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• Thermal interface.

  Dimitar • 10/26/2025 at 17:10 • 0 comments

  Hi,

  I was thinking how to glue the heaters to the vat. Also the vat is hollow inside. This was a concern for people, because air is bad conductor of heat. 

  I found this glue AS1803. On paper it has pretty good thermal characteristics, which one is to expect for 85 euros. I used to fill the gaps and attached the heaters to the vat. 

  I ran a test, with the hollow vat + high temp double sided tape / fancy glue and filled gaps. This is the result:

  I recorded the temperature of the heaters and the temperatures of the inside of the vat. In both cases the vat reached 51° the only difference is that it reached it one minute faster.

  Is the tape the best - no. Does it make sense to spend 80 euro for one minute improvement, also no.

  The tape is way easier and cleaner to use, the only tools you need is an exacto knife.

  In conclusion: I am relived that this expensive glue did not do a much of a difference and in general that the hollow vat is not a concern. 
  
  Cheers,
  

  M

• Vat cooldown

  Dimitar • 10/11/2025 at 10:00 • 0 comments

  Next simulation I wanted to run is how fast does the vat loose heat. 

  There is a number of assumption. One is that the whole vat is the same temp. In practice this is never the case. So the question what is the vat temperature depends where you measure. I decided that I will measure the temperature on the inside of the long side of the vat. In a sense there the temperature should be highest because the heater is located on the outside of the same wall. Next assumption is that the vat is empty. And the third one is we will test it a single lumped thermal mass.

  Since I already have a 3D model of the vat I can get the volume, and the surface of the vat. I can also measure the weight of it. 

  Again we are pretty close to the real deal. This gives me a starting point for another experiment. The walls of the vat are empty which is terrible for thermal conductivity. I plan to fill the gaps with AS1803 which is a great thermal conductivity and this will double as glue for the heaters as well. Will it make such a big difference to justify the price? 

  Cheers!

  M.

• Simulation time.

  Dimitar • 10/08/2025 at 15:13 • 0 comments

  After the first use of the heater in a real world environment, for a thirteen hour print at 12° C, something was clear. Just controlling the temperature of the PCB heaters is not enough. Two things became apparent. First one is that the PCB heaters will come up to temperature before the resin even has a chance to worm up. The second is that if we run the heaters up to 35° it will take for ever to heat the hole vat. 

  We need to run the heaters at 60° in the beginning (this is the maximum that I have set for safety) to warm up the vat as quickly as possible. After set amount of time switch to mode to maintain the temperature. The question is what is this amount of time? 

  Now can we just add a user defined timer to run the heater on max power before it goes to temperature keeping mode. The answer is yes, but is any fun - no.
  

  We need to simulate the vat + resin combo how they heat up and how much heat they loose to the environment. How much heat can the heaters themselves produce. And the last major player is the interface between the heaters and vat. We do have a sensor for ambient temperature and with this info we can make a formula that will give us the amount of time we need to run the heaters at 60° to reach the user set temp. We have a few assumption, the vat is full and we have not run the heater before. 

  I already modeled the heater using GNU Octave. I also made a test using a real heater and logged its temperature. 
  

  Math works... who would know. I think this is quite nice. Now I need to model the rest and work out the formula.

  Cheers,
  

  M

• Building the UI

  Dimitar • 09/27/2025 at 19:42 • 0 comments

• First Results: PID in Action

  Dimitar • 09/25/2025 at 16:14 • 0 comments

  Hello all,

  I wanted to see how well the heater could hold temperature, so I filled the resin vat with water and started a simple test run. The heater brought the water up from about 28 °C to 40 °C without trouble, and once it reached the target it settled nicely.

  Of course, I had to push it a bit. So I grabbed some ice, dropped it right into the vat, and watched the curve dip. For a moment the temperature slid down, but then the PID loop kicked in and pulled it right back — stabilizing within ±0.5 °C. There were two samples per second made, making the test run about 1h. 

  That’s exactly the kind of stability I was hoping for. The external 14-bit ADC really helps smooth out the control, and paired with USB-PD power it feels like the system has plenty of headroom.

  I have built a few test units to send to some friends for real world testing next :) 

  Cheers,

  M.

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