Hot End is on fire... literally =/

[Tincho85]

Hi guys, I was just finishing my build, started with the soft... and when I turn on the Hot End to check it was working, smoke started coming out.
After 1 min, the Hot End melted and broke in two pieces.

I'm so frustated, this is my first 3d printer and everything was going well.

Here is a pic:

Will upload a video in a few minutes.

[Toyguy]

Seems like the only possible cause for that would be a short in the resistor installation. Surprised you didn't blow a fuse on the Rambo though...

I'm a noob though, so let's wait for the more experienced guys to chime in.

[bubbasnow]

wowsers, this happened to me, but i caught it before fire.. My cause was i tried to exceed the temps of the PEEK unintentionally. gotta stay below the 250's mark or the PEEK will melt. I would also think that a short from the resistors would cause a fuse to blow... but that didn't happen here.

[Tincho85]

Seems like the only possible cause for that would be a short in the resistor installation. Surprised you didn't blow a fuse on the Rambo though...

I'm a noob though, so let's wait for the more experienced guys to chime in.

Let's hope not Dave. The Rambo board doesn't smell odd btw.

wowsers, this happened to me, but i caught it before fire.. My cause was i tried to exceed the temps of the PEEK unintentionally. gotta stay below the 250's mark or the PEEK will melt. I would also think that a short from the resistors would cause a fuse to blow... but that didn't happen here.

How can I check if I exceeded the temp of the PEEK? (don't know what that is )
Thermistor short... could be, but I double check that before putting the RTV.
did this: "In order to make them bigger, you’ll need to cut a strip of aluminum foil and wrap the resistor. You want the width of the foil strip to be about 1/16” shorter than the length of the resistor body so that it can’t come into contact with the leads on either end of the resistor."



But it does look like a short...

And I thought that the smoke was normal
[youtube]http://www.youtube.com/watch?v=c92-xtFcIg4[/youtube]

[Toyguy]

The PEEK is that tan plastic part of the hot end. It can only take around 240-250C before melting, but I don't think that's your problem here. This looks more severe than that. It does look a little bit like a short in the resistors there - especially that one spot on the head that looks blackened.

I did not use the tinfoil, based on some comments from one of the SeeMeCNC guys where he mentioned simply putting the resistors in and pumping the holes full of RTV. That's what I did, and it seems to work beautifully. My hot end heats up very quickly and there should be no chance of a short with everything filled with RTV.

Dave

[cope413]

Oh the PEEK definitely melted. Based on what I see, my guess is that your resistor leads were touching the heater block. You'll need at least one new resistor, a new PEEK section, and possibly a new thermistor. Get yourself some kapton tape and wrap the leads of the resistors from the body of the resistor up to the connection with the other resistor so that you can't do that again.


On the bright side, that could have happened after you left a print on and you could have burned down the house.

[Eaglezsoar]

I would do away with the outdated resistors and purchase a 40 watt cartridge heater.
Resistors work but they are old technology. Here's a link but they are available all over
Ebay and other online sites that sell printer parts. http://www.ebay.com/itm/12V-40W-6-x-15m ... 3f2b53225d" onclick="window.open(this.href);return false;

You only need one cartridge, you can use the other hole to warm up your salami or whatever.
The absolute maximum temperature on that type of hot-end is 240, if you exceed that your Peek
part of the hot-end will start to soften. You should invest in an inexpensive thermocouple and
meter to put into your hot-end to verify that the reported temperatures are accurate. Here is another
link: http://www.amazon.com/Extech-MN35-Digit ... uple+meter" onclick="window.open(this.href);return false;
It is a multimeter but it also measures temperature and comes with a thermocouple that is small enough to fit inside
the hot-end. This is but one example, there are temperature meters that are quite inexpensive on Amazon but I felt it
would be nice to have the other functions on the meter also.

[cassetti]

Yikes!

And I thought that the smoke was normal

Have you EVER watched a video of a 3D printer in action? Have you ever seen smoke? Nothing except for a smoke machine should produce smoke in normal operating conditions!

