heated bed

I am rebuilding my 3i printer, and have added a larger bed 300 X 300 mm , It is a mrk3 type.
on initial tests it's very very slow to heat, I realize it has a bigger surface to heat.
Is there anyway I can get it to heat quicker, it took a long time just to heat to 50 degrees, I think it may struggle to get to 100.
I am using a 12v 30 amp supply, would increasing the voltage have any effect,

Edited 1 time(s). Last edit at 05/24/2018 06:55PM by erniehatt.

Yes, Most heat beds work with 12 or 24 volts.

When using a 12v controller you can drive the heat-bed with a SSR

Before connecting to 24volts make sure your hot-bed will handle the power. (as fire can result from overpowering a hot-bed heater)

Edited 2 time(s). Last edit at 05/24/2018 08:13PM by Roberts_Clif.

Thanks for the reply Clif,
Not sure what you mean by, driving the heat bed with a SSR, could you enlighten be a bit.
Cheers

Quote
Roberts_Clif
Yes, Most heat beds work with 12 or 24 volts.

When using a 12v controller you can drive the heat-bed with a SSR

Before connecting to 24volts make sure your hot-bed will handle the power. (as fire can result from overpowering a hot-bed heater)

That's a very dangerous suggestion!
You can use the bed at 24V, only when you use the right terminals on the bed. But then it won't heat up faster....
Many 12V supplies have an adjustable output voltage. I raised mine to 14V and used the 12V terminals on the bed. THAT will lead to faster heat up and is save.

On other occasions, I added a DCDC boost converter between PSU and bed. You can only use bang-bang control then, which works fine with a thick cast aluminum plate.

Wait!!
Before proceeding is this the Heatbed you purchased.

RepRap MK3 300x300mm 480 Watt ALU Heatbed.

What size power supply do you have! You may not have enough power supply to run this hotbed.

Edited 2 time(s). Last edit at 05/25/2018 10:44AM by Roberts_Clif.

Clif,
3D Printer Heat Bed MK2A/MK3 Standard Aluminum Plate 300x300x3mm PCB Heatbed.
this is the one I bought off ebay.
The supply I have is 12v 30amp. but I do have a 24v 480w on hand. or I probably could get a larger 12v..

Edited 1 time(s). Last edit at 05/25/2018 07:00PM by erniehatt.

Your supply is a 12V X 30amp = 360 watt Supply. The 480 watt supply should give you enough.

If you decide to go with the 24V 480 watt supply, you will most likely have to adjust all the stepper motor current vref to the 24 volt supply.

Quote
o_lampe

What do you think o_lampe!

The steppers on my 12 volt supply are
My 12Volt Current vref X, Y, E0, and E1 = 0.695V
My 12Volt Current vref Z = 1.396V ; Dual Steppers wired in parallel

The steppers on my 24 volt supply are about half the 12 volt vref.
My 12Volt Current vref X, Y, E0, and E1 = 0.395V
My 12Volt Current vref Z = 0.710V ; Dual Steppers wired in parallel

Edited 1 time(s). Last edit at 05/25/2018 07:39PM by Roberts_Clif.

Thanks Cliff,
Just spoke to my son, and he has an ATX supply 12v 600W, I would think that that should do the trick for me, but would I still need to use a SSR.

It depends on the controllers mosfet and if it is capable of handling the heatbed.
What controller are you using for your Prusa I3.

Its a keyes base v1.4 ramps compatible.

Quote

What do you think o_lampe!

The steppers on my 12 volt supply are
My 12Volt Current vref X, Y, E0, and E1 = 0.695V
My 12Volt Current vref Z = 1.396V ; Dual Steppers wired in parallel

The steppers on my 24 volt supply are about half the 12 volt vref.
My 12Volt Current vref X, Y, E0, and E1 = 0.395V
My 12Volt Current vref Z = 0.710V ; Dual Steppers wired in parallel

Vref is independend of Vin. Maybe if your steppers are a bad match for the printer settings, they "get alive" at 24V and you can reduce Vref.
But lets stay focussed on the bed SSR stuff.

A 600W ATX PSU sure doesn't deliver 600W on 12V. That's 50A on 12V.
They have 5V and 3.3V output too, which share the 600W......is there a label for max. currents on the PSU?

Feeding 24V directly to the controller is only possible with a few 8-bit Atmega controllers. Even then, a 300W bed is a lot of current for the PCB.
You might need a DC-DC SSR or external Mosfet module to feed 12V to the controller and 24V to the bed. Don't pick up a (fake) AC-DC SSR, they get very hot.

Thanks,
So, lets see if I have this now.
I can use the 12v 30 amp supply to feed the controller board, and connect the heatbed with the 24v 20 amp via a DC DC SSR or Mosfet Module, which would be best.

you can also just use and external mosfet

eg [www.aliexpress.com]

Quote
o_lampe
But lets stay focussed on the bed SSR stuff.

Best Explained Here.

[forum.seemecnc.com]
or Here
[forum.seemecnc.com]

Dust, I am looking at this one.
[www.ebay.com.au]
Also this SSR.
[www.ebay.com.au]

Thanks for the info Clif

Edited 2 time(s). Last edit at 05/27/2018 09:18PM by erniehatt.

I now have some better figures on how long it takes to reach 50 degrees, it is 12 minutes, far to long.

