Introduction: Coaster Making
Make coffee cup rings on your table a thing of the past with these bespoke coasters.
In the main infill patterns are out of sight and are only considered in respect of the model strength, print speed and filament costs.
However, they can also act as decoration in their own right.
With these coasters I decided that rather than simply print a suitable shape, square or circle etc. that I would make a feature of the infill pattern too.
But not only would the infill pattern be a feature I would also fill the infill pattern.
This would give the coaster a flat surface, add strength and also enable additional patterning with colour.
The fill colour would be accomplished using epoxy resin.
Step 1: Design
First of all create your coaster blank.
In this case I used BlocksCAD, but you will have your personal choice of CAD software.
A suitable size is 100 mm x 100 mm x 5 mm
Step 2: Slicing
Once you have finalised your coaster blank its time to prepare it for printing with a suitable slicer.
As I used Cura I will use this to describe the process I used.
Open the file created with the CAD design software.
This is were we will make adjustments to the slicer print setting.
In order to display the infill you will need to set the the Top Layers to 0.
The top layer will therefore not be printed revealing the infill pattern.
Leave the Bottom Layers set to the defaults as we want to retain the fill within the confines of the printed coaster and not have the epoxy resin pouring out of the bottom.
For the infill pattern I have selected Tri Hexagon
In order to make filling the infill pattern post printing an easier task, do not set the percentage too large, I have chosen 20% the reason will become clear during the filling process.
Step 3: Post Print Preparation
You may use any colour for printing, although black will highlight a greater range of infill colours but feel free to experiment.
Once the coaster has been printed there is some preparation to be completed first.
The printing process is not without some imperfections and each cell my not be entirely isolated, small holes may exist within the structure of the walls.
A visual inspection may identify holes, cracks or layer separation which depending on severity can be filled in with Cyanoacrylate adhesive, putty, or tape.
As the process will also identify any holes in the perimeter walls of the print.
If you create multi coloured design you will need to be mindful of unintentional colour mixing from seepage between cells. Not an issue if you will be using one colour.
******* Sealing epoxy resin mix only required for multi coloured designs.**********
Remedial action is required as a precaution for multi-coloured designs using a sealing epoxy mix.
Using a suitable epoxy resin mix (there are many to choose from), I chose a 2:1, two part mix with 12hr cure time.
Make sure the product has a useful working time and not to make too much unless you can make use of the excess elsewhere.
Following the manufacturers recommendation and wearing suitable protective equipment make a clear mix without adding any colour.
Pour in to the infill cells up to a maximum of 75%, the thicker the object the more epoxy may be required to fill the bottom and side walls. Although, wicking action will pull the resin up the wall to seal holes nearer the top hence filling up to 75%.
But also having enough of a pocket to accept your chosen colour and that some post cure sanding will be required to level the surface.
However, these guidelines will vary subject to the infill pattern, size, imperfection density and epoxy viscosity.
Step 4: Colour Filling
If a multi coloured design is being created allow the epoxy to cure before adding colours.
Try not to place differing colours in adjacent cell in the same process, allow one colour to set before adding another to prevent colour seepage.
In the event of a single colour non of the afore mentioned issues should apply.
How to fill the cells.
As mentioned previously setting the infill percentage too high results in small cells and these resist taking up the epoxy due to the formation of air pockets.
Therefore, dripping or piping the epoxy into the cells allow the air to escape, these air pockets may not be obviously immediately but can erupt out of the blue if the cells are filled too quickly or the epoxy too viscous.
Therefore fill slowly and tap the object to encourage any air bubbles to show up sooner before the epoxy cures.
Although, depending on the cell size and colour complexity post filling again can be applied but much easier if its right first time.
Step 5: Post Fill Processing
Having completed the filling process and allowing full curing, you may yet still identify some imperfections.
These could be:
1: Poor definition of infill separation boundaries.
This may be recovered by sanding the surface use a fine grade paper such as 240 to minimise deep scratches.
Recommend washing in a mild detergent to remove grease and debris after sanding. Making sure its dry before applying further epoxy resin.
2: Voids in cells due to air pockets.
Refill again and/or checking more frequently during the curing.
3: Boundary seepage marks.
Remove by sanding, filing or cutting off excess.
If the seepage is in a noticeable colour compared to its surroundings it may be necessary to apply further epoxy or acrylic paint to the area blend it in to the surrounding material.
Step 6: Finishing
Once all the Post Fill processing is complete its time to apply the finishing touches.
This could be in the form of two methods.
1: Surface polishing with an epoxy resin polish to remove all surface imperceptions and add a shine.
2: Apply a layer of clear uncoloured epoxy to the surface
I applied the latter as it gives a superior finish as long as you ensure the surface is clean and grease free, IPA or Methylated spirit works well.
Once you can polished it or applied a clear epoxy coat and allowed it to cure your work is done.
Now is the time to sit back, relax have a coffee and make use of your coaster, you've earned it.