Hotend can no longer get to 235*

[mvansomeren]

I've got about 10 1/2 days of printing total printing time on my V2 so far and it has been peforming very well. Prints have been great!

I print ABS at 235* and up until the last few prints, the stock hotend has been able to get to that temp without any hesitation. However on the last few prints, it would top out at 231*. This of course would cause the print not to start until it got close to the 235* mark... So as a stop gap messure, I lowered the temp for the print to 230*. However, when I did that, now the Hotend would top out at about 228*.

I am planning to do an Auto PID tonight to see if that will correct the issue. I suspect that because lowering the print temp seemed to lower the max temp on the hotend as well. Hopefully that is it.

That said, it got me to start wondering about the heating resistors. What are the symptoms of the resistor going bad? Do they burn out and provide some physical evidence or do they just not produce as much heat? What is the life expectency of the resistors? Could it be only 10.5 days (252 hours)?

By the way, I use a Corsair modular 750W PSU so I don't thing that is the issue.

I do have a Promethus V2 that I haven't installed yet so I could always do that if it is the heating resistors.

Any opinion or experience would be appreciated.

[JFettig]

Set I and D to .5 and try heating up to 200, watch to see if it overshoots. If it follows perfect try going higher. Watch for overshoot

[Neptune]

I had a similiar issue happen when my Peek fan started to fail, replaced the fan, re calibrated the PID's (as you are going to do) and it works great now....this happened to me at 17days print time.

[mvansomeren]

Okay, good. I did replace my Peek fan but that was a 2 months ago. Anyway, hopefully calibrating the PIDs will take care of it.

[IMBoring25]

Check the Kapton wrap on your heater block. I've been losing extrusion partway through my last three attempts to print. It looks as though my Kapton was not only not covering the heater block effectively, but was billowing up and making a duct for the air from the PEEK fan.

[mvansomeren]

Update. I redid my PID calibrations and compared them to the original numbers I had written down...they certainly did change. That was a good sign - I figured, resistors are broken in now so an adjustment was probably necessary.

When I went to enter in the new numbers into the EEPROM, I discovered that the numbers in those fields weren't anything close to what I originally had entered when I built the printer. I mean, not even close! How could they change on their own? It must of changed a few prints ago, when I noticed the hotend suddenly having difficulty getting to temp. But I have no idea how it changed. Any insight from folks would be appreciated.

Now, I went ahead and updated those fields with the new numbers and sure enough, the hotend had no difficulty getting up to the 235* I had set so at least I know that it was just a configuration issue. But it shouldn't have changed, right?

[Neptune]

Do you use MatterControl? It updated about a month ago and the update could have gone a little sideways and defaulted your PIDS... Its a computer and if there is one thing I can tell you(being a Network Analyst) is that about the time you think that values are set in stone they will change on you.

[mvansomeren]

I changed them through MatterControl but I'm currently using Simplify3D. Now, last night it couldn't get up to temp again but I didn't have time to check the EEPROM settings to see if they changed again. If they didn't then I have to suspect that the heat resistors have weakened or perhaps one of them stopped working all together. If so, the the Prometheus will be replacing the stock hotend.

[K.E.N.]

Howdy, Names K.E.N., this is my initials/ first name, now hadn't read your whole article to notice about voltage, yep, that stuff, without it you do not get all the current ya need to keep the print head as hot as you want. So check the voltage if you can while the unit is running, and make absolutely sure that voltage is 11.8 vdc or more. Was my problem keeping the print head hot, I found that when the case of my V2 got warmed up, the voltage for the supply was dropping down to 10.8 vdc, not good for heating the print head to steady heat, unit acted like it jamming in the feed drive, just pla was not getting enough heat all the time and jammed up. Just so you know, well I like my 2 Rs Max V2's and both of them had the same problem until I replaced the power supplies with adjustable 12 volt dc power supplies, adjusted the voltage to 12.8 vdc and problems went away...... You can find them on Amazon, the units fit well in the lower section, need to add an extra fan on top of it, you will see why, and fix it to draft air from underneath, the supply has a in line switch on the power cord, so the switch on the deck can be used for a light or something, The supply is call (MegaWatt S-350-12), you can look it up that way, the output voltage can be set for about 9 to 16 volts, with 30 amps all day long, and 33 amp surge, the supply is actually designed for ham radio use and is super filtered, the price is not really bad either, about 65 with shipping, about 3 days to receive both times, so remember to order you a 80mm fan to set on top, some double sided tape should hold it well, and the power is right there. If this helped you, let me know. PS Make sure to mount the supply to the bottom with the case vents able to take air up from under the machine. Happy 3D printing!

