Using Inkscape to produce cutting files, a worked example

[MikeTrice]

I am making this up as I go along as you can probably tell, so I do not have a finished item yet. What I am intending to do, assuming it is of interest, is go through the design aspects as well as just the drawing with a view to getting my machine out and actually cutting one out and assembling it. Happy to upload the Inkscape svg file as well. I will admit that taking screen shots and posting them here is slowing the whole process down considerably and I am starting to feel the need for a break. If you are interested in things I have done previously with the Silhouette you might like to see these threads:

http://www.rmweb.co.uk/community/index.php?/topic/104851-the-coronation-the-silhouette-mr-jenkinson-and-me/?p=2084580

http://www.rmweb.co.uk/community/index.php?/topic/81902-completing-the-4mm-ner-6-wheel-coach/

[MikeTrice]

Before I lose my sanity for the day a few more images. I will pick up the pace a little or things will get extremely repetative.

 

The duplicated door is selected and "Object->Ungroup" selected a number of time to separate the various elements:

 

 

The objects to the right of the door are deleted as they will be replaced later:

 

I am trying to increase the width of the door and its droplights by 0.33mm so I added thjis short line and set it to 0.33mm (although I did not ultimately use it):

 

Select all the door objects but not the items to its left:

 

Going into node edit mode I realised that some of the items were still objects rather than paths. Oops:

 

Flipped back into select mode then chose "Path->Object to Path" then went into node edit mode. Much better:

 

Using the lasso the right hand nodes are all selected:

 

My intention was to drag the selected nodes to the right (holding the Ctrl key) until they lined up with my temporary spacer. In practice I noticed a counter at the bottom of the screen showing the amount of displacement in mm so I watched until the displacement read 0.33mm:

 

Select the now wider door frame and the centre line then using the Align and Distribute dialogue recentre the centre line. Note I selected the door frame and then the centre line and had to change the Relative To setting accordingly:

 

The quaterlight was selected and stretched to its new width:

 

 

As before the centre line is selected along with the left hand items and grouped:

 

Mirrored and moved to align the centre lines:

 

At this point the centre lines on the "Rough" layer were starting to get confusing when the door is correctly aligned:

 

Simple solution lock "Master", unlock "Rough" select and delete them, then relock "Rough" and unlock "Master":

 

 

 

 

 

 

 

 

 

[MikeTrice]

To produce the centre recess I needed to add two spacers 0.5mm wide:

 

A rectangle is added and located:

 

Curved as before:

 

Converted to a Path then the bottom node deleted:

 

And straightened:

 

Then shortened to match the guidelines:

 

To address the upper recess I changed the righthand one to a different colour:

 

Selected the left one and stretched it to overlay the right hand one then deleted the unwanted green version:

 

The waist beading was treated the same but I did not change the colour of the one on the right this time:

 

The small recess to the right is added using the same technique as before:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[BG John]

I will admit that taking screen shots and posting them here is slowing the whole process down considerably and I am starting to feel the need for a break.

No need to rush. I've only done the sizing bit so far, and I already had my own method of doing that! It will take me a while to catch up with the next steps, especially as I've decided to have a go at one of the K&ESR ex GER coaches as well. I can see why you chose the Metropolitan coach, as it's a much better drawing, but I think the ex GER drawings are good enough.

 

Are we doing all the twiddly bits, like axleboxes and springs, too?

[MikeTrice]

Are we doing all the twiddly bits, like axleboxes and springs, too?

Unknown at this point.

[MikeTrice]

So close to seeing something tangible so I will press on.

 

A filled rectagle with no stroke style is added to represent the veihicle body. Its length is set to the known length of 96mm and the top and bottom adjusted to fit the drawing:

 

A centre line is added:

 

And centred using the side as a basis:

 

The rectangle has now had its fill set to none and its stroke set to 0.1mm. I have hidden the other layers for clarity:

 

Select all the element from the centre line and to the right:

 

Group them:

 

Duplicate them, then mirror them and move to a position matching the centre lines:

 

Ungroup all elements. I am now going to stretch the panelling on the left to math that on the right but first I have changed the colour of the items I am going to replace:

 

The left hand items have been stretched and the unwanted ones deleted:

 

I have now duplicated the body rectangle and changed its hreight to provide the upper beading extent and the lower beading:

 

To finish the centre panel I zoomed in on it and moved the two guidelines on the "Rough" layer to butt up against the window surrounds:

 

Back with the "Master" layer the centre beading recess is added as before:

 

Converted to a Path then the centre node deleted and the bottom two straightened and raised to match the guideline:

 

Something I had failed to do earlier was add circles representing door and grab rail positions:

 

These were then duplicated and moved to match the other doors. Final job is to select all the objects that need converting to parallel cutting lines:

 

"Path->Path to Stroke", then turn fill off and set a stroke width of 0.1mm:

 

Lastly select all the lines and change them to Black and then increase the layer's opacity to 100%:

 

Just as a comparison, but not as a permanent part of my Inkscape file I have moved the drawn elements alongside the original diagram for comparison:

 

A BIG WORD OF WARNING AT THIS POINT. There is a frustrating "Bug" in Inkscape that when elements or layers have an opacity set to below 100% attempting to print them to a laser printer may result in a single sheet of wasted black toner. If in doubt save the svg file as a pdf and print that.

