DOH!

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GrueMaster
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3D Printer(s): Hictop 3DP-17, Hictop CR-10S

DOH!

Post by GrueMaster » March 31st, 2017, 11:37 pm

So, I had my 3DP-17 dialed in, everything worked well and most of my prints were awesome (including a skull I had scaled down to ~2cm - very nicely detailed even that small). Running the Marlin 1.1.0-RC8 with some of my own tweaks (still fine tuning a few things), and Cura 2.4 (need to update a few tools so I can build Cura 2.5 - I'm a Linux guy).

Started a print Wed night (~3cm^3 tooth), woke up Thursday to a white PLA blob below the print head and the head completely encased in PLA (see photo). Quickly disassembled the print head assembly from the main carriage and put it in a mason jar with enough acetone to cover it (was able to remove the thermistor and heating element first), then headed off to work.

Came home after a very long day, started cleaning the mess off the extruder. Discovered that the extruder tip was still very clogged and the throat was charred. Good thing I ordered a 5 pack of each. Reassembled the extruder and throat to the heater block, went to assemble the heater and thermistor, shattered the thermistor with the set screw.

So, now I wait for a replacement thermistor. Ordered a 5 pack (just in case).
Attachments
bad_tooth.jpg

shocksofmighty
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Re: DOH!

Post by shocksofmighty » April 1st, 2017, 8:56 am

Haven't had this happen on my Hictop, but it has happened plenty of times on my FFCP. Instead of removing the print head, just heat it up manually and slowly pry away the excess PLA. Because it heats locally around the hotend first you can usually pull it off in a single piece. Also, acetone will soften PLA but won't dissolve it. If you want to dissolve PLA use chloroform.

GrueMaster
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Re: DOH!

Post by GrueMaster » April 1st, 2017, 11:47 am

If only it was that simple. By encased, I mean it looked like I was looking at a block of ice. I know about acetone vs chloroform, I just don't know where to get chloroform where I live. Amazon, I guess.

This isn't the first time this happened. I did it once before I had everything tuned in and had black PLA all over the head, but not as bad. Then, when I was doing the temp calibration (square tube, temp change every 1cm), the printer crashed as it wasn't able to maintain temp (blower was blowing directly on the hot end, not the part - fixed now), I accidentally hit down instead of up on the Z axis, driving the hot end through the wall of the cube. Another cleanup job to do.

I am getting quite good at cleaning up messes now. Practice makes perfect? :P

GrueMaster
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Re: DOH!

Post by GrueMaster » April 9th, 2017, 2:09 am

Ugh. Not sure what is going on now.

Replaced the extruder assembly, now I am getting filament jams. Weird ones. Had to throw one throat away because the Teflon sleeve actually melted to the PLA. Now I have another that is doing something similar after heating up and extruding some material. This is the brass tip after cooling down and removing.
extruder clog.jpg
The filament broke trying to pull it out (used the stepper to reverse it out first, then released tension and pulled).

Not sure what is going on here. Been down all week trying to get it back online.

Update: Here is what the filament looks like after disassembling the throat. This was pushed hard against the Teflon sleeve.
Sleeve-clog.jpg

GrueMaster
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Re: DOH!

Post by GrueMaster » April 10th, 2017, 12:33 am

Ok, I think I have this resolved. Thermistor wires were melted due to the previous PLA blob (top post). Fortunately, I ordered a 5 pack. Replaced it, cleaned the rest of the goo from the hot end wires, replaced the heat block, tip, and throat, everything seems ok now (well, at least it is extruding again without clogging). Bed adhesion issues are next. Going to try this mod I found on thingiverse for the auto-level to make life easier. I hate spending 20 minutes readjusting the auto-level sensor everytime I drop the extruder from the unit.

GrueMaster
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Re: DOH!

