my hotend can't reach 240°

hi guys
i've got a hardbot hadron with a brand new ramp and arduino board, heating cartidge and 100k resistance
my old card could hardly reach 190° , that's why i sent it back ti the customer service, and they gave me new boards
i plugged the new ramp, and make the first try
and surprise, my hotend reaches194° and i was asking for 240°
heated bed is ok at 100°
i tweaked the small potentiometer of the power supply to increase voltage to 13V
my hotend reaches 204°
it's not hot enough to print abs ,where could this problem come from?????

anyway,something's going wrong and i can't print since january
please help me!
thank you

What kind of hotend? What are you heating it with?
My guess is whatever you are heating the hotend with is wrong or defective.

it's a magma hotend 40W
i usually use ABS

Quote
jaak lab
it's a magma hotend 40W
i usually use ABS

Could be a fluke heater cartridge.

Most heater cartridges come from China and many of them have incorrect specifications. I would just save yourself the trouble and replace it with a through hole resistor heater from DigiKey.

EDIT: a 4.7ohm through hole resistor heater will provide ~30W at 12V which should be more than enough. I have used this one from digikey and it works great. It only costs 85 cents...

Eric

Edited 1 time(s). Last edit at 03/09/2014 01:21PM by RP Iron Man.

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RP Iron Man

Quote
jaak lab
it's a magma hotend 40W
i usually use ABS

Could be a fluke heater cartridge.

Most heater cartridges come from China and many of them have incorrect specifications. I would just save yourself the trouble and replace it with a through hole resistor heater from DigiKey.

EDIT: a 4.7ohm through hole resistor heater will provide ~30W at 12V which should be more than enough. I have used this one from digikey and it works great. It only costs 85 cents...

Eric

Hi Eric, how long does it take to get to 200º with that through-hole resistor?

I am now using a ceramic cartridge, but I reckon it might be better to use a resistor so I can insulate my hotend better. However, if it takes 6 minutes or something, then I'll stick with what I got. Now it's on temp in about 1 minute.

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Ohmarinus

Quote
RP Iron Man
Could be a fluke heater cartridge.

Most heater cartridges come from China and many of them have incorrect specifications. I would just save yourself the trouble and replace it with a through hole resistor heater from DigiKey.

EDIT: a 4.7ohm through hole resistor heater will provide ~30W at 12V which should be more than enough. I have used this one from digikey and it works great. It only costs 85 cents...

Eric

Hi Eric, how long does it take to get to 200º with that through-hole resistor?

I am now using a ceramic cartridge, but I reckon it might be better to use a resistor so I can insulate my hotend better. However, if it takes 6 minutes or something, then I'll stick with what I got. Now it's on temp in about 1 minute.

Hey Marinus,

Heating times are dependent on the heat capacity of the "melt-zone" in question. This is a function of the mass and material used (aluminium, brass, etc...).

I use this 4.7ohm resistor for my Prometheus Hot End and using a standard MZ length of about 16mm (material is aluminium though mass is less than most hot ends) it heats above 200C in less than 1 minute. I think 30W is easily enough even for a larger MZ. If you want it to heat up lightning fast you can use a resistor with lower resistance though I would not recommend it as these through hole resistor are already used over the rated capacity. I don't think you should go over 30W.

Eric

Could it be that you have a 24V heater cartridge?????

Quote
RP Iron Man

Quote
Ohmarinus

Quote
RP Iron Man
Could be a fluke heater cartridge.

Most heater cartridges come from China and many of them have incorrect specifications. I would just save yourself the trouble and replace it with a through hole resistor heater from DigiKey.

EDIT: a 4.7ohm through hole resistor heater will provide ~30W at 12V which should be more than enough. I have used this one from digikey and it works great. It only costs 85 cents...

Eric

Hi Eric, how long does it take to get to 200º with that through-hole resistor?

I am now using a ceramic cartridge, but I reckon it might be better to use a resistor so I can insulate my hotend better. However, if it takes 6 minutes or something, then I'll stick with what I got. Now it's on temp in about 1 minute.

Hey Marinus,

Heating times are dependent on the heat capacity of the "melt-zone" in question. This is a function of the mass and material used (aluminium, brass, etc...).

I use this 4.7ohm resistor for my Prometheus Hot End and using a standard MZ length of about 16mm (material is aluminium though mass is less than most hot ends) it heats above 200C in less than 1 minute. I think 30W is easily enough even for a larger MZ. If you want it to heat up lightning fast you can use a resistor with lower resistance though I would not recommend it as these through hole resistor are already used over the rated capacity. I don't think you should go over 30W.

Eric

Okay, that sounds pretty good.

But, on the site of digikey it says the resistor is 3W?
How do you get to 30W?

Oh, and I can't find a seller besides digikey. I am in Europe and Digikey rates me around 55 dollars for postage.. :O

Edited 1 time(s). Last edit at 03/09/2014 05:59PM by Ohmarinus.

Quote
Ohmarinus
Okay, that sounds pretty good.

But, on the site of digikey it says the resistor is 3W?
How do you get to 30W?

Oh, and I can't find a seller besides digikey. I am in Europe and Digikey rates me around 55 dollars for postage.. :O

Oh god...that's insane!

For me shipping from digikey is an $8 flat fee but I live in Canada. I didn't think it would be so expensive for you. Since this is just a pretty standard 4.7ohm wirewound, flame proof, through hole resistor you can probably get one from any electronics parts wholesaler. Element14 (Farnell) is in the UK so they may have better shipping fees and they will likely have through hole resistors. I have no I idea why the shipping is so expensive. I have been looking into worldwide shipping and I managed to find a "light packet" service from Canada Post that is quick and costs about 6USD. Maybe Digikey does not bother to find cheap international shipping. Do you have any local electronics parts stores?

As for the power rating. The resistor is rated at 3W but you can push it well over its rated power. These resistors have fixed resistance so by ohms law (V = IR, and P = VI so P = V^2 / R) the power is dependent on the voltage you run through the resistor. For a 4.7ohm resistor running at 12V the power is about 30.6W. Running the resistor at 10x its rated power is ok as long as you have adequate thermal conduction between the resistor and the heat block as this prevents the inside of the resistor from overheating. If you were to run 12V through this resistor in air (insulator) it would overheat and fail. Standard J Heads use 6.8ohm resistors like the one I linked to but 6.8ohm only gives about 21W which is a little low. That's why I chose to use 4.7ohm resistors. I done all of my testing with these and they are very reliable as long as you are careful ensure good conduction to the theater block.

Eric

What's the resistance of your cartridge heater? What amps are you pushing through? With a heater rated 40W at 12V, by P=IE and E=IR means the voltage across the heater should be 12V, current should be 3.3amps, and the resistance of the cartridge should be R=E^2/P = 144/40=3.6ohms. Are you getting 12-13V at the power supply, or is that across the heater? If those values check out, then 40W of power is going in and the heat has to be going somewhere. If 3.6 ohms and 12V check out on the electrical side, then possibly the firmware could be limiting the PWM duty cycle somehow. For instance, a Marlin w/ MAX_BED_POWER 127 would only call for 50% power.

If you jumper the cartridge to +12/+13V and ground manually instead of to the board, while watching the temperature does it still plateau at 190?

that's what i wanted to try but i don't want to fry the cartidge
this one is brand new , and i've got another one in the cupboard
so i might try
thanks for this advice