Replacement heated bed

Hi I currently have a Labtek i3 clone which has been working well for a few years. It has a MK2B aluminium heated bed running on 12 volts topped with a glass plate. My problem is it struggles to get up to 115 degrees for ABS printing. Sometimes the firmware thinks it is overheating and shuts down which I think is due to the excessive heat up times. I've been thinking about getting a silicone heater and replacing the glass with a aluminium surface.

My idea is to use a MOSFET to bypass the ramps board
get a 12v silicone heater
acquire a good build surface.

Is this the normal upgrade path?
is there any preferred components used?
and lastly is there any good suppliers out there?

open to all ideas

If your PSU is the sort with a terminal block and a voltage adjustment potentiometer at one end of it, then a simpler option may be to turn up the power supply voltage. Increasing it from 12V to 14V will give you 36% more heating power. However, there are a couple of caveats:

- You must have sufficient spare power capacity in your PSU to provide the extra 36% heating power.

- If you have an LCD attached and you are providing the 5V supply via the diode D1 on the RAMPS and the Arduino voltage regulator, then the voltage regulator may already be overheating and increasing the voltage will make it worse. So either provide 5V by some other means, or connect 3 or 4 more silicon diodes in series with D1.

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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 for the reply. Luckily I don't use a LCD screen on the printer. I will try increasing the voltage .its running at 12.88v at the moment.

Theoretically you should also put couple of silicon diodes in series with the fans to bring the fan voltage back down to 12V. But some people run 12V fans from 14V and seem to get away with it.

Your hot end power will also increase, so you may need to re-run auto tuning on it.

Also check how hot the bed mosfet and the 11A polyfuse on the RAMPS are. If they get too hot, you can replace the mosfet by a better one, and the polyfuse by an auto fuse.

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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].

Don't forget about insulation under the heat bed.

I have some cork under the mk2b to insulate it. Not sure if its making much difference.Thought about adding tin foil between the cork to reflect the heat back.
is there a different controller board that would not require modding. I'm not that good at soldering boards.

There are plenty of alternative controller boards that work well without modifications. Which is best for you depends on how good the mechanics of your printer are (because a high-end controller would be in part wasted if the mechanics is poor), what facilities you want, and how much you want to spend. The Duet WiFi and Duet Ethernet that I co-developed provide TMC2660 stepper drivers which will make your printer much quieter when the head is moving, fast 32-bit processing, firmware configuration without having to recompile and re-upload the firmware every time, the awesome Duet Web Control web interface, fast file upload via the web interface, support for resume-after-power-fail, optional colour touch screen, and much more. See [www.duet3d.com] for more information.

If you don't want to move to a 32-bit controller yet, then IMO the RAMBO is the best-designed 8-bit controller.

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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].

I got tired of waiting on my 12V system, so I hooked the mosfet to a solid state relay and bought a 120 volt pcb heater. I now get to 120c in less than 5 minutes, and my power supply has less to handle.

Quote
dc42
There are plenty of alternative controller boards that work well without modifications. Which is best for you depends on how good the mechanics of your printer are (because a high-end controller would be in part wasted if the mechanics is poor), what facilities you want, and how much you want to spend. The Duet WiFi and Duet Ethernet that I co-developed provide TMC2660 stepper drivers which will make your printer much quieter when the head is moving, fast 32-bit processing, firmware configuration without having to recompile and re-upload the firmware every time, the awesome Duet Web Control web interface, fast file upload via the web interface, support for resume-after-power-fail, optional colour touch screen, and much more. See [www.duet3d.com] for more information.

If you don't want to move to a 32-bit controller yet, then IMO the RAMBO is the best-designed 8-bit controller.

I like the idea of upgrading to that board. It might be a bit overkill for my printer . I like overkill!

Quote
cwaa
I got tired of waiting on my 12V system, so I hooked the mosfet to a solid state relay and bought a 120 volt pcb heater. I now get to 120c in less than 5 minutes, and my power supply has less to handle.

That is my main problem at the moment.
What printer are you using that on?

My own design!