How to connect a 12 volts hot end to a 24 volts printer?

How to connect a 12 volts hot end to a 24 volts printer?

Postby EvaFlorian » 2016-Jul-Sun-05-Jul

Hi everyone,

We are Eva and Florian, 2 product design students at the academy of arts. We’ve bought an old 3d printer of a friend for a good price. We played around with it for a couple of weeks and decided to customize and improve it. To be able to print more types of materials we’ve bought the Printrbot “1.75mm Ubis Ceramic Style Hot End” + the “Printrbot Alu Extruder v2” at our local 3d-printer shop.

We discovered that our printer has an output of 24 volts towards the printer head. While the ubis hot end only needs 12 volts input. We figured we could use a resister to solve this problem.

Does anyone know which resister we need, or how many Amps (or Watts) the ubis hot end requires?
Maybe there is another creative solution we don’t know of…

We really appreciate any help you can provide!

Greetings from Arnhem :mrgreen:
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How to connect a 12 volts hot end to a 24 volts printer?

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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby RetireeJay » 2016-Jul-Sun-06-Jul

Speaking as an electronics engineer, I would have to say that putting a resistor in series with your hot end is not an easy or optimum solution. The resistor would have to have the same resistance as the hot end (so it will divide the voltage equally with the hot end). Now because it will see both the same voltage and the same current as the hot end, it will be dissipating the same amount of power. In a sense, your simplest solution to finding the right resistor is simply to get another hot end, and wire the two of them in series. If the hot end you select uses a heater cartridge (like the E3D's and some Ubis models) instead of a custom nichrome heater built into the body of the hot end (like the "ceramic" Ubis) then you only need to buy another heater cartridge. But beware of where you put it; it will be very hot, perhaps over 300C because it doesn't have the "heat sink" of the hot end connected to it.

A better solution would be to run the hot end from a 12 Volt supply. What kind of electronics does your printer have? Is it a RAMPS setup? Maybe you can run the hot end separately from the stepper motors or other parts. I'm sure the electronic "brain" of your printer does not really need 24 Volts; it regulates the incoming supply down to 5V internally to run the control chips. Maybe you could even run the whole printer from 12 Volts; stepper motors generally don't require 24V.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby thawkins » 2016-Jul-Sun-07-Jul

EvaFlorian wrote:Hi everyone,

We are Eva and Florian, 2 product design students at the academy of arts. We’ve bought an old 3d printer of a friend for a good price. We played around with it for a couple of weeks and decided to customize and improve it. To be able to print more types of materials we’ve bought the Printrbot “1.75mm Ubis Ceramic Style Hot End” + the “Printrbot Alu Extruder v2” at our local 3d-printer shop.

We discovered that our printer has an output of 24 volts towards the printer head. While the ubis hot end only needs 12 volts input. We figured we could use a resister to solve this problem.

Does anyone know which resister we need, or how many Amps (or Watts) the ubis hot end requires?
Maybe there is another creative solution we don’t know of…

We really appreciate any help you can provide!

Greetings from Arnhem :mrgreen:


What kind of printer do you have, the only printers i know of with 24v electronics are the makerbots or their clones like the flashforge, wahoo etc.
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225mm x 200mm - Heated Bed
RAMPS 1.4 running Marlin 1.1.0
Full Graphic display.
-------------------------------
Zen Toolworks CNC/3d printer
230mmx360mm bed
Dual j-head hotends.
Dual heated beds.
RAMPS 1.4 running Marlin 0.98
-------------------------------
Flashforge 3d Creator Pro
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby frankv » 2016-Jul-Sun-16-Jul

I am NOT an electronics engineer, so would welcome Jay's or anyone else's comment on this...

