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introducing myself

Posted by techristian 
introducing myself
November 15, 2016 09:50PM
I have programmed computers for over 35 years, designed 2 interfaces , one with a PIC CHIP and recently built a Reprap "kit".

I had been printing with my new printer for the past week when .........

Sunday night, after the printer was running for 3 hours I woke up to the smell of smoke. Apparently, the thermistor , which regulates the temperature of the extruder, malfunctioned. PLASTIC WAS BURNING....no flames but real stink. normally at 200c no smell with PLA but it must have been much warmer. I will be moving it out to the garage.

Actually, the thermistor came out of the hole on the extruder and stopped relaying the extruder temperature. The other side effect of this was that now my extruder nozzle is plugged up with burnt plastic.....and that is how I found this forum....looking for "Reprap parts in Detroit"

Anyway, my son-in-law who has built 4 CNC machines and a 3d printer himself, gave me another nozzle today....but I still want to fix the old nozzle with acetone...because the new one is longer and will require me to set up the Z axis limit all over again.....

I need to print these 10 boxes for my circuit boards in the next 2 weeks....so FUN !! That printer was a trip building too.....couldn't understand ENGRISH instructions but luckily the video got me there !!

Ok ...I get it. The thermistor came out of the extruder heater but......a few lines of Arduino code should fix this....if the temperature if the extruder is being polled every second or so, a line of code that says "IF TEMP changes suddenly....SHUT DOWN.

Dan

Edited 3 time(s). Last edit at 11/15/2016 10:04PM by techristian.
Re: introducing myself
November 15, 2016 11:20PM
Thermal runaway protection is baked into most modern firmware. It watches for situations where the thermistor is getting much colder than it should be, e.g. the heater is on but the temperature is staying too steady.

Of course, if you want real safety, install a hardware thermal fuse or a second thermistor.
Re: introducing myself
November 16, 2016 07:07AM
Acetone won't dissolve PLA. Look up "cold pull" and get a drill bit...


Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: introducing myself
November 16, 2016 10:20AM
...and welcome to the forum.

Yes, thermal run-away checks are on by default in most firmwares. Did you compile up your own or did the control board come pre-loaded?
Re: introducing myself
November 16, 2016 12:05PM
They gave me firmware on SDCARD and it was also pre-loaded on the controller. Since I'm on a deadline, I didn't want to play with firmware yet...and besides this, none of the software that was sent on that card worked. I don't know if CUSTOMS Xrayed it or what. I was lucky that most of the pdf instruction and video worked.

I have worked with PIC chips (only in machine language) ....and not the chips found on Arduino.

Dan
Re: introducing myself
November 16, 2016 10:54PM
Quote
the_digital_dentist
Acetone won't dissolve PLA. Look up "cold pull" and get a drill bit...

Well actually acetone and a hot torch and a wire. After a bit of sputtering up and running again....out in the garage...printing right now......not too cold yet....around 60 degrees today. I suppose the torch and wire did most of the work !

Dan

Edited 1 time(s). Last edit at 11/16/2016 10:56PM by techristian.
Re: introducing myself
November 20, 2016 06:30AM
Hi Dan,

Welcome. Thermistors and heater cartridges needs to be very securely fixed. These coming loose is a big fire risk. Make sure the screws are tightened and consider using Kapton tape to secure wires together.

Smoke alarms near the printer make sense. Thermal fuses help for heated beds, not easy to do for hot ends.


Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
Re: introducing myself
November 20, 2016 10:53PM
A real nice way to clean a nozzle is to place the nozzle in a stainless steel container dedicated to this purpose. Do not use your wife's pretty stainless steel dish and expect to live....this process will discolor the stainless steel. I use an ashtray I bought for $1.50 on eBay. I place the nozzle in the container 0n the bottom of a self cleaning over (rember to take out the racks). Turn to self cleaning and wait for the cycle to get done. Wallah...you have a clean nozzle and a clean oven.
Re: introducing myself
November 21, 2016 08:43PM
Quote
Lymphomaniac1
A real nice way to clean a nozzle is to place the nozzle in a stainless steel container dedicated to this purpose. Do not use your wife's pretty stainless steel dish and expect to live....this process will discolor the stainless steel. I use an ashtray I bought for $1.50 on eBay. I place the nozzle in the container 0n the bottom of a self cleaning over (rember to take out the racks). Turn to self cleaning and wait for the cycle to get done. Wallah...you have a clean nozzle and a clean oven.

And the next time your pizza tastes like plastic ??

BTW I printed my first box AFTER changing from .3mm to .4 mm WITHOUT RESLICING for the new hole size. I really didn't see a difference.

I have since made 6 boxes....4 more to go !

Dan
Re: introducing myself
November 21, 2016 08:43PM
Quote
Lymphomaniac1
A real nice way to clean a nozzle is to place the nozzle in a stainless steel container dedicated to this purpose. Do not use your wife's pretty stainless steel dish and expect to live....this process will discolor the stainless steel. I use an ashtray I bought for $1.50 on eBay. I place the nozzle in the container 0n the bottom of a self cleaning over (rember to take out the racks). Turn to self cleaning and wait for the cycle to get done. Wallah...you have a clean nozzle and a clean oven.

And the next time your pizza tastes like plastic ??

BTW I printed my first box AFTER changing from .3mm to .4 mm WITHOUT RESLICING for the new hole size. I really didn't see a difference.

I have since made 6 boxes....4 more to go !

Dan
Re: introducing myself
November 22, 2016 03:30AM
I've never even heard of a self cleaning oven.


Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions
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