Very bad Onyx heating (max 80°C)

[aehM_Key]

Hi!

The Viotek 450W, which was delivered with my RostockMax, has written on it's data plate "12V - 22A", but it delivers only about 10A.

It takes about 45min until the Onyx heated bed (ok, it's center..) reaches 80°C with the glass plate on top. 80°C is more or less the asymptote.

I already tried to add some small loads to the 3.3V and 5V-rails, but it changed nothing.

Is this normal? How is the behavior with the existing machines? John? Steve?

Thank you!

MK

[Av8r RC]

Mine will also only reach 80*C. Even after about two hours straight. I had it set for 100*C to do my calibration but would only get to 80* and would stay there like I set it for that. Anyone know if a stronger PS will increase it's temp?

[aehM_Key]

I continued investigating and found an error in my thinking. (So I changed the subject of the thread a bit..)
(I came to this, because I switched on the onyx and hotend at the same time, and saw, that the power supply could deliver much more.)

mhackney told me the resistance of his onyx and it is 1.3 ohms.(http://forum.seemecnc.com/viewtopic.php?p=5659#p5659)
I measured exactly the same for mine.

Doing simple Physics tells us P = U²/R = 111W. This is what I also measure at the power supply (120W on the primary side). This is what the onyx is capable of.
Everything fine so far.

I'm just really wondering, why mhackneys onyx heats up to 100°C in less then 5 minutes. (http://forum.seemecnc.com/viewtopic.php?p=5497#p5497)
It should also pull 'only' 111W. Regardless of his huge 30A power supply. (http://forum.seemecnc.com/viewtopic.php?p=4936#p4936)

I have no ideas where the huge differences are coming from
(No, I'm not living in an Arctic region, no I don't have a fan continuously blowing above the heated bed..)

Any ideas?

Thank you!

MK

[daftscience]

I may be wrong but he might be using a 24V power supply.

[aehM_Key]

I also thought about this, but the picture of his supply shows, that its' also a 12V one.
http://mhackney.zenfolio.com/img/s1/v54 ... 8982-3.jpg

[mhackney]

Hey folks, I measured the output on my 12 V 30 amp supply and it is actually putting out 15volts - there is an adjustment to tune output and this one was set to it's max out of the box. The other 4 were not. This one also was set to 230VAC out of the box whereas the others were set to 120V.

So some thoughts - I am actually getting a possible 173 Watts output to the heated bed. That's about 56% more power. The other thing is, are you sure you are getting 9.2 AMPS/12V to your heated bed?

I have ordered a 24V 14.6Amp supply which should give me about 277 Watts to try out on the MAX. It should be here the first week of March and I'll report back.

cheers,
Michael

[Godspeed]

I have been reading about the Onyx heating issues and people's suggestions here. I am wondering though Mhackney, is there any risk of damaging the Onyx bed due to overvolting it since it was designed to use 12v power? I am actually using a multi-output power supply to power my Rostock (still sanding the arms right now), it has 3 isolated outputs and each voltage can be adjusted. I think it would be interesting to see the result with just the one 15A module providing 12v power versus each module isolated.

Here is a link
http://www.roallivingenergy.com/products/more/rcb600

I am using the following modules
B @ 12v 15A - to the Onyx
C @ 12v 10A - to the Mosfets
C @ 12v 10A - to the motors & logic

I know this is an expensive solution, but it gives a good opportunity to experiment with the voltages.

[mhackney]

Godspeed, firstly, I don't think there are any major issues with the Onyx. This is a LARGE heated surface! It actually works fine even with a lower voltage supply. Heat-up time is long but that's a lot of area to heat. I'm already running at 15V and 11.5Amps and it has no problem with that. I'll check in with Steve and John before I try the 24V supply and report back here.

[Godspeed]

I am not saying anything is wrong with the Onyx at all.

Anyway, Steve was very up front about the heating times when I ordered my Onyx and said since he designed it for 12v (due to the standard 12v power supply) and it was larger than the Phebe, heating times would be longer. I think he actually said it might take 10 minutes or so to get up to operating temps.

I think though that having your heated bed at 80C after more the 30 minutes might indicate something in the build is different.

What is interesting to me and to others is how exactly your machine is heating the Onyx faster. That is a good feature we would all like to emulate consistently without damaging our printers,

Mhackney, what gauge is the wire did you use for the onyx power connections?

