A question to all the hot-end designers out there. Since it’s molten filament that comes out of the end and molten materials flow relatively easily around bends, is there any reason why one couldn’t be made mostly horizontal?
Did you read @Sanjay_Mortimer post on their multi-color extruder? It uses 90 degree bends. Makes cold pulls impossible though.
Just had a read of http://bukobot.com/nozzle-cleaning. I’ve not had to do a cold pull yet, guess I’ve got that fun to come… I wonder what bend radius you could go down to and still manage a pull?
Well you could do the equivalent of the sewer cleanout and make the nozzle in two parts such that the bottom part had a straight melt zone which screwed into the top part which had the 90 degree bend. But that would be some difficult engineering with materials that would want to expand with heat (brass, copper, what ever)
@Chuck_McManis It’d be really difficult to get those two parts to seal inexpensively. O-rings, etc don’t like those temperatures and pressures.
@Tim_Elmore
exactly (this was the challenge I alluded to). That said, silicone o-rings don’t mind the temperature. But you still have the joint movement due to thermal expansion.
@Chuck_McManis Where are you finding Silicone o-rings good to 300C+? Parker Hannifin (the hydraulic guys) only rate theirs to 232C.
Check McMaster for “Self-Lubricating Packing Seal Tape for Pumps and Valves”. Its graphite so it’ll lubricate to prevent stuck parts and goes way up there in temperature. I haven’t confirmed it but I think its this: http://blaylockgasket.com/products/25502551-crinkled-flexible-graphite-tape.html
e3d’s Cyclops does this. They use a ball-bearing pushed into the end of the drill hole by a setscrew to seal the extra holes(s).
@Tim_Elmore
try http://www.marcorubber.com/silicone.htm they claim they go to 260c which is good for most plastics.
+Mark Emery That is a reasonable question … but why do most of us limit our thinking/designing to right angles ? Maybe 45 or 60 degrees from the horizontal would allow more possibilities …
I’m thinking 90 or close to it as I’m playing with ideas for a printer where all of the electronics, motors etc are to the side so as much of the height can be used for printing as possible. I want a large printer to hang under my up-desk, which puts a limit on frame height to begin with. Start subtracting feed paths etc and that height quickly gets reduced.
I know nobody here is a fan of Stratasys, but many of their machines utilize a setup where the melt zone starts just after a 90 degree bend. Check my post here for pictures: https://plus.google.com/112079438186671979082/posts/foX4MfwYD64