Best practices for printing on a heated bed?

[LePaul 354]

I'm sure there's some really great tips out there....and I've tried to search for them!  

Here's my question and I hope others can chime in with what's worked for them/hasn't worked....

I'm a new member of the 'My printer has a heated bed club' ...I just installed the Heated Bed Upgrade kit in my Ultimaker Original.  A few complications but I really had a good time with it.

I did the first test robot print on a the 70C bed.  I noticed the little guy's hands, which are the big overhangs in this print, really had a tough time.  Since that's a small object and the hands are a 1/2 inch above the bed, it probably got pretty warm...maybe a tad cooked!  

On larger prints, I am guessing this wouldn't be a problem?

So, friends....what tips can you offer!  Maybe my question will help a newbie out someday!

Edited January 15, 2016 by Guest

[neotko 1,417]

IMO, most pla stick at 60. 65C to be sure. 70 for problematic ones. And with a slow layer even 55 can work.

For small objects a big brim helps cut some of the heat. Or a skirt separated by 0.3-0.6mm (so it's easier to peel off).

Anyhow, sometimes it's just better to bluetape it and go full fan.

[yellowshark 153]

Ditto @Neotko plus get those fans pumping. I do not print that type of small model but I would suggest 100% on layer 2 or 3 and experiment from there.

[LePaul 354]

ANOTHER little discovery....for those going from unheated beds to heated!

BED LEVELING!

For years, prior to loading the file, I would heat the print head to 175 and use a piece of paper to calibrate the bed. Just a touch of friction and I'd call it good.

Well with a heated bed, you need to HEAT THE BED as well! Heat rises, so that little gap you thought you had tuned in just right is no more! I discovered this the hard way. I had a print starting and the skirt lines only appeared on one side and nothing on the other (bed too close). Opps!

So...while this may sound silly to those who have had a heated bed forever, this was all new to me. The upgrade documentation really doesn't walk you through basic calibration as thoroughly as it should. (Especially, as in an upgrade situation, you've been doing your own way for years!)

I guess what I would be GREATLY interested in knowing is....How do you calibrate your bed?

What I did....and not sure it's the best way to do it...I pre-heated the nozzle to 175C and the bed to 55. Disabled steppers and did the 3 point bed leveling with a sheet of paper.

I find this kind of funny yet very educational.

[yellowshark 153]

I calibrate the bed levelling normally using a cold printer. I calibrate the nozzle the bed distance by printing test cubes so that is always hot.

[neotko 1,417]

I use a gauge feller 0.8 must pass 'felling it' and 0.10 with a bit of friction. Bed on and nozzle clean. But lately I just do an eye calibration with fans on I can hear the vibrations of the nozzle on the bed so I just make it vibrate on the gauge feller 0.8 and repeat the sound on every point.

[LePaul 354]

I'm also noticing...with the bed at 55, this print I am doing, it has a large square base....the front left as lifted up some from the bed.

Should the bed be a tad cooler? Or resort to brim?

[LePaul 354]

Let me add a photo...

[owen 19]

A tad warmer I would think plus a brim:)

[neotko 1,417]

Set the first layer to have 4-5C hotter hotend, and try to use a brim, or a skirt with 0.3-0.7 separation. And set the fan to start on a layer that needs cooling (top layer, curves, etc).

[yellowshark 153]

I'm also noticing...with the bed at 55, this print I am doing, it has a large square base....the front left as lifted up some from the bed.  

Should the bed be a tad cooler?  Or resort to brim?

 

Nope it needs to be warmer. I cannot remember the last time I had a part lift from the bed, at least 18 month plus. My settings are...

Bed with glass plate

Adhesive - two coats of lightly sprayed extra strength hairspray

Glass plate heated to 65c - as measured by digital thermometer over the area covered by the first layer.

1st layer resolution .3mm

Printer speed 20mm/s

Printer door open and roof removed

Fans off

Extruder temp. 210 - if I am doing a print with the extruder temp. below 195, then I might drop the 1st layer temp. down a bit from 210, it depends on the model.

I nearly always use a brim these days.

After 1st layer has completed I drop bed temp down to 50-55 and start adjusting the extruder temp to desired temp.

I start the fans after layer two, building up to 100% by about 1mm model height.

I always watch the first few layers go down; if you do not you cannot tell what, if anything, has gone wrong.

If I did get a lift I would clean the glass plate and reapply the adhesive. If that did not solve it I would go through bed levelling and nozzle to bed distance processes.

[LePaul 354]

Hmm so first layer at 70C bed temp then back it down to 55 after the first couple layers are on?

I usually print at 40 mm /sec , nice balance of slow but not crazy fast

Interesting to see what others are doing. From all the videos I've seen about the Ultimaker 2, I hadn't seen much discussion on bed temps

[yellowshark 153]

You can certainly print your model at 40 mm/s but that is fast for the 1st layer and may cause you problems

[LePaul 354]

So using the Ulticontroller, how high (in %) would it take to go from 10 mm/sec back up to 40 (or more?)

How high can the Ulticontroller go above 100%?

[yellowshark 153]

You can do it in Cura - go to the Advanced tab and under Speed, set the bottom layer speed to the speed you want.

[peggyb 171]

it can go really high..... once I had a group of students and a printer went like crazy...

They had been playing around with the controller, just turning the knob, apparently, on the start of the print, but because the first layer is slowed down, it didn't change much. On the second layer the print got crazy: they turned it to 800%....

[neotko 1,417]

If you change the max speeds on the ulticontroller you can change max speeds for everything, so it doesn't go bananas

By default x/y max speed it's at 500 or so, I changed mine to 180mm/s to avoid future errors.

[LePaul 354]

 

I'm also noticing...with the bed at 55, this print I am doing, it has a large square base....the front left as lifted up some from the bed.  

Should the bed be a tad cooler?  Or resort to brim?

 

Nope it needs to be warmer. I cannot remember the last time I had a part lift from the bed, at least 18 month plus. My settings are...

Bed with glass plate

Adhesive - two coats of lightly sprayed extra strength hairspray

Glass plate heated to 65c - as measured by digital thermometer over the area covered by the first layer.

1st layer resolution .3mm

Printer speed 20mm/s

Printer door open and roof removed

Fans off

Extruder temp. 210 - if I am doing a print with the extruder temp. below 195, then I might drop the 1st layer temp. down a bit from 210, it depends on the model.

I nearly always use a brim these days.

After 1st layer has completed I drop bed temp down to 50-55 and start adjusting the extruder temp to desired temp.

I start the fans after layer two, building up to 100% by about 1mm model height.

 

It appears the default first layer speed is already 20 mm /sec

[LePaul 354]

it can go really high..... once I had a group of students and a printer went like crazy...

They had been playing around with the controller, just turning the knob, apparently, on the start of the print, but because the first layer is slowed down, it didn't change much. On the second layer the print got crazy: they turned it to 800%....

 

I had something similar happen with the Move Z option. I was cranking the knob and suddenly the bed just zipped to the bottom and kept trying to go. I quickly powered the machine off, waited a moment, then back on. That controller seems touchy