 

A PDF of the side drawn so far is attached to this post.

 

 

 

 

 

 

 

Inkscape Coach Tutorial 9.pdf

[SimonME46]

This is great Mike, really appreciate your efforts. I'm using Inkscape to create files for a full spectrum laser, so this is right on topic for me. This weekend I had a problem specific to this laser where the 'retina engrave' software wouldn't show all vectors. Turned out it didn't handle layers at all well...

[MikeTrice]

This is potentially the most important post to date. Strictly speaking I should have created it earlier in the process, however I wanted people to feel comfortable with the software first.

 

It is all very well creating artwork to cut various sides to be laminated together, but far more important is, how are they going to be used? This is where the final design of how the coach will be assembled needs to be decided as it can have an impact on how I proceed. Having dabbled with various construction techniques I do have a lot of faith in David Jenkinson's method of styrene contruction as covered in the Wild Swan book "Carriage Modelling Made Easy". What an inspiration that book is.

 

David's method is to build up the side from multiple layers built on a flat base that includes a glazing strip inserted longitudinally through it. With this in mind it is imperative to work out how the various layers work together and what cross section is required for the partitions etc.

 

I do all these calculations using Inkscape, so fire up your latest Inkscape file and lets continue.

 

The basis for the calculations is the end profile of the source drawing. Here I have zoomed in on it and drawn a rectangle 32mm wide to represent the overall width of the vehicle. A centre line has also been added and using the Distribution and Alignment dialogue centred on the end:

 

A series of lines are added roughly against the profile. This is done by starting by left clicking the mouse, moving to the next position vertically with the Ctrl key held and clicking again then releasing the Ctrl key and clicking twice more to create line extensions. Hit "Return" on completion. At present I am intending that the side will be made up of 10thou (0.25mm) styrene laminations so the style width for the line has been set to 0.25mm representing a sinlge lamination:

 

Zooming in on the drawing allows the individual nodes to be moved to the correct locations. A peculiarity of this vehicle is that the panelling does not extend all the way to the bottom, however I have ignored this at the moment as I need to establish the side's curvature:

 

Here is an enlargement of the lower nodes as drawn and initially manipulated:

 

The lower three nodes are selected and the "Smooth curve" button clicked on the toolbar:

 

The changed nodes have now changed appearance and various curving handles now appear:

 

With the whole side "smoothed" the upper section is now curved so select the top two nodes and click on the "Straight" button in the toolbar:

 

Zooming in on the lower section I can see that the middle node is not in the correct location so I select it and drag it to the left:

 

The result is much better:

 

I have jumped somewhat in the process. I have taken the original curved side and moved it inwards to represent the side proper and added a straight section to its left to represent the panelling layer which only extends to the waist. The curve is further duplicated and moved to represent the anticipated layers and their anticipated thickness:

 

Perhaps more interesting is the lower view as it can be seen how some of the layers are cut short to form the curvature of the turnunder:

 

 

 

 

 

 

 

 

 

[MikeTrice]

A similar process takes place for the way the ends rebate into the side layers:

[BG John]

As you're using 10thou for 4mm scale, would you use 15thou for 7mm? Presumably anything thicker wouldn't cut right through, so would be more difficult.

[Edwardian]

Edwardian, can I give you a hint? Inkscape can open PDF files!!!!! Open in Inkscape and export as a PNG file. That is how I got the image I am using after exporting and manipulating in Photoshop.

 

Mike

 

Probably this is not the best time for me to try to catch up, after a series of mishaps this weekend, little sleep and a certain amount of pain (!), but I find it hard not to be simply over-faced by this software.

 

Rather frustratingly, I cannot make any kind of start on it, as I have failed to make sense of your instructions for importing the image.  It is the pdf one I sent you.  I opened it in Inkscape.  I then exported as a PNG, at which point nothing happened/it disappeared.  I don't understand why I was supposed to do that, or what I was supposed to do next, but exporting as a PNG had no apparent effect; certainly no file had been created as a result.

 

I finally cracked this, but the resultant PNG file is only part of the scanned image imported, so far as I can see..