The dangerous part about these 3D printers is the fact we are running these units near the threshold of what they can achieve. I print at 230C all the time with my Replicator at work, but I don't dare take it any higher than 240C, for fear of a melted PEEK or PTFE lining.

Follow everyone's advice, you can also buy a cartridge heater from hotends.com - that fits, but you will need some aluminum foil on it to hold it tight as well, make sure you still fit the whole cartridge INTO the whole, not hanging out the side.

Also, make sure you let the RTV caulk sit for 18+ hours to fully cure before you attempt to move it

I'm so frustated, this is my first 3d printer and everything was going well.

Lol, you only JUST started. Trust me, everything is not going well. You'll find plenty of other issues with your printer before you're able to print something big!

In all honesty, I was lucky - my boss bought me a Makerbot Replicator to play with. Since it was pre-assembled, I was able to spend weeks messing around and learning how to print with a working machine. Building one yourself means you not only have problems with how the plastic behaves, but also any problems you have with your build. Sometimes you will suspect it's a configuration issue when in reality something is sticking or too tight/loose.

It will be a love-hate relationship.

[Eaglezsoar]

Well said, cassetti.

[Tincho85]

I've just purchased another Hot End kit, a peek, thermistors, resistors and also two 40w cartridge heaters just to be covered. The Kapton tape is arriving this week, or maybe the next. Here in Argentina it doesn't exist.

I was very careful with the tinfoil, also with the wiring. I double checked those connections. My guess is that the thermistor was not working, because the Repetier-Host never showed the temperature increasing. And about the smoke... yes, I've seen some 3d printers working, and I know they shouldn't do that, that's why I film it. But I thought it was a onetime only thing, like part of the calibration process... now that I read what I was thinking atm, it seems wrong, I know =/


Thanks for all the help guys, I already appreciate this community.
Martin


EDIT:
What do you think of this thermistor?
http://www.ebay.com/itm/Modular-Screw-o ... 33873faca2

It's from this vid:
[youtube]http://www.youtube.com/watch?v=xvXKt3xDt4E[/youtube]

[geneb]

*coughs* I like that thermistor.



(FYI, use _one_ and _only_ one heater cartridge in the hot end. )

g.

[Tincho85]

Nooooo, I've just realized this:

It's my curse for living on the other side of the world.


Someone knows an alternative place to buy it?

Yup g., bought 2 just to have a spare one

[dpmacri]

*coughs* I like that thermistor.



(FYI, use _one_ and _only_ one heater cartridge in the hot end. )

g.

Gene, in your video you say to use a #32 drill bit. Is that because it's easier to come by than a 3mm or are you intentionally using a drill bit slightly smaller than 3mm?

[geneb]

A #32 bit is used in order to leave enough meat to take threads. I chose that size based on a poster-sized threading/tapping chart I have.

g.

[dpmacri]

A #32 bit is used in order to leave enough meat to take threads. I chose that size based on a poster-sized threading/tapping chart I have.

g.

Cool, thanks!

[626Pilot]

In all honesty, I was lucky - my boss bought me a Makerbot Replicator to play with. Since it was pre-assembled, I was able to spend weeks messing around and learning how to print with a working machine. Building one yourself means you not only have problems with how the plastic behaves, but also any problems you have with your build. Sometimes you will suspect it's a configuration issue when in reality something is sticking or too tight/loose.

It will be a love-hate relationship.

On the plus side, building your printer forces you to learn lots of things you wouldn't if you got a preassembled printer. If you want to do more than occasionally print weird vases, and if you have the time and patience, it's the way to go.

You only need one cartridge, you can use the other hole to warm up your salami or whatever.

Damn near squirted root beer out of my nostrils.

[Broose]

My guess is that the thermistor was not working, because the Repetier-Host never showed the temperature increasing.

I would agree that is a good possibility or the thermistor did not have a good thermal connection to the hot end. My thermistor worked its way out of the hole and I ended up melting the PEEK on my hot end.

[Jimustanguitar]

*coughs* I like that thermistor.

Oh wow, the guy in that video has a Rostock too. I hope he put it together right

[geneb]

No chance. He's a total idiot.

g.

[Lochemage]

awww, no fair!! Why does HE get to be an idiot?!