Thanks for everyone's responses so far. When I asked, it was both specifically about the nozzles (more below), and also a general question on machining practice. Am I mistaken about the idea of machining in a common flat across parts that are mated together into a finished assembly?
Now, about the nozzle.... I have the design for the previous generation extruder, Mk 7. The current design is basically the same. [image: Inline image 5] The piece that goes all the across the image is the plate to mount the extruder assembly to the printer. The "bar mount" block above the plate is threaded to accept the thermal barrier tube (essentially a drilled M6 stud). A M6 nut on top is used to lock the stud against the bar mount. They are then attached to the mounting plate, with another M6 to hold the assembly in place. The tube protrudes below. The tube has a small neck-down area, to lessen heat transfer from the heater core entering the upper part of the barrier tube. The brass piece at the bottom is the extruder nozzle which is threaded onto a heater block. That heater block is then threaded onto the tube so that the faces of the nozzle and the tube mate. So the nozzle height is controlled by the depth of the tube in the bar mount. Typically, we are doing 0.1mm thick layer passes -- so the nozzles should ideally be within 0.01mm or less of each other -- perhaps 0.03 mm or better in actual practice -- in order for the lower nozzle to not drag through the plastic extruded by the other nozzle. I've worked out that 0.01mm is about 4 degrees of turn of the M6x1 thread. That's certainly a doable adjustment -- however, that involves a great deal of work to disconnect the extruder assembly cables, and then having to disassemble a significant part of the extruder to adjust the height before mounting everything back and rewiring the cables. I think I can be meticulous enough to do this and do it right -- but it seemed like tramming the nozzle to a common X/Y plane by taking the last few tens of um's would be a much easier process. Thanks for reading and your responses! Joseph On Thu, Mar 7, 2013 at 10:30 AM, Jason Burton <[email protected]>wrote: > Comments below. > > Best, > Jason > > On Mar 6, 2013 11:34 AM, "Joseph Chiu" <[email protected]> wrote: > > > .... > > > > As assembled, the flatened tips of the extruder nozzles are not quite > > matched in Z-height, causing the lower nozzle to gouge the output of the > > higher nozzle. The recommended fix from the factory is that you can shim > > between the dual-head assembly to the carriage to raise the low side > until > > the nozzles are matched in height. > > > .... > > +1 on Jeremy's advice re: using paper feelers to set known offset & not > cutting the nozzles. > > Before shimming though, consider the possible causes: IIRC, makerbot > nozzles are threaded onto an M6 stud, with the plastic passageway drilled > through lengthwise. > > Check to make sure both nozzles are seated full depth, and not bottomed out > on a burr or threads cut too short. > > Which surface is the nozzle designed to "bottom out" on? > > > > > Joseph > > ------------------------------- > > ------------------------------------------------------------------------------ > Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester > Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the > endpoint security space. For insight on selecting the right partner to > tackle endpoint security challenges, access the full report. > http://p.sf.net/sfu/symantec-dev2dev > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > >
<<image.png>>
------------------------------------------------------------------------------ Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the endpoint security space. For insight on selecting the right partner to tackle endpoint security challenges, access the full report. http://p.sf.net/sfu/symantec-dev2dev
_______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
