Antique style signs

Every time we open our garden for charity, I notice something else that could look nicer. Several of the signs we have about the place were faded and tatty. I could buy better looking replacements for some of them, but there are a couple I could not buy anything that I liked the look of.

As usual, I made my own.

Designed and 3D printed in ColorFab nGen filament, which should withstand the weather. I used a paint pen to colour the text and gave them a coat of clear lacquer to better resist scratching. 

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Adding 3D text in FreeCAD

 Adding 3D text to a model in FreeCAD version 0.19 is fairly easy but it has a few steps.

Start in the Draft workbench.

Create a ShapeString. 

I always position them at Zero, Zero, Zero, and move them afterwards. The cursor automatically repositions the text and is a nuisance, making that bit of the user interface unusable, in my opinion.

Type the text to display in the String field and choose a font file. In windows, this can be selected from the "C:\Windows\Fonts" folder. Alternatively, the font files can be copied and saved elsewhere for more convenient use.

All text is initially drawn facing the top.

To align it to a model, go to the properties of the ShapeString.

Select Map Mode and then the face on the existing model to align the text to.

To change the position, select Attachment from the properties and change the Position x, y and z values. These are relative to the original position, so it is a bit of trial and error to work out which moves in what direction.

To attach or remove the text from the model, go to the Part Design or Part, workbench, depending on your preference, select the ShapeString and use the usual extrude or pocket options. 

In Part Design, the ShapeString object will need to be dragged in to the body, in the tree, before using the tools.

In the Part workbench you will additionally have to use a binary join, after creating the lettering.

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Circular Text

To include text following a curve, either poking out of curved plane or round a face like a clock, I have used the Add-On Macro FCCircularText.  

I find its user interface a little confusing but I managed to achieve what I wanted.

As a reminder to myself the start and end angles go in an anti-clockwise direction. Zero degrees appears to be along the X axis and the rotation about the Z axis. That means 90 degrees is straight up, along the Y axis and 180 degrees is back along the negative X axis.

Look out for the big Mode Flat or Mode Stand button. It's the press button among radio button choices. It's easy to miss that it changes the behaviour of two of the radio buttons! I always make the mistake of selecting the Clock radio button, instead of pressing the button to get flat.

Once I get my head round the options, I find the FCCircularText macro to be very handy.

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Big sign

We needed to put a sign outside to advertise Shelley's garden open days. Sunday 19 May and Sunday 16 June 2019.

She's letting people in to view the garden in order to raise money for charity. See the entry in the National Open Garden Scheme.

As part of the supplied stationery, we have some paper posters however, these are not going to survive the weather for very long. I put up a temporary solution in a plastic sleeve but to look nicer and to last a bit longer, we need something a little different.

Something 3D printed.

The 3D printer I have is an Ultimaker 2+. Its build area is 220mm x 220mm. That is not large enough for the sign I had in mind. I have, therefore, designed it in multiple parts.

I may have got carried away.

In addition to the 3D printed elements, I've made the supporting structure.

Now we just need people to come on the days.

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Mini filament review

For the last couple of days I have been printing some signs.
They are mainly flat with raised lettering.

Due to various failures I have been trying different types of filament among other things to fix the issues.

The results have led to some conclusions and preferences.

Filament choices in order of preference:

Rigid.ink PLA Plus
This is the best at the job so far. It stays flat on the glass with no warping even on the largest size flat prints.
It's not perfect though. The end of the spool is wound so tightly that the Ultimaker 2+ extruder struggles to get the last half dozen layers of coils off of the spool. That's a lot of wasted filament!
My guess is that the tight loops press against the inside of the Bowden tube so I can't even use it loose from the spool.
Heated to 225C with the bed at 45C.
The results have a nice tidy surface finish with sharp edges.
Takes spray paint well.
Update: Rigid.ink is no longer available. They suggest trying https://shop.3dfilaprint.com. I have used them before but have not got any in stock to try out. I'll update this article when I have tested some.
I'll probably try their Premium PLA:
https://shop.3dfilaprint.com/filaprint-black-premium-pla-285mm-3d-printer-filament-1380-p.asp


ColorFabb PLA/PHA
This was a lot better than standard PLA. It stayed flat on most prints with only a slight tendency to curl.
I get best result running it hotter than the suggested.

For me I heat to 215C with the bed at 60C.
The surfaces are nice and tidy. The raised details have a very slight bulge at the corners. If I was not comparing to other prints I would not have noticed.
When spray painting it is obvious the surface is porous along the print lines.

