- Low first layer
The first layer being sufficiently low (also known as crush or squish) is extremely important, as this is what will guarantee proper adhesion, with any solution or without (small parts).
A good way to gauge, whether the crush is sufficient, is when each loop of the skirt is twice as wide as a typical extrusion line further along the print. Too much - the loop is not only wider than twice, but also becomes transparent. The loop must remain opaque.
Why too much crush is a bad thing? The part will adhere to the glass/printing surface, especially with a solution, so much, that damage is guaranteed to either the surface or the model, or both. A good example for of sufficient crush
Too much crush
- ABS Juice - ABS diluted in Acetone
To guarantee any kind of adhesion, you must use an adhesive solution, like ABS juice.
ABS juice is commonly known and is very simple to make; a few scraps of ABS (supports, discarded and shredded parts, pieces of filament) diluted in Acetone (not nail polish!). A ratio of 1 to 5, or 2 to 5 works well, although i personally prefer to gauge by the viscosity of the resulting liquid. It needs to retain low viscosity, but just before it becomes somewhat thick. Any color works, but natural or white is advised.
There is one caveat when using juice - don't use it on bare glass, because this can happen...
Thats right, the part stuck so hard to the glass, that when the glass cooled off, the part popped off with a large sliver of glass still stuck to it. Now you might ask what's the point in it then? Well it is still the best adhesive solution, especially for large prints, it just shouldn't be used as it is.
It should be used either on kapton tape, tint film, or alternative printing surface, such as FR4 (PCB) or Garolite. There is another trick to ABS juice, that is not well known - you use an extract of the resulting liquid. The extract is the clear liquid, that will form on top of the dissolved plastic particles, if you let the juice to stand undisturbed for a day or two.
The extract, while retaining the excellent adhesion qualities of ABS, allows easier removal of the part off the printing surface, does not color the first layer, and less likely to cause damage to the printing surface.
Apply in small quantities to cold bed. Clean off with acetone after use, as a new application over an older layer, with increase adhesion properties.
A safer alternative to ABS juice, is hairspray. Unlike ABS it can be used on bare glass, but it is less effective for large parts. Not all brands work, so if the the two known to work brands are not available, some testing and experimentation would be needed. The two known to work brands are Aquanet, or Garnier Fructis (Ultra or higher strength). As juice, apply to cold bed, either by spraying over the bed, or spraying into a paper towel, and wiping it over the print surface.
Protecting the borosilicate glass from damage
The simplest way to do so, is to cover it with kapton tape, but since kapton comes only in specific sizes, a few strips might be needed, and that will cause lines on the first layer of the print. Requires reapplication after 2-3 uses.
Car window tint, is another option, and is easily found in most automotive shops. Comes in large sizes, so can be easily cut to fit the glass. Easier to apply bubble free than kapton, but like kapton can be used only a few times before requiring reapplication.
FR4 or Garolite, clipped to the glass, are an excellent way to avoid the hassle of re application, but at a price of minor XY print range reduction (because of the clips).
Armed with this information, ABS printing should be hassle free, and a lot less frustrating.
In the next post I will outline a simple construction of a easily source-able, and low cost enclosure for non enclosed printers.