Never reaches set temperature after dual nozzle upgrade

I have just started to print after upgrading to dual nozzle with the reprappro kit. Running firmware 1.04b-dc42 and zpl web gui 1.04.

My first print was a test piece i use for fine tune the nozzle height. The g-code file is the same as before the conversion of the printer.

When the print starts the temp is set to 220 and the printer starts to heat first nozzle/tool. The temp rises as fast as before to about 210 degrees. Then is slows down and settles at 215-216. Since the target temp is 220 the print never starts.

I made a copy of the g-code and manually edited the temp to 215. Started to print, same behavior as before, quickly heating up slowing down at about 208 but at 212 it started to print.

My first Idea was somthing that has to be clibrated due to the Duet shiled added to the mix. But since the measurement show too low temperature shouldn't the printer keep heating until the target temp is reached.

Then I thought it may be a bad connection, but both nozzle behaves almost the same and the quickly heat up to 210 degrees so the must be getting enough amps.

What could be the issue?

/Tomas

You may need a higher S or W parameter in your M305 commands. Run M305 H1 and M305 H2 to see what they are at present.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

M301 H1
Heater 1 P:10.00 I:0.100 D:100.00 T:0.40 S:1.00 W:180.0 B:30.0

M301 H2
Heater 2 P:10.00 I:0.100 D:100.00 T:0.40 S:1.00 W:180.0 B:30.0

M305 P1:
T:100000.0 B:4138.0 R:4700.0 L:0.0 H:0.0 X:3

M305 P2:
T:100000.0 B:4138.0 R:4700.0 L:0.0 H:0.0 X:2

Edited 1 time(s). Last edit at 04/03/2015 01:33AM by fotomas.

Sorry, brain fade, I meant M301 not M305.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

M301 H1
Heater 1 P:10.00 I:0.100 D:100.00 T:0.40 S:1.00 W:180.0 B:30.0

M301 H2
Heater 2 P:10.00 I:0.100 D:100.00 T:0.40 S:1.00 W:180.0 B:30.0

Tomas, you are using the default parameters, so it looks like either your heaters are a little less powerful than the ones that the default parameters are calibrated for or your power supply voltage is a little low. The easiest way to get faster heating is probably to increase either the S term (try 1.1) or the T term (try 0.5).

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I tested with S1.1 but with no apparent effect. So before going with higher values I measured the voltage at the probe. By inserting some bread board wires in the Z-Probes molex connectors I was able to measure the actual voltage going to the heater, under load.

The voltage was not terribly low but 11.46, so I adjusted the PSU under load to give 12.00 at the heater.

This had some effect so I stared testing diffrent M301 S-values. By having the voltage meter hooked up I could pretty clearly see the immediate effect of the different S values.

At 2.2 it over shot pretty much but interpolating back and forth I settled at S1.5. So now it reaches the desired temperature an stays there within a few tenths.

After reading about M301 command ath the G-Code wiki it is my understanding that the S parameter effects all other parameters as well. So nothing else has to be adjusted despite I have calibrated this when the extruder is idle and not being cooled by extrution.

Am I correct? Or should other parameters be adjusted too. An increase of 50% is pretty much,if you ask me....

/Tomas

Yes, and increase of 50% is a lot. What the S parameter does is to scale the output power, to take account of differing heater power without having to adjust the PIDT values.

Can you disconnect the heaters (with power off of course) and measure their resistance with a multimeter?

It could also be that the quickset nozzle (which I presume you have) has markedly different thermal characteristics from the original nozzle, and the PIDT values ought to be changed to suit it.

Edited 1 time(s). Last edit at 04/03/2015 05:35AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Measured the old heater and the new:

Old 3.7 Ω
New 4.7 Ω

The old heater, delivered with the Original Ormerod 2 kit and the newer heater included in the dual nozzle (quick set) upgrade kit.

Regarding thermal characteristics; to me it looks like there is thinner and less metal between the heater block and the cooling block. If there is a difference the quick set nozzle should cool slower than the original nozzle. What I think could have a much greater impact is the tolerance of the hole for the heater. A small screw pressing on the heater would not have hurt.

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Update:
After adding M310 S1.5, the last 5 degrees up to 220 are painfully slow. S1.5 does not seem to be the right or complete solution to this issue.

Edited 1 time(s). Last edit at 04/03/2015 07:26AM by fotomas.

Quote
fotomas
Measured the old heater and the new:

Old 3.7 Ω
New 4.7 Ω

The old heater, delivered with the Original Ormerod 2 kit and the newer heater included in the dual nozzle (quick set) upgrade kit.

Regarding thermal characteristics; to me it looks like there is thinner and less metal between the heater block and the cooling block. If there is a difference the quick set nozzle should cool slower than the original nozzle. What I think could have a much greater impact is the tolerance of the hole for the heater. A small screw pressing on the heater would not have hurt.

---

Update:
After adding M310 S1.5, the last 5 degrees up to 220 are painfully slow. S1.5 does not seem to be the right or complete solution to this issue.

So the new heaters are indeed less powerful than the old ones, and the ones I calibrated the default PID settings for (they were just over 3 ohms). I suggest you increase the T parameter to get those last 5 degrees faster.

Edited 1 time(s). Last edit at 04/03/2015 08:13AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42

Quote
fotomas
Measured the old heater and the new:

Old 3.7 Ω
New 4.7 Ω

The old heater, delivered with the Original Ormerod 2 kit and the newer heater included in the dual nozzle (quick set) upgrade kit.

Regarding thermal characteristics; to me it looks like there is thinner and less metal between the heater block and the cooling block. If there is a difference the quick set nozzle should cool slower than the original nozzle. What I think could have a much greater impact is the tolerance of the hole for the heater. A small screw pressing on the heater would not have hurt.