Maybe the easiest option would be to put a step-down regulator (e.g. http://www.ebay.com/itm/DC-DC-4-38V-to-3-3V-6V-9V-12V-24V-5A-Buck-Step-down-Converter-Voltage-Regulator-/311552007557?hash=item4889f25d85:g:4fIAAOSw5VFWOdwr) between the hotend and the 24V supply? This example would handle the current needed by the heater, I think.
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby Mooselake » 2016-Jul-Sun-17-Jul

The heater is pulse width modulated, rapidly turned off and on to control the power level. A DC-DC buck convertor probably will not work if it's inline between the extruder output and the hot end. I'd say definitely, but since I've never tried it we'll stick with about the same chance as a mosquito in a typhoon if used by itself.

However, might be workable if it was used to supply 12V to a solid state relay (SSR) controlled by the extruder output from the controller. A mechanical relay won't work because it won't switch fast enough, but an appropriately rated DC-DC SSR will.

What art academy are you attending? One of my daughters did some architectural research in the Netherlands last year while working on her masters.

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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby RetireeJay » 2016-Jul-Sun-18-Jul

frankv wrote:Maybe the easiest option would be to put a step-down regulator (e.g. http://www.ebay.com/itm/DC-DC-4-38V-to- ... Sw5VFWOdwr) between the hotend and the 24V supply? This example would handle the current needed by the heater, I think.

Well, if the load were reasonably steady I'd say yes a buck converter would be a good idea. I had no idea how cheaply you could get them!

However, as Mooselake points out, the output from the Printrboard is pulse-width modulated at a fairly high rate. And that buck converter by itself is basically a pulse-width modulated circuit. So I'd be quite concerned that the two pulse rates would get in a race, galloping along and ruining the regulation (and perhaps even overheating the converter.) For the same reason, I'd be skeptical of controlling the buck converter with an SSR; it's really not designed for rapid on/off operation.

If you put a good-size electrolytic capacitor across the output of the buck converter, you greatly diminish the effect of the pulsating load. Hmm... I just ran some numbers. Due to the very large currents involved, it might take a very large capacitor, hard to obtain with the requisite voltage rating. Check what the manufacturer of the buck converter recommends to give the smoothest, low-ripple output at rated load.
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GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby thawkins » 2016-Jul-Sun-18-Jul

RetireeJay wrote:
frankv wrote:Maybe the easiest option would be to put a step-down regulator (e.g. http://www.ebay.com/itm/DC-DC-4-38V-to- ... Sw5VFWOdwr) between the hotend and the 24V supply? This example would handle the current needed by the heater, I think.

Well, if the load were reasonably steady I'd say yes a buck converter would be a good idea. I had no idea how cheaply you could get them!

However, as Mooselake points out, the output from the Printrboard is pulse-width modulated at a fairly high rate. And that buck converter by itself is basically a pulse-width modulated circuit. So I'd be quite concerned that the two pulse rates would get in a race, galloping along and ruining the regulation (and perhaps even overheating the converter.) For the same reason, I'd be skeptical of controlling the buck converter with an SSR; it's really not designed for rapid on/off operation.

If you put a good-size electrolytic capacitor across the output of the buck converter, you greatly diminish the effect of the pulsating load. Hmm... I just ran some numbers. Due to the very large currents involved, it might take a very large capacitor, hard to obtain with the requisite voltage rating. Check what the manufacturer of the buck converter recommends to give the smoothest, low-ripple output at rated load.


Why not change the heater cartridge for a 24v one? They are about $5
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-------------------------------
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Dual heated beds.
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-------------------------------
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby Mooselake » 2016-Jul-Sun-19-Jul

thawkins wrote:Why not change the heater cartridge for a 24v one? They are about $5

The ceramic has a wound nichrome core rather than a cartridge.

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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby RetireeJay » 2016-Jul-Sun-19-Jul

Going back to the OP, I note that they bought a "Ceramic Ubis" - which has a nichrome wire wound around the threaded metal tube inside the ceramic sleeve; it doesn't have a heater cartridge.

If, after all this discussion, they still don't want to supply the heater with 12V directly, they could measure the resistance of the hot end with an ohmmeter and buy a commercial 50 watt resistor with the same resistance to put in series. It will get very hot, so it needs to be put where the heat won't damage anything.

