Catastrophic Hotend Failure

Well as some of you know I have been trying to get my heated bed hot enough to get ABS to stick reliably with no warping. Well I figured the reading was low (the thermister on the bed maxing out around 62c. I had some prints come out decent and stick well but the hotend wasn't getting hot enough and the extruder was eating up the filament so bad that I had what looked like yellow snow all over my extruder. I tried different temps lower and higher, it seemed to be extruding very well at about 225c but I could only achieve 225 by unplugging the heated bed all together.

So I got the bed up to its max temp and unplugged the bed, then let the hotend get to 225 and I started the print, it was going well then started getting globby and was having problems extruding. So I stopped the print and raised the extruder and started extruding ABS 30mm at a time, i noticed smoke or steam coming out with the filament, I just figured it had absorbed some moisture and that it was steam.

So I kept extruding figured I would push past a bad spot or something. I had a good pile going, i noticed my temp had dropped so I gave it a min to heat back up. Then I looked over and my nozzle was swinging by the wires... %$&@ me right?



It pulled the threads right out of the PEEK tube. The thermister must be off but why would I have such problems extruding ABS at 210 and have it extrude well at 225? If its accurate my PEEK tube became soft at 225c.

Luckily I had a backup hotend I just had to retap the threads(they were cross threaded).

I have had this happen a couple of times to me with J-Heads Mk IV and Mk V.

I also wonder if my temp is way off.

Like you I was generally able to clean and re-tap the PEEK.

you should get one of these, its the best hot end ever made period! the guy that makes them is very friendly and backs his product for life. its very strong because it uses metal and phenolic sheet construction so it doesnt rely on a polymer for its strength although it does has a ptfe liner for the top part. http://www.ebay.com/itm/SG2-hot-end-for-RepRap-3D-printer-Prusa-Mendal-Max-extruder-hotend-1-75-or-3mm-/130882942683?pt=LH_DefaultDomain_0&hash=item1e793b36db

i had the qu-bd before i had the watercooled version of that and i can tell you, you will be so happy. i know i was after spending hours messing around with that stupid mk 7 clone.

I ordered this one yesterday. I also ordered 2 rolls of nylon to play with.

[e3d-online.com]

I also found a way to hook it up to my rapidbot 3.0

[www.thingiverse.com]

I just have to drill 2 holes in my extruders base plate.

The new hotend I have coming uses a heater cartridge. Is this more efficient than a resistor? I have problems reaching over 225 with my resistor with my current power supply, will the heater cartridge get hotter with same amount of power?

Edited 1 time(s). Last edit at 04/10/2013 01:00PM by hendo420.

hendo420 Wrote:
-------------------------------------------------------
> I ordered this one yesterday. I also ordered 2
> rolls of nylon to play with.
>
> [e3d-online.com]
>

Please post when you've had some time with it. There's a lot of interest in this hotend.

> The new hotend I have coming uses a heater
> cartridge. Is this more efficient than a resistor?
> I have problems reaching over 225 with my resistor
> with my current power supply, will the heater
> cartridge get hotter with same amount of power?

Resistors and cartridge heaters turn 100% of the power they consume into heat. Cartridge heaters are designed for that purpose so they tend to be more reliable. Resistors aren't usually intended as heaters, so the leads and the conformal coating tend to be more fragile leading to the failures some people have. But as far as efficiency goes, a resistor and a cartridge with the same resistance will be the same.

I was planning on a power supply upgrade anyway.

How many amps should I bee looking for?

you should go ahead and get a 12v 30a power supply off of amazon, dont mess around with the an atx psu.

So something like this one?
[www.amazon.com]

How would I hook that up? My board has a 4pin power connector.

yes that one, it has screw terminals, so it will accept any wire, and for the 4 pin power connector get some crimps and attach the wires from the psu to it. also make sure the cable is nice and thick, haha i was running just two 22 guage wires at first and they got hot so i put in some nice 14ga speaker wire and they run nice and cool.

So are the 4 wires going to my board just +12v -12v +12 -12v?

yes exactly, and you can actually run up to about 35 volts as long as all the components are rated that high.