Hi all.
I was wiring up my extruder yesterday with http://reprap.org/wiki/Extruder/Mendel as a guide. I felt some steps were a bit difficult to understand before I sat down and did them myself, so I took some pictures of the process, which might fit on the wiki.

But I'm not sure I did everything right, so I'd love your opinions.

The images are posted on another forum, don't know if the links will work. If not the pictures hide in the spoiler tag here: [www.diskusjon.no]


I added some plumbers tape to make a good seal with the PTFE. Don't know what kind of material it really is. Does it matter that much?


Since I have the big head nozzle, I added some thermal paste to get a proper heat transfer to the nozzle.


Added a tiny bit rather high up on the barrel to avoid any leaking and potential clogging of the nozzle.


For crimping I skinned a few of these. We call them cable shoes, is that the proper international term?


They work okay, but doesn't make a exceptional sturdy connection. I probably should have cut if in half and crimp the nichrome wire and the connector wire at the same time.
I also see some people solder the nichrome, but the wiki says it's a bad idea. If solder melts at about 300 deg celcius, how would heating the barrel to 175 deg celcius for PLA, dissolve the solder? Or am I misunderstanding something here?


(Wiki) Wind the nichrome wire onto the brass in the valleys of the threads. Start at the PTFE end, run a length straight towards the tip...


...then wind round and round back to the PTFE covering the straight piece you just laid. (End Wiki)
Is this the correct way to do it? (Large image to see the details).


Then nichrome away. The connection got a bit bulky.


For the thermistor, I found it easier to use bigger bits of nichrome and cut away the excess, than trying to put on a tiny bit of nichrome.


I probably should have attached the thermistor to the nozzle, and wound the nichrome further up. Is this a deal-breaker so I should redo it?


More nichrome.


An ugly solder joint on the thermistor.


All done. Well, it won't fit on Adesina like that, as the connections are a bit too bulky, but it's a start.

While I'm messing around in the wiki, I'd like to add some calculations to http://reprap.org/wiki/Nichrome
I use this wire from UltiMachine. 1 foot is 8ohm, so 6 ohm would be 3/4 foot, 9 inches or approx 23 cm, right? When it's all wired up I measure it to be 5.8 ohm (thereof 0.2 ohm from the multimeter). Is that close enough, or should I redo it?

So, what do you guys think? Is this something useful to the wiki? Did I do it right? Is it possible to solder nichrome? Is it confusing to show off the big head nozzle alongside the one already on the wiki?

Sorry about the huge amount of questions and pictures.

-Peter / Nudel

Nudel Wrote:

> I also see some people solder the nichrome, but
> the wiki says it's a bad idea. If solder melts at
> about 300 deg celcius, how would heating the
> barrel to 175 deg celcius for PLA, dissolve the
> solder? Or am I misunderstanding something here?

Solder melts at 186 degrees not 300.

In anycase I enjoy seiing your pics of the extruder assembly, i've ordered last week fiberglass nicrhome wire to improve my extruder, ekse I had tried a fw variations on actually winding it with not much success

When I put that into the wiki, its based upon two types of common solder.

Tin/Lead also called 60/40, SnPb


The other is ROHS

Tin/Silver or 63/37 which has an even lower melting point at 183 degrres C

There are solder alloys around for different jobs all with varying melting points of about 250, above and below, but seeing as most people will use that which is easiest to come by, usually tin/lead, common sense prevails here.

I have used HMP solder that melts at 300C to solder the nichrome connections. It works fine but does not actually form a proper joint because solder does not stick to nichrome, it just forms a tight mechanical fit.

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[www.hydraraptor.blogspot.com]

Your pictures are great and should definitely be included in the wiki

Your pictures are great and should definitely be included in the wiki
!

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!