Custom size mk3 heatbed


Yeah that’s pretty odd… Which fan btw? The bottom one cooling the steppers? (I’m not sure if that one turns on) Or the ones on the head? (those definitely don’t turn on on my printer.

Kind regards!


the 25mm hotend fan turns on during preheat. both bed preheat and nozzle preheat. does not matter wich i choose.
and i have been searching the forums like crazy. and even googled how to in marlin. cant find jack about it.

finaly found where to edit the preheat fan speed.

in configuration.h

// Preheat Constants
#define PLA_PREHEAT_FAN_SPEED 0 // Insert Value between 0 and 255 ((These values where set at 165))

#define ABS_PREHEAT_FAN_SPEED 0 // Insert Value between 0 and 255 ((These values where set at 165))


OH during the preheating of ur head… I must advice to not completely turn these of its necessary to have a continuous flow downwards for the peek tubing and inside ptfe tube. I have these on 43 so the front fan just spins mildly


Ooh darn didnt think about that.
It is My first printer. And it’s only one month old.
Thanx for the advice!


Btw it’s at 43 but I swaped the turbine on top with a ball bearing one and higher rpm I think so it might not spin at all at 43 in your setup, try to lower the fan speed on the display and see what the exact value is for your case… Mat 40 mine doesn’t continue spins but in intervals so find that point and add like 5 or 10 to be safe, just make sure it moves a little air.


Yeah i might test that, thanx.

But isnt The turbine on top for cooling The ptfe/peek?
Mine blow hell of alot Air around The peek.

And The 25mm Ball bearing fan is for cooling The print?

Or am i totaly in The wrong thinking?

They do start up individually.


They are connected at the same fan output so you can’t control them separately. And yes the turbine also blows on the peek tube, but I’d rather be safe than sorry and like the front blowing a little as well. The turbine cools mostly the back side and the small cools the front and the print… The turbine also blows trough the xycarriage thus cooling the print… The peek and the ptfe tube are fragile parts which I had lots of issues with… So just saying turning it completely of is imho a risk.


Yeah that sounds about right. Thanx for your knowledge. It’s not Easy being new to 3d printing :slight_smile:


We are all newbies. :wink: Just with different ideas and solutions to problems.


Yes, exactly it’s also my first printer and I can tell you it took me longer than a month before starting editing the marlin firmware. So your allready doing better than I did. And like marlark said many different approaches could give you similar results. It’s just what you feel most comfortable with or even going with another approach you think suits best for your needs. So a warm welcome into the world of 3d printing.

Kind regards


Thats True Marlark :stuck_out_tongue:

Haha well thanx for that i think.
I just like to tinker around alot.
It’s kind of a great way to learn the machine.
And to know where The limitation is.

I must say that for The price of this printer the quality of The prints out of the box is amazing. But i have found small ways to make them Even better :smiley:

And this community seems really friendly and helpfull.
Altough most of The things i needed where allreddy talked about.


I agree with you. As long as you stick to PLA and dont start tinkering to much like a lot of us have done it is a fairly stable construction. But many of us want to extend the capabilities and mod the crap out of stuff and even improve. Is good that we can learn from each other and evolve the design and share ideas and knowledge. Is one of the reasons why i went for a DIY and i think it is a great way to learn the technology. Most of us here is friendly people. Spread the love and keep an open mind and help out when you can :slight_smile:

// Marlark


Got Marlark’s - MK3 bed yesterday.
Dying to test I started to mount the cables and thermistor today just to find out that thermistor broke in the middle while soldering.
After thinking a few minutes I searched my sparepart box and found a extruder thermistor. Connected that and installed it close to the heatbed. Temperature seems correct right out of box, and I validated with the Extruder temperatures for reference moving between 20 and 30 C.

Now after a 5 hour print with ABS, and No Warping I am confident that this was the right Option to install.
Have not decided witch way to go for fastning the wires or plate but Now I have better time on that, Since I can finaly print ABS :slight_smile:

Do you print with Raft on every print with ABS? or do you think I can skip that with the heatbed installed?


Nice that you like the bed Norx :slight_smile:

Well a raft is for the most not needed. I think it totally depend on the part your printing. Some parts need a raft regardless if you print PLA or ABS or any other type of filament. It is just the nature of the design of the part your printing that makes it so. In my own case i have maybe needed a raft for 1% of my prints. But then it have been large items with small gripping points to the plate. Even then i havent always needed it. Usually i have found it out when the print failed and then decided to redo it with a raft.

atm i have 85 left in stock so if anyone want a plate they are more then welcome to read the first post in the thread :wink:


yeah i have only printed with pla yet. getting some abs next week so would be fun to test that out too.
i´m gonna wait till i get some more knowledge in this before testing like ninjaflex and stuff =)

yeah just by doing a DIY build got me alot of knowledge how the thing is built. and if i have to do some repair or mod. i know where and how to start.
and as probably most of us here know. it´s damn fun to mod! :stuck_out_tongue:

yeah i would help as often i can if there is something i have to share =)

I have had a testrun with the bed now and damn i like it alot! the heat transfers really good to the glass.
it was really easy to solder, the only drawback i have is the server psu i got. cant fit it under the printer so i have it beside the printer.

so thanx alot for the heatbed Marlark!


Free evening, so alot of testing today:
Then I run Dualprint, and Heatbed is standing on to maintnance the temp. The printer “dies” for a few ms to seconds and continues. This does not seam to happen using 1 extruder, but as soon as It heats up the second. So it seams that I am only able to have two heaters on at once. Is a 320W powersupply to small, or might it be cooling of the drivers/main board or something thats gives this issue. I have not adjusted the Drivers, or done any settings that I am aware of.

I am able to print with dualhead if I pre-heat both extruders before I turn on the Heatbed. Maybee it is using less Power to maintnance tmperature than heatingup.

Put a fan that blows alot of air over the mainboard… Seems to work fine now. So temperatur might be the source for the issue…

Nope. It’s the power. Added a Raspberry on the same PowerSupply. stopping more frequent now. So Got to run two powersupplys…or get even a bigger one than 320w


The resistance of the bed for the 12V input is about 0.65ohm : there are two 1.3 ohm circuits in series for the 24V input (2x1.3=2.6 ohms) and in // for the 12V input (1.3/2=0.65 ohm).
So for a 15V input it’s sucking about 23A (15/0.65) = 345W! And you still have to heat the heads and power the printer.
So it seems indeed that your 320W PSU is a bit too little.


In one of the first posts I think the calculation was close to 100W
Are you sure you need to Divide the resistance in two?
Do we have numbers for how many Watt for the Extruder?


[quote=“Norx”]Are you sure you need to Divide the resistance in two? [/quote]Yes with identical resistors in // the resulting resistance is the resistance of one of the resistors divided by the number of resistors in //.

For the power consumption here are some measures I made some time ago (on the 220V side):

Printer idle : 23W.
Printing with 1 nozzle : 60-90W
Printing with 2 nozzles : 100-120W


[quote=“raby”]Yes with identical resistors in // the resulting resistance is the resistance of one of the resistors divided by the number of resistors in //.
For the power consumption here are some measures I made some time ago (on the 220V side):
Printer idle : 23W.
Printing with 1 nozzle : 60-90W
Printing with 2 nozzles : 100-120W[/quote]

I might misunderstand big time here, but.
That means if you are updating to heatbed you should not change to RSP-320 as in the Heatbed for dummies document but one with atlest 500-550w if you want to only use 1 powersupply running with two extruders ?
Still with original PSU adding the RSP-320 only for the heatbed you are on the short side.
Numbers are different if the Total resistance is 1,5ohm.