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--- reprap:anet:a8:improvements:understanding_my_heatbed [2018/12/30 09:24] – [First test results] cj_elec_tech
+++ reprap:anet:a8:improvements:understanding_my_heatbed [2018/12/30 10:07] – [Analysis with the simulator] cj_elec_tech
@@ Line 41: / Line 41: @@
 ==== Reproducing the test ====
-I reproduced the test with several configurations. A small (aparent) improvement was achived by taping the sides. But nothing dramatic.
+I reproduced the test with several configurations. Apparently a small improvement was achieved by taping the sides - but it was nothing dramatic.
 {{:reprap:anet:a8:improvements:heatbed_profile2.gif|}}
 ==== Investigating other effects ====
-A good hint by a facebook group memeber was to check the cables. There is an significant power drop from the voltage supply to the heat bed. Note that the power dissipated at the heat bed is proportinal to the squares of the voltage at the heat bed .
+A good hint from a Facebook group member was to check the cables. There is a significant voltage drop from the power supply to the heat-bed. Note that the power dissipated at the heat bed is proportional to the square of the heat-bed voltage.
-So by replacing the power suplly to heat bed wires with thicker, shorter wires I could increase the power a little bit. But this is not related to the heatbed heatloss or an inisulating effect. I also investigated if the problem was the forced convection due to the extruder fans. I could achieve slight imporvements but nothing spectacular. Dan Rogers posted his results (only 2 points) independently for his heat bed and it shows that mine is not out of family.
+Replacing the power supply to heat-bed wires with thicker, shorter wires meant I could increase the power a little bit - doing that does not affect the heat-bed loss or contribute any insulating effect though. I also investigated if the loss was caused by forced convection from the extruder fans. I could achieve slight improvements, but nothing spectacular. Independently, Dan Rogers posted results for his heat-bed (only 2 points) - the results suggested my bed was operating similarly.
 {{ :reprap:anet:a8:improvements:mypicture15.gif |}}.
-==== The power supllied to the heatbed ====
+==== Heat-bed Power ====
-As the curves where very similar I investigated if the controller was ajusting the PWM duty cycle and therefore the curves where a controler effect and not a thermodynamic. The voltage was a flat line on the osziloscope, therefore this theory was discarded.
+As the curves were very similar, I investigated if the effect was caused by the controller rather than being a thermodynamic effect (the controller adjusts the PWM duty cycle - and thus the curve). The voltage was a flat line on the oscilloscope, therefore this theory was discarded.
-Than I measured the current and observed that it drops with increasing temperature.
+Then I measured the current and observed that it drops with increasing temperature.
 {{ :reprap:anet:a8:improvements:mypicture2.gif |}}
-If the resistance is calculated by divinding the voltage through the current this leads to the following resistance{{ :reprap:anet:a8:improvements:mypicture3.gif?direct&400 |}}
+Resistance is calculated by dividing voltage by current - this lead to the following resistance{{ :reprap:anet:a8:improvements:mypicture3.gif?direct&400 |}}
-And this gradinet fits nearly to the gradient expected for cupper with an temperature coefficient of appximatly 0.0039 1/K
+This gradient nearly fits the gradient expected for copper with an temperature coefficient of approximately 0.0039 1/K
-This is probably also the reason why there are values of 1.2 to 1.6 Ohms mentioned in some forums and sites for this heat bed.
+This is probably the reason why there are values of 1.2 to 1.6 Ohms mentioned in some forums and sites for this heat-bed.
 ==== Simulating the heat bed ====
-In  order to undertstand the heat bed behavior in more datail I made a {{ :reprap:anet:a8:improvements:warm_up_2.xlsx |heat bed simulator}} in excel (dispite I don't like to this software for simulations). It fits quite well to the measured data, therefore it seems to be not so bad. But keep in mind that it is a model and not the reality.
+In  order to understand the heat bed behavior in more detail I made a {{ :reprap:anet:a8:improvements:warm_up_2.xlsx |heat bed simulator}} in Excel (despite not liking this software for simulations). It fits quite well to the measured data, therefore it seems to be not so bad - but keep in mind that it is a model and not reality.
 {{ :reprap:anet:a8:improvements:mypicture4.gif |}}
-The cool thing about simulations is that you can evaluate heat fluxes which are difficult to measure and to make a serios of variations which would require months of testing in a few minutes.
+The cool thing about simulations is that you can evaluate heat fluxes which are difficult to measure and to make a series of variations which would require months of testing in a few minutes.
 {{ :reprap:anet:a8:improvements:mypicture7.gif |}}
-When the steady state is nearly reached the initial 110W of electric power are reduced to 0 by the following contributions (for a heat bed without insulation). It can be seen that a large portion of the heat is irradieted by infrared radiation. This should possible to easily reduced by a factor of 8 to 9 by applying a aluminium foil(emissivity 0.11) beneath the heatbed or insulation.
+When the steady state is nearly reached the initial 110W of electric power are reduced to 0 by the following contributions (for a heat bed without insulation). It can be seen that a large portion of the heat is radiated by infrared radiation. This should possible to easily reduced by a factor of 8 to 9 by applying a aluminium foil (emissivity 0.11) beneath the heat-bed or insulation.
 {{ :reprap:anet:a8:improvements:mypicture8.gif |}}
@@ Line 78: / Line 78: @@
 ==== Analysis with the simulator====
-It can be seen with these curves that a quite thick insulation is nescessary for a large effect onto the heat curve.
+It can be seen with these curves that quite thick insulation is necessary for a large effect on the heat curve.
 {{ :reprap:anet:a8:improvements:mypicture9.gif |}}
 {{ :reprap:anet:a8:improvements:mypicture13.gif |}}
-Nearly half of the of the heat is lost by infrared heat radiation. Therefore an aluminum foil at the bottom is more effective than 6mm of kork. To reduce the heatloss even more combine them.
+Nearly half of the of the heat is lost by infrared radiation. Therefore aluminum foil on the bottom is more effective than 6mm of cork. To reduce the heat-loss even more, combine them.
 {{ :reprap:anet:a8:improvements:mypicture14.gif |}}
-It can be seen with these curves that increasing the voltage on the heatbed increases the speed and max temperature. This can be achived by 3 measures:
+It can be seen with these curves that increasing the voltage on the heat-bed increases the speed and max temperature. This can be achieved by 3 measures:
-  * Use thicker wires between HB and board and board and power suplly.(see the optimization chapter below)
+  * Use thicker wires between heat-bed and the board, and board and power supply (see the optimization chapter below).
-  * Solder the wires directly onto the heatbed (some soldering practice needed)
+  * Solder wires directly onto the heat-bed (some soldering practice is needed).
-  * increse the voltage of the power suplly. This might be risky and is only recomended if you have [[reprap:anet:a8:replace_connectors|replaced the orignal connectors]]. The power suplly might exeed its limits, therefore a power suplly with 30A at least is recomended by some users if 14V is used. Thoretically the arduino in the Anet board can go up to 18V but only 12V is recomended for arduinos. So it should be possible but it is your own risk.
+  * Increase the voltage of the power supply. This might be risky and is only recommended if you have [[reprap:anet:a8:replace_connectors|replaced the original connectors]]. The power supply might exceed its limits, therefore a power supply with 30A at least is recommended by some users if 14V is used. Theoretically the Arduino in the Anet board can go up to 18V but only 12V is recommended for Arduinos. So it should be possible, but it is your own risk!
 {{ :reprap:anet:a8:improvements:mypicture11.gif |}}