Using Inkscape to produce cutting files, a worked example

[JCL]

Hi John, my first experience cutting was a circle, rectangle and equilateral triangle. I then went on to produce a shed then a gate to get used to laminating before doing an M&GN coach. That progression worked for me, and I'm still working things out as I go along.

[BG John]

My only real success so far has been Peco point motor bases for my OO layout. They're designed to take a microswitch, and to be attached to the layout with screws at the back, as I won't be able to get to the front of them to remove screws if I need to get them out. I've made a few 7mm scale windows too that are OK, but I'll probably do better versions.

 

I found that working on the coach gave me the motivation to go backwards to do some easier stuff first. My brain works in weird ways!

[MikeTrice]

I found that working on the coach gave me the motivation to go backwards to do some easier stuff first. My brain works in weird ways!

On many occassions doing that coach I kept thinking why couldn't they have chosen something easier!!!!

[MikeTrice]

Progess has been made on the LNER Toad B some of which can be seen on this thread: http://www.rmweb.co.uk/community/index.php?/topic/79025-a-guide-to-using-the-silhouette-cameo-cutter/page-59&do=findComment&comment=2439485

 

I originally intended it to be cut in 20 thou styrene however that is very difficult to do unless you are prepared to do a lot of cutting out. Instead I decided to drop down to using 10 thou throughout and laminating the various 10 thou layers together.

 

The roof was done as per the coach using offcuts of 10 thou styrene laminated together over a suitable tin from the kitchen cupboard. Here is how it currently stands:

 

 

I realised too late that it should have had a planked foor.

[JCL]

Hi Mike

 

I took your idea of designing a wagon and decided to do it before cutting a coach to test a few concepts. After having a go at folding up those coach chairs, the main one is using tab and slot construction where possible. I used the Emblaser laser cutter and 1mm "butterboard". This meant that the slots and tabs were all 1mm thick. Interestingly I didn't have to take into account the width of the laser beam.

 

The drawing file. As this model uses 1mm card for most of the cut shapes I've not worried too much about different colours for different layers. Instead I used green for cut lines and pink for score lines.

 

Here's the sheet on the cutter

 

And a prototype tack glued together to make sure that everything fits.

 

Construction is pretty solid, and the tabs and slots ensures everything is square (not my forte).

 

And here you can see some of the tabs.

 

The strapping is also finished, and I'm thinking of cutting sticky labels to represent them. I've a couple of things to change around the vents at the top, buffer beam and rivet holes, but it's almost ready. I'm also going to see if I can include the springs on the chassis etc.

 

I'll paint it tomorrow, I think it should be similar to oxide red, so I'll try a can of undercoat.

All of this was done using Inkscape before converting into a format that can be used by the laser software.

 

cheers

 

Jason

Edited September 27, 2016 by JCL

[MikeTrice]

This is a quick proof of concept to show how I do rivets. The basic technique is to produce two layers of 10 thou, one to have the rivets embossed into, the other to act as a rivetting template. With careful thought the rivetting template can form part of the final build.

 

So taking a wagon as an example my intention here is to form the main sides from 4 laminations of 10 thou with a fifth layer of 10 thou strapping.

 

For the outside layers here I have a planked (engraved) side with the rivet positions cut out by the cutter then drilled 0.5mm. The rectangle to the left is the corner plate:

 

The corner plate has been welded in place and I have opened up the holes for one of the door straps. Note that to aid positioning when engraving the planking I also engraved an outline for the strap:

 

For the inner side one piece is engraved and the other spot marked for the rivet positions.:

 

The two inner sides are glued together then the rivets pressed out from behind using an old school compass with the work piece resting on a self sealing cutting board (I should have removed cutting burrs first, but forgot):

 

For the outer side the door strap was fixed in place using the outline as a guide and put aside for the solvent to harden. Finally the rivets were pressed in from the back again with the compass (again forgetting to de-burr):

 

I then laminated the inner and outer side together completely forgetting that I intended to have 4 layers + strapping so ended up with 3 layers + strapping.

 

A couple of images showing the side after having a quick coat of primer:

 

 

What I have done here may seem odd, fixing the strapping first with solvent rather than embossing in their own right. I have found in the past that the enbossing process can distort the strapping (typically bulging where the rivets go). This way the strapping tends not to do this.

 

I would also benefit by taking off the sharp tip of the compass against some wet and dry.

[MikeTrice]

Blunting the point of the compass and applying greater pressure results in heavier rivets being produced:

 

[Buhar]

I think lamination with the gentle solvent you use maximises the advantages of machine cutting, particularly accuracy and regularity. Coupled with this embossing method some very tricky tasks become achievable. I wonder if a blunted gravity riveting tool on a low setting would work.

 

Thank you for your imagination and experiments.

