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Fan doesnt let the bed heat up

Posted by Sardi 
Fan doesnt let the bed heat up
March 13, 2017 07:57AM
I noticed this a while ago but didnt take much of it, however, now Ive installed a second fan on the X arm to cool the parts, and it cools the bed a lot. So much actually the temp of the bed drops 7C when its on and cant rise.

Both fans actually cause the same issue.

The hot end fan (mounted on a One-piece fan/heatsink duct with modified cable tie point by dc42) slows the heating of the bed if left at x100y100, I could wait forever by the looks of it.

The added fan is a CPU Cooler Master A6015-40RB-3AN-PI 12v DC 0.23a 60x60x15mm. The airflow does not seem to be all that big, but never the less it cooled the bed during print for about 7-8C and untill I disconnected it, the bed couldnt keep up.

Could anything else be causing this beside the fans? Anything firwareish?
Re: Fan doesnt let the bed heat up
March 13, 2017 08:50AM
It sounds like you have an under-powered bed heater or the voltage on the 12V line is low or dropping under load.

If you are not using an ATX power supply then it probably has a voltage adjustment pot at one end of the terminal block, which you can use to turn the voltage up a little.

If your printer is an Ormerod 2, check the connections between the bed heater cable and the bed heater. They sometimes go bad. The design was changed on later Ormerod 2 kits.


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Re: Fan doesnt let the bed heat up
March 13, 2017 11:05AM
I used to have my Ormerod 1 in the signature, not sure how that went away ..

Anyway, I have the original ATX .. Maybe its time for a new psu? Could loose connections also be at fault?

Edited 1 time(s). Last edit at 03/13/2017 11:17AM by Sardi.
Re: Fan doesnt let the bed heat up
March 13, 2017 01:42PM
The original ATX is just fine, I run my two ormerod1 with those

Measure the voltage on the heatbed - where the cables is attached - 10.9V is sufficient to heat the bed to 125C in 10 to 12 minutes - if you have proper isolation under the bed that is - I use radiator foil with the aluminium side against the heatbed, it's OK to 125C degrees but not higher

BTW, its much better to keep the cooling air around the nozzle (cooling ring) where it's needed than flushing the whole bed

Erik
Re: Fan doesnt let the bed heat up
March 13, 2017 01:46PM
Quote
Sardi
..Could loose connections also be at fault?...

Yes but not on a longer timeline, it would burn out and you would smell it

Erik
Re: Fan doesnt let the bed heat up
March 16, 2017 03:59AM
Quote
ormerod168
if you have proper isolation under the bed that is -

I have the ol` classic cardboard insulator under the heatbed.

Quote
ormerod168
BTW, its much better to keep the cooling air around the nozzle (cooling ring) where it's needed than flushing the whole bed

Erik

The best thing here is to model a fan duct of my own and print it.
Re: Fan doesnt let the bed heat up
March 16, 2017 04:42AM
Quote
Sardi
I have the ol` classic cardboard insulator under the heatbed.

This is the material I use



Sealed around the edges with kapton tape



OK up to 125C, 150C not so much..



Cork and a reflective layer of alu foil would be a better choice for higher temperatures

Erik
Re: Fan doesnt let the bed heat up
March 21, 2017 10:04AM
As I see it now, even the original ormerod hot end fan (mounted where it should be) is lowering the bed temp as it prints the brim.

EDIT: Backslash eliminator eliminated the problem ...

Edited 1 time(s). Last edit at 03/21/2017 10:11AM by Sardi.
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