Duet 0.6 hot end heater

Guys i need one more info about my new printer . I know that my printer is sending 19v on the hot end . First question if anybody knows, is it true ? Secondly i have two heater cartidges one rated at 12v and the other rated at 24v. common sense says if it's 19v then i should go with the 24v heaters. So should i do it or use the 12v ?

If your printer is a RepRapPro Huxley or Fisher then 19V is correct.

Heating power varies as the square of the voltage. So a 12V heater run at 19V runs at 250% of its rated power. A 24V heater run at 19V runs at 63% of its rated power. So the 24V heater may be OK if you choose a high powered heater.

If it is a RepRapPro machine then the heater cartridge wil be 5mm instead of the more common 6mm, unless you are changing the hot end. You may be able to get 5mm 19V heaters from Emakershop.

If you are changing hot end, you might want to consider using a 24V supply instead of 12V. If you have a heated bed, this will have the side effect of increasing the heating power by 50%.

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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].

Thanks David for ur reply. I know that my heater is 5mm diameter and i ve talked already with emakershop asking one for a replacement on my rpp mendel ( spare ) . I ll order next week. I am really confused about the voltage that mendel is running. The documentation page (rpp) says 12v and after some lines it says 19v.

I 've made one heater block from scratch and i 've drill it 6mm for inserting the cartridge that i bought some months ago. At that time i didn't knew that my original heater was 5mm so i end up with this. Also the psu is one i have from an ibm server ( it has two but i think it can work with one only) my bed heater is 12v/24v so i think that one day i ll jump into the 24v .

Something more. I 've seen that the thermistor has a working temperature of 50c-200c in my mendel . if so how is it working with abs at 250c ? You are saying somewhere that the duet has a protection from a faulty thermistor. Is is for 0.6 or only 0.8.5 ? And when it detects a faulty thermistor or shorted cables it cuts the power to the heater or it stops the print totally ?

AFAIK, RepRapPro used the same hot end thermistor in all their printers, with a maximum temperature of 300C.

RepRapFirmware turns off a heater if the temperature reading is over 300C or if the thermistor appears to be disconnected. It does not fully protect against the thermistor coming out of the heater block; but RRP's instructions say to cable tie the thermistor cables in place, so that shouldn't happen.

I thought the Mendel used a 12V PSU, and the PSU in the images in the documentation page is indeed a 12V PSU. The Huxley and Fisher used a 19V PSU, and I understood that was because the absence of the bed heater on the Fisher and the small bed on the Huxley allowed them to use a lower power laptop power supply - and laptop PSUs are generally 19V.

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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].