3DFilaPrint.com PLA
This would not stay flat. Even before it had done the third layer the edges of the brim were curling up and by the time the print had finished, the main body had lifted by a couple of millimetres at several corners.
I've used this successfully on other prints. It just does not like the thin flat prints.
Printed at 210C with the bed at 60C

Inconsistent Information
Several of the manufacturers provide guides or printed temperature ranges on their boxes. This information often changes. One manufacturer has three different heated bed temperature suggestions for the same filament, one on their web site, a different figure on a card supplied in the box and yet another range on the side of the box!

I no longer take the instructions as fixed rules. I use the suggestions as a guide to get me in the right direction. Trial and error is the only sure way.

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Glass Thickness

As far as fixing the various issues, I think the glass is the main problem.

One of the problems is that the prints would warp. This always started in the rear right corner. For many prints that was the only issue but invariably the print would lift so high it would impede the print head and ruin the print.

I can only assume there is a slight inconsistency in the glass thickness. If I avoid printing on the rear right quadrant of the print bed, I get much more reliable results.
The affected area extends about 50mm from the right hand edge to about half way forwards from the back edge.

I managed to avoid this by rotating the largest prints and they have all worked since.

I plan to experiment with bed levelling to see if by deliberately setting a greater distance at the front left corner I can get better reliability at the rear right.

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Worn Nozzle

Before I was able to get anything working I had to replace the nozzle.
The filament would flow for a while then get straggly. Small blobs every few millimetres with thin thread like strands between!

I don't know if the hot end nozzle was contaminated or worn but after I replaced it the flow was even again.

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Printed with Thicker Layers

In the past I have found that thicker layers are troublesome. Now that I have done some more trials, I am able to successfully and reliably print with the following settings:
Nozzle: 0.4mm
Layer height: 0.24mm
Edge, top and bottom thickness: 1.2mm
Print speed: 60mm/s
Travel speed: 120mm/s
Adhesion: 7mm brim
Bed: Glass with hairspray (once in a while)

Rules of Thumb
I found on an Ultimaker forum, a rough guide to layer thickness and print speeds.
This approximately lines up with my experience, so I will use it from now on, rather than my usual guess work.

Maximum layer thickness: 3/4 of the nozzle diameter
e.g. 0.4mm nozzle can print a layer up to 0.3mm thick.

Maximum speed
The maximum print speed is determined by how fast the filament extruder can feed.
Stock Ultimaker 2 extruder, maximum throughput of 2.85mm filament: 7mm³/s

Calculation: Nozzle diameter x layer height x speed = throughput area
e.g. 0.4mm x 0.3mm x 40mm/s = 4.8mm³/s
Maximum speed calculation = Maximum throughput / (nozzle diameter x layer height)
Therefore the maximum speed is likely to be:
7mm³ / (0.4mm x 0.3mm) = 58mm/s

I have an Ultimaker 2+. According to the Ultimaker web site, the Ultimaker 2+, can print up to 16mm³/s with a 0.4mm diameter nozzle. It has a maximum travel speed of 300mm/s.
In theory, therefore, I could double the above speeds. In practice I have not been able to a achieve speeds much faster than the above calculations.
I tried, just as a double check. 0.4mm nozzle, 0.24mm layer and 90mm/s at 210C with PLA = 8.6mm³/s. It came out lumpy and did not stick to the bed properly.
The kit was clearly capable of pushing it at that speed but it would need a lot more tinkering to get close to something usable.


Nozzle Temperature
The hot end temperature is far more trial and error. That is partly because the thermostats in the printers are not that accurate.
Most manufacturers recommend starting at the low end of their suggested range of temperatures and work up.
According to most vendors, 2.85mm diameter filament tends to need to be about 5C hotter than 1.75mm filament for the same speed, so for a standard Ultimaker, which uses 2.85mm filament, start at 5C above the manufacturers suggested lowest temperature.
Increase the temperature for faster throughput. Alternately, it would be simpler to increase the speed for lower layer heights so the throughput is always roughly the same area per second, therefore the temperature could remain the same for all prints.

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More 3D signs

I like raised letter signs and with a 3D printer they are fairly easy to produce.

I have used a similar technique on the signs on my Scalextric track. In that case I carefully hand painted round the letters. That was not easy to get the finish I wanted because I did not prime the surface first and getting between the letters was fiddly.

This time I spray painted the whole thing and sanded away the colour to reveal the plastic under the paint.

I tried using the belt sander but that was too aggressive and removed too much plastic.

A hand held sanding pad worked perfectly.

The 3D printed plastic is a bit porous so the base colour paint can still be seen slightly after the sanding. To fix this I just paint the top colour over the letters. This is fairly easy as there is no need to be accurate. It just needs to sink in to the same thin gaps between the print lines that the base paint has already been pulled in to.

For the outside sign I gave it a top coat of clear lacquer.