Partially heated bed

Is that been done before, partially heated bed...?
On a larger printer it's a bit silly to warm the complete surface printing a small part.So the idea is to divide the bed in section that can be switched on or of as needed.
I posted this in another thread and someone pointed me to this section of the forum. He was told that a duet was capable of managing multiple heated bed sections.

That's correct. RepRapFirmware for Duet WiFi and Duet Ethernet supports up to 4 bed heaters and 2 chamber heaters. As there is only one high-current (18A) output on the Duet, you would need to use external SSRs or mosfet switches to control the additional bed heaters from heater outputs on the Duet or an attached DueX2 or DueX5 expansion board.

To tell the firmware that you have multiple bed heaters, use M140 in the config.g file, e.g. M140 H0:2 means that heater channels 0 and 2 are bed heaters. To set temperatures for bed heaters, use the P parameter in the M140 command when setting temperature. For example, M140 P0 S100 would set the first bed heater to 100C, and M140 P1 S100 would set the second bed heater to 100C. Currently, if you don't specify the P parameter then P0 will be assumed; but in a future firmware version we may default to all bed heaters instead.

Edited 1 time(s). Last edit at 06/11/2018 03:48AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

So I need to add G-code in the slicer to determine what section(s) of the bed needs to be warmed up...correct..?

Oh and btw way 4xbed + 2xchamber... Wouldn't that be the same as 6xbed...??

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chriske
So I need to add G-code in the slicer to determine what section(s) of the bed needs to be warmed up...correct..?

Yes. Although I am open to other suggestions, e.g. either another M140 variant to specify the default set of bed heaters to use.

You could use 6 bed heaters by declaring 2 of them as chamber heaters and using M141 to control them.

The limit of 4 bed heaters and 2 chamber heaters is fairly arbitrary, I could easily increase them but I haven't been asked to support more yet. Or you can increase them yourself if you recompile the firmware.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I was thinking about this the other day for Black Beauty.

How about allowing the user to configure the bounds of each heating zone, then when a file is printed scan the file to find the print bounds and only turn on the heaters needed to cover the print.

Yes that would be possible. Scanning just the first layer of the GCode file should be sufficient.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

How about printing multiple objects sequentially, wouldn't just scanning for 1st layer reveal the position (print bounds) of the just 1st object?

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xrodney
How about printing multiple objects sequentially, wouldn't just scanning for 1st layer reveal the position (print bounds) of the just 1st object?

Yes. But it's rare to print multiple objects sequentially, because unless they are small objects and the bed is large, the risk of the print head colliding with an already-finished object is too great.

Edited 1 time(s). Last edit at 07/18/2018 03:55PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

A good bed usually has a good heat spreader. ( per definion ) That's why multiple heat zones don't make much sense to me.
You could use a separated heat spreader per heating zone, then put a glass plate above. But would that really safe some energy?
A glass plate needs higher temps, AFAIK.

Edited 1 time(s). Last edit at 07/19/2018 02:10AM by o_lampe.

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o_lampe
A good bed usually has a good heat spreader. ( per definion ) That's why multiple heat zones don't make much sense to me.
You could use a separated heat spreader per heating zone, then put a glass plate above. But would that really safe some energy?

Another disadvantage of that arrangement is that you would probably need to use borosilicate glass to prevent it cracking due to the uneven heating; whereas ordinary float glass is safe to use if you have a single zone and a heat spreader.

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o_lampe
A glass plate needs higher temps, AFAIK.

In my experience, there is a drop in temperature across the glass of about 5C when using a bed temperature of around 60C, and 10C at 100C. So yes.

Edited 1 time(s). Last edit at 07/19/2018 05:31AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].