Edited September 29, 2016 by Buhar

[MikeTrice]

Somewhere I have a LRM gravity rivetter. I am sure you are right and it would prove ideal. If I could just remember where I put it!

[mvrattler]

Hi Mike, Just found this thread, and like some of the other members I too appreciate your time and skill to teach the pratical application.As a 7mm scratchbuilder I need to cut out coach sides to use as masters, as in my Queensland climate, Plastikard would warp in no time on my garden railway.Can you please give me a link or magazine source for the LSWR Metropolitian coach drawing so that I can replicate the Inscape operations, and hopefully move those acquired skills to some LMS Coronation (USA) coaches.

 

Regards,

Kerry

[Atso]

Hi Mike

 

I took your idea of designing a wagon and decided to do it before cutting a coach to test a few concepts. After having a go at folding up those coach chairs, the main one is using tab and slot construction where possible. I used the Emblaser laser cutter and 1mm "butterboard". This meant that the slots and tabs were all 1mm thick. Interestingly I didn't have to take into account the width of the laser beam.

 

The drawing file. As this model uses 1mm card for most of the cut shapes I've not worried too much about different colours for different layers. Instead I used green for cut lines and pink for score lines.

fruit van.jpg

 

Here's the sheet on the cutter

IMG_7563.JPG

 

And a prototype tack glued together to make sure that everything fits.

IMG_7564.JPG

 

Construction is pretty solid, and the tabs and slots ensures everything is square (not my forte).

IMG_7565.JPG

 

And here you can see some of the tabs.

IMG_7566.JPG

 

The strapping is also finished, and I'm thinking of cutting sticky labels to represent them. I've a couple of things to change around the vents at the top, buffer beam and rivet holes, but it's almost ready. I'm also going to see if I can include the springs on the chassis etc.

 

I'll paint it tomorrow, I think it should be similar to oxide red, so I'll try a can of undercoat.

All of this was done using Inkscape before converting into a format that can be used by the laser software.

 

cheers

 

Jason

 

Great choice of prototype Jason! I created a 3D printed GNR clerestory vent van in N gauge a year of so ago (I must get around to altering the CAD to produce the Fish van version!). It's currently unfinished as I'm awaiting a 9'6 chassis kit from the 2mm association. Looking forward to seeing your progress.

[JCL]

Thankyou. I have my folks visiting from England, but I'm determined to make a good fist of this fairly quickly afterwards. The only limiter is the weather because I cut outside. That said, if I put the cooker hood on at maximum I might get away with putting the laser cutter on top of the stove...

[MikeTrice]

Did you know that Inkscape supports layer groups? No? Neither did I until JCL pointed it out to me.

 

Here I have another work in progress that comprises a number of layers:

 

It would be nice if I could group the various construction layers together so I can easily turn off their visibility or lock them as a group. To achieve this I have created a "Work" layer:

 

To turn "Work" into a group, select one of the construction layers and with the mouse button pressed drag it over the "Work" layer:

 

Release the button and note that the "Work" layer has now gained open/close icons:

 

Repeat for the other layers:

 

If I click on the little "+" sign it will open the group thus. Clicking on the "-" sign will collapse it again:

 

Now I can select the lock and visibility setting for the group and impact the individual layers contained within the group:

 

Note that in the above example turning off visibility for the group has overridden the visibility of all the items contained within the group, but NOT changed their individual settings. If I reset the group to be visible the group members will become visible again but only if their individual visibility setting is on. A similar behaviour occurs for the lock icon.

 

Neat!

 

 

 

 

[MikeTrice]

Rob Pulham has put up some pictures of an LNER coach side he is experimenting with in 7mm (http://www.rmweb.co.uk/community/index.php?/topic/79025-a-guide-to-using-the-silhouette-cameo-cutter/page-61&do=findComment&comment=2444962). Mmmm, tempting.

 

I have always thought of having a go producing an LNER coach in 7mm just to see if I like it. Changing scale to 7mm makes it possible to include detail that would be difficult in 4mm.

 

Another issue with the technique shown previously based on Jenkinson's method resulted in the door droplight glazing being in line with the quarterlight glazing which is not prototypical. So I have set myself some objectives:

1. Be a detailed as possible.
2. Base on prototype dimensions where possible.
3. Use an alternative glazing technique of slotting the glazing in vertically and have the glazing inset to the correct depths.

At this point in time I have no idea how this will work out or even if my ideas will work out. 7mm is new to me so I may well make mistakes along the way, but here goes.

 

First off I need a drawing. Being 7mm it needs to be very finely detailed so conventional 4mm scale drawings may not be up to it. Fortunately I have access to a number of GA's which give prototype dimensions to great precision.

