Ramps 1.4 melting down

I was just sitting behind my laptop, while my printer was printing in another room.
Suddenly I've smelled a burning fume, like plastic. My first opinion was that the nozzle got stuck and that it was burning the PLA. But it seemed to be my Ramps 1.4 board when I got there.
The connector and also a piece of the cable of the heatbed was melting down. I managed to complete the print while I was checking the board after some minutes over and over. But it worries
me a bit. I want to go change the connector tomorrow. But I don't think I will get the full trust of leaving the printer unattended annymore while printing.

Has annyone else also encountered this issue?

(btw the heatbed temperature was set to 50c)



Edited 2 time(s). Last edit at 03/04/2016 04:19PM by Rockel83.

... have you soldered the wires ends?

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Sadly it's a common problem with RAMPS boards - those connector blocks are running at, or just over, their rated current capacity. It works if the connectors are the best quality, but the ones from China are rarely as good.

One solution is to use that output to drive a solid-state relay connected separately to the power supply (others will advise on the bast way to wire it up).

Thank you both for your replies.

To VDX: Yes, I've solderded all the wire ends of the printer.

To David J: Well It's strange to get this problem now. I'll be using this printer a lot for over a year now. Well I've tuned up the bed temperature from 45c to 50c to get more adhesion on glass. I've already mentioned that this was somewhat the maximum temperature for my setup because temperature wil rise verry slow above the 50c (think I'm even not able to reach 60c). Thought I was facing the bed limitations here. Well I.ve soldered a quite big and sturdy cable onto the headbed. So this probably gives some slight tensions on the connector while the bed is moving.
Well I've googled a bit, and burned Ramps connectors seems te be quite common problem. Especially the bed connectors. So using a relay would be a verry good option yes

Bought some new connectors today. Gonna replace all for new ones. It seems these can handle up to 16A, so I hope it will temporary holp up until I'll recieve the ordered 30A car relay.
Maybe I should turn the heatbed temperature back to 45c until then



Edited 2 time(s). Last edit at 03/05/2016 01:22PM by Rockel83.

Terminal blocks such as those on RAMPS are not designed to be used with stranded core wire at high currents unless you crimp ferrules on the ends. Tinning the wires with solder makes things worse, not better. What happens is that when high currents pass through the joint, the solder creeps and what was a tight joint becomes loose. Then the joint gets very hot and melts the connector.

Good quality kits have ferrules pre-crimped to the cable ends. If you can't crimp ferrules to them then you need to tighten up the terminal block screws regularly, especially during the first few days of use.

Edited 1 time(s). Last edit at 03/05/2016 02:52PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

... yes, soldering the ends for use in screw-terminals is a bad idea! - either use end splices or nothing ... simply twist the end and compress/thighten the strands with the screw ...

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Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Another update:

I've been printing a lot while replaced the connectors keeping a close eye on the scew tightness and the cable temperature. But everything works quite well again
Still waiting on a 12V car relay I've ordered. Once this will arive, I will use it for switching the headbed directly on the power supply.

Thanks for al your input!

Working on swapping from RAMPS board to a new Duet board. In swapping wires, my power input ends were tinned and worked fine but my hot end fans were just twisted and screwed down. However, looks like the hot end had a short at the terminal and overheated really fast...PLA was bubbling out the nozzle and even had some smoke at one point. Fortunately I also wired the fan to the always on by accident for cooling.

Can anyone provide any examples for how they terminated their wiring?

People above where recommended ferrules.


I've used these also on my previous job and are indeed great for wirring a lot of cables. Case is that you'll need for every cable diamter a matching ferrule. They're not quite cheap and you'll need a special tool to crimp them together, which is also not quite cheap. I didn't had these tools so I choose to soldering the wires (which will work if you'll check an tighten the screw connectors regelur as mentiond above by someone).

Cheapest i could just find:

[m.aliexpress.com]

[m.aliexpress.com]

[m.aliexpress.com]

Edited 1 time(s). Last edit at 03/13/2016 06:29AM by Rockel83.

Local hardware store didn't have anything small enough, will need to keep looking.

However, I did try tinning and adding heat shrink in the short term to make sure I wasn't dealing with any stray strands causing shorts. But in both the Duets hot end connectors, once I connect the wires, I seem to be getting shorts in the connector. Gonna try posting the issue in the Duet forum incase I screwed up the software, but wanted to follow up. Thanks for the help Rockel.

Again, just a quick update in case anyone ever has a similar issue as I encountered.

Turns out my problem wasn't with the hot end wiring, but rather a difference between how RAMPS and Duet handles end stops. I plugged my end stops into 3v3 and ground instead of signal and ground. Once I swapped out the 2-pin connectors for 3-pin connectors with the middle pin empty, board lit right up...literally. Apparently the Duet has LEDs for displaying your endstop status.

Plus, I managed to find the correct size ferrules with my 3-pin connectors.

No! the problem is NOT the connectors, it is the heated bed ohms. The resistance is too low on the heated bed. You are pulling too many amps.

I'd wholeheartedly back the automotive relay idea. I've been running a 30cmx20cm heated bed from one for months now and have had no issues. The clicking on/off is a useful audible alert to whats going on if you have your back to the printer. Found a great relay with built in blade style automotive fuse holder. Compared to an SSR its cheap, effective and the bed does not require precise control like the hot end, its a large thermal mass and bang bang control is more than adequate. Taking the high current switching off the ramps board is the best thing you can do. Plus it allows you to use a smaller PSU for the ramps, if you decide to use a second PSU @ 24v for the bed.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions