Noob questions, The Machine

[Todd-67]

So I'm learning. From what I've read, if I want stronger parts with better inter layer adhesion, I want to go to a larger nozzle. The supposed advantages are that the previously laid down layer retains more head, it will bond better as the new layer is laid down. It also speeds printing considerably. For aquarium parts I think I should actually consider the E3D volcano. As a start, I will get the largest nozzle my head supports.

It really depends on what your accuracy requirements are. A larger nozzle will print faster but I am not sure it has the advantages that you are citing. A normal .4mm nozzle can be setup to produce those exact same results. Extrusion width, your multiplier, and extrusion temps are you friends. These parameters are in your slicer.

For water tightness, is that all down to inter layer bonding?

I don't think varnish will hold up long term in salt water. I'd have to talk to the smoothing compound manufacturers to see what might leach into water and how well those compounds hold up. It is definitely an option.

If I can print water tight from the get go, its almost 'holy grail' product for my application. If plain pet-g turns out to be too flexible, I can always go for a carbon fiber reinforced product.

Bonding would be the one issue. The only product available to bond to other plastics like PVC or acrylic it Weldon 40, a rather expensive two part bonding agent. If it works and this is the only down side, I can live with that.

Water tightness is going to rely pretty heavy on your shell/perimeter settings. Lots of perimeter/top/bottom layers. You and I both know that coating anything in a saltwater environment is something to proceed with extreme caution.

The fumes from abs are not as much of the problem as it's shrinkage and all the acetone you end up breathing in.
Yes people use it, I suspect many of them do so beacuse they haven't bothered to look seriously at the alternatives. The materials advances in 3d printing filaments in the last few years is just astonishing.

You don't breath in acetone during printing. It's a solvent that dissolves ABS. You use acetone as a method of smoothing, creating slurry, or cleaning the bed with Kapton tape. What you are smelling during printing is the styrene. ABS = Acrylonitrile Butadiene Styrene. Does it smell? The short answer is yes. The real answer is that when processed at the correct temps the toxicity of the fumes is minimal. ABS when burned as in a fire condition is very toxic which is why they have flame retardant grades for certain applications (molding option) but that is not what we are doing. Extrusion temps are below injection temps. If it were toxic when processing OSHA would be all over the injection molding industry as it and nylon are the most processed plastics on a large scale and they don't require breathing aspirators for the workers. Can it irritate some peoples noses? Certainly.

Like i stated before the application defines the application. Material selection is based application. The array of thermoplastics is pretty wide ranging and application specific. Check out the range of what is out there on matweb http://www.matweb.com/search/MaterialGroupSearch.aspx Each of these has a use as matweb just covers the most common for each category not the full range from Dow, Bayer, GE, etc.... Yes the printing industry has brought out a lot of filaments but they are based on existing polymers with a modifications to make them easier to print. I use a lot of the stuff that is out there. There are applications for all of it.

Edit: Regardless of the material I work with, I plan to enclose the machine. I've spent enough time around injection mold machines (very large ones) to understand how finicky plastic can be. Since I'm concerned with long term structural integrity, I want to manage the print environment as much as possible.

Controlling the environment as much as you can is a very wise approach.