Using Inkscape to produce cutting files, a worked example

[BG John]

One thing I'm not quite clear on, is whether the blue guidelines are intended to be drawn to the centre of the lines on the drawing, or the edge of the line. Everything is bigger in 7mm scale, so I can't just make them the same width as yours and see where they come out. Scaling them up by 7/4 doesn't work out quite right.

[MikeTrice]

They represent the width of the various beading. Does this help?

[JCL]

It's worth clicking through to the Darkly Labs thread to see what Gaz has done using these methods

 

http://www.rmweb.co.uk/community/index.php?/topic/108310-darkly-labs-emblaser-affordable-laser-cutter-review/page-24

[JCL]

Hi Mike

 

As you know, I'm going to use some of your method of producing the coach. As mine will be in different thicknesses of card, I spent quarter of an hour measuring card thicknesses. The result is the image below. The colours used match the ones on the side elevation with the exception of the glazing spacers. It's going to be a combination of cereal packet, 110lb card and dollar store card.

 

 

Column 2 is the thickness of the number of sheets in column 3 to give an average value in column 4.

 

 

I'm not going to update my thread anymore as you're doing a much better job of it. On that note though, with a view to using the files in the future, it might be an idea to put the window X's on a separate layer as, while these are very useful to the silhouette with styrene, they shouldn't be necessary with a laser cutter cutting card, etc.

 

Finally, I haven't forgotten about the burning. I got back late, I laser cut outside, there's a bear about, and I'm not feeling lucky!

 

cheers

 

Jason

Edited September 13, 2016 by JCL

[MikeTrice]

Thanks Jason. That is looking very neat.

 

One side, floor and main partitions assembled as square as I can get them:

 

Ends laminated while the above sets:

 

Also at the same time I have laminated two offcuts of 10thou styrene around a suitable former (in this case gravy granules) and held in place with masking tape:

 

Here is the roof after removal from the former having been left overnight:

 

Second side added:

 

After fixing the remaining partitions, something not seen on this thread before, the door ventilators in place:

 

Earlier I was asked about matching the curve of the turnunder on the end with that of the coach. They seem to be a near perfect fit:

 

After careful trimming of the roof I could not resist putting these up showing what is to come:

 

 

[Siberian Snooper]

Very nice Mike, it certainly improves the cutting accuracy for scratch building and probably speeds up the process where several vehicles of a similar sort are required to make up a rake.

[JCL]

Re: the discussion about offsets, you really do get very square corners don't you Mike. Much squarer than some I've seen on the Silhouette thread (and squarer than I can deliver on my Silhouette).

[MikeTrice]

Not if you look at this direct scan of an earlier sheet:

 

I suspect it is more to do with it not being so noticable unless viewing under magnification.

[JCL]

Very nice Mike, it certainly improves the cutting accuracy for scratch building and probably speeds up the process where several vehicles of a similar sort are required to make up a rake.

 

Certainly. If the only thing that is different between different diagrams is the location of doors, windows and compartment walls, by the time you've drawn your first coach diagram you've almost drawn the second one.

[JCL]

Here you go Mike. This is my GNR 1st (toilet) that was in the 1938 RCTS special. The sides have been split out, the compartments drawn ready for duplication, and floor worked out (it'll be the mat card @ 1.5mm). I've kept a copy of the original non--split drawing just in case I mess up. I've the ends to work out now, then I'll test them on one piece of 110lb paper at the same time that I do yours later.

 

 

 

[MikeTrice]

 I've the ends to work out now, then I'll test them on one piece of 110lb paper at the same time that I do yours later.

Just to explain I sent my Inkscape file to Jason so he could try it out on his Emblaser Laser cutter.

[MikeTrice]

Two of the roof formers were fixed to the roof keeping them inboard somewhat from the ends proper. A piece of scrap styrene was then cut and fixed between them. The formers protrude below the sides of the coach so act as locators for the roof:

 

Two "hooks" were created using 3 layers from offcuts of 20thou styrene and left to set:

 

One of the ends is placed in position and the "hook" clamped to the top and a very very sparing amont of solvent applied:

 

Once set the end can be removed and after fitting a spacer from spare 20thou more liberal amounts of solvent applied:

 

Once they have cured the excess is trimmed off:

 

The ends are now clipped in place. When the roof is added it locks the ends in place.

 

The roof can now be put on.