 

As with the previous examples my first task is to create a master drawing that will be used as a basis for generating the various layers:

 

I did use the GA as a guideline but got suspicious as to its accuracy:

 

Not being satisfied I ended up blocking out the various elements using the prototype dimensions suitably scaled:

 

Once happy that everything worked out the main master drawing was traced on top:

 

The end profile just did not look correct so I changed my approach and started working out the profile and layers against the side based on a 3" turnunder:

 

Two profiles have been put on showing the relevant layers across one of the quarterlights and another across the door and droplight:

 

All layers have been worked out based on 0.25 styrene to ease cutting out and increase the options for different indents in the side:

 

Positions for the glazing slots have been superimposed:

 

And the cutouts for the rear that will retain the glazing:

 

And yes I am only doing a section of the side to see how it works out.

 

 

 

 

[Siberian Snooper]

I will follow this with interest, too see if it might transfer back down to 4mm.

[MikeTrice]

I need to explain some of my ideas.

 

This how I intend to produce the door ventilator hoods. On the prototype they are hollow at the bottom, scale to 0.55mm at the top and 0.73mm at the base. 3 laminations of 0.25mm styrene should do it with the base lamination being hollowed then filed to produce the taper. The red outline shows the shape that they should be:

 

Closeup of the door where the droplight is set in. On the prototype the baulk of the recess is tapered on the bottom edge so the styrene needs to be cut to allow this to be filed into it. Again the red outline shows the proper profile with the little arc representing the mechanism that holds the droplight up. There is also a 1/8" gap between the door and the droplight which I don't recall being modelled before so I will indent the last but one lamination to give a visible gap.

 

For the lower beading I am going to try Jenkinson's suggestion of using round rod let into grooves in the panelling layer. On the prototype these are quoted as 1" half round which equates to 0.58mm in 7mm. Plastruct do a 0.6mm styrene rod which is as close as I am going to get:

 

Again on the prototype the window glazing is rebated into the various side members then a shaped 5/8" * 7/8" fillet fixed in place to fix it in place. This results in the fillet projecting beyond the panelling layer and some photographs do show this feature. Interestingly some photographs of preserved vehicles show this fillet being slightly recessed behind the beading rather than in front so it could be that there were two variations used on the prototype:

 

Some carriages featured an india rubber spacer between the body and the underframe and my chosen prototype is one of these. Where this happened the bottom of the turnunder was curved. At present I intend to scribe this but might use the 0.6mm rod instead as shown below:

 

Following up to the hollowing out of the door ventilator hood this is where I intend to hollow it out.

 

There are a lot of laminations involved and some shaping will need to be made before they are all fixed together. No doubt for my first attempt I will get it wrong!

[MikeTrice]

Time to start separating out the layers.

 

Before doing that I had introduced a number of layers that had been created on top of my Master drawing giving lamination thicknesses etc. These were getting difficult to manage so I created a new group and moved the various layers into it:

 

I then selected all the elements in the Master layer and the window cutouts and duplicated it moving it above the original:

 

The reason I did this is I wanted to add some extra styrene around the edges that would ultimately be filed, in an attempt to hide the laminations. So I draw new rectangles (in blue for visibility) around the originals and enlarged them a little:

 

The same was done for the door ventilator hood:

 

This would now become my new master as far as deriving the laminations is concerned.

 

The revised master was again duplicated and the result moved to a new 10 thou layer:

 

I selected those black lines I wanted to keep on the panelling layer and changed them to blue:

 

When 100% happy I could delete the unwanted black lines leaving me the final panelling layer:

 

For the door ventilator hood one of the rectangles was modified to include the vent cutout and the other duplicated giving my target 3 layers for the hoods:

 

For convenience I grouped all the panelling items then grouped all the vent layers.

 

So this is what I have to date. At the bottom is my original master drawing which will (hopefully) remain untouched. Above it is a clone but with the filing allowance added in blue which will form the basis of generating the other layers. Above that is my derived panelling layer and door ventilator hood layers:

Edited October 8, 2016 by MikeTrice

[MikeTrice]

There are around 14 layers making up my 7mm Gresley coach side. To help keep track of them I saved the view showing the various layers as a PDF and printed it off (see attachment). Not only does this help me co-ordinate the changes but also confirms the relative heights of some of the inner layers.

 

Having completed layer "a" the panelling layer I decided to try and label the various layers to ease identification once they were cut.

 

For layer "b" again the revised master was copied and labelled:

 

The droplight offset was adjusted as required:

 

Removing all unwanted lines resulted in:

 

Layer "c" is similar but with the droplight offset adjusted upwards slightly:

 

Again unwanted lines were removed. This is the first layer where the vertical slot is needed for holding the quarterlight glazing the positions of which are as previously determined:

 

Converting all rectangles to paths I was able to use the "Path->Difference" command to remove the unwanted window slots:

 

Things were getting a little cramped so I repositioned the various layers over to the left. Cloning layer "c" provided the basis for layer "d" which is identical but not as tall. Here is has been duplicated:

 

Using the layer guidelines as a basis the side is reduced in height by moving the bottom up to match the guidelines:

 

So that is layers "a" to "d" sorted. Only another 10 to go!

