Robo3d claims to support abs and pla... But Nylon and PVA?

It doesnt officially say on the web page these are supported, but do I risk any problems in attempting to print with these materials?

 

Nope it'll work fine. It can print most any material that works with a bed below 85C and a nozzle below 290C

 

Mike is 85c the bed limit?

 

Yes, though if you have a power connector clip on your bed you should remove that to prevent it from overheating and shorting. The latest versions with ribbon cable should support higher no problem.

Still a good idea to ensure your Ramps board is sufficiently cooled. If that gets too hot it can cause issues as well.

 

I have the kickstarter version with e3d v6 and significant improved bed wiring. So what limits does the original bed have? I notice that it climbs slowly above 100c. Ive wondered if the limit is the power supply?

 

As mark said it's a combination of the power supply voltage leading to the max wattage. It's around 130W heater which is sufficient to get to 110C, just takes a really long time.

There's a couple things you can do without resorting to a new PSU. The original PSU has a potentiometer that allows you to increase the V_ref. If you turn this up a little you should be able to squeeze a few more watts out of the existing PSU. Since P=V^2/R even a little bit of voltage increase is beneficial.

Then there's a way of replacing the mosfet on the ramps board to have lower forward voltage, further increasing the available power to the bed.

Without any modifications to the ramps you can run 16v for a total power of 180W. With some modifications to the ramps you can run around 24v, though I'd suggest running an external SSR rated to 40W if you want to do that with the stock bed. Since that will be pulling around 400W at ~17A. A 20A SSR tends to trip off from heat so a 40A is really a better alternative.

@Ziggy has made his own SSR that seems to work great for him and greatly improved heat times.

 

Thanks I appreciate clarity. Your suggestion of tweaking the voltage on the power supply is appealing. For the sake of Safety can you clarify the head room if you are running 16 volts... Do you know what the limit is for

1. the RAMPS board
2. the limit of the bed
3. the power supply

Or were you saying that 16 volts was the limit of the headroom and to stay under that for safety? If that was the case, being the frady cat that I am I would probably only go to 13.5 since most 12 volt electronics allow for a 14.4-15 volt over voltage.

Will the POT allow tuning the Beds 12 volt rail only? I don't want to exceed the Arduino's regulator limits.

 

The 16v limit is I believe a function of the MFR1100/RGEF1400 polyfuse for the heater line. The MFR500 is apparently rated to 30v.


Looking at the Ramps 1.4 Wiki they suggest not using more than 12v and keeping the D1 diode in place: http://reprap.org/wiki/RAMPS_1.4#D1.2C_D2_-_Diodes If you want to run the ramps off of more than 12v it's a good idea to remove that diode and run the Arduino off USB power or 5v supply.

I don't think voltage fluctuations are really a thing unless you live somewhere with very unreliable power. The PSU is a single rail and will adjust both inputs.

 

With only minimal fires...

 

Mike I finally got around to this. I installed the SSR this morning (40amp) with massive heatsink. I tested it before installing and made sure I knew the wiring and tested the internal MOSFET it was using. I think the 12v 300 Watt heat pad that I was sent installed and tested two months back (they accidentally sent me the wrong one) weakened the RAMPS MOSFET because it recently died on my new heatpad (stuck on thanksfully I was there to see it). The 300 Watt heat pad would have caused the MOSFET to dissipate 13.75 watts of heat. I have since replaced the mosfet with an identical part and routed that to turn on my SSR. I wanted to ask you about adding a poly fuse to the SSR Source. The RGEF1400 only has a 14 amp ihold current which seems to be too small long term. I was thinking a ihold of 20 was a better choice if I ever decide to go with a bigger heat pad (current one is 13 watts). The problem with a bigger one is that the trip current is higher than I would think would be a good idea for the power supply. So I though I would ask if you had a suggestion?

17.5 ihold 29 trip
http://www.mouser.com/ProductDetail/Littelfuse/16R1750SGF/?qs=vNwBHymccZ/HpTDk7o%2bGNg==

20 ihold 32 trip
http://www.mouser.com/ProductDetail/TE-Connectivity/BD280-1927-25-16/?qs=bZ3KlHYEm0YeK3bvf6QNuw==

 

I don't think that the dissipation from the relay is off the RGEF

Maybe I'm not understanding your concern right

 

Sorry I did a poor job explaining. Most of that was just my adventure. My actual question had to do with adding a polyfuse to the SSR 12v Power Source so that I don't overload the power supply if the heat bed shorts. I installed a heavier heat pad and may someday install and even heavier one still. Here is my question. What is the highest amp rated poly fuse you would feel safe putting in? I've seen these two that have 17.5 or 20 amp ihold values but have a very high trip current (29 or 32 amps) that is well beyond what the power supply can provide. After looking around I'm thinking that a automotive fuse might be better but I'm not sure what the in-rush current from a heating element will do to it.

17.5 ihold 29 trip
http://www.mouser.com/ProductDetail/Littelfuse/16R1750SGF/?qs=vNwBHymccZ/HpTDk7o%2bGNg==

20 ihold 32 trip
http://www.mouser.com/ProductDetail/TE-Connectivity/BD280-1927-25-16/?qs=bZ3KlHYEm0YeK3bvf6QNuw==

 

I ended up installing an automotive fuse holder going to 30amps. I put in a 20 amp fuse for now. That should keep it safe.