There seems to be a cool spot on my X1C bed

Bambu Lab X1 Series General discussions
1

I had a problem with some small parts falling off the rear left corner of my bed. This surprised me, I wasn’t sure if it was due to the Aux fan, so I took a thermal camera and took a look at the bed.

Wouldn’t you know it, even with the Aux fan off, there’s a cooler spot! With the Aux fan on, it’s more pronounced as the fan helps to cool that area.
Attached are some images of what I’m seeing. I circled the cool spot in black.

Depending on when you capture the thermal image, the cool spot can be from 2 to 4 degrees cooler than the rest of the heat bed (or your build plate).

Of course, letting it heat for a longer period of time brings the temperature difference of the cool spot closer to the temperature of the rest of the plate due to heat soaking, but it’s always cooler than the rest of the plate even after several minutes.

At first I thought the issue was only due to the fact that the Aux fan seems to concentrate its airflow in this corner (looking from the front door, it’s on the left rear corner. But after making tests with the Aux fan off, I see it seems the bed has a cool spot.

I don’t have a contact thermistor to double check this yet, but perhaps I’ll get one for testing.

Note that the orientation is not the same for all of these photos due to the way I was holding the camera from various angles, but the circled spot is the same location, looking in from the front through the door, the cool spot is in the rear most left corner of the heat bed.

I’m not sure if I have a defective bed or not? Perhaps I should enter a support ticket?

I’m open to any and all ideas. This may not even be a problem, perhaps this is within their normal specifications for the heat bed?

IMGT0008
IMGT0011
IMGT0013
IMGT0014
IMGT0015

1 Like
2

I have this problem as well. I don’t know what causes it, but it’s a nuisance for most of my models because the bed isn’t wide enough, so they have to angle into one of the corners. Unfortunately, I keep forgetting the back left corner isn’t so great…

3

Do you notice it only with the Aux fan on?

The Aux fan accentuates the issue as it cools the area off even more than it does naturally.

I don’t know why the Aux fan doesn’t evenly cover the build plate?

4

i haven’t noticed it, but i’ll check it out the next time I print something.

5

For what it’s worth I was very impressed when I did a quick check of my X1C bed with my thermal camera. It looked way better than I anticipated.

6

I wonder if there is an air pocket under the magnetic sheet. That would create a localized cool spot. Not sure how to go about fixing it if that’s the issue. As a last resort, I’d consider punching a very small hole in the magnetic sheet to let the trapped air out.

1 Like
7

On my X1C, the cool spot is always in the same location no matter which plate i install.

So whatever the problem it seems to be in the heat bed.

8

Its even worse on the P1 series, I’ve learned to stay away from that area if at all possible.

9

To follow up on this, support is sending me a replacement for my heat bed.

10

I installed the new heat bed. The new one has a cool spot on the other side (right rear)! :rofl:

Perhaps also a slight cool spot in the center.

I need to evaluate it again to be sure. This makes me wonder what their QC process is on these heat beds.

I know they can be ok, as i checked two printers when I visited a Microcenter store and checked two operating printers that they had on display which looked perfect.

11

Ha, that’s exactly where and only where parts start warping on my P1S (with PLA and other materials). I try to avoid the upper left like hell.

12

Just to finalize the events of my heat bed that had the cool spot.

The original heat bed had a definite cool spot on the left rear corner that coincided with small parts not holding onto the plate well. I could easily see the cool spot with a thermal camera right in the area where some small parts failed to hold onto the build plate during a print that had most of the build plate covered in these parts (I was printing a bunch of filament roll clips).

I submitted a ticket, and after sending photos and details, Bambu sent me a replacement heat bed, and I installed it.

It’s a bit of work to replace the head bed. Most of the work is because you must remove the right hand panel on the X1C to gain access to the ground screw that’s hidden behind the right rear panel.

This replacement would have been a much easier job to perform if they had located that ground screw on the chassis so that it could be accessed when removing only the rear panel.

I think they could easily update the design to move this ground screw behind the rear panel. then the service job would be a lot easier to perform! Perhaps they can take this as a suggestion on how to improve the serviceability of the X1. :wink:

I installed the new heat bed and watched it heat up with the thermal camera. During the heat-up phase, I saw that thankfully, the left hand cool spot issue was solved.

However there appeared to be a cool spot on the right hand rear corner of this new replacement heat bed. I reported this to my ticket thread.

Upon further testing, it appears that this right hand rear cool spot on the new replacement heat bed seems to warm up and dissipate so as not be an issue by the time the heat bed is fully at the target temperature. It certainly disappears with time during a ‘heat soak’ of the heat bed.

I’m not sure what caused this, perhaps the heating element in that area is slightly lower in the bed (further from the surface) than the rest of the build plate, which causes it to take more time for the build plate to reach a constant temperature? Without knowing the construction of the head bed, it’s hard to guess the cause.

As a separate bit of information. I’m sure that some people have questions about how the Aux fan could possibly cause issues with warping parts (possible bed adhesion issues). I took a quick look at the effect of the Aux fan on the bed temperature.

At a chamber temperature of about 26C, if I set the bed temperature to 30C, and turn the Aux fan on 100%, the bed next to the Aux fan only appears to be approximately 1C cooler than the rest of the build plate. By the time you get to the center of the bed, this 1C temperature gradient is gone. If you turn off the Aux fan, the bed temperature seems fairly consistent after a couple of minutes.

Note that this is an approximate number as my thermal camera is not calibrated for the emissivity of the build plate. But this should give you a ballpark idea of what is going on.

13

Do you have your emissivity set right?

Thermal image of a prototype diamond nozzle for fun

img_thermal_1667698183859
img_thermal_1667698183859960×1280 61.2 KB

1 Like
14

My understanding of how the aux fan affects warping is that it causes subsequent layers to cool too fast and/or at a different rate from the balance of the print. This causes it to shrink at a different rate than the rest of the print. It’s this differential that pulls the part off the bed rather than the aux fan pulling heat out of the bed. Of course, I could be wrong.

15

I dont think anyone is debating the action of the Aux fan.

I simply took a look to see how the Aux fan may affect the bed temperature while I had my thermal camera in my hand.