 

Really, I am such a complete duffer, but having put you up to this, I find I literally cannot begin to follow what you've done. 

 

Hopeless!

Edited September 4, 2016 by Edwardian

[Edwardian]

Finally got to the position below by rotating in Inkscape, then cropping the exported PNG prior to re-importing..

 

What should I do now, please?

Edited September 4, 2016 by Edwardian

[MikeTrice]

As you're using 10thou for 4mm scale, would you use 15thou for 7mm? Presumably anything thicker wouldn't cut right through, so would be more difficult.

Good question. I think 10thou is overscale for 4mm so is probably more suited to 7mm, however as you suggest I would also use 15thou. You would need to go through the same steps I did to work out the layer thickness in Inkscape at your chosen scale.

[MikeTrice]

Edwardian, you are now at the point I was in after importing the jpg. Drag the image to the centre of the page and continue to create a new layer to use for sizing.

[Siberian Snooper]

Mike, I may have the odd query, but as I am about too embark on a 3 week holiday on the wrong side of the pond, it will be a while before I get around too asking, assuming that I cannot suss it out when I actually can have a play with it.

[MikeTrice]

Mike, I may have the odd query, but as I am about too embark on a 3 week holiday on the wrong side of the pond, it will be a while before I get around too asking, assuming that I cannot suss it out when I actually can have a play with it.

Not a problem.

[Edwardian]

Edwardian, you are now at the point I was in after importing the jpg. Drag the image to the centre of the page and continue to create a new layer to use for sizing.

 

Thanks, Mike.  My problem seems to be an almost absolute lack of confidence, which I shall simply have to overcome, otherwise I am beaten before I start.

 

My weekend really did not go at all as planned, but I hope to return to this later in the week or this coming weekend! 

[MikeTrice]

Thanks, Mike.  My problem seems to be an almost absolute lack of confidence, which I shall simply have to overcome, otherwise I am beaten before I start.

Well said. I felt exactly the same when trying to learn Blender 3D. Watching various video tutorials on YouTube helped in that instance. You will get there.

 

I should add that a lot of the things you need to do in Inkscape to produce cutting files are repetitive which helps a lot and things will then become second nature.

Edited September 5, 2016 by MikeTrice

[MikeTrice]

Remember those objects created by converting a stroke to a path. Strangely if you select them they are still treated as a single object. For the next stage, separating out the various layers, this needs to be rectified.

 

The guilty objects are selected then "Path->Break Apart" clicked:

 

Select all the items in the "Master" layer including the centre line and click "Object->Group":

 

Create new layers to take the various styrene layers. I started at the lowest layer and added a reminder of the styrene thickness to the end of the names.

 

Select the group on the "Master" layer, duplicate it (Ctrl/D) right click it and click on "Move to Layer":

 

Select the first layer "Inner Side 20":

 

Repeat the process for all the new layers. To prove it has worked turn off the visibility of all the other layers and check each one in turn:

 

The next stage is to take each layer in turn and delete the bits of the drawing that do not apply. Sounds easy, but there are times it caused me much head scratching. First off the waist panels:

 

On the panelling layer various redundant objects have been selected (done to help illustrate which ones I mean):

 

For clarity of the next steps I have changed the colour of the door frames to red. These represent areas that should be scored on cutting rather than cut right through:

 

First the door frames are converted to paths ("Path->Object to Path") then entered node edit mode and all the lower nodes selected then the "break node" button in the toolbar clicked:

 

Our door outlines have now been converted into two aspects, the top part and the bottom joining line, however they currently still appear as a single object. To resolve click "Path->Break Apart":

 

Once that has been done in selection mode the individual lower lines can be selected and deleted:

 

In order that the score lines for the doors are only done on the panelling part of the sheet the door outlines are all selected, switched to node edit mode, the lower handles lassoed and the nodes dragged vertically with the Ctrl key pressed:

 

 

Switching to the droplight layer a similar process is adopted selecting those items to be deleted:

 

At this point I noticed that I had lost my centre line so had to go to one of the other layers, select and duplicate it and then move it to the droplights layer. Referring to my construction diagrams the droplight layer needs to be rebated to take the ends and thus needs to be shorter by 1mm than the normal sides. Selecting the current body outline shows it is 96.1mm (the 0.1mm is due to the line thickness of the stroke and is correct):

 

Changing the body length to 95.1mm has the effect of shifting the body left compared to the centre line so the Distribute and Alignment dialogue is used to centre the body on the centre line:

 

Now the bolection layer:

 

At this point I thought it might be an idea to change the remaining objects stroke colour to match the colours I used earlier when working out which layers were needed. Note that the length of the bolection layer has been reduced from 96mm to 95.5mm:

Edited September 5, 2016 by MikeTrice

[MikeTrice]

Side proper really caused me problems. I could not get my head around it as it appeared identical to the bolection layer. In the end I rationalised that unlike the bolection layer it is still full length over the body. I think this is a case of pressing one and then actually trying to cut a set of sides and see how they work out. They can always be revised in the light of experience.

