1 Topic by carl_m1968 (edited by carl_m1968 2015-08-13 02:24:42)

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Topic: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

I have been seeing a rash of threads such as "My printer stopped after cleaning", My printer won't connect after cleaning", and the list goes on.

I have never seen this mentioned in a manual so I thought I would throw it out here. Most of us use a brass brush now to clean our nozzles. Some machines even include the brush. Of course we know this brush will only work while the nozzle is hot. So here is the problem. If you have the nozzle running then you have 12 or 24 volts depending on your model going to the heater. On most heaters with the ceramic core, the most common type the wires going into the unit have a gap in the insulation near it's body.

This gap is big enough for the brush to go through and being conductive puts a direct short across 12 or 24 volts.

Depending on your model this could simply blow a fuse on the controller. Could blow one or more zero ohm resistors on the controller, or could even take out your power supply. The later is less likely but possible.

People if you want your machine to continue running with limited down time, use the brush but turn off the heater and use it while the nozzle is still hot. Once the heater is off the nozzle will remain hot enough for cleaning for a good 5 to 10 minutes.

Please people DO NOT USE THE BRASS BRUSHES ON A NOZZLE THAT IS HEATING. Only use the brush during cool down when no power is applied to the heater.

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2 Reply by wardjr

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

Well stated, I am confused as to why everyone suddenly is busy cleaning their nozzles.  I rarely have to clean my nozzles and then I use a round nylon brush like the ones used to clean paint guns.  Even then there isn't any mess up around the area of the heat cartridge or thermistor.  So I have to ask, what are people doing to get filament way up there in the first place?

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3 Reply by carl_m1968

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

Must be a new fad, guess we missed that memo..

Printing since 2009 and still love it!
Anycubic 4MAX best $225 ever invested.
Voxelabs Proxima SLA. 6 inch 2k Mono LCD.
Anycubic Predator, massive Delta machine. 450 x 370 print envelope.

4 Reply by grob

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

The bits of anchor/skirt that don't adhere to the bed (especially when tuning/adjusting its height) sometimes get kicked up at the start of the print and hit the heat block. I have a few stripes on the block from that. Figure as long as they're not on fire probably best to leave them be haha.

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5 Reply by eduardogarcia3049

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

Maybe something similar to this is how i completely fried my board. Not cleaning it, but touched the thermocouple screw with the Allen key. Would that short it out?

6 Reply by Stoney

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

carl_m1968 wrote:

People if you want your machine to continue running with limited down time, use the brush but turn off the heater and use it while the nozzle is still hot. Once the heater is off the nozzle will remain hot enough for cleaning for a good 5 to 10 minutes.

Please people DO NOT USE THE BRASS BRUSHES ON A NOZZLE THAT IS HEATING. Only use the brush during cool down when no power is applied to the heater.

Just an additional note ..
the heater always has 12V present so long as the power supply is on, so even with the heater off one must take care not to allow anything earthed to touch the wires. So if you has some sort of brass brush that also contacted chassis or a grounded part of the heater, sparks could still fly.

7 Reply by josh.aeauto

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

Stoney wrote:

Just an additional note ..
the heater always has 12V present so long as the power supply is on, so even with the heater off one must take care not to allow anything earthed to touch the wires. So if you has some sort of brass brush that also contacted chassis or a grounded part of the heater, sparks could still fly.

This seems really impractical. The way electricity works, if 12v is supplied constantly at the heater, then the heater would always be hot. If voltage was constantly present, the only way to regulate it then would be to regulate the current, and that's not possible since current is a direct relationship between voltage (12v), and resistance (3-8ohms). Current regulation is common, but not on something that has to cut completely off. If voltage is supplied, there will be heat.

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8 Reply by wardjr

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

I don't know the specifics here, but I think what he's saying is that the negative or ground is what's being switched.  This would leave the positive pin live and therefor shorting that pin back to ground in any way would cause a direct short.

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9 Reply by josh.aeauto

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

wardjr wrote:

I don't know the specifics here, but I think what he's saying is that the negative or ground is what's being switched.  This would leave the positive pin live and therefor shorting that pin back to ground in any way would cause a direct short.

My bad then, I misunderstood!

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10 Reply by heartless (edited by heartless 2015-09-11 17:52:15)

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

Cant say I have ever thought about using a brass brush for cleaning the outside of the nozzle... and what printers come with one?

SD ships a a basic toothbrush with their name on it with their printers... I have 2 of them. On the rare occasion I have felt the need to "clean", a quick wipe or two of the nylon bristle toothbrush over a hot nozzle works fine.

