Heat bed Mk3

hi one question i got a heatbed MK3 im having a hard time achiving temperatures of 90 degrees, i was looking into connections of bed and all this time i had only 1 circuit enable it was connected 1 to positive and 2 to negative, i was searching and i see that this bed is plugged 1 to positive 2 and 3 to negetive to enable the 2 circuits
i have wired all and now and i notice that the ramps 1.4 Mosfet is getting to hot and that when red led is blinking it does click noises non stop and i measure amps and i read 15 Amps,,bed seems to heat way faster, is this normal?
if so do i need to replace fuse with one bigger like 20 A maybe and replace the mosfet with a better one?
what about the litle clicks i hear from the led blinking cause of PID?

Edited 1 time(s). Last edit at 10/11/2017 09:42PM by Meph.

90C is about the best you get with a 12v supply ...I wouldn't use PID with the bed with a RAMPS at 12V too many horror stories with burnt connectors and blown fets. grab one of these mosfet boards its simple to install and protects the main board from thermal damage.

that Mosfet Board might be a good option
was wondering if odify the system for 24v if a 16.8 Amps power supply would be ebought for all system
right now i have a 12V 30 Amps power supply

My 1st 3D Printer came with a 12V at 30 Amps power supply, don't get me wrong but it works for what I print but Could use a little push..
My 2nd 3D Printer came stock with a 24V at 20Amps 480Watts supply, and it appear to be just right.

I have a 12v Mk3 heatbed on my Prusa i3 - it will make 100C if I wait long enough (20+ minutes). It struggles to maintain it if the room is cold though.

To achieve this I had to put insulation on the bottom of the heater - 2 layers of 2mm cork, with a 1.2mm aluminium plate to hold the cork on. I used the screw holes in the heatbed to hold everything together, using nuts and washers to get the correct spacing.

I also find that a piece of corrugated cardboard sitting on top will speed up the heating.

I should add that my CoreXY printer also had a Mk3 heat bed up until recently, but has been replaced by a 200W stick-on heater at 24v - got to 120C in about 8 minutes! It did put a heavy load on the power supply, so currently I'm modifying it (again) to a 230v 200W heater. Obviously this is not trivial as there are so many safety issues to be dealt with, but it does mean that I can use a far smaller power supply (120W, I believe) for everything apart from the heat bed.

Edited 1 time(s). Last edit at 10/13/2017 12:28PM by David J.

Many (perhaps most) PCB bed heaters are under-powered for printing ABS. You can get more power out of them by turning up the power supply voltage, if your power supply is the usual LED/CCTV sort that has a voltage adjustment potentiometer AND it has spare power capacity. For example, turning up a 12V supply to 14V will give you 36% more heating power.

However, if you are running Arduino/RAMPS with a graphical LCD attached, then the voltage regulator on your Arduino may be overheating already, and turning up the voltage will make it even hotter unless you provide 5V power to the Arduino a different way.

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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 guess i would need to modify my ramps 1.4 i see many videos in how to do it from what i understand it needs to remove a diode that powers arduino ,then use a buck converter to step down voltage to power arduino, change the poly fuses, most like needs to also change the fans i would say to higer voltage

If you increase the PSU voltage to just 14V, you don't need to change the polyfuses. You can put a couple of silicon diodes in series with each fan to being the voltage back to about 12V; although I know of people who run 12V fans form 14V with no apparent problems.

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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].

just got my 3rd MK3(think the pads are a little different) mainly because when used with the openbuilds buildplate it makes a nice simple sandwich.

...but havent wired any up yet though Soon i'll have one done ) and might not need the other 2
as I plan to be able to move working bed between machines.
I got the MKS Mosfet with Red Heatsink, I got my 12AWG Silicon wires(and yes they are a little thick me thinks)
I probably dont have a good enough solder iron to do the job might put the bed on the stove.
I also have some 18 awg but I'm guessing I need something inbetween to solder to bed.
I have some thermistors on the way, but not the ones I wanted,
I couldnt find what I really need for the Pads on the MK3 Led's & resistor or NTC therm block?

I'm thinking of sandwiching a Silicon Trivet under the bed

these are cheap in Home Bargains, but wouldnt mind one of these honeycomb ones in Black

(with laser cut perspex) to keep the heat up/even, (maybe one ontop during warm up)
but doubt i'll be going above 60 for a while. still contemplating XT60's or something for quick change...of relay/mosfet to other machines. not sure what wires/connectors i'll use for the signal, i have some JST connectors so probably them.

It would be good if some sort of Clip/Guard/shield/clamp could attach to the bed where the wires go too
but probably not a great idea using PLA.

I found this pic on a site and the wiring for the bed doesnt look like how I intended to do it. Maybe for different relay setup & mainboard


Edited 2 time(s). Last edit at 10/15/2017 06:42AM by MechaBits.

i dont think that a power supply 24v with 16 amps would be enought to power all systems(heatbed, 2 hotends, motors, arduino, fans etc..)
just heatbed is like 8 A , 2 hotends like 12 A at 24v
maybe could be enought if using a stepdow to conver 24 to 12v for the extruders sense they warm pretty fast, then would ne like 6 A for the 2 hotends

Hot end heaters are normally 40W or lower, so less than 3.5A for two. Assuming of course that you use 24V cartridges.

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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].

my E3D v6 heater i have pluged in my power bench with 17 v to see and i get 4.88 Amps

Quote
Meph
my E3D v6 heater i have pluged in my power bench with 17 v to see and i get 4.88 Amps

So you just turned your 12V 40W heater into a 17V 83W one. A 24V heater has four times the resistance of a 12v heater with the same output power, so at a given voltage it will draw one quarter of the current.

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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].

got to order some 24v 40 W Hot end heaters

If you use a silicone sock on your heater block, 30W or even 25W is enough power for an E3Dv6 hot end printing PLA, ABS etc.

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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].