Arkitex (00) - Expanding a 1960's System

Thanks Paul, I'll take a look, Jim

 

Default rendering in SketchUp Make 2017 is for display only, 'height maps' and 'displacement maps' are key terms.

3D printing is a new application for these established CAD tools, they will catch up I'm sure, widens their customer base.

Many times when trying to find something I am thwarted by not knowing the correct terms (or rather the strange way the authors define them), whether learning about new software or hardware (including domestic DIY), certainly, until you know enough jargon to phrase answerable questions.

Thanks for looking, appreciated

Jim

 

4. Type A Panel - The Basis of All Panels that Follow

This is the longest article on panels because this one forms the basis for all the other panels and the component parts they are made up from, here the brick effect surface of the fascia is built from scratch and is made separate from the frame which mounts it to the connector beams.

Frame 'A'

The first frame was simply cut from the first one piece panel CAD model and printed face down with supports positioned by the slicer for the hook at the top of the frame and the aperture for the lug of another panel above in a building to locate.

The lug at the bottom edge of the panel was too small to have a support added but it printed well enough, although on some prints a part of the outer edged drooped, which needed to be trimmed off, even so it still performed its function satisfactorily.



Fascia 'A'

The bricks were modeled as individual SketchUp components so that modifying one modifies all. This makes it easier to determine the required vertical and horizontal pitching of the bricks which needs to be taken into account.

The background mortar was created as in :-



This video shows how to add depth to an otherwise flat decorated wall in a SketchUp model, from approx 9:18 it applies to 3D printed walls as well, remember that the coloured textures will not be printed, only the physical form the model represents.

It is important to note during the scaling process that you need to scale beyond the surface and let it snap back, this I found to be the trickiest aspect of the process.
Test prints were made of the result.

Initially a raised circular mark was provided to identify orientation to ensure that the brick face is correctly orientated as it needs to match neighbours all around it, later this was revised to a larger raised triangle pointing towards the top edge which was much easier to see and its meaning obvious.

Splitting Fascia Layers.

It was intended to perform a two colour print to avoid the need for painting the bricks and mortar separately which helps keep to the spirit of the Arkitex components, and makes creation of these panels much quicker as a bonus. This could be accomplished on the Raise3D E2 which has two independent extruders although they share a common X-axis gantry rail.

Fascias as designed here can still be printed on a single extruder machine albeit as one piece and colour.

To allow two colour printing the fascia was then split into two, the bricks and the mortar base, the latter is plain on one surface and contains locating pins on the reverse to align to a frame and provides most of the thickness of the fascia.



The first fascia design was to match the other warehouses with a coarse grey brickwork with brown mortar, exact match for size was not required and would be a compromise to enable an array of these panels to be used together and for the brick pattern to flow between them, vertically and horizontally. This took a bit of juggling of brick and mortar gap dimensions but worked out well in the end. It was required that the

• brick pattern will flow to all adjoining panels.
• bricks can be printed with a 0.4mm nozzle, even though they cannot be square ended due to their size relative to the nozzle diameter.
• bricks were to be printed in HATCHBOX matte light grey.
• mortar was to be printed in HATCHBOX brown.

The fascia was to be printed face down so that the smooth BuildTak surface governs the external surface of the bricks and the locating pins are printed upwards, this means that no supports are required for this part. The bricks were designed as 0.3mm thick (brick face to mortar face) and matches the first layer printed on the build plate, the only layer in brick colour. If greater depth is required between brick surface and mortar surface then adjustment of the first layer thickness can be made in the slicer settings, or the number of layers changed, or both.

For these tiny (brick) parts to stick well make sure that your build plate is clean as even a single half brick lifting can ruin the whole appearance, so it is worth monitoring the first layer to ensure that it appears sound before the other extruder starts work. Usually after a short delay while it reaches operating temperature.

The mortar base is printed on top of the brick layer, the mortar gaps between the bricks of 0.5mm are easily bridged as the second layer is printed at 45 degrees, except for the edges but no problems occurred there either. Much larger gaps are bridged after a 10% infill is completed, not that these parts are thick enough to require infill.