 

 

Gresley Non Vestibule v05 - Temp.pdf

[MikeTrice]

Picking up the pace a little bit layer "e" requires the droplight surround to be rebated a little to see if I can give the appearance of a gap:

 

 

Layer "f" is the droplights themselves with the lower droplight bar etched in at the same time:

 

Layer "g" features the first of the glazing slots for the droplights:

 

and layer "h" the second. Layers "h" and "g" are identical except the adjustment of the bottom edge to suit the curve:

 

Layer "i" has the retainer for the droplight, which is slightly larger than the droplight glazing aperture:

 

Layers "j", "k", "l" and "m" are all identical apart from the bottom edge position:

 

 

Phew!

 

All that is left now is to separate out the window beading:

 

Then duplicate to give me 4 of them:

 

I then lay out the individual layers on the A4 page deciding to add a couple more window beading and door ventilator hood as spares. Everything just fits (more by luck than judgement):

 

Imported into Studio. Again only just fits:

 

Now I need to wait for a suitable moment to get out my cutter, hopefully this evening.

 

I suspect that the finished sides are going to be quite thick. In hindsight I reckon I will be able to abandon layers "l" and "m" which might help. My biggest concern is how visible the rear cutouts will be through the windows.

[MikeTrice]

Tried sending the new artwork to the cutter but Studio had other ideas and kept crashing on me. In the end I ended up splitting the file into two and removing the text and finally had some success.

 

Using a brand new Icky Sticky Mat and my new Premium Blade all items cut right through in 10thou without a problem:

 

Even the tiny window beading:

 

Whilst the machine was doing its thing I made some new sanding sticks in 400, 600 and 800 grits:

 

Layers b and c were precurved with the craft embossing tool against a ruler, a little too much, however it does not ultimately matter. Lamination started in two distinct groups. Layers a, b, c, d and e then f, g, h, i ,j and one of the k layers:

 

Close-up of one door. I drilled through the various holes for handles and door stops in preparation (then subsequently forgot to continue doing so. Bother!):

 

A length of Plastruct 0.6mm styrene was butted up against the top of the lower recess to form the first length of lower beading:

 

Two vertical pieces were then cut and fixed in place. The little rectangle shown below is one of the cut-outs from the panelling layer ready to apply in the recess:

 

After pre-curving it  snapped into place between the applied rodding without modification (at this point the verticals have been fixed to the curve):

 

Middle beading applied hard against the filler piece:

 

Lower filler inserted ensuring it leaves a gap at t'bottom:

 

 

 

 

[MikeTrice]

Last rodding applied in gap:

 

To fix the verticals to the curve hair clips were used:

 

Before continuing I decided I was unhappy with the idea of applying the very thin beading around the window apertures so modified my technique (again using Jenkinson's suggestion) to use a simple rectangle which I could round off the edges on one of my rubbing sticks and solvent in place:

 

On setting the centres were then cut out ready to be filed back:

 

This is what happens if too much solvent is applied to the lower beading. My own fault for being impatient:

 

Whilst all was curing I laminated the door vents toether and filed them to a slope and rounded the visible edges:

 

 

The slope of the door recesses have been filed and the window beading filed back and rounded, then the two sub-assemblies laminated together and on cuing sprayed with Halford's Plastic Filler Primer. Glazing added with 15thou pvc:

 

Here the glazing positions can be seen from the top:

 

The stagger for the glazing is more apparent here:

 

A couple of views of the current state of the sides:

 

 

Really need to work out how I am going to drill the door stops holes and handle holes now I have lost my original guide holes.

 

Overall I am very happy with the way this has worked out. It needs some tidying up now that the primer and photos let me see the issues. The thickness of the sides does not look so bad in hindsight.

[Rob Pulham]

That looks excellent Mike,  I think that I may need to read it several time before getting it into my head how you have arranged each layer of the side - although it means more on the drawing board and cutting, the manual work at the end is greatly reduced over my effort - with the added bonus of getting the turn under too. - Unlike mine that is stubbornly flat at the minute.

[MikeTrice]

Thanks Rob. Apart from the slots on the top to take the glazing the whole side is solid and as you say the turnunder is automatically formed so should be consistent from coach to coach. If you want any more photos let me know.

[MikeTrice]

Inkscape .svg file attached for anyone interested in having a go at cutting and laminating in 7mm.

Gresley Non Vestibule v08 - Export.svg

[MikeTrice]

I have revamped the pdf showing the various laminations for the Gresley coach. Hopefully it will be easier to follow.

Gresley Non Vestibule v08 - Thicknesses.pdf

Edited October 12, 2016 by MikeTrice