[mhackney]

I have two 18 gauge wires for each of the (+) and (-) connections to the RAMBo. You can see them in my build thread I think. Nothing fancy.

[aehM_Key]

@mhackney: Thanks for measuring.

I did also some new measurements, now on the secondary side.
I get 7,5A @ 11.42V = 86W

Why is this printer sold with this power supply? Do they all have this model?

[aehM_Key]

I just ordered a 24V 300W supply. Have just to change the fuse on the Rambo, because I have the 1.0e version, and the fuse is only rated for 16V. Mhackney you have v1.1 so it should be no problem.
Looking forward to rewire everything and find a place to connect the emergency switch...

[mhackney]

That's one advantage of the v1.1 RAMBo! The only minor annoyance is doing a 12V drop down to power my LEDs and fan. But I ordered a 24V-12V step down inverter. You can get these to 5 volts too if you are running 5V fans and LEDs.

[theverant]

I'd just like to pipe in saying that I am using the stock PS and I get my Onyx to 90 for sure, and I think I've had it to 100. It takes awhile to get that hight, I usually heat to 85, which takes about 20 mins, maybe 30. I have two 16 gauge (I think?) wire running from the RAMBo to the Onyx, I have three of the cables from the power supply bundled as suggested elsewhere going into the RAMBo. If you want more exact info I can recheck, but basically I just wanted to let you in the provided power supply DOES heat the Onyx up to acceptable levels (just not as fast as mhackney's awesome supply).

But also, I've had no problem getting ABS to stick to glass @80-85 - why are you needing to go higher?

[thenewguy]

Here is a solution i attempted to fix this problem using mineral oil.

Note: I also have the v1 onyx plate with 10ga wire then i knew ahead of time that the glass was too big but i bought it anyways. I knew i would get something to work.

I figured your grabbing more heat being released through the top and now i have my glass leveled and suspended on high temp caulk.
however heat being released through the bottom of the pad is killing me.

* It seems to heat up faster than what some claim but i think the bonus here is it can hold the temp longer if you wanted a slower cool down
* The glass is not pressured down in pressure areas. Just flat, as long as the heat dont warp it inward or something. The mineral oil in the sealed environment should prevent that.
* Eliminates hot spots on the glass.

IDK it was fun let me know what you think.

********keep in mind before you attempt this im not even sure if this method is better, also the flash point of mineral oil can turn into an instant fire once it reaches a certain temperature. The sealed heat bed helps change the flash point but lets say you slam into your glass and break it and have high temps on your bed could be an instant fire, or burns on skin, eyes, ect!.
i got the cheap mineral oil like 99.5% at your common food store. Companies do make higher rated temp oil ********

also abs juice applied on cold glass grabs well, then when cooled down slides right off! but im 100% new to 3d so i cant compare with my testing.

I also may be the first one to even attempt this... I looked around didn't see anything like it. : )

maybe ill post an image tomorrow if i get time. It looks BA : )

[Highcooley]

I'd just like to pipe in saying that I am using the stock PS and I get my Onyx to 90 for sure, and I think I've had it to 100. It takes awhile to get that hight, I usually heat to 85, which takes about 20 mins, maybe 30. I have two 16 gauge (I think?) wire running from the RAMBo to the Onyx, I have three of the cables from the power supply bundled as suggested elsewhere going into the RAMBo. If you want more exact info I can recheck, but basically I just wanted to let you in the provided power supply DOES heat the Onyx up to acceptable levels (just not as fast as mhackney's awesome supply).

But also, I've had no problem getting ABS to stick to glass @80-85 - why are you needing to go higher?

Same with me. Three cables form the power supply paired and using the thicker cable that came with the kit from the RAMBo to the Onyx, running two strands in parallel. The bed heats to 70°C in less than 4 min and to 90°C in about 10 min. Never had the urge to push it higher but PLA sticks perfectly @ 60-70°C.

[aehM_Key]

I'd just like to pipe in saying that I am using the stock PS and I get my Onyx to 90 for sure, and I think I've had it to 100. It takes awhile to get that hight, I usually heat to 85, which takes about 20 mins, maybe 30. But also, I've had no problem getting ABS to stick to glass @80-85 - why are you needing to go higher?

Have you printed already large, massive parts? Sticking is usually no problem for small parts (like the calibration objects).
100°C is the recomondation for ABS and I want to get to this.
I also do not have the time, to wait 30 or more minutes until the first print can start.

