, re-positioning if necessary.
6. With the fifth snap button highlighted, the line will snap to a position half way up the rectangle if that's what you need.

Converting to strokes

1. Select the rectangle and line, and choose Path ► Stroke to Path
2. Now, if not selected, re-select, and choose Path ► Union

This will convert the two objects into a single object. If you do step two and your line disappears to just leave the rectangle, then you forgot to do step one. If the union was successful, then you won't be able to individually select the line any longer. If you click on the second image, you might just be able to tell that in the left hand panel, there is a dotted line around the outside rectangle. If you change fill to none (X),stroke to a colour and stroke width to something visible, you will see the three rectangles you've just created. This is as far as you need to go.

 

If you want to test to make sure that the lines are real cutting lines as opposed to some jiggery-pokery, then choose Path ► Break Apart. I did that in the right hand panel above, and you can see that there are now dotted selection lines around all three rectangles. You can select each rectangle individually and move them around.

 

Pitfalls

 

My advice would be to draw your rectangles and lines and get them in the correct position and to the right size before you do conversion to Path to make sure that the beading stays the same width. Figure three shows what happens if you stretch beading that has already had a stroke to path action run on it.

 

 

Note, you can also use this method when creating the window layers (in pink)

 

 

 

 

[MikeTrice]

Mike has mentioned to me that GNR beading is 1⁵/₈” on the lower panels and 1¹/₂“ on the upper panels.

1 5/8" on upper panels, 1" on lower panels.

[JCL]

Cheers Mike, good job you're here.

 

My drawing gives an overall length of the coach, but only shows half of the exterior. Next steps are:

 

Next steps. Note: guides have been removed for clarity

1. Select and copy all of the parts that don't straddle the centre-line.
2. Click on the black arrow button in the toolbar (used for selecting and moving objects)
3. Flip the copied parts (in blue) using the flip button on the top toolbar
4. While snapping to the guides, move the copied panels to the correct position.
5. Stretch the panels (in cyan) that straddle the centre of the coach to the correct width.
6. At this point I could finish the beading for the centre panels.

Flip button and width change

 

For step 5, you can either click and drag, or change the width using the boxes at the top of the screen. Be sure to change the units to percent. If you use the boxes, you'll probably have to re-position those parts.

[JCL]

Three posts I know, but I thought it better to break up the process I'm using.

 

The last thing I decided to do was try to work out what was going to be on each layer. With regards to Silhouette and laser cutting, I would be creating the coach side using layers of plastic or card, or indeed veneer. The beading would be on one layer, the panelling on a second, etc.

 

 

In the trippy diagram above, I looked at the object and how proud from the side of the coach they are positioned (if you see what I mean). Each colour would denote a different layer, and each object on a particular layer would be the same colour. The layers I ended up with on my drawing are as follows:

1. pink
2. green
3. blue
4. red

Two things; the black line around the edge of the coach is common to all layers, and the red over the top of the door is just showing me that the top of the door and coach are aligned, nothing else.

 

 

That's pretty much the coach side for now, next will be the end of the coach.

[JCL]

One more, something I'm not afflicted with with regards to the GNR is the idea of panels that are rounded at one end. If I were, this is how I'd do it:

 

Rounded panels

1. Create guides and draw a rectangle.
2. Click on the edit nodes button, click on the circle in the top right corner and drag it downwards to create the corner curve
3. Click on Path ► Object to Path, then Select the two nodes shown in green and click on the - button (shown on step 3)
4. Drag the two nodes that are left to the guides. These are the new bottom corners
5. The bottom two corners need to be smooth, so select them and click on the "Make the selected nodes corner" icon.
6. The sides probably won't be straight (see the right-hand side), so click on the anchors at the top (the circle in the magnified area) and drag them to the lines. They should snap to the guides.
7. Finished.

As with the Pitfalls diagram above, you should only resize the object until step 3, because after that, unless you preserve the height/width ratio, the rounded corners will no longer be quarter circles, but quarter ellipses. That said, if there are say three different panel widths, you make three masters. Create a panel to the end of step 2, copy and paste it twice for the three widths, then resize a appropriate and proceed for all three to step seven. After that, just make copies of each finished panel master and paste where appropriate. I hope that makes sense.

 

I'm only showing the way I'd do things, but there is always more than one way to skin a cat. If you do this a different way, then please feel free to add your method.

[JCL]

I've just realised that Mike is doing something similar, and in more detail here : http://www.rmweb.co.uk/community/index.php?/topic/114528-using-inkscape-to-produce-cutting-files-a-worked-example/&do=findComment&comment=2419948 . It'll be interesting to see how our two drawing processes differ and where they come together.