 

Unwanted items removed. As with the door outlines in the panelling layer they need modifying using the same technique here however reducing them from the top:

 

Changed the colour as before. The yellow is not the easiest colour to see so went for something a bit clearer:

 

By switching on or off the various layers it is possible (just) to work out how the laminations will work:

 

For the inner layer the initial side the initial objects were deleted:

 

With the inner sides it is best to have a cutout for the rear windows larger than the cutouts at the front so the side lamination does not show through the opening. As it is on the inside it does not matter if it is square cornered so a new rectangle has been drawn slight larger than the original quarterlight frame. The blue line is a 0.5mm marker just to check I am leaving sufficient meat between the two cutouts:

 

The rectangle is duplicated and moved over. With the first class it needs to be made slightly wider:

 

Here the rectangles have been finished and the original outlines deleted:

 

The glazing spacer is next. The point this is to work out the width and positions of the horizontal spacers along which the glazing can be slid:

 

Reference to my original contruction notes and selecting the glazing spacer layer tells me that the bottom edge of the layer needs to 20.35mm (approx) from the top edge:

 

A rectangle was then added to the correct depth, aligned with the top edge, to show me how far the lower glazing spacer needed to be lowered:

 

After lowering:

 

Switching on the visibility of all the styrene layers the final fit of the various part can just about be seen:

 

 

 

 

 

 

[MikeTrice]

So close to be able to cut something and see if my theories can be turned into practice.

 

I have added 4 new layers, 10thou Cut, 10thou score, 15thou cut and 20thou cut to represent my final cutting layouts:

 

The various elements on each of the individual component layers are duplicated prior to be grouped and moved to the new target layer:

 

 

Once on the new layer they can be moved to a new position:

 

The same process is followed for the Panelling fretwork:

 

The remaining 10thou items are treated similarly:

 

A coach needs two sets of sides so the set of items are duplicated and moved to the side of the first set:

 

The red door outlines have both been moved to the 10thou score layer:

 

So they no longer appear on the cut layer:

 

Set visibility back on both layers and they can be seen in place:

 

 

 

 

 

 

 

 

[MikeTrice]

The process is repeated for the 15thou and 20thou items.

 

The glazing spacers are duplicated and moved to 15thou layer:

 

I wanted to retain the distance between the two spacers as it is easier for the software to do it than me to do it manually when assembling the laminations. To do this I stretched the spacers horizontally to increase their length. I then added two rectangles to the ends:

 

"Path->Union" combined them into a new object:

 

New spacers duplicated and moved over:

 

Finally in comparison the inner side at 20thou is straightforward:

 

I have almost reached the stage of actually cutting out the parts. Unfortunately that will have to wait for the moment.

 

 

 

 

 

 

[BG John]

I have almost reached the stage of actually cutting out the parts. Unfortunately that will have to wait for the moment.

I need plenty of time to catch up, and I'll need to order more plasticard!

[Edwardian]

I need plenty of time to catch up, and I'll need to order more plasticard!

 

I will need a month's sabbatical to go through these posts one or two at a time (interspersed with gin or a good malt to steady the nerves and then a suitable recovery period), and to repeat the whole process at least twice until it sticks.

 

Thanks to Mike, I am sure I will get through this learning process eventually.  He really is doing a great job for the community and I am determined to become a worthy pupil, eventually. Trying to master software induces flash-backs and panic attacks, which I blame on PTSD (Post Templot Stress Disorder) - I'm never going there again!  

[BG John]

I will need a month's sabbatical to go through these posts one or two at a time (interspersed with gin or a good malt to steady the nerves and then a suitable recovery period), and to repeat the whole process at least twice until it sticks.

 

Thanks to Mike, I am sure I will get through this learning process eventually.  He really is doing a great job for the community and I am determined to become a worthy pupil, eventually. Trying to master software induces flash-backs and panic attacks, which I blame on PTSD (Post Templot Stress Disorder) - I'm never going there again!  

The only reason I need time to catch up is that I'm busy tracklaying on Cheapside Yard at the moment. I'll need somewhere to run the coach when it's finished, so I'm preparing in anticipation of it being completed before I build Holman's End!

 

Your form of PTSD is at least partly curable. It's worth persevering enough to get the very basics, so you can use it to help with building pointwork, even if not whole layouts.