12v to 24v

[MSURunner]

So now that I'm feeling more confident in the ability of the Rostock, I was thinking of bumping up my build area from the little Phebe I have to a larger round bed. Only problem is the Onyx is sold out currently and there seems to be some concern about heating times for it on 12v (or have those been alleviated?). The options that I'm finding for several of the round units on the larger side (must be big enough to justify upgrading the current setup) are based off of 24v. While I could just as easily buy a 24v PS and us the SSR that many of you guys have done, I was curious what you guys would have for opinions on using a step up converter such as this one: http://www.ebay.com/itm/Waterproof-DC-D ... 1171930705. My thought would be to simply use that as a step up from the 12v coming out of the Rambo to 24v for whatever heated bed would be used, rendering the need for an additional PS and allowing the components of the Rambo to run at a much more tolerable 12v. Thoughts? If that would work, would any of you guys have any sort of preference on using a Kapton, silicone, or Onyx PCB based heater? I've got the equipment to cut/machine adapters for any of the setups if the Onyx is going to be out of stock for a while, so that's not of concern, FWIW.

[Eaglezsoar]

So now that I'm feeling more confident in the ability of the Rostock, I was thinking of bumping up my build area from the little Phebe I have to a larger round bed. Only problem is the Onyx is sold out currently and there seems to be some concern about heating times for it on 12v (or have those been alleviated?). The options that I'm finding for several of the round units on the larger side (must be big enough to justify upgrading the current setup) are based off of 24v. While I could just as easily buy a 24v PS and us the SSR that many of you guys have done, I was curious what you guys would have for opinions on using a step up converter such as this one: ://www.ebay.com/itm/Waterproof-DC-DC-Co ... 1171930705. My thought would be to simply use that as a step up from the 12v coming out of the Rambo to 24v for whatever heated bed would be used, rendering the need for an additional PS and allowing the components of the Rambo to run at a much more tolerable 12v. Thoughts? If that would work, would any of you guys have any sort of preference on using a Kapton, silicone, or Onyx PCB based heater? I've got the equipment to cut/machine adapters for any of the setups if the Onyx is going to be out of stock for a while, so that's not of concern, FWIW.

Running the Onyx at 24V requires approximately 17 amps, there is no way that the booster could handle the current requirements.
The 24 V power supply most of us used is rated at 30 amps because you need the overhead so the power supply doesn't run so hot it destroys itself.
The small PC type power supply simply does not have the ability to drive a 12 to 24V converter, even if you could find a converter that can handle the 17 amps required.
There should be no mickey mousing of this, if you are going to run the Onyx at 24 V I recommend that you purchase the one we know works. Here is the link to it:
http://www.ebay.com/itm/Meanwell-Power- ... 4246547%26

If you were to purchase a 24V heatbed other than the Onyx and use it with the above power supply, the bed would need to be rated at 450-500 watts.

Another option is to use a silicone heatbed that glues to the bottom of an aluminum plate and operates off of the AC power in your house. You would need the silicone heater ($85) and a DC-AC SSR to control it and you would need to
use an outside controller to control the temperature or somehow place a thermistor compatible with the Rambo in contact with the aluminum plate. My opinion is to use the 24V power supply along with the Onyx when they are back in
stock, this method is simpler, has been tested and doesn't use voltages that could kill you.

[MSURunner]

Fair enough. Just thought I would toss it out there and see if it had been done or thought of before I attempted. Sounds like a waiting game is in order/building something similar and SSR'ing it. I take it from your response that 12v simply isn't enough to get the Onyx to a reasonable temp in a reasonable time?

[cope413]

doesn't use voltages that could kill you

It's not the voltage that kills you, it's the current

You run 12v 10a across your heart, and you sir, are a dead man

[Eaglezsoar]

doesn't use voltages that could kill you

It's not the voltage that kills you, it's the current

You run 12v 10a across your heart, and you sir, are a dead man

I agree with the statement about the current but you would have a tough time
passing 10 amps through the human body with a voltage of 12V. The human
bodies resistance is too high. You can grab hold of the bare leads of a 12V
power supply all day long and no harm will be done. Current is the actual flow
of electrons and voltage is the force that pushes them, in between is the resistance.
It takes far less than 10 amps to kill, I believe that it is in the milliamp range but
it's not going to happen with only 12 volts doing the pushing.

[Captain Starfish]

My shiny new Max with the onyx bed and borosilicate cover gets from 20C ambient to 65C in about 3 minutes... is that not fast enough?

[Eaglezsoar]

My shiny new Max with the onyx bed and borosilicate cover gets from 20C ambient to 65C in about 3 minutes... is that not fast enough?

Only you can make that decision. Some people want it to go from 20C to 90C in 20 seconds and I'm not joking. They cannot bear to wait for anything.
Your printers heatup time seems fine to me and you but some would say it's slow. Happy Printing!