 

Having got this far I think that is as far as I will take this model. Hopefully I have included enough to get people started on designing and implementing their own models.

[MikeTrice]

Last version of Inkscape svg file (minus the initial drawing) attached.

Inkscape Coach Tutorial 20 - upload.svg

[BG John]

Made some more progress, but not rushing it. I'm finding it easier to use Inkscape's Guides for positioning, so I'm doing that as well as following the instructions, in case I come unstuck later! I kind of knew how to do this already, but it's much easier following the example than trying to do it on my own.

[MikeTrice]

Throughout this thread my target method of cutting out has been the Silhouette Portrait cutter. In some ways this is easiest as the cutter blade follows the centre of a path. But what happens if I was to try and send the file to a laser cutter?

 

With the following screen images you might have to click on them to enlarge to fully see all the lines present.

 

On the left is the shape of a window I want reproduced. The red signifies my intent throughout. When sent to the Silhouette my cut is as intended. Likewise a laser cutter follows the same path but as it has a width of cut (in this case I have assumed 0.15mm) the final aperture ends up bigger than I intended:

 

So I can adjust this in Inkscape by thickening my original line to 0.15mm, then selecting "Path->Stroke to Path" then "Path>-Break Apart". Change the fill to nothing and set the strokes to something thinner. Resulting path shown in green:

 

Now the unwanted outer path can be deleted leaving me with an inner path offset exactly 0.075mm from the original:

 

If I now send the revised path to the laser cutter I get a cut that results in my intended cut:

 

A similar technique can be used to produce etching artwork.

[Western Star]

Thank you for this tutorial - used several times whilst mapping out the layers of a Mk.1 vestibule partition and sliding door.

[SimonME46]

Thank you for this tutorial - used several times whilst mapping out the layers of a Mk.1 vestibule partition and sliding door.

I need to do this for Dad's 5" gauge Mk.1. I've so far failed to find any drawings of the partitions/sliding doors - may I ask where you found your drawings?

[JCL]

Hi Mike

 

I managed to do some cutting yesterday of the GNR coach using the Cut2D software that comes with the Emblaser lasercutter. Like the free Silhouette software, Cut2D does not allow importing SVG files at the moment (parts of their website say that it does, so it either did, or this is an aspiration), so I'm stuck with DXF, AI (Adobe Illustrator), PDF and EPS (amongst a few others). I covered this on the other thread I started a little while ago.

 

The problems with the spurious lines in the DXF export seem to be an Inkscape thing. If I load the SVG file into Illustrator and export as a DXF file, those diagonal lines aren't present in the export file.

 

Kerf, or laser beam width

The only other remark is to say that you need to take into account the material being cut. Some materials are more forgiving than others when talking about strips that are very thin. Below is an image of the beading on the end of the coach that was cut into 110lb cartridge paper from Staples. The first end is the drawing in Inkscape, the second is without adjusting the offset, and the third is with an adjustment that gives me a cutout that isn't too fragile to move. It's a test piece, so there are other things wrong with it such as broken lines, but these are cleared up with the output settings.

 

 

I create a master drawing without a particular machine in mind, and then make adjustments when I explode it out into layers. My own method of working is to make the offset adjustments in Cut2D - mainly because it's easy to do!

 

The image below shows the offset settings. The inner parts of the end have been selected, and the offset button pressed. The dotted lines shows the original location of the beading edges, and the black inner lines show the new locations. I set the distance to .4mm for clarity. I would also normally tick the "delete original" box.

 

 

DXF Files

I'd like to add something about DXF files if you don't mind Mike. The DXF file format seems to convert curves into a series of short straight line segments with hundreds of nodes (squares). The tighter the curve, the shorter the segments will be. The result of this can be seen in the image below. What looks like a thick black line is a series of squares, and each of the small squares is the start or end of a segment.

 

 

For comparison, here is the Illustrator file which looks like the SVG file that was created in Inkscape. You can see that there are only six nodes in this file as opposed to the hundreds in the DXF file. This isn't so important with the Silhouette, but it is very important if using the Emblaser.

 

 

At the end of each line segment, the Emblaser laser momentarily pauses. This isn't noticeable under normal circumstances, but when the lines are so short as found in the DXF file, the laser slows down considerably. Unfortunately the power of the laser doesn't reduce to take this into account, so you are left with over burning. If this is taken to extreme, then it would be possible to char the material that is being used. For this reason, it is never safe to leave the Emblaser laser cutter alone when it's running.