Post by GrueMaster » April 17th, 2017, 1:29 am

Well, ~12 decent prints later, and now my system is dead. I smelled hot electronics ~3 hours into a 14 hour print, ran into the room the printer is in, and it went lifeless except for the LCD a few seconds later. The hot end reported a temp of 216C (I had it set for 205C for PLA). Cura was showing an error from he printer, and the power supply had gone into standby. I quickly unplugged everything, then did a smell check to pin point the area. Control board chassis.

I spun the printer 180 and removed the cover to find the power switch had gone slightly molten.
printer switch.jpg
Being the hacker/tinkerer type (and since it was Easter Sunday), I went to an autoparts store, bought some 14 guage wire, found a replacement switch, along with an inline fuse holder, and did some rewiring. I tested the power supply output to make sure it was good and the wiring was sound (all connections soldered with heatshrink tubing), and connected to the controller. Nothing. Board wouldn't power up, just flickered an LED and the LCD flashed. Tested the power, 3.5V coming in. I powered down, removed the power leads and checked the PS again, still 24V. When connected to the controller, low power. I'm thinking the VRM went out as well. So now I am down again. Sent an email to Hictop, time to test the one part no one wants to test; warranty service.

Sigh.

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Roberts_Clif
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Re: DOH!

Post by Roberts_Clif » April 17th, 2017, 9:59 am

GrueMaster wrote:Well, ~12 decent prints later, and now my system is dead. I smelled hot electronics ~3 hours into a 14 hour print, ran into the room the printer is in, and it went lifeless except for the LCD a few seconds later. The hot end reported a temp of 216C (I had it set for 205C for PLA). Cura was showing an error from he printer, and the power supply had gone into standby. I quickly unplugged everything, then did a smell check to pin point the area. Control board chassis.

I spun the printer 180 and removed the cover to find the power switch had gone slightly molten. printer switch.jpg

Being the hacker/tinkerer type (and since it was Easter Sunday), I went to an autoparts store, bought some 14 guage wire, found a replacement switch, along with an inline fuse holder, and did some rewiring. I tested the power supply output to make sure it was good and the wiring was sound (all connections soldered with heatshrink tubing), and connected to the controller. Nothing. Board wouldn't power up, just flickered an LED and the LCD flashed. Tested the power, 3.5V coming in. I powered down, removed the power leads and checked the PS again, still 24V. When connected to the controller, low power. I'm thinking the VRM went out as well. So now I am down again. Sent an email to Hictop, time to test the one part no one wants to test; warranty service.

Sigh.
Added Heat-sinks and insulators to anything I felt was getting hot.
No guarantee this will stop a meltdown, It gave me more assurance not having a meltdown.

Like the old saying where there is smoke there is fire.


Heatsinksjpg.jpg
Electronics Technician / Computer Programmer

GrueMaster
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Re: DOH!

Post by GrueMaster » April 19th, 2017, 2:27 am

Replacement board and power switch are being sent from the factory. In the mean time, I have a new board coming from Amazon tomorrow. One thing I am curious about, the heated bed is rated at 250W/24V. Simple math says this is 10.41 amps, over the 10A rating for the switch. I haven't had a chance to do a full check on what the power load is, but I am really surprised that there is no overload protection.

Of course, Murphy's Laws of hardware (specifically #4) acknowledges that the mainboard would have blown to protect the fuse anyway.

rcabor
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Re: DOH!

Post by rcabor » April 19th, 2017, 8:27 am

That switch should be installed on the input to the power supply(120VAC). It will see way less than 10 amps at full power supply output.
GrueMaster wrote:Replacement board and power switch are being sent from the factory. In the mean time, I have a new board coming from Amazon tomorrow. One thing I am curious about, the heated bed is rated at 250W/24V. Simple math says this is 10.41 amps, over the 10A rating for the switch. I haven't had a chance to do a full check on what the power load is, but I am really surprised that there is no overload protection.

Of course, Murphy's Laws of hardware (specifically #4) acknowledges that the mainboard would have blown to protect the fuse anyway.

GrueMaster
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Re: DOH!