Or, maybe they could just go ahead and use 24 volts. I don't think there will be any problem with arcing, and the feedback loop should prevent overheating. This should work, BUT ONLY IF they are very careful about tuning the PID loop. They will be getting 4X the amount of power that the stock PID loop expects, so they've definitely got to re-tune it. My recommendation would be to give a very low setpoint, like 100C for starters, and use the PID Auto-tuning command to set the parameters for 100C. Then up it to 150C and tune again, finally tuning at 200C (if they are printing PLA). (Read up on auto-tuning in several posts in the forum, be sure to save the results to EEPROM with M500.)
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby thawkins » 2016-Jul-Sun-20-Jul

RetireeJay wrote:Going back to the OP, I note that they bought a "Ceramic Ubis" - which has a nichrome wire wound around the threaded metal tube inside the ceramic sleeve; it doesn't have a heater cartridge.

If, after all this discussion, they still don't want to supply the heater with 12V directly, they could measure the resistance of the hot end with an ohmmeter and buy a commercial 50 watt resistor with the same resistance to put in series. It will get very hot, so it needs to be put where the heat won't damage anything.

Or, maybe they could just go ahead and use 24 volts. I don't think there will be any problem with arcing, and the feedback loop should prevent overheating. This should work, BUT ONLY IF they are very careful about tuning the PID loop. They will be getting 4X the amount of power that the stock PID loop expects, so they've definitely got to re-tune it. My recommendation would be to give a very low setpoint, like 100C for starters, and use the PID Auto-tuning command to set the parameters for 100C. Then up it to 150C and tune again, finally tuning at 200C (if they are printing PLA). (Read up on auto-tuning in several posts in the forum, be sure to save the results to EEPROM with M500.)


Given that 99% of systems drive the heaters by switching one end of the heater to earth via a MosFET, and tie the other to the posative supply. if you get a second 12v PSU, connect the 12v+ to tbe heater, tie the ground on the 12v psu to the ground on the 24V PSU, then connect the other end of the heater to the switched terminal thatnis connected to the FET. It should just work.
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-------------------------------
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Dual j-head hotends.
Dual heated beds.
RAMPS 1.4 running Marlin 0.98
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby blort » 2016-Jul-Mon-12-Jul

the PID tuning is likely the best way to go for this. as Jay stated, you will want to start very low and work your way up to the desired temp tuning or you will burn up the hotend. With luck you would trip your maxtemp before doing any damage, but the ceramic ubis has a relatively low meltdown temp due to the PEEK lining of the heatbreak. if you exceed the meltdown temp even once, the hotend will be ruined totally.

if I were in your situation, I would toss the ubis hotend and all of its challenges (low temp, 12v, odd nozzles,nonserviceable design) and put your money into an e3d lite which natively has 24v heater cartridges, common ecosystem of nozzles, very replaceable and serviceable design. the lite still has the PEEK meltdown temp risks, but you will be less likely to encounter them when using a 24v heater with a 24v source.

you can easily use the lite or a v6 with the extruder that you have on hand (i do). there are many locking adapter plates and spacer kits that can help to easily secure a lite at the correct mounting position. if you are using the lite, you could even scavenge the thermistor from the ubis to skip having to reflash firmware as the temp ranges are effectively the same.
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby Mooselake » 2016-Jul-Mon-12-Jul

blort posted while I was typing, but we came to essentially the same conclusion. Being the moose I posted anyway.

RetireeJay wrote:Or, maybe they could just go ahead and use 24 volts. I don't think there will be any problem with arcing, and the feedback loop should prevent overheating. This should work, BUT ONLY IF they are very careful about tuning the PID loop. They will be getting 4X the amount of power that the stock PID loop expects, so they've definitely got to re-tune it. My recommendation would be to give a very low setpoint, like 100C for starters, and use the PID Auto-tuning command to set the parameters for 100C. Then up it to 150C and tune again, finally tuning at 200C (if they are printing PLA). (Read up on auto-tuning in several posts in the forum, be sure to save the results to EEPROM with M500.)