Initial printing tests were performed with just the default left hand extruder in one colour before using both working together

Resulting Coarse Brick Fascia A

The resulting CAD model of panel type A fascia brick and mortar parts.







An example print.




Promising start, some tweaks to filament retraction settings will probably improve it.


Summary

This first phase of designing Arkitex compatible parts lays the foundation for the work that follows in creating the other panel shapes, reusability of CAD models to create further parts is key to uniformity of design, and reducing design effort.

Also necessary was a structured naming convention to keep track of all the parts both in development and final designs.

Next

The process of importing to the slicer and printing a fascia.

Jim

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Hi Paul, consulted Mr Google and found this for Fusion 360 :-

https://github.com/hanskellner/Fusion360Image2Surface

Just installed the free Fusion 360 and after a short while found the correct place to put this add-in for F360 to find it so now I 'Just' need to determine how to fire it up and use any of it.

Hopefully as a tool aimed at engineering rather than animation I just might get somewhere without being bogged down with uneccessary tools and features, I'll keep you posted.

Jim

 

5. Printing Fascias

Printing of all the fascias is performed the same way, but different to the straightforward printing of the frames.

Although I am printing my fascias in two colours it is by no means essential, all that is essential is that from the CAD model of the fascia the brick pattern and mortar base are aligned in all three planes. This can be done in one of two ways, at the CAD model or in the slicer.

Alignment in the CAD Model

This is the simplest way especially if you are unlikely to use a multiple extruder 3D printer, in which case you just export a single STL file to the slicer.

However if you might one day use a multiple extruder printer then alignment in the slicer would be better now rather than having to change the designs later when your wallet gives you the thumbs up.

Alignment in the Slicer

With the Raise3D printer I stick with the supplied IdeaMaker slicer although this may change in the future.

In this project the brick and mortar parts have the same width but, the total brick pattern height is slightly less in height, the difference is due to horizontal mortar lines top and bottom, as shown in the CAD model images of the previous article.

I generally create both brick and mortar parts in the same SketchUp CAD model file to ensure compatibility and as two sets of grouped parts so they do not stick together.

It is preferable to finally save the CAD model the same way up as the parts are to be applied to the build plate, not 100% essential but saves multi-axis re-orientation at the slicer when imported which rapidly gets rather tedious.

The two groups are exported in STL separately with e.g. 'name brick' and 'name mortar' for simplicity.

The printer and slicer are set up such that the left extruder prints the bricks and the right extruder the mortar base, the choice is purely arbitrary, however the left is the default extruder and I use that for printing the frames in grey.

Future brick designs may include light red bricks and a sandy mortar.

I first import into IdeaMaker the brick STL file whereupon it is (by default) centred on the build plate at height Z = 0 mm.

The mortar base STL file is imported second and is placed by default next to the brick pattern at Z = 0 mm too.

The position of the mortar base is then set to Z = 0.3mm (the thickness I use for the brick pattern), and centred.

All being well the two are perfectly aligned with the brick pattern on the build plate and the mortar base sat on the bricks.

Alignment of dissimilar parts is covered in the support tutorial below.

Using the two extruders the brick pattern is assigned, by default to the left extruder and the mortar base I re-assign to the right extruder.

Configuring the IdeaMaker Slicer for Dual Extrusion Operation

When performing dual extrusion printing for the first time there is a useful support web page provided by Raise3D which takes you through the process, although for the Pro 2 it applied well to the E2 when I used it :-

https://support.raise3d.com/Pro2-Series/dual-printing-guide-4-67.html

Once you have made the necessary setting changes save the modified slicer profile with a different appropriate name for next time, forgetting wastes a lot of time!

Once the slicing is complete a quick look at the preview should show that the brick pattern is the first print layer and the mortar base starts at print layer two, by default the second layer is printed at 45 degrees to the brick pattern layer so it does not fill in the gaps left between the bricks.