Post by GrueMaster » April 22nd, 2017, 2:01 am

Well, this week has been fun (not). Backup board (from Amazon) came Wednesday. I removed the original board and just applied power to the new board. Nothing. Thought the PS had blown. Tested the PS, 24v at the PS when the switch was off. Switch on, 5v at the board. So, I ordered a new PS. It arrived today. Wired it up, same issue. Did a few more checks, then went to eat (and sulk). Just came back to it and checked my wiring. I have the power to the switch going to one of the two outer connectors, and the center going to the board. Switch is lit by an LED.

For those of you that are familiar with DC electronics, you can understand and appreciate my facepalm moment here.

Essentially, the LED (Light Emitting Diode) is polarity sensitive. Wires backward, low power. :-o

I clipped the PS from the switch and (still through the fuse holder) went directly to the board (using the switch on my power strip to control everything). Works! Swapped power supplies and (yea, you know)...

This is why I do mostly software.

GrueMaster
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Re: DOH!

Post by GrueMaster » April 23rd, 2017, 8:54 pm

And ... down again. Seems I also blew out the 24v blower fan and the circuit for it. Fan doesn't work. Period. Original control board has the fan set to max power, no control (I tested with both a multimeter and the extruder fan). Warranty replacement board is stuck in China customs. Thankfully, I have Amazon Prime.

This has been a really frustrating week.

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jonnybischof
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Re: DOH!

Post by jonnybischof » April 25th, 2017, 4:01 am

rcabor wrote:That switch should be installed on the input to the power supply(120VAC). It will see way less than 10 amps at full power supply output.
...
When you realize that Reprap electronics are made by people with no understanding of electronics whatsoever... :-P


/edit:
Just to clarify:
That switch has a 10A AC rating (no need to see exact model, they all have an AC rating because these are AC power switches...). That is nowhere near a 10A DC rating, especially not at 24 V DC. Every time you flip that switch, there is a nice spark that burns the contacts and increases their electrical resistance a bit. And every time you flip it, it will get a little hotter because of that growing resistance...

/edit2:
Just solder the wires together with no switch. If you need one, you can put it into the AC power cable. If you're not comfortable messing with AC mains stuff, just get some cable / extension that already has a switch.
Best regards,
Jonny

GrueMaster
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Re: DOH!

Post by GrueMaster » April 25th, 2017, 11:30 pm

I already replaced the switch with a 24v 17a DC switch (same dimensions) from O'Reily Auto Parts. $2.85 US. The blower fan is now on order, will arrive tomorrow. If they fail again, I found Delta Electronics (a well known manufacturer in the electronics industry) has them on Digikey for $13ea. Better quality, better CFM, lower db rating. Worth the investment.

GrueMaster
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Re: DOH!

Post by GrueMaster » April 29th, 2017, 12:00 am

So, replacement board and switch finally arrived. The board is identical to the board I bought last week off Amazon, but different than the original. Either I was given a replacement from old stock, or this is a new rev. The key difference is the SD card slot on the bottom of the control board next to the USB port. It is marked MPK V1. The original is MPX .3. People with systems over a year old may know the difference. I'm guessing that it is from old stock.
20170428_203934.jpg
20170428_204111.jpg
Back of boards


The replacement switch is much bigger and beefier. Still an AC switch, but now rated 16A 250v or 20A 125V. Will look up the specs online shortly. I am concerned that they are using an AC switch for DC application. My Principle Engineer said that isn't good (at least on the original switch).
20170428_204630.jpg
Switch

kool65
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Re: DOH!

Post by kool65 » April 30th, 2017, 2:04 pm

I've discovered that having a good stock of spare parts works. Having had failures of the main board, the power supply, a stepper motor, several thermistors and whatever the extruder heating element is called, I realized that backups are a good idea. Hictop customer service has been superb, but there is still a delay in getting replacement parts. I have bought them at Amazon and now keep the service replacements as spares for the next fault.

I wouldn't bother cleaning the nozzle; they are something like $10 for 5 sets of extruder tubes and nozzles. The heater block they go in is also 5 for $10. Much easier to replace than to mess around with.

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