Extruder Heater Problem

Hi Vicious your site has improved a whole lot since my purchase of My MPCNC from you. The organization and working links are great
I had purchase one of your mk8 extrude heads and it performed great until just recently. The .04 original nose became loose and some pla was leaking from it and from the heater block under the tape insulation I was able to clear the goo with a dry Q tip and lots of patience while hot I also tighten the nosel and the body of the heater to the threaded heater break. After that repair/cleanup I have been unable to heat the extruder how do you suggest I test the connections or what thoughts do you have so i may repair my mk8 Thank you for your time.

Did you tighten it up while powered? If so you might want to check your heater cartridge wires with a multimeter, may have shorted it while tightening.

Barry is right, make sure to tighten it while hot, but don’t use pliers on the side with wires.

The other thing some people get wrong is, you want to tighten the nozzle to the throat, not the actual heater block. So if your nozzle is threaded all the way into the block it probably isn’t tight enough. It should look like there is a washer missing at the nozzle. Does that make sense? I took the wraps off a new nozzle so hopefully you can see what I mean in the picture.

Thank you Barry and vicous1 for your reply i have cleared the nozzel from the wrap tape and the remaining ozed pla the nozzel seems to look just as you show in your picture the spacing is about the with of an exact o knife opposite to the cutting edge IE the back of the blade. I tested the heater block for continuity and it does have continuity. I continued by checking the heater sensor ie the white wire item they do not have continuity on its leads. Is this last one supposed to have continuity?. any thoughts on how to repair if possible?

I tested the resistance of a new one, your numbers won’t be the same but close.
thermistor, at room temp 94kohm
heater, 4ohm

If you’re heater doesn’t have a resistance, that is the problem see if you twisted the wires.

Hi Guys I have tested the resistance of both the heater element and the thermistor reading 84 ohms and 4.4 Ohms respectively
is there a way to bypass the safety features on the extruder just to test if the temperature wire is working. while reading the Arduino code I noticed that if the thermistor does not register at least 5 degrees the extruder would not work to prevent a wiring problem cause a fire.

Not sure What you are asking. If you plug the thermistor into the ramps stack if it shows the right temp you are okay (room temp is about 25C), as for the heater you can give it 12v directly for a few seconds and see if it gets warm, if not no go. You could have a mosfet issue though they usually screw up in the on position, meaning always adding heat, or maybe a poly fuse blew and you are getting no power.

You can check the ramps board with your multimeter, see if you are getting the LED and 12v out of the heater port when you turn it on in the software.

I continue to work thru the extruder issues what voltage would you use on the stepper for the extruder I noticed it was running very hot to the touch and I lowered the voltage to .70 seems that its now too low as it refuses to work now how high would you consider prudent. also on an unrelated matter what is the white material that surrounds the heater block called along with the orange tape. Do you sell replacements?

Lets start fresh, what exactly is happening and how are you trying to make it happen?