Bed temp only goes to 83C

[BONE]

I've been printing in PLA when I start with my Rostock MAX v2 about a month ago, and only have had the bed up to 60C. I switched to ABS today for the first time and the bed will only go up to 83C. It took half an hour, maybe a little longer, to go from 30C to 83C also. When it reach 83C, I heard a small click from the machine and the display read "Killed" on the bottom line. What are some things to check out or possible causes?

[nitewatchman]

Most likely the RamBo timed out and killed the job. It will do this after an extended period of inactivity.

While the slowness to heat could be a variety of things, most likely is wire size to the bed and/or Power Supply size. Many people will throw a towel over the bed to help control heat loss until the bed comes up to heat.

To prevent the RamBo from timing out any activity on the LCD panel will keep it awake.

nitewatchman

[BONE]

Thanks, I'll give the towel trick try.

I think the instructions said to use the 18AWG that was part of the CAT5 wiring. Should the wiring size be bigger?

[Mac The Knife]

When it say's "killed" on the display, I believe it is timing out. Others have addressed the slow warm up issue with covering the bed with a towel. Then there are those that power the bed with a 24 volt PSU, and use a solid state relay to power the bed. My solution was a cheap 30 amp. 12 volt power supply from Amazon. The output voltage is adjustable, and wide open is 15 volts. It cost me 28 bucks. I splurged and ran three pair of 12 gauge, silicone jacketed wire to the rambo, since the PSU has three, 12 volt outputs. I cut the back off an old PC power supply to use the cord socket, and to fill in the hole where the old PSU was. I used the existing power switch to turn the power supply on and off.

I have the Rev 2 bed, and a stock hotend with two, 40 watt ceramic heaters, and I can start printing in under 5 minutes, with the bed temp set at 80C, and the hotend set for 250C.

http://www.amazon.com/Universal-Regulat ... wer+supply

[McSlappy]

What version of the heated bed do you have?

There are two things you can do for now:
- Add more wires from the power to the heated bed (using the same guage just add another wire per side)
- Put a piece of paper / manila envelope / towel on the bed as it warms up - you'll hit 80º waaay faster

[BONE]

Thanks for the replies guys. I have a towel on the bed right now and it is heating up much faster. I am shooting for 105C on the bed. I'll add more wires in the near future, but I have a job to do first. I'll update later.

[nitewatchman]

Thanks, I'll give the towel trick try.

I think the instructions said to use the 18AWG that was part of the CAT5 wiring. Should the wiring size be bigger?

That could be some of the problem. The bed pulls a fair amount of current, for #18 wire it should more likely have 3 or perhaps 4 wires on each leg. I used a #14 Stranded Copper wire all the way from the Power Supply to the RamBo to the Bed.

With the bed, a 1/16" copper plate, glass plate and 1/32 PEI sheet I heat to 105C in about 8 to 9 minutes using a 750W Single Rail power supply.

nitewatchman

[Russ]

It might also be worth trying the bed PID autotune again. Also, you may want to seal the holes on the top plate that cause a bit of a draft under the bed. I sealed mine with plugs, but kapton tape worked just fine.

[critical_limit]

Thanks, I'll give the towel trick try.

I think the instructions said to use the 18AWG that was part of the CAT5 wiring. Should the wiring size be bigger?

That could be some of the problem. The bed pulls a fair amount of current, for #18 wire it should more likely have 3 or perhaps 4 wires on each leg. I used a #14 Stranded Copper wire all the way from the Power Supply to the RamBo to the Bed.

With the bed, a 1/16" copper plate, glass plate and 1/32 PEI sheet I heat to 105C in about 8 to 9 minutes using a 750W Single Rail power supply.

nitewatchman

Even if you install a 5000W power supply you can´t beat the ohm´s law!

Due to my information the Rambo is able to handle 15A for the heatbed. That means, if your using a 12V Power supply it will only draw 12A out of your Power supply. Because the Onyx has around 1ohm at Room temperature. And that means your Bed is at 144W max.
If you use a 24V Power supply be careful!!!!! It will draw 24Amps (576W). But that will blow your Fuse on the Rambo.
Even if you are able to adjust the output Amps on your Power supply to 15A, the Heatbed is on 360W.

What we have learned? 750W Power Supply means nothing.

So, be careful with the Power Supply you are using!!! The only way to get the full power of more than 350w to the bed is using a SSR. That´s already discussed.

I´m using a 15V Power Supply connected to the Rambo. Due to Ohms Law it is 225W delivering to the Heatbed. And that is much more than a 12V Power Supply is delivering to the Bed (144W). And: you are on the safe side! Otherwise I recommend: use a SSR!

Don´t get me wrong, but I do not believe people telling they are using a 24V Supply on a Heatbed directly connected to the Rambo. It will work. But only for a very short time

But as we all know, there is a big BUT....

You can use the 24V 750W Power Supply which is connected to the Rambo. If you set the max.PWM for the Heatbed in the Firmware lower than 255. This will work. But finally your Bed will use only 360W. So, no need to install a 750W Power Supply for the Bed

Or did I missed something?

cheers
Dirk

[critical_limit]

.....Or did I missed something?

cheers
Dirk

or is it:

...did I miss something
...do I missed something
...do I miss something


aaaargh. Cant remember. School is sooo far away and english is quite difficult.

But the ohm´s law I remember: U=R*I

Funny, because I´m actually in Israel and URI is a favorite Name here. That forced me to write my post...

... and: no, I´m not bored!

Sitting here and have so much issues to fix on my Rostock.....

[BONE]

Put this together last night. I'm planning on using the plastic make a nicer chamber, put this is working for now. Towels helps get the bed temp up to 100C. When I take the towel off before printing, it drops to 95C for the first few layers, them starts to climb back up to 100C over the 3 hour print time.

I'm going to try increasing the number and size of the wires first. Then look at power supply upgrades after that, but sticking with the 12V systems.

[teoman]

Put this together last night. I'm planning on using the plastic make a nicer chamber, put this is working for now. Towels helps get the bed temp up to 100C. When I take the towel off before printing, it drops to 95C for the first few layers, them starts to climb back up to 100C over the 3 hour print time.

I'm going to try increasing the number and size of the wires first. Then look at power supply upgrades after that, but sticking with the 12V systems.

I believe the reason for it rising back up is somewhat of an error. The whole bed is not rising, but the center part is, and the reason for that is that the thermistor is in the center of the heated bed, and you are probably printing in the center of the heated bed. So the ~200 deg filament deposited close to the sensor is giving an erroneous reading.

[DarrenAnton]

Most likely the RamBo timed out and killed the job. It will do this after an extended period of inactivity.

While the slowness to heat could be a variety of things, most likely is wire size to the bed and/or Power Supply size. Many people will throw a towel over the bed to help control heat loss until the bed comes up to heat.

To prevent the RamBo from timing out any activity on the LCD panel will keep it awake.

nitewatchman

how does one adjust the Rambo time out due to inactivity?