Image shows the completed brick layer just before the right hand extruder starts to apply the mortar base.



Front and rear view of a printed fascia mounted on a frame, glued together with DeLuxe Materials Plastic Magic.



Next

With the first panel assembly modeled and printed the remaining panels can be generated, mostly as cut down versions of the type A panel with some having cut outs for personnel and large roller shutter doors.

The printing of the remaining frames and fascias to make a panel will be the same as for the panel just described, so there is no need to bore you further with that aspect, only how the remaining panels are designed!

But first, Type A Panel - Refinements.

Jim

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Me too, I decided to do something about it now I have caught the 3D printing bug, Jim

 

Mind you there is no such thing as a sharp corner with a 0.4mm nozzle working in 4mm scale

 

It is difficult to photograph as rather small for my basic camera so I have knocked up the image below, the blue are the printed layers and the circled part is where the layers start to droop over the edge of the slicer supplied supports, maybe one or two layers droop by almost a layer thickness (approx 0.3mm) at the outer edge, I'm sure the support should extend beyond the part it is supposed to support, must have a closer look at the slicer support settings.

The unsupported overhang is between approx 0.25 to 0.5mm which seems rather a lot.


Jim

 

Agreed, I don't know why it is so adrift, it's fine on the DaVinci with it's ever so basic 'XYZWare Pro', ho, ho slicer.

Have no trouble with bridging on the R3D, a benchy confirmed that, yes, must give the IdeaMaker support settings a very close 'scrute'.

Sometimes it is the route taken by the extruder which exacerbates the problem, especially if the overhang is small, e.g. 1.5mm, resulting in reduced inter-layer strength of overhangs.

On larger parts, non-railway, I use fillets to aid support of overhangs, I might try tiny fillets, but they could easily get in the way, one of my goals is that my parts are fully interchangeable with standard injection moulded Arkitex parts, luckily there is some scope to the tweak design of my parts towards filament based 3D printing which I discuss in future articles.

Current results are tolerable, just, so I must improve it, mad that I am

Jim

 

6. Type A Panel Refinements

As work progressed a few refinements were made to improve the look and fit, I would like to say that they were all implemented in panel A before I started creating further panel types but they were not, so some later panels were reworked to have these refinements.

Fascia Thickness

This was a design hiccup when I split the fascia into bricks and mortar, the total fascia thickness should have been 1.4mm, unfortunately the mortar base stayed at 1.4mm on top of which I added the 0.3mm thick brick face. It only became obvious when fitting the roof edging to the Royal Mail warehouse frontage.

To correct this the mortar base thickness was reduced by 0.3mm and makes a neater fitting panel when the roof edging is attached, oddly enough the difference did not show up between these panels and Arkitex panels on a wall face.

On this building only a few at the top of the front wall require the thinner (1.4mm) fascias, the others are left as originally printed (1.7mm).

It is not that I am going to keep changing this building, it is custom built as part of the 'permanent' scenic items, parts for playing with later will be of the correct 1.4mm thickness.

Frame Shoulders

The original Arkitex parts had an extra shoulder feature (circled below) but were too thin to be reliably formed so was left off the initial panel A frame design, however it proved to be necessary to seat the top of the frames firmly against vertical connector beams, in particular the short ones so they sat squarely.



As the original Arkitex parts were too thin to replicate the size of these features was increased to make printable shoulders as below, this is where design for 3D printing overrides design for injection moulding. Original fit and function is maintained.

CAD Model



Printed Parts





Lug on Frame Base

This was initially too small to be supported when printed, but by increasing the depth of this feature to 1.8mm it becomes supported, although it still seems to have outer edges starting to fall off the support, however the resulting lug secures the panel base to either another panel or the base plate more effectively than before.

This can also be seen in the above 3 images.

Summary

It was a little annoying reworking some of the panel designs but I wanted them to be right for future designs I have in mind.

As design and development proceeds adjustments are being made to aid the production of parts by a 3D printing process whilst maintaining the fit and function of the original parts.

