Printing with a 1 mm diameter nozzle.

2012-11-06 17.09.40-2-crop2

FYI – The above picture is a 1mm printout.  It weighs 35 ounces (a measure of it being quite solid) and took only 20 minutes to print!!  It is very hardy, and this is because the infill is more sturdy.

The idea of reprap is that you can print excellent resolution by relying on highly accurate steppers to form a perfect outline, and filling in the center.  This makes it possible to use a 0.5mm nozzle to create and object that is say, 2.3 mm wide, and to fill it perfectly, because the steppers have 10 micron resolution (assume no backlash).

So…why not 1mm?  Or more?  Why is the push towards ever smaller 0.25mm nozzles smaller nozzle sizes (see link to makergear site with nozzles)?  Well, 1 mm is a great solution that makes stronger, faster parts, with virtually no disadvantage!  And 3D printing is SLOW, but within the realm of being really useful.  So any speed improvements here are a big deal.

 

Procedure:

I succeeded at this mod – by drilling out the prusa makergearv2 nozzle (plastistruder) to be 1mm diameter (order exact drill bits online). Then smooth the nozzle by brushing it against a flat brass surface (acts as superfine sandpaper).  There is nothing shockingly new here, but the take-home-message is that it was totally unintuitive before doing the mod how much easier plastic would flow, and how much stronger and faster the parts print.  Always challenge the status quo, it doesn’t know why it exists.

Some assumptions/requirements

  • You will need to have optimized the pololu RAMP output for the plastistruder to maximum amperage for maximum force
  • You need to balance the force on the filament – too much and the bearing roller won’t turn. Too little, and the filament won’t move.
  • In my case, I drilled and tapped the plastistruder so that i could use screws with stronger springs and to be able to remove them more conveniently.
  • You need to understand that for PLA, the filament does not behave normally when it has been sitting hot in the hot end for more than 5 minutes. Even if it doesn’t flow out, it will get “sticky”. Once you push it through (about 50mm filament) you will not believe how effortlessless filament flows through.
  • You should know that for 1mm, even though 4 times the material can go through, there is exponentially less resistance to flow through the nozzle, so the plastistruder can keep up. Also, technically, the layers only print twice as fast because slicer prints based on diameter, not diameter^2. I’m not quite sure why that is.
  • You will print about 1.15 mm in reality.
  • For a strong part, you have to let slicer overlap
  • I’m also assuming you optimized firmware for max acceleration and 350mm/s between print moves (prevents ooze)
  • There are some obvious modifications for slic3r. I am printing around 55mm/s for the part linked here. I also print onto cardstock paper to help set the first layer.

Advantages of 1mm as compared to a 0.5 mm nozzle

  1. Because more comes out of the nozzle per second, your prints will be more consistent on the first layer, and stick well.
  2. Less nozzle ooze (wow!)
  3. Infill
  4. Stronger parts
  5. Much (MUCH) faster prints. I am printing 3 ounces of plastic per hour right now…way faster.
  6. Ability to do 0.5-.75 mm layers with success
  7. Fewer “stringy polymer hairs” loose between distant prints
  8. Much cleaner top surfaces (overlaps between lines look better)
  9. Bridging seems slightly more reliable.

 

Disadvantages

  1. You will loose sharp edges (slightly). This is noticeable (and may be an advantage)
  2. Minimum resolution is 1.15 mm (instead of 0.55 before) is somewhat noticeable, especially if you manage to print 0.5mm layer thickness. However, resolution is not really lost much. The reason is you can still print 0.1 mm layers. Your steppers also have 10-20 microns of accuracy, so the ability to print lines instead of individual points (like an inkjet) really allows you to potentially do 2, 3, even 5 mm diameter if you wanted, you just need thicker objects to print a small hole. Also, if really needed desperately small feature sizes, you can rely on your Z-axis for accuracy (like you do now).
  3. When you get “stringy hairs” coming off the nozzle, they will be thicker and harder to remove
  4. Anything else obvious I’m missing?

 

Comments are closed.