---

Update:
After adding M310 S1.5, the last 5 degrees up to 220 are painfully slow. S1.5 does not seem to be the right or complete solution to this issue.

So the new heaters are indeed less powerful than the old ones, and the ones I calibrated the default PID settings for (they were just over 3 ohms). I suggest you increase the T parameter to get those last 5 degrees faster.

Sounds like a few places are starting to supply 25 watt cartridges instead of 40 watt ones now I know E3D do and they are normally characterised by having blue wires on them rather than red ones.

Doug

One of the heaters I received from RRP a long time ago measured 2.8 ohms, which comes to about 50W. That's what prompted me to introduce the S parameter in the M305 command, because I needed an easier way to adjust to different heater powers or supply voltages than adjusting all of the P, I, D and W parameters. But I wasn't expecting to have to increase the S parameter above 1.0.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

btw here is how to calculate a good value for the T parameter in the M301 H1 command. Get the heater up to temperature and stable. Then send M573 P1 to report the average PWM value for heater 1. Call this value P. Then:

T = (255 * P) / (S * (temperature - 30))

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Dave

Thanks for that

However I have come across another problem with mine.

The Bed is heated with An AC Pad the thermistor reports room temp to within 1 degree or so (I can live with that) if I command it to 110degrees it gets to about 90 (Panel shows 110 and stable but Thermocouple on top of the bed shows 90) any suggestions?

Doug

p.s. got my Glass now

Edited 1 time(s). Last edit at 04/03/2015 11:21AM by dougal1957.

Quote
dougal1957
The Bed is heated with An AC Pad the thermistor reports room temp to within 1 degree or so (I can live with that) if I command it to 110degrees it gets to about 90 (Panel shows 110 and stable but Thermocouple on top of the bed shows 90) any suggestions?

The possibilities I can think of are:

1. You don't have the correct thermistor parameters set in the M305 command. If it is reading correctly at room temperature, then you presumably have the R25 value right; but do you know the correct B value?

2. The thermistor is reading the temperature in the midst of the heating elements, but that is 20C hotter than on top of the glass. You are probably getting 10C temperature drop across the glass anyway. If you place an insulating mat on top of the glass and thermocouple, the temperatures will probably converge.

3. Thermocouples don't read accurately when in contact with surfaces that are poor conductors of heat, such as glass, because heat gets conducted away through the wires. So the thermistor is under-reading.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42

Quote
dougal1957
The Bed is heated with An AC Pad the thermistor reports room temp to within 1 degree or so (I can live with that) if I command it to 110degrees it gets to about 90 (Panel shows 110 and stable but Thermocouple on top of the bed shows 90) any suggestions?

The possibilities I can think of are:

1. You don't have the correct thermistor parameters set in the M305 command. If it is reading correctly at room temperature, then you presumably have the R25 value right; but do you know the correct B value?

2. The thermistor is reading the temperature in the midst of the heating elements, but that is 20C hotter than on top of the glass. You are probably getting 10C temperature drop across the glass anyway. If you place an insulating mat on top of the glass and thermocouple, the temperatures will probably converge.

3. Thermocouples don't read accurately when in contact with surfaces that are poor conductors of heat, such as glass, because heat gets conducted away through the wires. So the thermistor is under-reading.

Actually there was no glass there it was directly on the Alluminium Heat spreader and I used the Beta value from the supplier of the silicon heater of 3950 but you never know wonder if its quoted at 50 degs rather than 100 or however they are rated not exactly that up on them.


Doug

p.s. this is from the EBAY Listing if it makes any sense to you

Silicone Heater Pad
•Size: Dia 300mm ( 11 3/4")
•Power: 500W @ 220V
•Accessories:
◾1m power cable
◾Surface mount NTC 100K thermistor + 1m extension wire
◾3M adhesive backing
•Qty: 1 pc




Description:

•Wonderful silicone heater for your 3D printer heat-bed.
•Rated at about 4.5 watts per square inch with fast and even heating.
•Integrated with NTC 100K thermistor ( Beta 25/50 3950K) as temperature control sensor(datasheet available upon request).
•3M adhesive backing offers excellent and easy mounting onto most surfaces.
•Versatile and may be used in many other applications.
•Keenovo carries a full range of standard and custom designed silicone heaters, contact us if you need a special heater made for your machine.

Edited 1 time(s). Last edit at 04/03/2015 01:56PM by dougal1957.

It sounds rather like the one I just received (also 300mm), except that I specified 350W @ 230V instead of 500W. I hope that's enough power. How long does yours take to reach 110C from cold?

Some suggestions:

0. Do you have an insuilating mat under the heater?

1. Make sure the thermocouple is in good contact with the bed. If it is not actually touching, the temperature reading will be several degrees lower.

2. Dip the thermocouple in boiling water, and see how close the reading is to 100C.

3. Since the beta is quoted at 25/50, try heating the bed to 50C and see how closely the temperatures correspond.

4. When the temperatures are stable, try turning the heating power off. Then see how closely the temperatures track as the bed cools.

5. If all else fails, and you trust your thermocouple, you can always adjust the M305 beta value.

Edited 2 time(s). Last edit at 04/03/2015 02:21PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
It sounds rather like the one I just received (also 300mm), except that I specified 350W @ 230V instead of 500W. I hope that's enough power. How long does yours take to reach 110C from cold?

About 3.5 minutes it is quite quick so think you will be ok mine is on a 400 diam alloy plate that is 5 mm thick so there is a definite lag for it heating guess due to the thermal mass think it may just need a bit of a pause to allow the bed to come up but Will try your suggestions.

It will probably be after next week now we are going Caravanning for the second week of easter.

Doug