This is what 'design for manufacture' is all about, it is even more critical in an industry where design for mass production is essential to be able sell in a cost effective volume, Henry Ford and Isaac Singer knew the value of this.

Next

Fitting doors to Type A panels.

Jim

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7. Type A Panel - Doors

Ground level door ways are cut from type A fascias, two types of doors were to be created to suit the Royal Mail warehouse frontage, roller shutter doors (RSD) for vehicle movements and conventional personnel door (PED). These were to be of closed doors and inserted from behind into the fascia.

Variants of the basic type A panel required two features to accept these doors.

• A suitable aperture in the fascia with a lintel above the door.
• Clearance cut into the frame cross member to accommodate the door thickness.

The process consists of two stages, first the cutting of an aperture in the fascia aligned with the brick courses, second the design of the doors and frames to fit the apertures.

Fascia

Cutting the fascia was performed using the technique of passing a block of the required size through both parts of the fascia, bricks and mortar, this is illustrated in the video "Intersect with Model", Method 2, Ref 7.1.

To do this whilst preventing the bricks and mortar sticking together the fascia and the block were copied so that two copies could be processed separately, one for the intersection of bricks and a block the second intersection of the mortar and a block. In both cases the fascia part not being processed was deleted.

Once the cut was cleaned up on both, which was still rather involved with the cut bricks the two fascia parts with the aperture cut into them were each grouped as individuals again and overlaid onto each other to confirm the cutouts matched.

I'm not sure this approach was really much easier than just cutting and editing the bricks individually.

Roller Shutter Door

This was to be as large as possible with a substantial lintel supported at each end on a full width brick column.

With the aperture defined a frame was then drawn and the surface for the roller shutter door effect defined, to do this I use a tool in the free plug-in 1001bit tools which can be downloaded from ref. 7.2.

A video of using the 1001bit tools plug-in can be found at ref. 7.3.

The tool I used is the 'Create horizontal groove lines on selected face', now a gotcha with this tool and some others even in SketchUp Make is that it does not like parts which are as small as those I model. I model full size in SketchUp, now SketchUp was developed for real full-size architectural modeling in 1:1 not 1:76 so when I tried to use this tool nothing would happen and no explanations about why. The penny dropped it was probably to do with the size of the parts I was designing, so I tried using the tool on a surface 10x the dimensions and it worked fine, once done I rescaled the result back to the dimensions I wanted, job done.

It needs a little trial and error to get the grooves right.

The first image is of the complete fascia with RSD.




The next is the group representing the door




The next is the group representing the brickwork and lintel of the fascia.




Finally the mortar base of the fascia.



All of these are kept separate by each being a self contained group, in this way a separate STL file can be exported for each of them. The bricks and mortar for printing in two different colours on a dual extruder machine, but can also be printed in one colour on a single extruder machine. The RSD which is printed separately in another colour, in this project I printed the ground floor doors in red for the Royal Mail.

Another reason to model the doors separately is so that I can design and fit other styles of doors including open or part open versions.

From a printing point of view, the bricks and mortar are printed face down on the build plate and the doors laying on their back, by splitting them into two separate parts in this way neither require supports. Also doors and panels are interchangeable for further designs.

The next step was to modify a type A frame to accept the extra thickness of the door protruding into the frame from the fascia.

Frame

This was straightforward for a closed RSD, all that was required was to push the lower cross members face back 1.6mm so they became like this :-



For an open door the upper cross member would need removing and a step or ramp made over the bottom one as you need to retain the lug at the bottom for anchoring the base of the panel assembly to a base plate. The lug could however become part of the door frame.

The resulting assembly in coarse grey brick on brown mortar became :-



Ideally the lintel should be white as other Arkitex parts representing concrete which could either be by painting or making that a separate insert printed in matte white.

Personnel Door

The same process was applied for a personnel door and uses the same modified frame as for the RSD, a representation of a lever type door handle was just printable on the second attempt to shape it such that it would stay on the door.