 

Update:

 

When I say cruel close ups, please bear in mind that these sides are about an inch in height. I didn't fettle the parts in any way. They were glued using 3M spray photo mount and primed.

 

Mike's coach side and the GNR coach side.

 

Both sides side-by-side. Unfortunately there was a problem with the primer can, but hopefully you can see the sides. With both of them, I only did the 10 thou layers in 110lb card as a test to see how square everything was.

 

Closeup of Mike's coach side.

 

This has a couple of trial pieces of beading below the windows. One of the beading pieces wasn't quite glued on, and I've noticed I didn't get one of the off-cuts pressed out.

 

Closeup of the GNR coach side before the grey primer.

Edited September 15, 2016 by JCL

[JCL]

Today I've been looking at 1st class seats. Taking Mike's info from the GNR Diagram3D thread, I've put together a cutting file. This is for cereal packet card 0.62mm/ .024" thick, but maybe .020" styrene will work. Possibly the seat ends might pose a problem or need a lot of cleaning up. This works perfectly for the laser cutter. I haven't made any special accommodation for the machine, so it *should* work for the Silhouette as well. I remember my Silhouette will cut cereal card.

 

For completeness, for the laser, I used 100%, 10mm/sec 1 pass for cutting, and 40% 20mm/sec 1 pass for scoring.

 

After cutting, it's just a case of folding up and super-gluing along the corners.

 

 

The back width is the width of the base plus the width of the two sides so that the outer arms have something to glue to. This comes to about 1 inch. The slots are wide enough for the separate armrests. I scored between the nick lines with a Stanley knife blade, folded up, glued the backing strip to ensure that the back of the seat bases are all the same height., then the outer sides, glued the outer seats, then the middle, and finally dropped in the two inner seat armrests. The only thing to do after gluing is to paint and/or add some printed seat material on the seats.

 

 

I've included the file which has the locating strip to glue along the lower inside back not shown in the top diagram. I'd be really interested if someone cuts this on the Silhouette.

 

 

I need to do a bit of a refinement, and as I build the coach, it might change slightly, but as Mike said, the beauty of all this is that files can be scaled up and down.

 

Edited to add a link to restored GNR seating photos http://www.lnersvrcoachfund.org.uk/teak_set.html

Diagram 84 - toilet 1st - seats.svg

Edited September 18, 2016 by JCL

[MikeTrice]

I do like the idea behind those.

[MikeTrice]

Quite fiddly and crude in styrene. One problem is the styrene actually snaps rather than folds.

 

 

Question is, is it worth the effort? In reality you cannot see the seats once in place. All that is visible is the partition backing:

 

Worth a try though.

[Western Star]

I need to do this for Dad's 5" gauge Mk.1. I've so far failed to find any drawings of the partitions/sliding doors - may I ask where you found your drawings?

Here, there and everywhere - seriously...  on preserved Mk.1s and making allowance for what looks like any modifications which have been made in preservation.

 

If you or anyone else sets off on the slippery road of modelling Mk.1s in detail then try to take all your measurements from one coach - I did not and found differences in the height of seats and placing of interior glazing.

Edited September 18, 2016 by Western Star

[JCL]

IMG_9241.JPG[/url]

 

Worth a try though.

But Mike, when you start your next project of an authentic oil lamp simulation....

 

It's actually pleasantly quick and easy to fold up in cereal box card, and partition walls supporting the roof would be bomb proof, but in reality, for styrene, I agree. It looks a complete faff for no gain. Thanks for giving it a go.

Edited September 18, 2016 by JCL

[MikeTrice]

Wagons without panelling should hopefully be much easier. Here I have an LNER Toad B in progress. Exactly the same process as described for the coach was followed with the added benefit that there are almost no curves to worry about. A drawing from Peter Tatlow's LNER Wagons Vol 4B forms the basis:

 

The way I have designed this is to use 20thou styrene throughout. After separating out the various components I get this:

 

Just need to get the Silhouette out now.

 

[BG John]

I've put the coach on hold for a while, and am working on some simpler stuff. I've got a 4mm broad gauge open wagon coming along quite well, and I'll be trying a test cut of some windows for a scaled up to 7mm Scalescenes building in a bit.