I Wish to Upgrade my Print Bed

Hello everyone.

I own a MakerFarm 12” Pegasus printer that I’ve been very unsatisfied with. I’d like to replace the PCB heat bed because it’s causing horizontal banding on any print that needs temperatures higher than 50c. I could try replacing the mechanical relay with a solid state replay and enable PID, but I’m not sure if I want to bother.

I would really like to switch to an aluminum plate and silicone heater. My worry is that the Y axis Nema 17 stepper would not be able to move the weight of a 4lb block of aluminum plus heater and a sheet of glass or PEI.

Anyone have a recommendation? The Pegasus uses a RAMPS board so I’m limited to 12v. The stepper motors I have are 42 BHH48-151K-24B. I've looked, but I can't find a data sheet for the motor.

Thanks!

"uses a RAMPS board so I’m limited to 12v" well that false for a start, many use ramps on 24 volts. You just need to know what your doing.

Basically if you want just a 24v bed, replace the 11amp poly fuse with a thick wire. And put a inline 24v fuse in the heated bed wire.
Hook up 24v to the 11amp input.

That is all there is to it.


Now if you want full 24v conversion, steppers, hot end etc that more complicated, but also doable.

You can also just make the stepper 24v, by removing the vmot pin on each of the pololu modules and applying a 24v to the now isolated from the ramps vmot pin
(some people make the pin stick up instead of going down, and then attach the 24v to the upward facing pins)

Edited 1 time(s). Last edit at 12/02/2016 10:44PM by Dust.

You will have no need for the glass if you switch to the aluminum. Silicone heaters don't weigh much more than the pcb heaters. Don't over think this, the motor you have is most likely more than adequate.

Remove the relay circuit and run directly through the MOSFET on the RAMPS board for the heated bed and use PID - Try this first, but also put a small fan onto the RAMPs to keep it cool if not already doing so.

If the reasons for your banding are releated to use of "bang bang" control on the bed heater, using PID will resolve this.

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Flex3Drive.com

I am running my RAMPS on 12V and my relatively big heated bed on 24V.

You can use your RAMPS with 24V, however you should power the Arduino through a separate voltage source (which is always a good idea as the integrated AMS1117 voltage regulator is much too weak if you are running a big screen and servos) and check if your caps can handle the voltage (normally they should be rated for 35V but there are different RAMPS versions - you should check).

About your idea to use a SSD - please do not. The cheap DC-DC SSDs are no good. The RAMPS can only handle a 10A heated bed and only with additional cooling so if you are going to use a more powerful heated bed the easiest way to do this is with a simple MOSFET circuit - check out for example the sevenswitch - just remember to use a proper heatsink.

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Self-sourced Mendelmax 2.0-based Reprap Machine -- Ramps 1.4 & Mega 2560 -- DRV8825 (Z@1A, [email protected], [email protected], E@1A) -- genuine E3D v6 direct setup -- 350W custom silicone heated bed -- ABS 1,75mm -- Marlin 1.1.0-RC7 -- Cura 15.04.6

+1 on the sevenswitch for higher current heatbed

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Flex3Drive.com

Thanks for the great tips! You all have given me more to think about.