[Captain Starfish]

It is mildly frustrating watching the bed take a leisurely stroll to setpoint as the hot end sprints towards 4 times the temp. And I do understand the impatience of wanting to get that job kicked off so you can go and do something else.

But for me the warmup time is a lull during which I can do some "pre-flight checks", like go through the parameters and make sure everything's set correctly, make sure the right filament is loaded and there's enough of it there, make sure that there's nothing around the unit that will catch fire and burn down my house if anything goes wrong, and so on.

Instant print would be nice though!

[AlexBorro]

That will be my next upgrade.

Now with room A/C off it takes about 20 minutes to reach 100ºC(yes, it is needed for ABS stick on glass and avoid warping).
I have a cartesian printers (graber I3) with 550W on the bed.. it reaches 100ºC in about 1 minute.. is amazing.

I have the Onyx as well and will power it on a 24V power supply. I will build a 24V PS from 2x 12V PS with one 12V outlet to RAMBo and 24V for the bed - that's the way I power my Graber I3.

Course you need an external FET/SSR to interface the bed, since RAMBo does not handle such voltage and current.

Best Regards.

Alex.

[Nylocke]

RAMBo 2.0 supports 24v at whatever you fuse it to, previous versions can't handle it because of the fuse they use (easily solvable through hacking), though the rest of the board can take 24v AOK. You also gotta keep in mind the size and development of the MKII heated bed you probably have on your Graber vs the sheer size of the Onyx and state it is in development wise. Of course it's going to take a while to heat up. Sorry for being Mr. Pissy pants today, but the MAX i used on stock PSU ran beautifully and heated to 110 in just a couple minutes.... All I'm hearing is a bunch of complaining.....

Excuse me while I go take a chill pill....

[Blade-Breaker]

It took over 35 minutes to heat my onyx bed to 100 with the stock power supply. I changed to a larger adjustable voltage power supply. It now takes around 10 minutes to get to 100 at 12.5v. At 15v it takes around 5 minutes to get to 100. This power supply has a current meter so you can ensure it stays below the 17 amps that was mentioned as the max for the rambo.
After load testing the stock power supply I noticed a voltage drop to 11v. I am confident this was just a defective p.s.
5 to 10 minute warm up times are perfect for me.

Here is the p.s. I am using. Pricey but I use it for many other things.

http://www.progressiverc.com/junsi-s120 ... upply.html

[Eaglezsoar]

I'm glad you got it working the way you like.
Happy Printing!

[Jimustanguitar]

So silly question... I know that the main goal of the 24V conversion is to make your heated bed reach temp faster. If the Rambo accepts several different voltages, is there any reason not to just use the 24v supply for everything? Get rid of the ATX and just use the industrial unit?

[neurascenic]

And, where are you putting this PSU?

chris

[Eaglezsoar]

So silly question... I know that the main goal of the 24V conversion is to make your heated bed reach temp faster. If the Rambo accepts several different voltages, is there any reason not to just use the 24v supply for everything? Get rid of the ATX and just use the industrial unit?

The only reason the Rambo is not run on 24V is the puny little connectors that it uses for the Heatbed. We've seen the pictures of the Rambos with the melted connectors that is
caused from having the heatbed current going through them. They are too small and they overheat from the 17-18 Amps going through them. It is much cheaper on the wallet to
use a DC-DC SSR to handle the current rather than a Rambo whose connectors were not designed for that much current. There is also the fact that the more voltage you put into the
Rambo, the warmer all the components get and the possibility of parts failing from getting too hot. My opinion on this whole affair is that it is your Rambo, if you want to run it at
24V and drive the Heatbed with it at that voltage, go ahead. Just be sure to have an additional $200 for when it self destructs.

[mhackney]

I have both a 12 and 24 V supply (photos in my build thread) installed in the base of the Max - they fit nicely with a little modification to one of the bulkheads. I originally intended to power everything from the 24V supply but burned through the heat resistors in short order. I then replaced those with 24V cartridge heaters. But, the all of the accessories like LEDs and fans operate on 12V. The hot end also heated up extremely fast. I decided to use 12V for all of those items and dedicate the 24V to the heated bed.

The connectors to the heat bed are not ideal for this as Eagle and others have pointed out but I've run 2 RAMBos with 24V on the heated bed and (knock wood) have not had any problems. I do run three 18 gauge wires on each terminal to the heated bed. The SSR is a good idea for peace of mind, you don't want that happening if you are out of the room while printing.

[edwardjanderson]

I would like to do this mod to get higher heat out of my onyx bed. Is there a wiriing diagram for the SSR and The Meanwell Power supply hook ups? They are mentioned in many threads, but it is not obvious to me on how to put them in. (Chemical Engineer)

Thanks

[mhackney]

It is very easy but if you are struggling to make such a basic connection PLEASE PROCEED WITH CAUTION.

