I have nearly got my Prusa up and running and am now making a hot end for the Wade's extruder, but I haven't seen anything on the geometry of the nozzle. Should the nozzle have a flat tip? If so, what diameter? Maybe it would be better convex - and here again, what raduis? Thanks for any info you can give, Mike https://reprap.org/forum/read.php?70,93531,93531#msg-93531 Sat, 05 Sep 2026 19:32:58 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?70,93531,97215#msg-97215 https://reprap.org/forum/read.php?70,93531,97215#msg-97215 I find it hard to make a flat tip for two reasons: the width is hard to fit (especially that it may vary a little), and also the perpendicularity of the flat plane is hard to achieve - at least for me with simpler DIY tools. In the end, I find it best if the nozzle is just sharp, as it is easier to achieve and somewhat safer. I also find the flatness of top layer to be nice with sharp tip, in fact it never came to me that it might be an issue like that. I guess most of the filament width is still flattened by the tip during travel, and sides are just more tempted to stick to the others or fall to gravity, or something like that.

What i did found in a nozzle build similar to your, is that inside the block, the top thread and the nozzle lower thread have to match perfectly. If they dont, they leave a wider gap and it will create a pocket of air (i seen it while disasembling the block with the melted plastic inside and a big air bubble to one side). And that air doesnt like to go downwards, hence it will be something like an air pocket inside a water tank of plumbing - that is will try to equalize the pressure, hence it will give tones of more ooze and will also have problems if extruder needs to start extrude fast at top speed. Maybe it could give some bubbles also if at least some air parts get trapped.

So basically, i would advise to make sure that from the top entrance of the block, till exit, the plastic will basically travel inside a single cylinder which has the width as close match to filament width, not too big/wide at any point. For minimal ooze and proper response time, etc.

Good luck!]]> NoobMan Plastic Extruder Working Group Fri, 09 Sep 2011 07:10:17 -0400 https://reprap.org/forum/read.php?70,93531,94882#msg-94882 https://reprap.org/forum/read.php?70,93531,94882#msg-94882
While I am waiting for a delivery of ABS and PLA filament, I have been trying to build a hot end with rapidly replacable nozzles; the present design has a silver steel nozzle clamped in a purpose made heatsink. this seems to work quite well and the cold end of the steel nozzle maintains about 36 degrees when the tip is at 300 degrees.I have managed to push 1.75mm ABS filament through this nozzle which has a 0.26mm hole 3.5mm deep

[attachment 5093 Hotend1.JPG]

I have started on Mk2 of this design based on what I have found and the heater block will have a single support post and will be a push fit on the nozzle - the present nozzle is screwed into the hot block. I have found the a surprising ammount of heat is conveyed to the heatsink by convection so am insulator made of cuttlefish bone will be put between the hot block and the heatsink.

Mike]]> leadinglights Plastic Extruder Working Group Sun, 21 Aug 2011 15:28:37 -0400 https://reprap.org/forum/read.php?70,93531,93670#msg-93670 https://reprap.org/forum/read.php?70,93531,93670#msg-93670 marnargulus Plastic Extruder Working Group Wed, 10 Aug 2011 12:25:33 -0400 https://reprap.org/forum/read.php?70,93531,93546#msg-93546 https://reprap.org/forum/read.php?70,93531,93546#msg-93546 nophead Plastic Extruder Working Group Tue, 09 Aug 2011 12:29:54 -0400 https://reprap.org/forum/read.php?70,93531,93531#msg-93531 https://reprap.org/forum/read.php?70,93531,93531#msg-93531
Thanks for any info you can give,

Mike]]> leadinglights Plastic Extruder Working Group Tue, 09 Aug 2011 09:43:11 -0400