300mm Heatbed Options

Hi All,

So I have got my delta printer working with PLA but I want to print with ABS so I need a 300mm heatbed, I have had a look around and am leaning towards the mains powered silicone heatbed, are these any good? What would I need to hook it up to the Ramps 1.4? is it something that can be bought or is it something that has to be made?

This is the one I was looking at [www.aliexpress.com]

Cant see any reason why this wouldnt work in the UK, Voltage is about right.

I also saw this one [www.aliexpress.com]

Much cheaper but I doubt it would heat up that fast only being 12v.

What do you guys think?

Here's one who has a silicone heatbed, I think you'll find all necessary info there!

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Make_3D
Hi All,

So I have got my delta printer working with PLA but I want to print with ABS so I need a 300mm heatbed, I have had a look around and am leaning towards the mains powered silicone heatbed, are these any good? What would I need to hook it up to the Ramps 1.4? is it something that can be bought or is it something that has to be made?

This is the one I was looking at [www.aliexpress.com]

Cant see any reason why this wouldnt work in the UK, Voltage is about right.

I also saw this one [www.aliexpress.com]

Much cheaper but I doubt it would heat up that fast only being 12v.

What do you guys think?

Silicon pads are great all you will need in addition to the pad is a DC-AC SSR (ebay for around £4) and to set the heatbed to bang-bang heat control.

Doug

Thanks for the responses,

is this the relay i would need? [www.ebay.co.uk]

So if i combine that relay with this heatbed it should work fine? [www.aliexpress.com]

From a safety standpoint, with the heatbed being powered by the mains in a printer with a metal frame is slightly worrying, as long as the frame is earthed with a fuse it should be okay?

Quote
Make_3D
Thanks for the responses,

is this the relay i would need? [www.ebay.co.uk]

So if i combine that relay with this heatbed it should work fine? [www.aliexpress.com]

From a safety standpoint, with the heatbed being powered by the mains in a printer with a metal frame is slightly worrying, as long as the frame is earthed with a fuse it should be okay?

That SSR would do but you can get this one AC-DC SSR which is a little cheaper and UK based stock.

You don't want a fuse in the Earth line just make sure that the metal parts are either earthed to the mains supply (Common with the PSU Earth) and make sure you are protected with a RCD on the supply (Most modern consumer units have them as std) you can use an RCD Adaptor on the Printer power cable something like this RCD

HTH Doug

Edited 1 time(s). Last edit at 09/25/2015 06:46AM by dougal1957.

This supplier [www.aliexpress.com] sells a 300mm round heater at a lower price and will make it to your voltage and power specifications. I chose 230V 350W. I suggest you use a SSR-10DA or SSR-25DA to control it, both are widely available on ebay.

Edited 1 time(s). Last edit at 09/25/2015 06:51AM 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].

Would 350w be enough on a heatbed of this size? Heatup times on my i3 used to drive me mad

I use a 300mm diameter 230V 350W heater with a 330mm x 5mm thick alu bed plate. It reaches 120C in 8 minutes and the temperature maxes out at about 200C. I wouldn't want it to max out any higher because that is also the maximum rated temperature of the silicone heater. If you use a higher powered heater, you risk damaging it if something goes wrong.

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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].

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dc42
I use a 300mm diameter 230V 350W heater

David, I read your article - are you still using seller supplied bed thermistor? Is thermistor very close to 230V wiring or not? Is 230V/~1.5A alternating current affecting thermistor ADC reading?

I still use the thermistor that is embedded in the heater. The Duet has filtering on the thermistor inputs, so mains pickup isn't a problem. OTOH the thermistor is embedded in the heater pad instead of being in direct contact with the aluminium bed plate, so it over reads. I use 70C indicated temperature for PLA, and 130C for ABS.

Edited 1 time(s). Last edit at 09/25/2015 06:05PM 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].

Quote
dc42
I still use the thermistor that is embedded in the heater. The Duet has filtering on the thermistor inputs, so mains pickup isn't a problem. OTOH the thermistor is embedded in the heater pad instead of being in direct contact with the aluminium bed plate, so it over reads. I use 70C indicated temperature for PLA, and 130C for ABS.

David

on the subject of the thermistor that is embedded I now have a full temp sheet for the one that Keenovo use and the B Value is quoted at 25/50 to be 3950.

How would I work out an adjusted b Value to get closer to say 100 degrees as a happy medium between PLA and ABS.

I have attached the table here if you would like it?

Doug

Quote
dougal1957
on the subject of the thermistor that is embedded I now have a full temp sheet for the one that Keenovo use and the B Value is quoted at 25/50 to be 3950.

How would I work out an adjusted b Value to get closer to say 100 degrees as a happy medium between PLA and ABS.

I have attached the table here if you would like it?

Doug

You can try different B values in the attached spreadsheet until it predicts a resistance @ 100C that matches the value in the table.

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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].