On Oct 7, 2019, at 8:57 AM, John Lindo <bechetboat@...> wrote:
Why be blowing air around the bed and nozzle when you are trying to heat things up. ?? this always puzzled me.
I generally run the first layers without any forced cooling air, then bring my bed fans (plural) as i use 2 up to about 8 V (depends on the air temp under the hood) at the time, and a gentle flow of 6V to the extruder.
There¡¯s potential for a lot of confusion here, especially if you venture into 3D forums.
The extruder, properly speaking, is the part that shoves the filament into the hot end, which is often a fair ways off from the hot end; John¡¯s printer ( just got the Digital Machinist with pt II of his printer article in it on Saturday :-) like ¡®real¡¯ prusa printers has the extruder mounted directly over the hot end, this can limit the issues with filament mis-feed, but also adds considerable mass to the moving print head. Offsetting the extruder to the frame and feeding the filament via a close-tolerance bowden tube greatly improves the precision and speed at which you can move the print head, at the cost of having to deal with a greater chance of a mis-feed.
The filament goes through a narrow tube down into the hot-end block itself. The fans you see on the hot end are to prevent heat from the hot end creeping up to soften the filament which will cause a jam; you only want the hot end itself (or more precisely the melt chamber within the hot end) to be melting anything.
One way this is managed on many hobby machines is an insulating wrap around the heatblock itself; this helps with maintaining temperature control of the actual heating part without getting cooled by all the fans blowing through.
--
Bruce Johnson
The less a man knows about how sausages and laws are made, the easier it is to steal his vote and give him botulism.