Have finally got the printer doing it's job quite nicely, even though I still have the heating problem, hopefully this will be corrected nce I have a few extra bits.
I would like to thank those here on the forum that have been of great help. Ernie

Quote
erniehatt
I now have some better figures on how long it takes to reach 50 degrees, it is 12 minutes, far to long.

This sounds, like you are using the 24V terminal with a 12V PSU. Or you haven't wired both positive 12V terminals and gnd.

So far I am just using a single 12v 30amp supply for everything, have the 24v 20 amp but I am waiting for a mosfet module and a SSR, then will decide which to use.
The board I am using is a Keyes mrk gen 1.4, it only has one input for voltage it will accept 12 or 24v.

I was talking about the wiring between controller and bed heater. Usually there are three solder pads on the bed heater. For 12V use, you have to "shorten" two of the pads with the positive wire.

This heater bed only has 2 pads, all other beds I have ever seen are the same, never seen one with three.

This one has three
Pin1 Pin2 and Pin3
+12, GND and GND.
None +24 and GND



Edited 1 time(s). Last edit at 05/31/2018 07:54PM by Roberts_Clif.

Thanks, now that you showed me this, I had a look around and found many.

Hi Guys,
The mosfet unit arrived today, connected it up, and wow, what a difference, it reach 60c in about 2 minutes.
But then things changed for the worse, it did not stop heating at the set figure, it just kept going until I turned of the power.
It started to heat up when powered up. Also it still was heating while disconnected from the controller board.
Any ideas what is going on.

Edited 2 time(s). Last edit at 06/09/2018 04:06AM by erniehatt.

Looks as though I got a dud, wasn't sure if I had damaged the controller or not, so change every thing back to normal, just using 12v supply and it worked, although be it very slow.
From all of this I would say its a dud mosfet.
should receive the SSR shortly, will see how that goes.

Got a replacement for the Mosfet module, working real good now. Thanks all

Quote
o_lampe

Quote

What do you think o_lampe!

The steppers on my 12 volt supply are
My 12Volt Current vref X, Y, E0, and E1 = 0.695V
My 12Volt Current vref Z = 1.396V ; Dual Steppers wired in parallel

The steppers on my 24 volt supply are about half the 12 volt vref.
My 12Volt Current vref X, Y, E0, and E1 = 0.395V
My 12Volt Current vref Z = 0.710V ; Dual Steppers wired in parallel

Vref is independend of Vin. Maybe if your steppers are a bad match for the printer settings, they "get alive" at 24V and you can reduce Vref.
But lets stay focussed on the bed SSR stuff.

A 600W ATX PSU sure doesn't deliver 600W on 12V. That's 50A on 12V.
They have 5V and 3.3V output too, which share the 600W......is there a label for max. currents on the PSU?

Feeding 24V directly to the controller is only possible with a few 8-bit Atmega controllers. Even then, a 300W bed is a lot of current for the PCB.
You might need a DC-DC SSR or external Mosfet module to feed 12V to the controller and 24V to the bed. Don't pick up a (fake) AC-DC SSR, they get very hot.

Thought that both 3D Printers 3DP11 and 3DP12 had the Same Stepper motors I was wrong in my Assumptions.

Settings for My 3DP12 V-Ref current below for a 24 volt supply
X, Y, E0 and E1 = 0.395v // Only Date on Steppers - it has 5.5 ohms
Z Dual Stepper = 0.710v // 42SHD0026-20B Steppers

for a 12 volt supply
X, Y, E0 and E1 = 0.695v // 24HD4027-01 Steppers
Z Dual Stepper = 1.396v // 24HD2037-01 Steppers

I found out today after about a year of operation that the V-Ref Settings for the 24V 3D Printer were all incorrect and the settings should have been.

Settings for My 3DP12 V-Ref current below for a 24 volt supply
X, Y, E0 and E1 ~ 0.720v // Only Date on Steppers - it has 5.5 ohms
Z Dual Stepper ~ 0.800v // 42SHD0026-20B Steppers

Doing some mathematical calculations of using known information.
I have came up with an ideal of some of the Specs for the "Date code only Steppers".

1.8º 200 steps ~900ma 5.5ohms coil resistance puts us in the neighborhood of 48~54 mN/m torque.
With this information I believe that the steppers are being under driven with only 0.395 V-Ref.
By my calculations .9 * 8 *.1 = V-Ref .720 will test on the bench with my spare Controller.

******************* SOME TESTING TIME LATTER ********************

After completing the initial setup of a spare Controller to test my theories I connected the Stepper and tested with a V-Ref Voltage of .700v
Testing with 1mm steps first then changing to 10mm steps.

I cannot believe I have been running this 3D Printer with only about 1/2 the required V-Ref voltage needed to perform correct operations.
And it only took 1 year for it to mess up and force me to start testing to see why it was acting up an going so wrong.

Originally I used the setting that were on the controller having this 2nd 3D Printer working so well.
Did not think that the controller adjustments was incorrectly done as It was purchased used from E-Bay and work so well on every print.
Until last week when it suddenly started to print with only the Y-Axis shifting the layers..

Edited 4 time(s). Last edit at 01/21/2019 10:42PM by Roberts_Clif.

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Computer Programmer / Electronics Technician