One issue that arose when printing was that a combination of slight shrinkage of the fascia combined with a slightly larger door print meant the door was nearly 0.5mm too high to fit the fascia aperture. This occurred with two different PLA for the door and both the RSD and PED. So the door heights was reduced and appears to be undersize in the SketchUp model of the assembly but now the printed parts fit correctly. Width clearance was fine. These differences are shown in the next image of the PED CAD model.




Summary

This process has been covered in quite a bit of detail so when I cover the other panels with doors I will assume that the panel type A process has been read and so avoid a lot of repetition.

The effect of contraction when cooling and the effect of some parts to spread beyond their design dimensions on the build plate can be addressed to some extent with practice as you get to know your printer and materials, however a test print should always be made before producing in quantity to avoid wasted energy, materials and time.

The 1001bit tool plug-in provides many other useful features such as panels, grills and louvres.

Next

Type B Panel - Short Panel

Jim

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References

7.1 Video "Intersect with Model", Method 2



7.2 Free 1001bit SketchUp Plug in

https://www.1001bit.com/freeware/

7.3 Video of using the 1001bit plug in - Grooves at 14:11

 

8. Type B Panel - Short Panel

The type B panel is full width but is used in a 'penthouse' mode as the base of the frame sits on a roof panel instead of either engaging with a panel below it or a base plate.



As such it is just a cut down version of a type A panel, so the frame becomes :-



The brick fascia was trimmed from the bottom up so that the brick pattern remains a match at the top of the panel with adjacent full height panels which can occur in this building formation e.g. as the top centre panel in the image below.




Roller Shutter Door (RSD)

Doors are required for the goods entrances to the Royal Mail warehouse at roof level but as type B panels are required there the RSD needs to be lower too. Unlike the ground level RSD which needs to be tall enough to accommodate a lorry or van reversing up to it these doors will be used to wheel goods in and out on carts.

As before the front cross members are recessed 1.6mm to accept the depth of the door parts.
As before the depth of door is modeled short and becomes full depth relative to the fascia when printed as was the case for the type A panel :-




and the door :-




The printed panel with RSD, this time in silver PLA :-



Personnel Door (PED)

This door remains the same height as before but I have added a ramp to it to align the doorframe better to the wall and also give it more detail, as before the representation of a door handle just prints.

Design :-






The printed panel with door :-




Summary

The separation of fascia and frames is starting to pay off along with developing further panels from the type A panel.

As before further fascia and door styles may be easily designed and fitted to the common frames.

Jim

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Next

Type C Panel - Full height, 3/4 width.

 

9. Type C Panel - Full height, 3/4 width

Once again this panel is derived from the type A panel but this time the width is reduced so that it fits to an inside corner, unlike the office windows an inside corner that contains two solid walls need not employ two 3/4 panels as any overlap is not visible as would be the case with window panels. In which case a type A may be combined with a type C thus saving a 3/4 panel.

Frame

Original Arkitex 3/4 panel parts have additional top brackets to aid retention as shown here.



Modeling this frame was relatively straightforward from the type A frame.

CAD Model



Fascia

Maintaining the flow of the brick pattern into the corner was not easily achievable, two approaches were possible.

• Modify the brick pattern by inserting shorter bricks, typical of a full size build, where the ends of a wall, corners or door frame openings are erected with full size bricks and the brickie builds towards the centre fitting reduced length bricks as required.
• Alternatively align the brick pattern to the open edge and crop them as required where the bricks reach the inside corner.

Modified Pattern

Common fascia for use either side of an internal corner.

This proved rather difficult to design and did not look very good, too many bricks needed to be changed and the brick courses in the middle of the panel did not look too good in the CAD model and looked worse when printed.

CAD model



Printed fascia




Align Pattern at Free End

Handed fascias for use on one side of an internal corner.

This retains the brick pattern flow at the free end to match adjacent panels, e.g. type A with the part bricks at the inside corner, however this approach requires left and right hand fascias.

