1mm Jhead

Any experimental tests or upgrades for the gMax printer will reside here. Check back for new ideas and to follow the progress.

1mm Jhead

Postby gCreate_Kyle » Thu Dec 08, 2016 10:49 am

Is a large nozzle a better option for your application? If you need to decrease those long print times, than yes. The 1mm nozzle will bring you models to completion much faster than the standard 0.5mm nozzle. A model that required 3-4 hours can be processed in less than 1.5 hours using a 1mm nozzle. You may also benefit from thicker extrusions if you need to make parts as strong as possible. With a wider extrusion there is more surface area for the material to create a strong bond.

The obvious downside to a 1mm nozzle is the loss in detail. With a 1mm nozzle, the smaller features in your model will be lost in the slicer since a 1.2mm extrusion width is too large to create these details. In addition to losing detail, large nozzles are not able to process overhangs or bridges as well as a 0.5mm nozzle. A fat extrusion will not cool as quickly.

Top layers:
Because top layers are often bridges, they can be tricky to process with a large nozzle. You may find that you need 3 or 4 top solid layers to achieve a good finish. Depending on layer height, this is a very thick top shell. I found that setting the top solid layer extrusion width to a value less than the width of the nozzle, produces a great finish. For a 1mm nozzle set the top solid layer extrusion width to 0.8-9mm.

Limited by melting capacity:
As the nozzle diameter increases your print speed, that is the speed the extruder is moving, will slow drastically. Extruding a 1.2mm extrusion width at 0.5mm layer height will require the extruder is process 5 times the volume of material the 0.5mm nozzle would process over the same distance. The limitation in print speed is set by the volume of plastic the hotend is able to melt. This brings up another problem you can encounter using large nozzles. If extruded too fast, the plastic in the center of the filament may not be molten, compromising layer adhesion. A speed of 20-30 mm/s is a good start, however it depends on your layer height. Do some test printing to figure out the best print speed to use with your material.

Auto temp:

This is an experimental feature for advanced users. It will automatically adjust temperature in relation to extrusion rate. This can be very helpful using a wide nozzle. Autotemp is adjsted in the start gcode script. When autotemp is enabled, low extrusion rates will decrease the hotend temperature while high extrusion rates will increase temperature.

Ideally when using autotemp, temperature is only controlled in the start gcode. So you must set temperature controllers in the filament tab to 0 to disable normal temperature control commands. Add this line to your start gcode to make adjustments to temperature using autotemp.
M109 S(minimum temperature) B(maximum temperature) F(Factor)

F is the factor by which the maximum extrusion rate of the next 16 buffered moves is multiplied, and then added to the minimum temperature to obtain the set temperature. It is a small value. Try 0.1- 1 for F. The larger the temperature range the larger the value for F should be. Here are some examples. Don't forget it is based on volumetric flow rate not print speed.Therefore layer height and extrusion width will affect temperature.

M109 S195 B220 F0.7 ; Big range, big F

M109 S205 B215 F0.3; Small range, small F

A good test print for autotemp would be a cone on spiral vase mode. The speed overrides in the Cooling tab of Simplify 3D can set the amount of time spent printing each layer. Because the model is a cone, each layer will require less material than the previous. Keep an eye on your temperature graph so you know how autotemp is behaving.

Easier first layer:
A larger nozzle is able to make thicker layers. This means there is a wide tolerance for imperfections in the first layer. That perfect first layer can come with ease using a wide nozzle.

Less prone to clogs.
Dirt and debris that would otherwise cause a clog will pass through a wide nozzle. This allows the use of low quality filament without running into the occasional pesky hotend clog. Which is great since you will be going through a lot more material with a 1mm nozzle.

Spiral vase:
Everyone loves the clean finish of model created with spiral vase mode. However these models will be especially weak when created with a nozzle of 0.5mm or less. This is due to the relationship between extrusion width and nozzle diameter. Since a large diameter nozzle will produce a much wider extrusion width, it will create thicker walls thus making your spiral vase model stronger.

Interested in the 1mm J-head? You can purchase one from our online store. https://shop.gcreate.com/products/j-head-1-0mm-mk-v-bv-hotend

Installation instructions are covered in the User guide. http://www.forum.gcreate.com/downloads.php?view=detail&df_id=55
These users thanked the author gCreate_Kyle for the post (total 0):
R. Kyle Gress
gMax Technical Support
3D Printing/Electronics Enthusiast
User avatar
Posts: 169
Joined: Mon Feb 02, 2015 8:47 am
Location: Lancaster, Pennsylvania
Has thanked: 11 times
Been thanked: 18 times

Return to gMax Experimental Tests

Who is online

Users browsing this forum: No registered users and 1 guest