[theverant]

Have you printed already large, massive parts? Sticking is usually no problem for small parts (like the calibration objects).
100°C is the recomondation for ABS and I want to get to this.
I also do not have the time, to wait 30 or more minutes until the first print can start.

Fair enough. I've been printing with ~110 on the MBI Replicator 1 at work, but the heat up time on that bed seems even slower than the Onyx, even though it's a smaller bed. And I must admit, I haven't printed anything very large yet, so 85/90 may not cut it when the time comes.

Ideally heat up time would be quicker, and I am thinking of looking at another power supply. I was just pointing out that the power supply that came with should be able to heat the Onyx up, albeit not with any great urgency.

[thenewguy]

Mineral oil bed.

[cambo3d]

just have to ask a very basic question when you wire up the 6 pin connector. Did you combine three or more of the 12 volt wires for the heat bed and its still not giving you enough juice?

From the manual page 74

"Now find the six pin connector that has three yellow and three black wires attached. Cut the wires right off at the connector and route the wires into the electronics bay.
Take the black six pin terminal connector and attach the wires as shown. You only need to trim off about ¼” or so of insulation. Note that the picture only shows one black and one yellow wire in the “Heater Bed” positions. To get the most out of your power supply, it’s recommended that you put three yellow and three black in the “Heater Bed” (the two terminals on the right) positions to get more power to the heated bed. I recommend twisting three together and then soldering them to ensure good contact.


If the included power supply is inadequate even after wiring them as suggested. I have two spare server power supplies lying around I could use. Each are rated at 12v 75 amps.

Although, I believe a higher voltage will help the get the bed up to temp faster, I could try to run these for 24volt operation instead.

The reason why hackneys heats up quicker, is that his power supply holds a consistent voltage under load which helps maintain the amount of current flow needed to get the bed up to temp.

[dbarrans]

I timed my Onyx today. With nothing else happening, it took 14 minutes to go from 15 degrees to 70 degrees C. Stock power supply, three wires to both poles of the RAMBo heated bed power connector, 12 gauge stranded wires to both poles on the Onyx, borosilicate glass clamped to the Onyx.

Doesn't seem like it should take that long. The temperature curve was flattening out so it looked like it would never get to 100 if I had tried.

- dan

[thenewguy]

Look again. : )

when the heating bed does power up you can hear the draw of current being pulled from the supply. My fans rpm change which means voltage drop.

However I don't think that's the main problem.

I'm going to put my rostock in an enclosure and will recirculate my lost heat. And vent slowly to attic or outside.

I will also beef up the power supply down the road since i'm going to add many mods to my new fun hobby I will eventually need it.

[cambo3d]

Look again. : )

when the heating bed does power up you can hear the draw of current being pulled from the supply. My fans rpm change which means voltage drop.

However I don't think that's the main problem.

I'm going to put my rostock in an enclosure and will recirculate my lost heat. And vent slowly to attic or outside.

I will also beef up the power supply down the road since i'm going to add many mods to my new fun hobby I will eventually need it.

did you measure how much voltage you are actually getting to your heatbed? If your voltage drops to much it affects the temperature of your heatbed and how fast it heats up.

[Eaglezsoar]

Look again. : )

when the heating bed does power up you can hear the draw of current being pulled from the supply. My fans rpm change which means voltage drop.

However I don't think that's the main problem.

I'm going to put my rostock in an enclosure and will recirculate my lost heat. And vent slowly to attic or outside.

I will also beef up the power supply down the road since i'm going to add many mods to my new fun hobby I will eventually need it.

May I ask where you purchased that fuse holder that I see in your picture?

[aehM_Key]

Did you combine three or more of the 12 volt wires for the heat bed and its still not giving you enough juice?.

Yes, I did. The voltage drop in the wires is negligible. The problem is, that you will never get more power out of this bed, if you work only with 12V.

The reason why hackneys heats up quicker, is that his power supply holds a consistent voltage under load which helps maintain the amount of current flow needed to get the bed up to temp.

Not really the reason. The most im portant thing is, that his supply can be adjusted to deliver 15V.

ATX spec allows a drop down to 11.40V, but that's it, what this standard supply could drop, until it has to shut down.

I'm going to put my rostock in an enclosure and will recirculate my lost heat.

Would be great, if you cold open a new topic for this, when you have ideas how to do it. I thought about this too.