Tuesday, June 26, 2012

Pondering the Nozzle Orifice Drill Bits

From time to time I see people mention that the J-Head nozzle extrudes slightly under what is expected.  This may be because I have been drilling out the nozzle orifice with a similar concept to what is done with machine tools.  A quality lathe will be built with the tailstock that is about 0.001" high.  This way, as it wears, it will eventually line up perfectly before wearing to a point under the center line.  Taking this concept to the hot-end, the J-Head nozzle orifice is drilled out slightly smaller than the specification in order to provide room for wear. 

A 0.50mm nozzle is therefore drilled out with a 0.4572mm drill bit.

This concept has been creating issues.  For example, in Slic3r, the nozzle diameter needs to be set to a lower size in order to generate the proper gcode.

At this point, I am considering abandoning strategy of providing room for wear, and using exact size drill bits.  While there will be less room for wear, this should result in a hot-end that is easier to use.

Comments?

Monday, June 11, 2012

Machining Mk V-B brass nozzles.

Today, I made a video of the first turning operation performed on the J-Head Mk V-B brass nozzle blanks.  This is the 4th step undertaken when machining these nozzles and is performed on a Hardinge DSM-59 turret lathe.

Sunday, June 10, 2012

Machining J-Head Nozzle Blanks

Sometimes I get requests for machining pictures.  Here is a series of pictures detailing the process of machining the J-Head nozzle blanks for the nozzles that fit the J-Head Mk I to Mk IV hot-ends.  Note that the fixture has 20 pockets.  The rear 10 pockets are for the J-Head Mk V hot-ends.

The brass stock has been cut and placed in the fixture.


Machine has been started and is performing the first CNC operation on the brass stock.


The first operation has been completed.


The brass stock is removed and flipped so that the opposite end can be machined.


The second CNC operation is in progress.


A view of Mach3 running the second operation.



The second CNC operation has been completed.


Finally, the completed nozzle blanks are removed from the fixture.  They are now ready for the turret lathe.