Adding a small 8.5x8.5 heat bed.

[konton]

Hi,

Has anyone added a heat bed? I'm still waiting on my relay for my 18"x18" headbed, so I thought I might try using a 8.5"x8.5" head bed I have lying around. Will I need to replace the power unit in order to make this happen? I'm wondering if adding the heat bed will pull too many amps.

Justin

 

[raykholo]

You could tap it into the 3rd screw terminal where the hotends plug in, but you'd have to re-route the cooling fan to a different port and make that change in the firmware. A circuit like this would be needed: http://www.geeetech.com/wiki/index.php/Reprap_Ramps1.4_RRD_Fan_Extender
The small bed can be powered directly through the control board that way.


I've had a lot of success printing PLA onto COLD glass by putting a thin layer of glue stick on the glass. Works beautifully and lasts through multiple prints. So if you ever take the blue tape off, give this a shot.

Can't say if it'll be enough for ABS (good chance it won't be, but I'll let you know as soon as I get my filastruder).

 

[konton]

Thanks Ray,

I was more concerned if the power source can take the amps.

Actually right now I am just trying to figure out why boards heat so slow. I did a heat test connecting them directly to a power source and they seem to max out at 70c.

Justin

 

[raykholo]

Yes, the included power supply should be able to handle the small heatbed.

I never ran it higher than 70 on the Printrbot, but some people print ABS on a 110 degree bed so who knows?

See what the temp. readout is in Repetier-host if/when you end up installing the bed.

 

[sherpa_chris]

With no insulation, could the rest of the bed be acting like a huge heat sink that prevents the board from getting past 70 degrees? If you try to heat up the bed while it's sitting by itself can you get above 70?

 

[raykholo]

Cork sheet and an exacto blade, gentlemen.

 

[konton]

Turns out it was actually more of an issue with the wiring. Not a good enough gauge to handle the wattage. Plugged directly into the power supply with proper wiring it high 90 and was creeping to 100 when I decided it was a good enough test. I'm still concerned the gMax can't handle the current with the power supply it's using. Luckly I have an extra Ramps 1.4.

I'm not sure if I should up my voltage. I was told this thing was supposed to get to 100C in 5 minutes. More like 40 minutes.

Justin