It took some searching to find (I remembered that Marlin had this capability, but thought it could be set by g code), but you can limit the maximum power applied to the extruder by setting a parameter in configuration.h and rebuilding the firmware. PID_MAX (normally set the same as BANG_MAX, used for on/off (bang bang) temperature control implying that bang bang can use PWM) will set the maximum time the extruder power is on (it's normally switched on and off rapidly, where the heated bed is either on when below the set temp or off when it gets there). Setting this to 64 would cut the applied power to 25% and compensate for the higher voltage.

Now without trying it I'd be a little worried that it might reduce the bed heater, and more worried how it would affect the MOSFET controlling the extruder temperature since it'll be exposed to twice the normal current for those much shorter on times. RJ? And, of course, it requires learning the whole firmware rebuilding process, and might be a bigger effort than the OPs want to undertake.

Rather than tossing the Ubis (most students don't have a lot of extra cash) the best solution to this might be returning the unused hot end to the local 3D printer shop, and purchasing one that can handle 24V (like blort's E3D light suggestion). Inline resistors, new power supplies, firmware rebuilding, SSRs, etc. are all more difficult than swapping hot ends, carry at least a small potential for magic smoke letting out disasters, and may be more effort than the OPs want to undertake. Rather than digging out the Ubis's thermistor, since the original printer isn't a Printrbot and the disassembly would make it impossible to return, the one from the original hot end would work better.

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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby RetireeJay » 2016-Jul-Mon-21-Jul

Mooselake wrote: worried how it would affect the MOSFET controlling the extruder temperature since it'll be exposed to twice the normal current for those much shorter on times. RJ?


Good point. Obviously the OP's are not using a Printrboard, so we don't know the current-carrying capacity of the MOSFET that is in their system. That said, MOSFETS with quite high current ratings are very cheap, so chances are we won't be overstressing the MOSFET by running it at twice the "expected" current.

Overall, as others have pointed out, the most foolproof, bulletproof way to solve this problem is to return the UBIS and get a hot end that is designed for 24V. Everything else is a work-around with various risks (some risks worse than others, but always some risk that things won't be smooth sailing).

BTW, I had my student traineeship with Philips in Eindhoven, Holland. That was when room-sized computers used magnetic tape drives the size of refrigerators for their data storage.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby EvaFlorian » 2016-Jul-Wed-08-Jul

Hi everyone,

We are overwhelmed & happily surprised by the many reactions and want to thank you all for sharing all this information & research with us!
We have to say, most of the technical talk is rather new to us…
For example we don’t know what a RAMPS setup is. We tried to read something about it on RepRapWiki but we still don't have a clue.

thawkins wrote: What kind of printer do you have, the only printers i know of with 24v electronics are the makerbots or their clones like the flashforge, wahoo etc.

We have a fabbster. Fabbster is an old German 3dprinter company that made very ugly but solid reliable 3d printers.
(we could not add links because it looked 'to spamy for a new user ', see the .pdf attachment below)

Mooselake wrote:What art academy are you attending? One of my daughters did some architectural research in the Netherlands last year while working on her masters.

We are studying at ArtEZ in Arnhem. We also have an Institute of Architecture ;)

RetireeJay wrote:BTW, I had my student traineeship with Philips in Eindhoven, Holland. That was when room-sized computers used magnetic tape drives the size of refrigerators for their data storage.

Wow, we are visiting these same buildings every year, during the Dutch Design Week :)

Ok, now back to the printer talk.

Unfortunately we cannot return the hot end, because we already welded new connectors to it. Our only option would be to sell the hot end second hand.

Here is some more information about the printer we are working with;
The power supply of the printer has a DC output of 24 volt & 14.6 Amps. (See picture)
All the output ports on the print board are 24 volts, except 8 ports on print board 2, on the left bottom corner. They deliver 5 Volts.

