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baseball43v3r

UM original, print head temp drops.

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Hey all, I have an unusual problem that started this morning. I've tried to print several objects and each time after the first layer, the temp (or temp controller) will drop off but the temp seems to stay constant as the machine still prints. At least I think its constant as its reporting a temperature that should be too low for the printer to adequately print yet on my last part I printed which took 7 minutes it came out just fine, previous ones I didn't have as much luck as they were longer. I've tried tests so far with different parts, and also quickprinting in Cura and I get the same results each time. I looked through the gcode and I don't see any lines indicating a temperature change.

Specs

Ultimaker Original with ulticontroller

e3d printhead with e3d hotend and thermistor

Updated marlin firmware

Octiprint interface with raspberry pi

Gizmodorks filament

a timelapse of my print, heats up normally, and then after the first layer the print temp drops into the 180's for the rest of the print until the command to shutdown.

temp%20fluctuation.JPG

If i set the print to heat up to temperature this is the graph

temp%20fluc%202.JPG

If I turn on the fan with the print temp this is the graph, seems consistent to me, not sure what the problem is

temp%20fluc%203.JPG

 

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Yes, I stopped the print where it was and just moved it on x/y to to do the fan test.

Bed is not heated, printing PLA.

I did not retune the PID, do you have a link on doing that? I assumed it didn't need a retune because it's pretty consistent showing the 220 in my tests above.

my heater is 24v. I assumed it wouldn't be a problem on a 19v system, I just figured it would take longer to heat up.

 

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The "load" on the hotend impacts the PID loop's ability to maintain the temp as does the hotend design.

http://reprap.org/wiki/PID_Tuning

The other issue might be that the 24V heater may not generate enough heat at 19V for your configuration. You would see this as a solid, always on LED for the heater when the temp drops.

Check all heater connections to make sure you aren't losing power in a bad connection. This will show up as heat in the connection which can destroy the connector or worse....

 

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In your first graph you can see the *goal temp* is consistently at something around 220C. So there was no need to look at the gcode. The display on the UMO also shows two temperatures: actual, and goal.

I'm pretty sure the actual temp is showing correctly. I have printed many things at 180C. Especially the higher quality filaments. But you have to print a bit slower.

Anyway something is seriously wrong with your PID values. A quick fix would be to adjust them by the amount of wattage change for your heater. So for example a heater designed to work at 24V and 30W will put out 30*(19/24)^2 or 18.8 watts at 19V. I don't know what the wattage is for the original UM. I would then divide all the PID values by the ratio of the new heater divided. So for example if UMO is 40W (I'm not sure) and new heater is 20W then double the 3 PID values. This is just to get close. Then I would try to auto tune. Take your time - do maybe 10 cycles.

Read about M301, M303, M500, M503 on this web page:

http://reprap.org/wiki/G-code#M301:_Set_PID_parameters

Use M503 to read back current PID values. Make sure to save your new values before you turn off the printer with M500. Also write down the original values in case the new values are bad.

Also your PID may actually be just fine. Consider that maybe the fan is blowing on the heater now. Maybe you need to insulate your e3d a bit from the wind using some kapton tape. Or maybe angle the fan down just below the tip of the nozzle and keep the wind off the rest.

 

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Maybe you got a nice flat temperature graph (3rd and last graph) because earlier the fan was blowing off the bed or the part and wind was bouncing back up onto the e3d and in 3rd graph your bed may have been out of the way.

 

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So I've done a little testing and I'm not sure where to go. I measured the amp of the heater off the ultimaker board, and it was about 1 amp, multiplied by 19 volts gives me around 19 watts (I rounded to 20 to make my math easier). My heater from e3d is a 40 watt heater, so I ran the PID auto tune and cut those values in half and tried that, still no luck. Then did autotune again and used those values, still no luck. Also tried the values not cut in half. The terminal says the values are saved.

I tried a little more testing, I extruded 100 mm of filament close to the bed with the fan on and off, the biggest temperature drop I got was 3 degrees, not nearly the 30 I am getting while printing. I'm wondering if it's the board at this point? Is there any way I can use an external PID controller with the board? or is that too hacky?

 

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I noticed in my last round of testing it is now hovering in the 190 range instead of the 180 so that's progress. I don't know enough about math to know how the PID equation affects the heater, so does anyone know which of the values affects the expected temp drop or bringing it back up to level, ie which one in which direction I should play around with?

 

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Also, are you sure the heater isn't "full on" indicated by a solid light on the shield. Place the printer on a shiny surface and dim the lights, you should see the LED pulsing if it isn't "full on". If it is "full on" and the temp isn't at the set point, no amount of PID tuning will fix it.

 

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I did use the the Marlin PID tuner like you linked. I don't think the problem is not pulling enough power, I switched heater cartridges and retuned the PID for the original ultimaker heater cartridge and I'm still getting the same error, so I think I have a problem with my board somewhere. I tried unplugging the external fan on the heater and still no dice, and thats the only other new thing I have on there. So I'm not sure :?: :roll:

 

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A little update... Still think I'm not pulling enough power from my power supply. tried the new heater with the same setup, but this time disabled the fan after the first layer, and the temp seems to be holding steady. So it looks like I'm simply not getting enough power to the machine. I'll look for another power supply that gives more amps at 19v but does anyone think that will fix the problem, or is the board regulated by how many amps it can take in?

 

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