<p>The heated bed is a reasonably good thermal conductor, so the difference in energy between heating all or 10% of the bed (assuming a 3x3 grid split 1 and 8) isn't going to be that significant. </p>

<p>In terms of heating speed, 200W across the whole bed will heat it faster than 40W applied to the centre square, and will also be less likely to cause warming or heat cycling effects (unless PSU regulation is a problem).</p>

<p>If the bed is much larger, or has thermally separated zones, then there might be some justification in the increased control complexity.</p>

<p>As an example, although glass has a thermal conductivity around 1% of a metal, it is still 30x better conducting than air. Conductivity towards the unheated areas of even a solid glass bed will roughly match the surface loss - so best case you would reduce losses to somewhere 20%-50% of what heating the whole bed might cost (assuming the same 3x3 grid).</p>

CC BY-SA 4.0
2018-07-11T12:22:42.530Z
I had the same concerns as you about conduction, but not come to putting it in words! The only thing I can think of to dispute this is thermal silicone heating pads (on an insulated body) in conjunction with a glass bed, glass is a poor heat conductor. Nice addition!
0scar
CC BY-SA 4.0
2018-07-11T10:41:57.237Z
2018-07-11T12:33:46.650Z
2018-07-11T12:33:46.650Z
Sean Houlihane
<p>As the etched version is very impressive (thanks 0scar for that), there are other possibilities to build zones on the bed:</p>

<ol>
<li>Using <a href="https://www.aliexpress.com/item/UD-wire-box-6-in-1-with-a1clapton-wire-braided-twisted-ni200-wire-nichromme-wire-for/32666221193.html" rel="nofollow noreferrer">resistance wire</a>;</li>
<li>Using a etched bed with zones.</li>
</ol>

<p>The challenge with zones is mainly down to:</p>

<ol>
<li>When and how to switch on/off particular zone;</li>
<li>Temperature control needs to be added to every zone to avoid over/under heat in the particular zone.</li>
</ol>

<p>This last point brings <em>even more</em> challenges as that requires a PWM channel and a temp sensor (per zone), so standard RAMPS need some extensions in the wiring.
One could overcome that using custom G-Code to set on/off zones and a double temp sensor for the main zone to follow the temperature changes.</p>

<p>In detail: a dedicated Arduino with PWM outputs that will read the temperature from a secondary temperature sensor in the main zone and follows it. </p>

CC BY-SA 4.0
2018-07-09T09:24:45.533Z
The commercial dual zone beds come with a controller to do that, indeed a simple Arduino should be able to do that. You could even alter the Marlin bed heating code to include an extra parameter that determines which bed to heat up. It seems that reprap firmware already has such functionality (parameter H). `Recent versions of RepRapFirmware also provide an optional 'H' parameter to set the hot bed heater number. If no heated bed is present, a negative value may be specified to disable it.`
0scar
CC BY-SA 4.0
2018-07-09T10:11:15.643Z
thanks for that @0scar, I have a 500mm X 500mm  bed, so I am thinking to slice it in 100mm zones, that gives 5 zones to be controlled, and RAMPS will not handle that without extending it as that requires at last 8 extra pins and some extra computing power which we know is limited.
profesor79
CC BY-SA 4.0
2018-07-09T10:19:30.850Z
100 mm squared makes 25 zones ;) What about control using i2c?
0scar
CC BY-SA 4.0
2018-07-09T10:20:20.107Z
it extends by 100mm so we have 5 elements
profesor79
CC BY-SA 4.0
2018-07-11T05:29:57.857Z
A rotary switch can help 2P6T, also are called selectors.
Fernando Baltazar
CC BY-SA 4.0
2018-07-11T10:06:46.040Z
@FernandoBaltazar thanks for that - great idea, but it will not be driven by G-code :-)
profesor79
CC BY-SA 4.0
2018-07-11T21:01:23.697Z
@profesor79 Can be driven normally the heat bed, you only select the area to be heated manually.
Fernando Baltazar
CC BY-SA 4.0
2018-07-09T09:04:05.150Z
2018-07-11T13:21:29.830Z
2018-07-11T13:21:29.830Z
profesor79
<p>It makes more sense to insulate &quot;unused&quot; areas, since the heat conduction goes with the surface area. Heating the plate at some place (instead allover the area) makes no big difference (aluminium is a very good heat conductor, this is already mentioned). But insulation will do. I would propose a downside full insulation (5-10 mm) and some &quot;windows-shaped&quot; square silicone (other thin material?) mats to cover the unused areas (mostly on the outer side of the bed) on the top side. Beware of collisions and auto-leveling algorithms (starting very often at corners). Side effect: you may reach much higher temperatures at the uncovered areas (might be doubled if covering half of the surface).</p>

