I Can't Get A Break

[Zulfe]

If you've checked my recent posts, I've been having trouble with filament recently. I finally fixed the issue and printed off some quadcopter pieces. I noticed the next morning that they had layer separation on them, which was weird being that they were in a small, closed space (better environmental heat) and they were short (better inner heat). When I tried heating up my bed for tonight's prints, it wouldn't heat. The screw-down connectors for my bed are melted. The board has burn marks on it and the connector is done. I can't think of what to do next other than buy a new board or find a way to run the bed off of D09.

Any tips?
Photo Oct 14, 12 08 28 AM.jpg

[Mjolinor]

Take some better pictures.

It doesn't look too bad but it isn't good to see. Certainly I have seen a lot worse.

You should be whinging at whoever built the printer as that is caused by not tightening the wires enough.

It seems that for some reason a lot of these 3d printer makers decided they should solder the ends of the wires that fit into screw connectors. Tinning the wires for screw connection is an absolute no, the wire should be stranded and not tinned with anything if it is to fit into a screw connector. If you do tin them then this is what can happen.

[Zulfe]

I built the printer myself, but I know for a fact that I tightened all the screws down very much. I've broken screws in the same type of connector in the past due an issue of over tightening in the past. Maybe vibrations caused the screws to loosen over time? I could easy be the problem too, as much as I'd like to think otherwise.

[Mjolinor]

Did you put solder on the wires before putting them in the connector?

[printbus]

Whether you use the direct solder screw terminals or the pluggable connectors won't make a difference in whether loose wire strands or something shorts between wires. The biggest difference you'd be making with the heat bed relay is that any high current issue related to the heat bed is kept on the heat bed relay, not the main controller. As mentioned earlier, adding an inline fuse would be one way to ensure some protection beyond what the power supply itself will do.

Whether you move the heat bed control to D9 sort of depends on whether you're ever going to want to have a print cooler controlled by the slicer with that controller. We don't even know that the D8 is unusable - the picture isn't good enough to offer much input on that. I'd pull the RAMPS board off the Arduino board and inspect both sides of the board any trace or component damage. If you don't see any, reinstall it and test it, maybe using a light bulb or voltmeter as an indicator rather than the heat bed. If that works I'd then wire in the heat bed just for the shorter heat up time.

Since the 10-inch i3v comes with a heat bed relay by default, this must be an 8-inch i3v?

[Zulfe]

Yeah, it's the 8-inch i3v.

I've taken some more images with a better camera, though it still had trouble focusing because of how close I had to be. I tried to avoid disconnecting all the motors, switches, and thermistors, but I feel like I've taken a few good images.

I can't upload the images here because they're too big, so you can find them here:
http://s2.postimg.org/c4lxy58jt/DSC_0004.jpg
http://s14.postimg.org/ykriyxifl/DSC_0003.jpg
http://s27.postimg.org/cidl51wmb/DSC_0001.jpg

If you're still having trouble seeing the issue, I can take down the entire board.

[printbus]

Like Mjolinor said, the picture doesn't show us much. Another possibility is that the wires to the heat bed were allowed to flex at the screw connector and wire strands slowly started breaking off, leading to remaining strands overheating at some point.

[gmay3]

Sorry to hear it Zulfe, don't be discouraged by these few issues you're having, stuff like this can just happens when you build your own 3d printer! You'll get it working!

Personally, I've tinned my wires that go into each screw terminal because in my experience, connections pull out more easily and are weaker when left stranded. Regardless, whether they are tinned or not, I don't think this alone is the root of your issue. It is more important to make sure that all of your wire slack is anchored to the frame so the wires aren't pivoting at the board connection when the printer moves. Your issue is that that one wire touched another while both were in the connector either by loosening slightly after being pulled on by the printer or by having too much wire exposed between the connection and the insulation during the installation. This also makes me want to go back and check that my screw down terminals are still tight!

Before buying a new board, does it still provide all other functions except the heat bed? If so, could you remove the burned connector and solder the heat bed wires directly to the board? To test this I would power down your printer first and remove the heat bed connector. Once it's cleaned up command the heat bed on with prontorface and measure the voltage between the two pins on the board where the connector used to be, also being careful not to touch the multimeter leads together. If everything's working the best practice would be to order a new screw down connector to replace the burned one. If you need help finding a replacement I'm sure we could help you look.

UPDATE BEGIN
I recently redid all the wiring and wire routing on my printer and after testing the strength of tinned wires and untinned wire terminations in the screw terminal, I 100% agree with printbus and Mjolinor that the wires in a screw terminal should NOT be tinned. Especially if you are trying to fit more than one wire into the terminal. Make sure that you twist the ends of your stranded wire before inserting the untinned end into the screw terminal. Many thanks to printbus and Mjolinor for educating me!
UPDATE END

[printbus]

There's probably a NASA workmanship standard out there somewhere that details it, but Mjolinor is correct in how stranded wire should never be tinned when the wire will be crimped or tightened under a screw head.

Yes, it appears to provide a more solid initial feel for the crimp or the screw terminal. The problem is that solder isn't as solid as it seems. When put under pressure (as in a crimp or screw terminal), the solder will slowly creep and flow out of the way, loosening the connection. It's just a matter of time - maybe months or more, but it will eventually lead to a poor connection.

[Zulfe]

Thanks for all of your suggestions, guys. It really shines some light on this crappy situation. I'm actually quite lucky I didn't burn my house down when this happened, as my printer is located in my room's closet. If the wooden frame caught fire, who knows what could have happened.

I'll take the board off the frame and analyze it some more and take some pictures when I get home. Maybe we can find a solution that won't require me buying a whole new $50-$80 board/shield. Funds are tight right now and I'm really counting on my printer being up and running to create pieces for some of my current projects. I don't really see the usefulness of a screw terminal on a vibrating machine since the potential of the vibrations loosening the screw is always a possibility. I would've preferred a pin connector like the rest of the board uses for the motors and thermistor. I also assume that it was entirely my fault for this happening since there was a very small amount of exposed wiring sticking out of the connector, creating the possibility for this issue to occur. My first solution is to modify the board's code to run the bed off of D9, which is completely unaffected. In the pins.h file, the bed runs off of '5', so I'm not sure how to go about moving it to D9. I'll eventually upgrade to a RAMBo board anyways, but I just need a quick fix in the mean time.

Thank you everyone.

EDIT [10/14/2014 @ 9:30AM]: Colin just replied with:
"I have seen that before if the heat bed is struggling to maintain the target temperature. There are a couple things that can help with this, first make sure you have insulation under the heat bed, next a heat bed relay will be the biggest help, if you get the heat bed relay you can move your heat bed to d9, if you do not get a heat bed relay d9 will quickly get damaged if trying to run the heat bed. The relay will let you reach higher heat bed temps at faster speeds, otherwise 110c may be difficult to reach.

From what I have seen in the past this is just due to very high current, not from shorting. The heat bed technically is shorting the two wires out so it can't be protected.


Here is the relay:http://www.makerfarm.com/index.php/p...bed-relay.html"