Heatbed redesign
Posted by twicx
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Heatbed redesign April 19, 2014 12:35PM |
Registered: 10 years ago Posts: 42 |
So having found that my old heatbed couldn't get up to the right temperatures for ABS, I've been battling a serious redesign over the last few days. And now I'm stuck.
Originally, it had 4 x 4.7R power resistors in parallel. Now just a note on this, these were from the original manufacturer, and were rated for 15W. I'm fairly sure they were operating WELL outside their recomended tolerances.
Anyway, at first I figured I could just swap them out for 4 x 2.2R power reisitors, but I just noticed that I got 15W ones too, so I don't think they're much use without drilling holes and adding more resistors. So I've picked up some nichrome wire today in the hope that I can set something up with that.
The situation is that I have a 260 x 260 Aluminium printbed that will have a glass print surface on top. Ideally, I'm looking for around 100-120C temperature wise, but the maths side of working out how much nichrome I need is not going well. I have 0.375mm nichrome with a resistance of 4R7 per metre, so I need to figure out whether I want to do 2 coils in parallel or some other configuration.
Anyone able to help?
Originally, it had 4 x 4.7R power resistors in parallel. Now just a note on this, these were from the original manufacturer, and were rated for 15W. I'm fairly sure they were operating WELL outside their recomended tolerances.
Anyway, at first I figured I could just swap them out for 4 x 2.2R power reisitors, but I just noticed that I got 15W ones too, so I don't think they're much use without drilling holes and adding more resistors. So I've picked up some nichrome wire today in the hope that I can set something up with that.
The situation is that I have a 260 x 260 Aluminium printbed that will have a glass print surface on top. Ideally, I'm looking for around 100-120C temperature wise, but the maths side of working out how much nichrome I need is not going well. I have 0.375mm nichrome with a resistance of 4R7 per metre, so I need to figure out whether I want to do 2 coils in parallel or some other configuration.
Anyone able to help?
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Re: Heatbed redesign April 19, 2014 06:04PM |
Registered: 11 years ago Posts: 1,592 |
Dunno if this will help but its something to read while sat on the bog!
[reprap.org]
[www.reprap.org]
_______________________________________
Waitaki 3D Printer
[reprap.org]
[www.reprap.org]
_______________________________________
Waitaki 3D Printer
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Re: Heatbed redesign April 20, 2014 04:59AM |
Registered: 13 years ago Posts: 7,616 |
Quote
twicx
Anyway, at first I figured I could just swap them out for 4 x 2.2R power reisitors, but I just noticed that I got 15W ones too, so I don't think they're much use without drilling holes and adding more resistors.
When used as heating elements, the specified power rating doesn't matter. Typical RepRap hotends use 3W resistors to heat with 25 watts, after all.
What matters is the achieved temperature. It shouldn't exceed the rated maximum temperature.
| Generation 7 Electronics | Teacup Firmware | RepRap DIY |
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Re: Heatbed redesign April 20, 2014 08:53AM |
Registered: 10 years ago Posts: 42 |
Quote
Traumflug
When used as heating elements, the specified power rating doesn't matter. Typical RepRap hotends use 3W resistors to heat with 25 watts, after all.
What matters is the achieved temperature. It shouldn't exceed the rated maximum temperature.
Ah I see!!
[uk.farnell.com]
Max temp is 190, so considering I'm only looking for about 100, I should be ok, right?
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