Print Bed Almost Refuses to Heat Past 100°

Hey all,

I just started experimenting with ABS today and am experiencing something really frustrating. My print bead gets up too 100° and then creeps up at a rate of .1° every ten seconds. It's like pulling teeth, and I'm sure this isn't how it's supposed to be.

Anyone have any ideas why this is happening? At this rate it is going to take damn near a half hour just to get the print bed hot enough to print ABS.

 

Really? I was looking around on the web and 120° seems to be what people are shooting for.

http://forums.reprap.org/read.php?1,93574,93574

 

The stock robo only has like 130W of power running to the heated build plate.

If you want to go higher you need to increase the voltage. I'm converting to 24v for this reason.

 

Mike, what temperature are you aiming for on ABS prints?

 

You don't need any more than 80 for ABS, if that. I was running 60 on another printer just fine. You'll get good sticking on most prints at 80 and if you're getting edge curl (depending on the print), 85 might take care of it.

I don't even think for nylon you'll need anything above those. Yes, there are other folks doing 120 - but in general, it's not necessary.

Do not use something to keep the heat in unless you are putting the entire printer in a chamber. You're inviting disaster if you do.

 

ABS? 100, but that can be difficult in a 10C garage. Mostly for HIPS

Now I hear there's some materials that use 200C beds... 400W can do that for sure...

 

Huh? A couple of things:

1. If you're printing in a 10C garage, you should have the printer in an enclosure. Adjusting a device's temps to overcome ambient temps is not a good practice.
2. I would strongly avoid anything above 80 - 85, not because of sticking but I think you'll have quite a bit of distortion as the result of really high heat. It's not necessary. Truly.
3. If you do need the additional bed temps - for other materials, add a separate 24V power supply with a relay. There are threads in here that describe how to do it. I wouldn't run it through the Arduino Mega...cooling fan or not.

 

It was in an enclosure but according to my math you need an ambient temperate of around 30-40C around the kapton heater in order to maintain 100C at 130W of power. This means even with my enclosure the ambient temperature was pulling enough heat out so it couldn't reach the setpoint.

I'm running my setup using a 24V 700W psu that drives a 240W 24v to 12v converter to power the arduino. The HBP is controlled using a relay. The issue I've been having is the 25A relay I've been using keeps failing on ~22A load with active cooling on the heatsink. Just draws way too much too quickly. I have a 40A coming in a day or 2 which I'm hoping resolves it, but I'm thinking I need to go to a higher quality company.

See: https://plus.google.com/115065176676738755459/posts/BeJZp7W1f9b and https://plus.google.com/114513371427179260186/posts/RDsYcHisb67

Though that also requires upgrading to thermocouples...

 

Bandaids. I think you're going to have to heat the enclosure. Hell, you might even have to pre-heat the ABS! I guess with those low temps you're not going to have to worry about humidity content in the ABS. Bonus! Sorry for your troubles...

 

Heated enclosure is on the agenda as well. Problem is if you heat the enclosure you need to find a way to keep your timing belts tight... Though my intention is a heated enclosure around 60C. I don't need the 80C stratasys machines push.

Always more considerations to make. 24v is just a fun project, and the prospect of going from 20-100 in 1 minute is a lot better than the 15-20 it was taking before. Cheap relays tend to give you what you pay for though so hopefully I can stick to $20 relays instead of $40-100

 

I think you'll be ok with belts. Not sure but I don't think they're that sensitive. Should be specs on them somewhere...

 

When I was playing around with ABS before getting my enclosure setup I tried aiming a heater at the print to prevent warping. What ended up happening was my x-belt got really loose and caused skipping. Obviously this was a highly uncontrolled situation so for all I know the belt got into 90C or so. Though I still have the concern.

 

Makes sense.