However this looks much better despite requiring handed fascia parts which is not really an issue as they will fit a common frame.

CAD Models



Printed Fascias




The next image shows the use of a right handed 3/4 panel used in conjunction with a Type A panel, if one was a window then both would need to be 3/4 panels.*

*Update Jan 24 - This can only be done on either face on the ground floor when a horizontal beam is not present for joining two baseplates, in that scenario the full width panel would be placed against that beam.




Summary

The resulting parts justify the generation of handed fascias for a regular brick pattern which must connect properly with adjacent panels.

The extra brackets on the top edge proved reliable to print, the sharp tops were rounded off to avoid any breakaway of layers at their tips.

Next

By natural progression the Type D Panel - Short, 3/4 width.

Jim

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10. Type D Panel - Short, 3/4 width

These are derived from the type C panel, they only needed to be shorter from the base up, whilst retaining the same top flange arrangement. So I only present the results this time.

The frame shown has the smaller top lug hole to be outlined in article 12.

Frame

CAD Model




Printed




Fascia

Brick pattern trimmed from the bottom up as for the type B panels.

Modified Pattern

Common fascia for use either side of an internal corner.

CAD Model




Printed



Align Pattern at Free End

Handed fascias for use on one side of an internal corner.

CAD Models




Printed Fascias



Summary

Just a straightforward edit of the type C.

Next

Type E & F Panel - Full Size, Handed

Jim

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11. Type E & F Panel - Full Size, Handed

These are unique panels for use where a low level roof area and its roof edging join with a taller wall. They require a cutout on the lower corner on one side and need to be handed parts.

Their use is shown in the handbook as the left hand and right hand windows A/00/45A and 46A, an edited page of the handbook below identifies them more clearly.

• E - Left hand
• F - Right hand

Frames

Created from a type A frame and cut accordingly, they were created as a pair in one CAD model but kept separate as individually grouped items, which is also necessary when their associated fascias are overlaid for cutting to shape.

CAD Models (revised top lug slot, article 12).




Printed frames (original top lug slot).




Fascias

Created from a type A fascia and cut according to their frames, the bricks being cut so their edges would be covered by the end of the short roof straight shown in the handbook extract above.

CAD Models




Printed fascias




Assembled Panels




The next image shows the completed panels in position on a 'porch' example.




Summary

These were a little more involved to get the frame modified and the cut outs correct but they worked out fine.

Next

Frame Top Flange - Revision for Strength

Jim

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12. Frame Top Flange - Revision for Strength

Top Flange Lug Aperture

This aperture is much larger on Arkitex parts than it needs to be to engage the lug on the bottom edge of a frame mounted above it in a building assembly. The reason for this is likely to be that these parts were designed to be manufactured using injection moulding techniques, hence to create the hole a part of the mould tool needed to slide into place when the mould was readied for injection and needed to retract to release the part.

An original Arkitex part.



If the aperture was made minimal size then the mould part that passed through the flange would have been very small in cross-section and therefore potentially weak with a reduced life before failure. So as there was ample space for a larger than functionally necessary aperture it was created thus, this had an additional benefit, it reduces the amount of plastic required for the part, a small amount multiplied by thousands mounts up fast.

However when it comes to filament 3D printing of this feature a different set of design guidelines are required. In this case the vertical part of this flange is made of many layers of narrow width and short length, the strength between layers is somewhat less than along layers and here lies the problem.

Most frames I have printed have been fine but about 1 in 10 have had a layer line fracture between the large lug hole and the outer edge of the flange either when removing the supports for the top part of the flange or later in use.



To overcome this the size of the hole to accept the lug of a panel above in a building assembly has been dramatically reduced to widen the vertical face of this flange but sufficiently large enough to allow for hole shrinkage and lug expansion during printing and cooling.






Summary

This has increased the strength of this feature and so all frame designs have been modified to match, I am not reworking panels already assembled, the couple that failed on one side were successfully repaired with Plastic Magic.

Next

Type G Frame - Full Height, 2x Width

Jim

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