The only other time i needed to clean was after a major print malfunction that caused a spaghetti mess - had plastic all over the heater block & the nozzle... sad

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11 Reply by carl_m1968

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

The XYZ Da Vinci ships with a brass brush and was my main reason for making this thread.

The heater core has exposed wires and if you clean with that brush while energized it will short and blow the zero ohm resistors on the main board that feed the heater circuit.

Printing since 2009 and still love it!
Anycubic 4MAX best $225 ever invested.
Voxelabs Proxima SLA. 6 inch 2k Mono LCD.
Anycubic Predator, massive Delta machine. 450 x 370 print envelope.

12 Reply by carl_m1968

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

Stoney wrote:
carl_m1968 wrote:

People if you want your machine to continue running with limited down time, use the brush but turn off the heater and use it while the nozzle is still hot. Once the heater is off the nozzle will remain hot enough for cleaning for a good 5 to 10 minutes.

Please people DO NOT USE THE BRASS BRUSHES ON A NOZZLE THAT IS HEATING. Only use the brush during cool down when no power is applied to the heater.

Just an additional note ..
the heater always has 12V present so long as the power supply is on, so even with the heater off one must take care not to allow anything earthed to touch the wires. So if you has some sort of brass brush that also contacted chassis or a grounded part of the heater, sparks could still fly.


This thread was made in response to an issue with XYZ brand printers. I know others switch the grounds so you will always have 12 volts at point in respect to frame or PSU ground. However XYZ switches power on all of their outputs. So if the circuit is off there is no power on any of the heaters or fans.

Printing since 2009 and still love it!
Anycubic 4MAX best $225 ever invested.
Voxelabs Proxima SLA. 6 inch 2k Mono LCD.
Anycubic Predator, massive Delta machine. 450 x 370 print envelope.

13 Reply by carl_m1968

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

josh.aeauto wrote:
Stoney wrote:

Just an additional note ..
the heater always has 12V present so long as the power supply is on, so even with the heater off one must take care not to allow anything earthed to touch the wires. So if you has some sort of brass brush that also contacted chassis or a grounded part of the heater, sparks could still fly.

This seems really impractical. The way electricity works, if 12v is supplied constantly at the heater, then the heater would always be hot. If voltage was constantly present, the only way to regulate it then would be to regulate the current, and that's not possible since current is a direct relationship between voltage (12v), and resistance (3-8ohms). Current regulation is common, but not on something that has to cut completely off. If voltage is supplied, there will be heat.


What happens in most printers, they use a mosfet to switch the ground for a certain circuit off and on. It is a common practice even beyond printers.

What happens however is you can go out and measure 12 or 24 volts on one side of the circuit if you use frame ground or PSU ground as a reference. Like was if you where to short the side of the circuit not receiving the power to frame or PSU ground it would actually come on and heat or run.

So in the case of the heater core in this setup, both sides of the core would show having power if you ground your meter to the frame or PSU ground. The circuit however will not operate till ground is connected via the mosfet thus allowing current to flow. Remember it is not voltage that makes a circuit work, but current.

Printing since 2009 and still love it!
Anycubic 4MAX best $225 ever invested.
Voxelabs Proxima SLA. 6 inch 2k Mono LCD.
Anycubic Predator, massive Delta machine. 450 x 370 print envelope.

14 Reply by heartless

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

carl_m1968 wrote:

The XYZ Da Vinci ships with a brass brush and was my main reason for making this thread.

The heater core has exposed wires and if you clean with that brush while energized it will short and blow the zero ohm resistors on the main board that feed the heater circuit.

Ah, i see... maybe DaVinci should switch to nylon bristle toothbrushes? lol

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15 Reply by Stoney

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Re: PSA TO ALL PRINTER OWNERS TO AVOID DAMAGE DUE TO CLEANING!!!

I must admit to be considering a small wire bristle brush mounted just off the side of the build plate. I do not want to mash the nozzle into it, just wipe the bottom mm or so in the start G-code just to get off any dags.
Modded my gcode yesterday to sit the nozzle on the glass while preheating, seems to work well, although the cooling after a print causes a small dag that then gets mashed up the side during the heating phase.
I thought nylon would perhaps melt or deform over time, but if it works ok then I will try it first.

Did not realise about the XYZ printers, my bad.
I did fact check using the sanguinololu schematic before i posted.
http://www.reprap.org/mediawiki/index.p … p;limit=50

As you can see, both the hotbed and hotend are always powered with 12v.