CC BY-SA 4.0
2021-01-27T08:51:29.927Z
2021-01-27T12:38:11.770Z
2021-01-27T12:38:11.770Z
stoker
<p>it is probably too late for the party but i thought about grid heated bed recently. about controlling which zone to turn on and off, i think we can treat the grid as Led matrix, the matrix led signal can be used to drive mosfets to power the heat pads.</p>

CC BY-SA 4.0
2019-12-22T11:30:42.233Z
2019-12-22T11:30:42.233Z
Bùi Tuấn
<p>I've wondered that myself a while ago and fact is that such beds or silicone heating pads do <a href="http://www.formbot3d.com/dual-zone-heated-build-plate-and-digital-controller-for-t-rex-2_p0015.html" rel="nofollow noreferrer">exist</a>. Usually these are quite large (and expensive) and usually referred to as "dual zone heat beds/pads".</p>

<p>As far as energy consumption; less area to heat is faster heat up times (depending on the control) and less energy consumed. For small prints this may be beneficial. The price of such beds are very high, so to break even you would have to print a lot. An alternative to buying would be to <a href="https://reprap.org/wiki/Etched_heatbed_construction" rel="nofollow noreferrer">etch your own bed</a>.</p>

CC BY-SA 4.0
2018-07-20T19:56:27.410Z
Thanks. As I've been thinking over people's answers I can see you'd want to segment the heated areas in a number of ways: ideally a bit of a heat break, some kind of switching to turn on/off zones, they'd need their own thermistor, and finally something to control/interpret all of this back to the main board. Not something you'll find any time soon on a sub-$200 printer.
Gone
CC BY-SA 4.0
2018-07-08T21:39:27.063Z
2018-07-08T22:01:01.190Z
2018-07-08T22:01:01.190Z
0scar
<p>Waiting for a heatbed to get up to 85˚C for a relatively small part got me wondering why beds aren't hardware/G-code configurable for what area is heated? I'm sure it would be an increase in parts costs and electronics, but it seems that being able to just heat an area a little larger than the part(s) being built would save in time and energy use.</p>

CC BY-SA 4.0
2018-07-08T21:35:04.483Z
That is a *very* good question. It would require switchable sections of the PCB track, but how would those sections be configured? Differing radii of circular PCB tracks? or if in square blocks how would they be arranged, and how many (in halves, quarters, eighths etc.)? I guess the permutations for a square one are a bit more complex and numerous to be practicable. Doing it for a round heatbed seems simpler though. Also, how big would the market be, and would the added complexity in electronics (i.e. cost) and code be worth it. It seems a good idea though... Design a prototypePCB in EagleCAD?
Greenonline
CC BY-SA 4.0
2018-07-09T09:31:28.950Z
@Greenonline RepRapFirmware already has an optional parameter (`H` for `M140`) to select heatbed, this could possibly be used for that. For Marlin it will require some extra coding as `H` is not yet a supported parameter. Nice project!
0scar
CC BY-SA 4.0
2018-07-09T15:21:33.730Z
You must learn patience, grasshopper.     No, seriously: when you're printing anything that takes longer than 30 minutes to complete, the heating time is insignificant.
Carl Witthoft
CC BY-SA 4.0
2018-07-10T00:03:59.343Z
Well, not just all about patience ... do we really need a full 200W (~) element heating up non-used space for hours (days)?
Gone
CC BY-SA 4.0
2018-07-11T05:21:19.150Z
@Jer well, Using the whole heating element the heat bed reach the printing temperature in 3 or 5 minutes, using the half heating element the time increases between 8 to 12 minutes. I don't want to wait to get roots on my feet.
Fernando Baltazar
CC BY-SA 4.0
2018-07-12T12:10:13.103Z
I'm not sure why you are saying it will take more time to heat up. If I turn our stove's small burner on high it doesn't take longer to warm up than the large burner. Now, if there's zones each zone will also need to have its own thermistor to know when it has reached temperature.
Gone
CC BY-SA 4.0
2018-07-20T06:41:24.513Z
@Jer, the reason why it takes longer is called "conduction"; heat flows to the rest of the plate that is not heated, so it takes longer. Does any of the answers helped you to get an answer on your question or helped you come to your own conclusions then please do vote and accept an answer. This helps us reduce the [unaswered questions list](https://3dprinting.stackexchange.com/unanswered). Found an other answer (then the already posted) yourself? Please add that answer (and accept after 48 hours) to share your experience with the community.
0scar
<heated-bed>
Heatbed with zones?
Gone
# Heatbed with zones?

