electronics suggestions or limitations

Hello to all

I have a MakerFarm prusa I3 8" and collecting information on building a new printer with larger dimensions and options as far as hotends. My Makerfarm printer has the ramps 1.4 board on it and I like the ease of use and marlin firmware. I am seeing people talk about different hotends and higher temps for other filament types, and was wandering what electronics they are using, I know I have tried to set my temp higher than 230 in my slicing program and then it errors out at the printer trying to heat up, so I guess it is a limitation setting in the marlin firmware for safety. I have done some minor searching on the web, but probably just not entering in the right keywords to get the correct answer.

Thanx in advance for any information the group can share
Natas70

Check the following line in your Configuration.h and see what it's set at:
#define HEATER_0_MAXTEMP 275

275 looks to be the default but it's possible that's set lower for your firmware, especially if it was preconfigured by someone for you. It's also possible that 230 is the limit of your thermistor and beyond that it goes to a state that your electronics doesn't understand. What is the specific error you are seeing?

If you are using a J-head or other type of hotend with a PEEK body, you probably don't want to go much hotter or you risk melting the PEEK.....

I do have the j head hotend. I am gathering information for a future build of a reprap that will have a larger build platform and be able to print various filament types. I was watching a video of someone testing an all metal hotend and was pushing 350 degrees celsius. My question was basically asking what brands of boards are able to handle these hotends. It would be great if a Ramps board can handle the requirements to heat a hotend to 350 +

At 350C+, you'll probably want a board with thermocouple support.....

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Natas70
My question was basically asking what brands of boards are able to handle these hotends. It would be great if a Ramps board can handle the requirements to heat a hotend to 350 +

How hot the hot end can get is not a function of the board's capabilities. The board is just interpreting what the thermistor is telling it and either turning on or off the heater. Each thermistor that gets configured has a lookup table that specifies that associates a range of resistance values with the corresponding temperature for that resistance. Want to have a hot end that can go to 900 degrees C? Just use a thermistor that's good to that temperature and create a table for it's values. Almost all thermistors that are readily available don't go that high though. Most are good for somewhere between 200-300 degrees C.

The metal oxides that are used for thermistors decrease resistance as temperature increases so as they reach higher and higher temperatures, resistance gets lower and lower until the resistance curve is essentially flat and not usable in an accurate manner. That's where thermocouples can come in as they don't change resistance values, they generate minute voltage readings as temperature increases. These voltage readings need to be amplified to be understood by the electronics which is why thermocouples aren't preferred for printers...it's something extra that needs to be purchased and isn't usually necessary.

So there is no amp load limitation? I have seen people talk about the Ramps board cannot handle a larger heated bed than about a 8". Is this a totally different situation, to me it seems to be the same condition, thermistor and heating element of some sort. and not necessarily the ramps board itself but the arduino/ramps combination.

and the video i saw was talking about printing polycarbonate at 315c not 350.

There are always amp limitations, but most circuits are designed for 10A - 15A as long as you use the right connectors as well as MOSFET and heatsink choices. You do need to watch the connectors because some of the cheap ones are only rated for 8 amps.

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Natas70
So there is no amp load limitation? I have seen people talk about the Ramps board cannot handle a larger heated bed than about a 8". Is this a totally different situation, to me it seems to be the same condition, thermistor and heating element of some sort. and not necessarily the ramps board itself but the arduino/ramps combination.

Using just the standard designed RAMPS board you're limited at 11 amps for the heated bed and 5 amps for everything else. The heated bed can be ran at 24v which either divides the needed current in half for the same power, or doubles the available power at the same current enabling a larger area to be heated. Beyond typical needs, the output could be used to control a relay (solid state or even just mechanical) to switch even higher current or mains voltage.

For the hot end, the typical 40w cartridge heater (12v @ 3-1/3 amps) can easily get to 300 or 350 degrees. It may require some type of insulation around the heater block to keep the heat in and not let it serve as a heat sink at higher temperatures. Consider your typical 12w soldering iron, 1/3 the power of the cartridge heater. They can easily get to 400 degrees C at the tip. They may not be able to heat something that hot once the heat starts being drawn away, but that's where the larger capacity (and possibly insulation) comes into play.

Thanx to all that replied, CDRU that is the explanation i was needing, it is beginning to make sense.