I ran my Onyx at 24V from my RAMBo for over a year without incident. Most folks use an SSR and I recently changed to that when I moved to an Azteeg X5 Pro board. It's a simpler connection this way.

Unplug your printer and disconnect from you computer (USB cable).

Locate the input side of the SSR - it is usually clearly marked on the unit. The terminals will be marked + and -. Connect plus on the SSR to the + heated bed output on your controller (RAMBo) - make sure to use heavy gauge wire, I use three 12 Gauge wires! Then connect the - terminal to the controller. At this point you can test things before hooking up the 24V and Onxy. Connect to your printer from your host and instruct it to heat the bed to 50°C. You should see the indicator LED on the SSR (every unit I've seen has one) flicker as current is supplied to it. If so, you are ready to connect the 24V and Onyx.

Again, unplug your printer and disconnect from you computer (USB cable).

Connect the 24V supply's ground (-) to the Onyx ground terminal. Connect the 24V + to the SSR's output (-) terminal then connect the (+) output terminal to the Onyx (+) terminal. Power up and set the temp of the bed to 50°C again. Now you should see the SSR and the Onyx LEDs flash.

At this point you need to configure the heated bed in Repetier firmware. I use the PID tuner to tune the heated bed for 60°C and be done with it.

Good luck.

[jdurand]

The 24V - or ground from the power supply goes to the system ground.

The 24V + goes to a 24V to 12V converter and to the + side of the OUTPUT of the solid state relay (large screws on top).

The outputs of the 24V to 12V converter power everything on the Rambo board.

The output for the bed heater goes to the INPUT of the solid state relay (small screws on bottom).

The - screw of the OUTPUT of the relay goes to the PLUS/RED wire for the bed.

The black wire from the bed goes to power supply ground or -.

[DeltaCon]

It took over 35 minutes to heat my onyx bed to 100 with the stock power supply. I changed to a larger adjustable voltage power supply. It now takes around 10 minutes to get to 100 at 12.5v. At 15v it takes around 5 minutes to get to 100. This power supply has a current meter so you can ensure it stays below the 17 amps that was mentioned as the max for the rambo.
After load testing the stock power supply I noticed a voltage drop to 11v. I am confident this was just a defective p.s.
5 to 10 minute warm up times are perfect for me.

I definately need to check that, because heating to 90 degrees C already takes about 40 minutes in my setup, but...

Here is the p.s. I am using. Pricey but I use it for many other things.
http://www.progressiverc.com/junsi-s120 ... upply.html

I guess that this is the current (!) link to the meant PS:
http://www.progressiverc.com/chargery-s ... upply.html
This is a rather expensive upgrade...

[JFettig]

So silly question... I know that the main goal of the 24V conversion is to make your heated bed reach temp faster. If the Rambo accepts several different voltages, is there any reason not to just use the 24v supply for everything? Get rid of the ATX and just use the industrial unit?

Works great as long as you use all 24v equipment, fans, heaters, LEDs, etc. My second printer is all 24v.

[DeltaCon]

So, I took the time to do some measurements...
If all is idle (machine is on, but no heating is done and no fans are turning) I measure 11.75V going into the Rambo (upper 2 contacts from the power connector on the Rambo)
When I start the heated bed (ordinary 12V setup) the Voltage drops to about 11.35 My guess is that that is not out of the ordinary
When I measure the heated bed output on the Rambo brake-out connector, I measure around 8,3V, my guess is that is not good...
When I also start heating the hot end, the V on the input is steady at 11V, and the V on the heated bed fluctuates between 8.1 and 8.3

How come I measure so much a difference between what is going into the Rambo and what is coming out of it?
Should this be of concern? I am reaching 80 degrees C in 16 minutes, and 90 degrees takes about twice that time.

I have this PSU installed.
[img]http://hennekens.info/rostock/PSU.jpg[/img]
Since I got my machine secondhand I am not sure if this is a original one from SeeMe. It does not look like the PSU in the build manual, but it could be a previous original one perhaps.

Other question:
From various threads I read that people upgrade their Rostock with a 24V PS in order to speed up heated bed temperature. Do I understand correctly that the existing 12V heated bed can be powered with 24V without problem?
If so, why do they sell 24V heated beds from Onyx also?

[Eaglezsoar]

The 24v beds that they sell were not printed good enough to be used on 12 Volts (they would not get hot enough) so they sell them for use as 24 Volt units.
As a group we have discovered that all the beds work at 24 Volts.

[IMBoring25]

At a given voltage, resistance is inversely tied to current. Current is the primary driver dictating wire size. Higher-resistance beds would allow you to either run lighter-gauge wire or get somewhat more power without increasing the gauge of the wire, depending on the voltage you chose to drive them.