[sudo-discuss] 3D Printer - needs new heating element

[Jake]

I retract my assertion that you hadn't put any text in your email.

as for the printer, it seems clear that you and steve are right that the 
resistor is burned out.  I wonder what caused this - i haven't heard of it 
happening a lot but miloh would know.

perhaps our machine has a bad solder joint on the transistor that turns 
the heating element on and off, and it got left on somehow?  I remember a 
while ago (before the element was replaced i think) that the temperature 
was not very well controlled.  surely there's an explanation somewhere.

There are PID values programmed into the heater controller, sent as G-code 
to the machine, which may be having an effect on the way the heater is 
controlled.  That would be a software explanation.  We should try to get 
more info about what the correct PID init string should be for our 
machine.

that init string lives in the config for the slicer, as it is inserted at 
the beginning of any gcode generated.

I expect miloh will help us replace the heating element, which is made of 
aluminum, a resistor, and some sort of heat-conducting glue i believe. 
The design is open-hardware so we should be able to find out the part 
number of the resistor and the type of glue if we want to replace it.

We should add an LED to the heater connector so we can see if it gets left 
on somehow.  Actually that is one possible explanation - since the machine 
has no timeout function for the heating element, anytime a print is 
aborted before the G-code is completely executed the heater will be left 
on.  It's supposed to be thermostatically controlled so it shouldn't 
overheat, but it will still cook the PLA inside the head into a hard resin 
that clogs everything up, if not burn out the resistor eventually.

-jake

P.S. Hol I read the discuss list on the web rather than letting it into my 
inbox, so i click on messages to read them.  Yours looks like this:

http://lists.sudoroom.org/pipermail/sudo-discuss/2013-October/004279.html

there is no content there, although there is an HTML attachment which I 
didn't click on because usually there is nothing in it, and if there is 
the formatting is so bad it's pretty hard to read.

On Sat, 2 Nov 2013, Hol Gaskill wrote:

> jake you forgot to read at all - this is what showed up in my inbox:
> 
> "Hi Folks,
>  
> The 3D printer needs a new heating element.  Steve and I got everything fired up and ready to start singing dubstep, and then had to do a little probing to reveal the cause.  Whoever knows what
> kind to get, can you PM me a link to the specific model required?  I'll go ahead and order a new one, or a few if they're cheap.
>  
> Thanks,
> Hol
> "
>  
> steve covered it - it's the heating element
>  
> cheers,
> hol
>  
>  
> on Nov 01, 2013, Jake <jake at spaz.org> wrote:
>       Hol,
>
>       you forgot to put any text in your post at all! please be clear of how
>       you came to this conclusion.
>
>       The heating element is a resistor glued into a block of metal on the end
>       of the extruder. It has two wires which go to a connector a couple inches
>       from it, and they go back to the machine.
>
>       To test the heating element, one can unplug this connector and use a
>       multimeter to measure its resistance. It should be something like 8 ohms,
>       i don't know the exact value but 100 is too much and indicates it's bad.
>
>       it was replaced a little while ago by a technician from the corporation
>       that made it.
>
>       If the machine is acting up about heating, we need to know whether the
>       problem is with the heating or the temperature sensing. If the
>       temperature sensor is reporting ambient temperature, it's probably
>       working.
>
>       if the temp sensor is working but the heating element isn't making it heat
>       up, it could be the heating element (see test above) or it could be the
>       connector near it, or the wires from there back to the main board, or
>       where those wires connect to the brain.
>
>       can you give more information about what you tried and what you observed?
>
>       -jake
> 
>  
> 
>