(Asked by: username_0 on 2018-07-08)

Waiting for a heatbed to get up to 85˚C for a relatively small part got me wondering why beds aren't hardware/G-code configurable for what area is heated? I'm sure it would be an increase in parts costs and electronics, but it seems that being able to just heat an area a little larger than the part(s) being built would save in time and energy use.

**Tags:** heated-bed

> **Comments:**
> **username_1**: That is a *very* good question. It would require switchable sections of the PCB track, but how would those sections be configured? Differing radii of circular PCB tracks? or if in square blocks how would they be arranged, and how many (in halves, quarters, eighths etc.)? I guess the permutations for a square one are a bit more complex and numerous to be practicable. Doing it for a round heatbed seems simpler though. Also, how big would the market be, and would the added complexity in electronics (i.e. cost) and code be worth it. It seems a good idea though... Design a prototypePCB in EagleCAD?  
> **username_2**: @username_1 RepRapFirmware already has an optional parameter (`H` for `M140`) to select heatbed, this could possibly be used for that. For Marlin it will require some extra coding as `H` is not yet a supported parameter. Nice project!  
> **username_3**: You must learn patience, grasshopper.     No, seriously: when you're printing anything that takes longer than 30 minutes to complete, the heating time is insignificant.  
> **username_0**: Well, not just all about patience ... do we really need a full 200W (~) element heating up non-used space for hours (days)?  
> **username_4**: @Jer well, Using the whole heating element the heat bed reach the printing temperature in 3 or 5 minutes, using the half heating element the time increases between 8 to 12 minutes. I don't want to wait to get roots on my feet.  
> **username_0**: I'm not sure why you are saying it will take more time to heat up. If I turn our stove's small burner on high it doesn't take longer to warm up than the large burner. Now, if there's zones each zone will also need to have its own thermistor to know when it has reached temperature.  
> **username_2**: @Jer, the reason why it takes longer is called "conduction"; heat flows to the rest of the plate that is not heated, so it takes longer. Does any of the answers helped you to get an answer on your question or helped you come to your own conclusions then please do vote and accept an answer. This helps us reduce the [unaswered questions list](https://3dprinting.stackexchange.com/unanswered). Found an other answer (then the already posted) yourself? Please add that answer (and accept after 48 hours) to share your experience with the community.  

---

## 5 answers

### Answer by username_2 on 2018-07-08. Score: 3 | Accepted answer

I've wondered that myself a while ago and fact is that such beds or silicone heating pads do [exist](http://www.formbot3d.com/dual-zone-heated-build-plate-and-digital-controller-for-t-rex-2_p0015.html). Usually these are quite large (and expensive) and usually referred to as "dual zone heat beds/pads".

As far as energy consumption; less area to heat is faster heat up times (depending on the control) and less energy consumed. For small prints this may be beneficial. The price of such beds are very high, so to break even you would have to print a lot. An alternative to buying would be to [etch your own bed](https://reprap.org/wiki/Etched_heatbed_construction).

> **Comments:**
> **username_0**: Thanks. As I've been thinking over people's answers I can see you'd want to segment the heated areas in a number of ways: ideally a bit of a heat break, some kind of switching to turn on/off zones, they'd need their own thermistor, and finally something to control/interpret all of this back to the main board. Not something you'll find any time soon on a sub-$200 printer.  