Thanks again for helping us out!
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby frankv » 2016-Jul-Thu-13-Jul

And another option...

You could use a circuit like this http://www.instructables.com/id/How-to-Make-an-Universal-DC-Motor-Speed-Controller/step2/Theory/ to only turn on the heater for about 1/4 of the time.
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby RetireeJay » 2016-Jul-Thu-13-Jul

frankv wrote:And another option...

You could use a circuit like this http://www.instructables.com/id/How-to-Make-an-Universal-DC-Motor-Speed-Controller/step2/Theory/ to only turn on the heater for about 1/4 of the time.


Presumably, the circuit controlling the heater already uses pulse-width modulation (as described in the article you reference). Hence my suggestion to try running with 24V on the heater circuit, but re-tuning the PID loop for temperature control. Mooselake added that in Marlin it's possible to set a maximum duty cycle on the pulse-width modulation.

I think putting two pulse-width modulation circuits in series is asking for trouble. One will modulate the other and you'll end up with a "beat note" that may make the overall control circuit impossible to tune.
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Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby BobP » 2016-Nov-Mon-08-Nov

I might be a little late to the game as I see the original post was some time ago and I hope the problem has been solved but...just a thought-
Perhaps the 24 volt hot-end output from the printer control board could be fed into a voltage regulator IC such as an LM388T. This is a programmable voltage regulator IC with a 5 Amp rating (7 Amp surge). Maximum input voltage is 40 volts so it will be OK with the 24 volt system. Choose voltage setting resistors (see National Semiconductors application notes) to provide a 12 volt output. The LM388T is easy to mount but it must be used with a heatsink and its mounting tab must be electrically insulated as it is connected to the output terminal. Perhaps it could be mounted to a part of the printer's frame if the frame is metal.
This is an un-tried, un-proven suggestion.
As was mentioned in previous posts, it is not easy to throw away the equivalent of 200+ degrees of HEAT.

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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby Mooselake » 2016-Nov-Tue-13-Nov

The extruder is controlled by rapidly turning it's voltage off and on (aka PWM, pulse width modulation), using a MOSFET on the Printrboard connected to ground, with the other side always hot.

Hmm, while my first thought was to reject an external voltage regulator because of this, it might work. Connect the regulator to +12 and a constant ground, then connect the regulated voltage side to the hot end and the switched ground. RJ is the real electrical engineer, I only played one in college. Perhaps he'll comment.

However an external SSR would most likely be the easiest and (from the user standpoint) simplest approach, short of using the right voltage hot end.

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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby RetireeJay » 2016-Nov-Tue-15-Nov

The idea of using a voltage regulator is attractive because then you don't have to match the resistance of the hot end in a voltage divider. But you still will be dissipating a lot of power. You'll need a big heat sink and maybe even a fan to keep it cool enough. Simplest solution is to find a spare laptop power supply brick (you can probably find one for free if you look around enough) and run the hot end off that 12V supply. (But all of this is probably out of date by now; presumably the OP has solved it some way.)
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Printrbot Plus operational January 2013
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GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby plexus » 2016-Nov-Wed-02-Nov

Wouldn't it be easier to change the hot end? say to an E3D. then you get a better hot end in the process.
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Re: How to connect a 12 volts hot end to a 24 volts printer?

Postby Mooselake » 2016-Nov-Wed-11-Nov

plexus wrote:Wouldn't it be easier to change the hot end? say to an E3D. then you get a better hot end in the process.

What fun would that be?

The OPs haven't been back here since a few days after their original post; the last we heard they were unable to return the original Ubis. As college students perhaps funds are short, or the First National Bank of Mom and Dad (don't laugh, one of our college student EMTs says this with a straight face...) isn't going along with it.

Wonder what finally happened. As the father of a former architectural student (and now teaching and Fulbright Fellow) they can be pretty resourseful.

Kirk
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