Custom size mk3 heatbed


#181

I’m using a MeanWell SNT RSP-500-15. It fits easily under the printer.[/quote]

Hi raby,
are you using one or two heads? I’ve got two so I’d like to know if your psu is enough for my setup.


#182

I have 2 heads but I seldom use them both at the same time.


#183

Thank you very much. I’ve ordered one to use in my printer.

The reichelt catalogue (paper version) for 2016 only mentions the SNT MW-SP500-15 wich is 93 mm high. Obviously that one is not going to fit.


#184

Thanks Marlark, the heatbed did arive today.


#185

size=150 Current Stock Status : 71, Sold : 40[/size]

41 being used or on it’s way to someone so far with my own counted in :slight_smile: Im very happy with mine and i hope everyone else that got one so far is to.

If someone want one i stil have 71 left that want a new home in a printer somewhere.

Best Regards
Ted aka Marlark


#186

One thing I must emphasize about Marlak’s bed is that mine is perfectly flat witch is a great improvement as neither the glass plate nor my MkIII where flat (even far from it).


#187

Like Raby pointed out but i dont think i have mentioned here before. They are flatness tested one by one both by the manufacturer and by me because you never know when or if you print strait on the heatbed or using a top surface of some kind.

The shipping bag is padded and the bed is put in a zip bag when i send them to make shure they do not get dmg’d in the parcel. It is going to take alot of pressure by the “postman” to fuck one up so to say :wink:

A side tip :slight_smile: The zip bag is somewhat good to store your roles of filament in to protect them from moisture :wink:


#188

[quote=“raby”]@Marlak : the SSR is a 40A! No problem.

@svdv : The bed drains 220W at 12V and 345W at 15V.[/quote]

I am a bit curious how you computed this. At 12V the printbed has a resistance of 1,5 Ohm (as described in the first post).
When taking U = R * I (thus I = U / R) and P_el = U * I (for direct current, ofc.) we get P_el = U^2 / R.
Which in our case would be 12^2 / 1,5 = 96W.
IMHO the resistance of the board should stay somewhat constant (expect for the fact that the resistance of the 24V circuit is greater).
To draw 220W the resistance would have to be around 0,65 \omega, which is half of the described resistance.

I guess another 100W for the heatbed would be enough.


#189

Actually the resistance is 0.65 ohm and not 1.5.


#190

There has been some confusing info about the resistance and power consumption of this heated bed.
I hope I can clarify some of this confusion with this post.

There are two heating resistors on the heated bed. The heating resistors are made up of two copper tracks each about 1,3ohm. When the HB is configured for 12V operation (PIN 2 and 3 connected together) these two resistors are connected in parallel resulting in one 0,65ohm resistor.
When the HB is connected for 24V, these two resistors are placed in series, resulting a total resistance of 2.6 ohm.
So, when configured for 12V and connected to a 12V power supply you get:
P (power) = U² / R = 12² / 0,65 = 222W
I (current) = U / R = 12 / 0,65 = 18.5 A

When configured for 24V and connected to 24V power supply you get:
P (power) = U² / R = 24² / 2,6 = 222W
I (current) = U / R = 24 / 2,6 = 9.2 A

So it does not matter if you use a 12V or a 24V supply, when properly connected the power is 222W. But the current for the 12V solution is double, so the power expander and wires must be able to handle this current.
To heat up faster, you need to increase the power consumption. The only way to do this is to increase the supplied voltage (you can’t change the resistance of the copper tracks). e.g. you could supply 15V when the HB is configured for 12V (30V with the HB configured for 24V would be the same).
P = U² / R = 15² / 0,65 = 346 W
I (current) = U / R = 15 / 0,65 = 21.5 A
This can be combined with the power supply for the printer if the supply is powerful enough. 350W for the bed plus 150W for the printer = 500W

I found a cheap 15V / 400W PSU. No enough to use for both HB and printer. So I will install this power supply in addition to the original Vertex PSU.
http://nl.aliexpress.com/item/400W-15V-Single-Output-Switching-power-supply-for-LED-Strip-light-AC-to-DC/621198939.html?detailNewVersion=1

As power expander I found this :
http://www.benl.ebay.be/itm/181829639918?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


#191

Thanks, your assumption is correct. Mine was that the resistance was already the total resistance not just one side :slight_smile:
Question: What does us keep from using both lines in serial? - This would reduce power consumption (ofc to the price of the heatbed heating up slowly)?
I mean 96W should be sufficient to keep a heatbed at 80°C, or am I wrong here?


#192

[quote=“Tanemahuta”]This would reduce power consumption (ofc to the price of the heatbed heating up slowly)?[/quote]Not only it will heat up (very) slowly but probably won’t reach the 90-100° needed to print ABS.


#193

You are right. I just checked this. The heating will reach is max at around 48°C.
So obviously it is a new 500W PSU for the heatbed :slight_smile:


#194

My bed arrived today in the post from Marlark. That’ll be my weekend project! 2.6 ohm for the 24v pads, just as others have found.


#195

Guys,
Can someone tell me where to get the small 2- pin and 4- pin white female connectors which need to be attached to the wires and eventually to the motherboard ?

Tnx in advance


#196

@Tanemahuta
So the MeanWell AC-DC PSU - RSP-500-15 - Enclosed 15V/0-33.4A should be sufficient as a replacement PSU?

@rigged
I bought them at an ‘analog’ electro shop In NL. But if you google for idc connector I am sure you’ll find something.


#197

Hi,

looks like Molex KK5051 series (or clones) should fit, but compare the pictures first.


#198

Hello, Just made some time to add Marlarks heatbed to my Vertex, following the “HEATBED FOR DUMMIES” instruction manual (great manual, thanks!). Can anyone help me with the following questions I have?

  • Is it advised to leave the buildtak on the glassplate, or is it better to remove it? Can it withstand the heatbed temperatures (what is max for buildtak?) I will be printing with PLA and ABS.
  • Will heating stop when the thermistor malfunctions? Or is there a chance of overheating with a malfunctioning or disconnected thermistor?

Many thanks in advance,
Zoek


#199

[quote=“Zoek”]Is it advised to leave the buildtak on the glassplate[/quote]No it’s of no use.
I don’t use the glass plate either. To use it you’d have to provide a good heat transmission between the bed and the glass (with thermal compound).
To get the objects sticking I’m using Dimafix which is great especially with ABS (never warps again).

[quote=“Zoek”]Will heating stop when the thermistor malfunctions?[/quote]Depends on the malfunction. If it’s broken or disconnected the bed won’t heat. If it’s functioning but doesn’t measure the right temperature the bed could overheat (but the same goes for the print head). That’s why it’s recommended not to leave the printer alone. That said I’ve never heard it happened to someone.


#200

Thanks for the quick reply!
It triggers another question, in the “HEATBED FOR DUMMIES” the use of thermal compound is not mentioned. Does that mean the heating is sufficient when installing the glass directly on top of the heatbed, but better results can be expected by using thermal compound between the bed and glass? Or will the glass be heated insufficient without using thermal compound?
Can anyone share experience with the setup as explained in the “HEATBED FOR DUMMIES”, so glass directly on the heatbed (assuming I understood the instructions correctly)?

Zoek