---

### Answer by username_5 on 2018-07-11. Score: 3

The heated bed is a reasonably good thermal conductor, so the difference in energy between heating all or 10% of the bed (assuming a 3x3 grid split 1 and 8) isn't going to be that significant.

In terms of heating speed, 200W across the whole bed will heat it faster than 40W applied to the centre square, and will also be less likely to cause warming or heat cycling effects (unless PSU regulation is a problem).

If the bed is much larger, or has thermally separated zones, then there might be some justification in the increased control complexity.

As an example, although glass has a thermal conductivity around 1% of a metal, it is still 30x better conducting than air. Conductivity towards the unheated areas of even a solid glass bed will roughly match the surface loss - so best case you would reduce losses to somewhere 20%-50% of what heating the whole bed might cost (assuming the same 3x3 grid).

> **Comments:**
> **username_2**: I had the same concerns as you about conduction, but not come to putting it in words! The only thing I can think of to dispute this is thermal silicone heating pads (on an insulated body) in conjunction with a glass bed, glass is a poor heat conductor. Nice addition!  

---

### Answer by username_6 on 2018-07-09. Score: 2

As the etched version is very impressive (thanks username_2 for that), there are other possibilities to build zones on the bed:

1. Using [resistance wire](https://www.aliexpress.com/item/UD-wire-box-6-in-1-with-a1clapton-wire-braided-twisted-ni200-wire-nichromme-wire-for/32666221193.html);
2. Using a etched bed with zones.

The challenge with zones is mainly down to:

1. When and how to switch on/off particular zone;
2. Temperature control needs to be added to every zone to avoid over/under heat in the particular zone.

This last point brings *even more* challenges as that requires a PWM channel and a temp sensor (per zone), so standard RAMPS need some extensions in the wiring.
One could overcome that using custom G-Code to set on/off zones and a double temp sensor for the main zone to follow the temperature changes.

In detail: a dedicated Arduino with PWM outputs that will read the temperature from a secondary temperature sensor in the main zone and follows it.

> **Comments:**
> **username_2**: The commercial dual zone beds come with a controller to do that, indeed a simple Arduino should be able to do that. You could even alter the Marlin bed heating code to include an extra parameter that determines which bed to heat up. It seems that reprap firmware already has such functionality (parameter H). `Recent versions of RepRapFirmware also provide an optional 'H' parameter to set the hot bed heater number. If no heated bed is present, a negative value may be specified to disable it.`  
> **username_6**: thanks for that @username_2, I have a 500mm X 500mm  bed, so I am thinking to slice it in 100mm zones, that gives 5 zones to be controlled, and RAMPS will not handle that without extending it as that requires at last 8 extra pins and some extra computing power which we know is limited.  
> **username_2**: 100 mm squared makes 25 zones ;) What about control using i2c?  
> **username_6**: it extends by 100mm so we have 5 elements  
> **username_4**: A rotary switch can help 2P6T, also are called selectors.  
> **username_6**: @username_4 thanks for that - great idea, but it will not be driven by G-code :-)  
> **username_4**: @username_6 Can be driven normally the heat bed, you only select the area to be heated manually.  

---

### Answer by username_7 on 2021-01-27. Score: 0

It makes more sense to insulate "unused" areas, since the heat conduction goes with the surface area. Heating the plate at some place (instead allover the area) makes no big difference (aluminium is a very good heat conductor, this is already mentioned). But insulation will do. I would propose a downside full insulation (5-10 mm) and some "windows-shaped" square silicone (other thin material?) mats to cover the unused areas (mostly on the outer side of the bed) on the top side. Beware of collisions and auto-leveling algorithms (starting very often at corners). Side effect: you may reach much higher temperatures at the uncovered areas (might be doubled if covering half of the surface).


---

### Answer by username_8 on 2019-12-22. Score: 0

it is probably too late for the party but i thought about grid heated bed recently. about controlling which zone to turn on and off, i think we can treat the grid as Led matrix, the matrix led signal can be used to drive mosfets to power the heat pads.


---

