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Hot end stops extruding??

Posted by Bernie 
Hot end stops extruding??
June 22, 2019 11:07AM
I just completed a reprap cartesian style printer. Trying to print my first item. The test xyz cube from Thingiverse. The printer preheats fine. Bed just right and hot end so the tft screen says. I choose the cura sliced test print and the head/carriage goes through its pre print ritual. Even extruding a few mm of filament. The head then moves to the center of my heated bed and starts to print. It’s ok for 3-4 layers then the filament stops flowing and I end up stopping the print. It has done this exact same thing 3 times now. I have pulled the hot end each time making sure nothing is physically impeding the flow. The extruder is exceptional with a fine gear that grips the filament strongly enough to pop the tubing out of the compression connector at the cold end of the extruder when the filament stops flowing. I’m thinking it has to be cooling down for some reason unknown. It has an exchanger fan that turns on/off at 50c. It also has two side fans blowing through small funnels on the extruded filament when actually printing. The head says it’s maintaining 220c. The system is an MKS v1.3 32 bit with a tft screen, running Smoothieware. The primary power is a 24vdc supply split to heat the bed at 24vdc and goes through a buck boost to feed the MKS board at 12vdc. All steppers fans and hot end operate at the 12vdc. Hot end thermistor is accurate. I’m thinking either the fans are efficient enough to be cooling the head so the filament stops flowing(but the tft temp gauge says it’s maintaining at 220c) or the power/voltage is somehow an issue? Maybe even the configuration code is the issue? Attached is the website showing the printer design and electrical and mechanical components as well as the GitHub site location of the configuration file I’m running. I have 4 months in this build from scratch, parts sourcing and the like after work and on weekends. Any ideas?? THANKS IN ADVANCE.


Re: Hot end stops extruding??
June 23, 2019 07:14PM
I’ve been working at investigating my problem. Obviously different people have different ideas. One has suggested cooling is my problem. Not sure but will try no fans for a print effect if nothing else sounds better. One idea is to do a PID auto test before anything else. I like it not knowing if current settings are correct. I’m including the web site address for the Smoothieware config file I’m running. If anyone interested in helping cares to look at it. I really don’t know how to do this test. Maybe some help to write and or set it up would be great. Some have said upgrade my hot end to 24vdc. That’s fine but how can I switch on say a mosfet to run this new hot end with the terminals on my mks sbase 1.3 board running on and feeding the existing 12vdc hot end. Also the 12vdc has a PWM component controlling the hot end temperature. Any way here’s my existing code file source. The second site is the printer design. Thank You in advance. Config....[github.com] / Printer... [repalmakershop.com]
Re: Hot end stops extruding??
June 23, 2019 08:23PM
Ok..... as I keep finding out, I’m so behind the curve in 3D printer knowledge. I had a suggestion to change my hot end to 24vdc and do not power it through a buck boost device. Now my situation , yes has a 24vdc main power supply but I am only using the full voltage to power the heat bed. The buck boost knocks down the 24 to 12vdc witch then feed someone my mks sbase 1.3 board. It in turns powere my steppers, fans and hot end. Learning or actually reading specs I should have considered a long time ago. The mks board will run 12-24vdc. That being said if I were to run it/power it by the full 24vdc would it then portion out 24vdc to my fans or hot end? Should the steppers still operate as in voltage protected. Would the thermistor That would come with a new replacement hot end running at 24vdc still work within the. Infighting file? Would the whole config file need to be changed? Would my tft screen operate if the board were refer with 24volts instead of the 12 volts currently? Soooooo... many questions. Ideas?? Input? Thanks,,,,!!!!!
Re: Hot end stops extruding??
June 24, 2019 08:43AM
Thermistors and Stepper motors/drivers are no problem at 24V. The fans however will burn out and need to be replaced with 24V models, just like the hot end heater cartridge.
If the TFT has an own PSU connector you need to match that voltage. The common displays that connect directly to the board get their correct voltage from the controller board already.

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