m6 threaded aluminium tube for 3d printer

[jcb121]

So, I'm making a 3d printer.

and I've bought most of the parts from around the world but I can't find this part.

so m6 thread on the outside, 3mm internal hole, about 50mm long and in Aluminium.

it's so I can pop one of these on the end.

I'm using 3mm filament so I'm hoping a 3mm aperture will be fine.

thanks.

[Clive S]

I think you will find that 3mm filament is more often than not oval in shape and can be 3.2 x 2.8 etc here is a link HydraRaptor to a guy that has been around a long time and has a lot of good knowledge. The tubes are quite often made out of brass. a link here to a typical nozzle http://reprap.org/wiki/J_Head_Nozzle I have built a few of these printers in the past and the extruder is a very important part to get right for success. Good luck with your build. ...Clive

[m_c]

If you can get a drawing of what you'd like, I should be able to knock a few out with minimal hassle.

One thing I wonder is if a reamed finish would be better than a drilled?

[jcb121]

A reamed finish would be great, I think brass may be a better material as it may hold the heat a bit more then Aluminium.

I don't want the heat to travel up into the cold end too quickly.

[FatFreddie]

Have you seen the reprappro hot ends - I have the older version and it has been very reliable (the only problem was with a section of oversize filament - 2mm instead of 1.75 - can't really blame them for that) - I've put well over a kilometre of filament through with no other problems.

New
http://reprap.org/wiki/RepRapPro_Men...t_end_assembly

Old
http://emakershop.com/RepRapPro_Mend...-2013-0205.pdf

The principle seems to be to create an abrupt transition between hot and cold zones by force cooling above the heater - this minimises the time the filament is semi molten and therefore the bulging which can cause jams.

The new version looks like it uses a PTFE liner which would remove the necessity for a smooth barrel as well as insulating the filament until it got to the melt zone.