Can't print test pieces

Hi,

So I'm having some trouble getting my Ormerod 2 to print test pieces. The hot end doesn't always heat up and when it does the printer moves as if was printing but it does not extrude anything. The extruder gears don't turn.
When I give manual commands in pronterface I can get the filament to extrude after sending G032 P1. When I heat up the hot end in Pronterface it heats up very slowly. I had some problems with the hot end fan previous to this. Before I fixed the fan problem the hot end would heat up in a matter of seconds but now it hardly ever reaches the temperature required before the 150 second time out.
I've checked all the wiring around the fan to make sure nothing came loose while I was fixing the fan, everything seems to be in order.
Any ideas about what the source of my problem might be?

Shauna

Quote
shauna
The hot end doesn't always heat up and when it does the printer moves as if was printing but it does not extrude anything.

You must select the first tool by sending "T0" first before you can heat up and extrude any filament. Also see [reprappro.com]

If your nozzle takes a long time to heat up, the easiest way to speed it up would be to increase the 'S' term via M301. You could try this out by sending M301 S1.1 which will increase the heater output by 10%.

Quote
zombiepantslol
You must select the first tool by sending "T0" first before you can heat up and extrude any filament. Also see [reprappro.com]

I did have the tool selected with all my original problems.

Quote
zombiepantslol
If your nozzle takes a long time to heat up, the easiest way to speed it up would be to increase the 'S' term via M301. You could try this out by sending M301 S1.1 which will increase the heater output by 10%.

This made the hot end heat up slightly faster initially but as it gets closer to its target temperature it slows down and doesn't ever reach it. I've also tried increasing the heater output to higher percentages such as M301 S1.2, M301 S1.3 etc. with the same result.

Do you think it might be a temperature sensing problem rather than a heating problem?

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shauna

Quote
zombiepantslol
You must select the first tool by sending "T0" first before you can heat up and extrude any filament. Also see [reprappro.com]

I did have the tool selected with all my original problems.

In this case it sounds like you never reach the target temperature and the cold extrusion prevention kicks in. You can verify this by checking the G-Code log for warning messages.

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shauna

Quote
zombiepantslol
If your nozzle takes a long time to heat up, the easiest way to speed it up would be to increase the 'S' term via M301. You could try this out by sending M301 S1.1 which will increase the heater output by 10%.

This made the hot end heat up slightly faster initially but as it gets closer to its target temperature it slows down and doesn't ever reach it. I've also tried increasing the heater output to higher percentages such as M301 S1.2, M301 S1.3 etc. with the same result.

Do you think it might be a temperature sensing problem rather than a heating problem?

Well, you need to ensure the thermistor is all the way in the heater block. If it doesn't make good contact, the temperature readings will be off by a significant amount. If you have a multimeter with a temperature sensor, you could feed it into the nozzle instead of the filament and check if your readings are close to the values reported by Pronterface or by the web interface while heating it up.

Hi shauna

We've had a couple of people report this problem, since the v1.09 firmware update. The PID values (which control the heating) were changed. Generally, this is okay - we tested in house, and didn't see any problems. But if there is something not working quite correctly, it can cause the heater to take too long to heat up. It tends to hit the temperature about 10C below target quickly, then creep slowly up to the target.

There's a couple of things you can check, and do, to overcome this:
1. Check your heater is fully in the heater block, and the thermistor is too. Do you have a fan blowing on the heater block? This may cause it to take longer to heat up.
2. Check the resistance of your heater cartridge. It should be around 3 ohms. If it's higher, it will take longer to heat up.
3. Probably the easiest thing to do is to revert to the settings we used in firmware 1.04. with the hot end cold, send:
M301 H1 P20 I0.5 D100
Heat up the hot end, and see how it responds. If it works better, please let me know. If it overshoots the temperature by a long way, like 10C, reduce the 'P' value to 15; send:
M301 H1 P15 I0.5 D100
You can also add this to your config.g to make it permanent.
4. You can increase the heater timeout with M570, see: [reprap.org]

There is also a thread on the forum about this problem; see: [forums.reprap.org]

Ian
RepRapPro tech support

Quote
droftarts
Hi shauna

We've had a couple of people report this problem, since the v1.09 firmware update. The PID values (which control the heating) were changed. Generally, this is okay - we tested in house, and didn't see any problems. But if there is something not working quite correctly, it can cause the heater to take too long to heat up. It tends to hit the temperature about 10C below target quickly, then creep slowly up to the target.

There's a couple of things you can check, and do, to overcome this:
1. Check your heater is fully in the heater block, and the thermistor is too. Do you have a fan blowing on the heater block? This may cause it to take longer to heat up.
2. Check the resistance of your heater cartridge. It should be around 3 ohms. If it's higher, it will take longer to heat up.
3. Probably the easiest thing to do is to revert to the settings we used in firmware 1.04. with the hot end cold, send:
M301 H1 P20 I0.5 D100
Heat up the hot end, and see how it responds. If it works better, please let me know. If it overshoots the temperature by a long way, like 10C, reduce the 'P' value to 15; send:
M301 H1 P15 I0.5 D100
You can also add this to your config.g to make it permanent.
4. You can increase the heater timeout with M570, see: [reprap.org]

There is also a thread on the forum about this problem; see: [forums.reprap.org]

Ian
RepRapPro tech support

Hi Ian,

Thanks for the help. I found the M301 H1 P20 I0.5 D100 fixed my problem. It did cause the temperature to overshoot by ~5C but this dropped back down after around a minute or so. Switching to M301 H1 P15 I0.5 D100 made no difference to the overshoot, nor did using other P values.
I ignored the problem since it was only a few degrees and my test pieces have now printed correctly!

Thanks again,
Shauna