[mvansomeren]

Well, voltage and current aren't isn't the problem. The PSU is a Corsair 750W which is a very robust power supply. It was the PID tuning. I redid it a second time and all is well. I think over time, the resistors don't put out as much heat...and will probably put out less as they get even older. That's my assumption anyway..

[Eaglezsoar]

Well, voltage and current aren't isn't the problem. The PSU is a Corsair 750W which is a very robust power supply. It was the PID tuning. I redid it a second time and all is well. I think over time, the resistors don't put out as much heat...and will probably put out less as they get even older. That's my assumption anyway..

Good job of getting your printer working again.

[bot]

I bet it is the connections where you crimped to the resistor leads. That is not a proper connection -- crimping to "solid core wire" (or a resistor lead, for that matter) is not technically a proper way of making a connection. Mine have roasted themselves twice now.

[Mac The Knife]

I bet it is the connections where you crimped to the resistor leads. That is not a proper connection -- crimping to "solid core wire" (or a resistor lead, for that matter) is not technically a proper way of making a connection. Mine have roasted themselves twice now.

Tell that to manufactures that have been using that method for decades to connect the heating elements in portable heaters, toasters, hairdryers etc.

[bot]

I would certainly love to. Send me along their contact info, would ya?

[K.E.N.]

I've got 2 each of the V2's, had gone through this problem with both machines with the stock PS, the power supplies need to be monitored, so you might want to set up a couple test points off the 12 rail, (+,-) and watch them once in a while if you are having print issues, you might not like what you see. If the voltage drops below 11.2 volts dc, you start loosing wattage enough to keep that print head hot enough for abs, you start cutting back on speed to compensate for the heat loss happening as the abs comes out of the extruder, anyways that's what I did for a while, found a great fix if you are interested, a power supply that is 15% adjustable so you can set it to what you need. Your heat times can be improved greatly, as I said I have 2 V2's and they quit giving heat problems from power related issues. Go to Amazon, type in MegaWatt S-350-12, cost was 63.49 which get you that 12vdc at 30 amps very stable power supply, which is used for ham radios normally, fits in the area of the old power supply, would add a second fan on the top of this power supply, and fix it to draft up, pulling air from under the printer. Talked with the makers of the RAMBo processor, the extra voltage you can get is not an issue from this power supply. I am running at 12.8 volts, the RAMBo is designed to handle twice the voltage we are using from the stock power supply. Just a little math to help things along here. You have a print head with 2 resistors 6.8 ohms in parallel or to say 3.4 ohms. At 11.2v divide by 3.4 ohms you get 3.294 amps, now take 11.2v multiply by 3.294 gives you 36.89 watts. Now ideal is 12.0v divide by 3.4 ohms which is 3.529 amps, for watts take 12v multiply by 3.529 amps you get 42.348 watts , now you should understand that 40 watts for heat is needed to run normally at 100% print speed at the print head to keep optimal abs heat out of the extruder 100% of the time. This is were the fun part is, again, 12.8v divide by 3.4 ohms = 3.764 amps, now 12.8v multiply by 3.764 amps = 48.179 watts, which will maintain the print head extruder heat at all times and will allow you to exceed print speeds of 100% if desired or needed. So making it clear, the S-350-12 can be adjusted to what you desire, up to 16 volts, but I wouldn't go there myself, 16.v/3.4 ohm = 4.7amps, 16v x 4.7amps = 75.2 watts. I like to save the resistors in the extruder, but get the heat I need, so I keep it under 50 watts. The extra voltage also effects the hot plate current draw, so keep that voltage under 13v is a good idea, had not checked the current draw on it but I do not want to exceed the 20 amp protection fuse on it anyway. PS, I run my printers at this time 24/7 since I got the new power supplies about 2 weeks ago.