3D Printer heated bed repair

I was happily printing away when I heard a noise to my right, which is where the 3D printer is located.  Quickly looked over and saw flames...  Real, honest to goodness, flames, like FIRE......  Now I know why there's a STOP button....

I pummel the stop button with my finger and everything stops and all temperatures are set to zero, PHEW.  However, there is an aftermath, and a resolution, documented here....  Here is the complete album.

Angst ended here

I took divine inspiration from what Michael Peters did from the RigidBot Google Plus community.  My setup is very very similar to his, with some changes based on materials I could find and my overall setup.  Here is his larg'ish step by step documentation on what was done.

Now, my moment of angst ended like the photo shown.  Upon reading the community, everyone says this connector is a ticking time bomb, yet I never thought it would happen to me..  Famous last words, amiright?  Am lucky in that the damage started on the far right and stayed away from the thermistor leads, otherwise it would've been more work and/or replace bed itself.

My lug

As didn't know exact parts he used (part numbers and the like), did the best I could.  My first bit of hassle was finding the copper lug he referenced in the document.  Wound up getting these from an auto parts store (AutoZone I think).

Finished "lug"

To resize it, used a Dremel and snipped off the end, then trimmed the side.  Did both of these with the copper piece in a pair of lockjaw pliers.  I know, not safe but when in need do the needful.

In the picture, you'll notice that one side is smaller than the other.  In a later picture will notice had to do this to keep the hole as far from the outer edge as possible, and trimming only one side let me do a little less work.  Used a little buffing wheel to make it shiny and remove oxidation.

Hole Marking

After cutting the lug up, marked an area on the platform to get drilled out.  While marking the hole, also decided to mark the outer edges as will have to scrape the green stuff away.  Not sure what it's called, but green coating is protective and covers the copper underneath, preventing damage, and also insulates it so nothing gets shorted..

Starting the hole

To get the hole started, used a scratch awl to make an indentation, then a small drill bit to make the first hole.  As Michael said in his document, it's best to start small and go larger to prevent cracking the board.

Hole complete!

Kept enlarging this hole, ever so slowly, until used a 5/16" drill bit.  When using a 1/4" bolt, this gave, ideally, 1/32" on either side as an insulating factor.  In my case, had to expand this a little, details to follow.

Almost to the end

Then came the scraping, and more scraping, and more scraping.....  I used a retractable box cutter to make it happen.  While I didn't use it for nefarious purposes, it came in handy for this task.  With the blade extended, very lightly traced along the black marks.  Traced very lightly so wouldn't cut through the copper itself.  Then slowly, and lightly started scraping the green stuff off, holding the blade at about a 30 degree angle.

Even though there was a lot of green stuff left after scraping, figured had exposed enough copper to get great contact with the solder.  From that picture did scrape a little more, though was worried would scrape too much so decided to stop.

Dry fitting

In order to clean this, for good contact and easy flowing solder, I used some Carb / Choke cleaner.  Brand doesn't really matter, but some brake cleaner would have been better.  I was too lazy to walk outside and get some brake cleaner.

Another dry fitting of the copper piece proved that had shaved off just enough.  Next step was to solder it in place, which was harder than I imagined, though finally got it.

Now, just as am writing this, realized didn't capture a post image of what the top side looks like.  Rest assured, it's soldered in place securely but doesn't look all that pretty.  That's not the reason no picture, it's I plum forgot.  There's a larger overview picture that will be shown later.

Bolt centered

Due in no small part to the "fun" I had while soldering everything in place, the copper lug came a little off center.  Rather than try and remelt all the solder with my 40 watt iron, chose to use a dremel to make things right!  This picture is after I made things right!

Here is another step where I deviated from the guide, only because couldn't find a nylon shoulder washer locally. NOTE:  First prices I found on Amazon seem astronomically high.  Not sure if it comes in a multi-pack or not, but still very high.  With that aside, this is what I should've used.

Gasket Sealer

In my case got the chance to use some Gasket Sealer, picked up from Ace Hardware.  According to the package instructions this is good until 400 degrees Fahrenheit, which is much higher than bed is capable of.  Not sure what electrical resistance is like, or long term durability, but will find out soon enough.

I squirted this stuff in the hole, around the bolt, and let it sit overnight.  Neglected again to take a picture of this process, though have one later.

Negative wire pad

All of this work was for the positive wire.  It is now time to hook up the negative.  In this case only had to clear a space on bottom of the board.  Judging by this, I would have to say top of the board is almost exclusively positive current, while bottom is negative.  That's only a guess on my part, educated, guess nonetheless.

Now, here is my glorious soldering job, at least on the negative wire.  The soldering iron I have seems to have been a "tad bit" underpowered for the job, though was able to make it work.  There shouldn't be all those blobs of solder, yet at this stage didn't want to change a thing.  Was more than ready to stop it all.

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Here will also find the completed assembly for the positive (red) wire  Notice the gasket material (black) under the nut and connector?  This is what let sit for the night.  This allowed the liquid to settle down and around the bolt where used the dremel to make nice edge clearances.

Now came a problem..  Only had one meter (~3 feet) of wire, and if followed the instructions, wanted me to create a stress relief loop (great idea).  Problem with that is would've needed to splice additional wire in place, as control board is on other side of the printer.  It was here that a novel idea cometh upon me.

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The novel idea was to run wire directly underneath the bed to control board.  In and of itself this provides a stress relief of sorts.  And, yet again, fail to take an overview picture of the whole thing, though here is one of the spots where put a glob of sealant, then pressed the two wires in.  Can also notice how I routed this away from the thermistor.  Didn't want the potential to give it improper readings.

As a cheat trick, instead of waiting overnight for the stuff to firm up, turned the heat on for build plate (also to test) and set it for 60 degrees Celsius.  Within 10 minutes the outside was firmed up, and within twenty everything was firm enough.  Not quite sure what the longevity of this will be, or if additional damage could happen to the board (like green stuff peeling away), but for now it seems OK.

Wires connecting to board

On the other side, after getting it in place, I scavenged one of those cable clips from the satellite dish install on top of the roof.  It was a little too big so used some zip ties to secure all the wires in place (two power and two thermistor).  It seems to keep everything in place really well with no movement.

One change not documented in pictures is the thermistor cable.  I had recently begun taking apart my MakerFlop(Bot) CupCake 3D printer for parts, and had a female connector that accepted two prongs.  Simply cut the old thermistor wire, attached this new one, spliced everything together, and it's all acting hunkey dorey after plugging it in.

Glass

There are two additional changes I did, the first was to replace the aluminum build plate with glass, and second is to put cork underneath.  As a temporary solution got some glass from Home Depot.  This came in at exactly build size area, 12 x 16 inches.  Ideally would have wanted 13 x 16 inches so that the clips (holding glass in place) wouldn't reduce the available build area.

Money shot

Here's the money shot...  Everything in place and printing.  If notice the clips holding glass on, underneath will also see some thin cork.  This cork helps prevent heat transfer from going down.  Doesn't prevent all, but a good portion.  Am thinking of enhancing this by adding another layer of cork as well as maybe some aluminum foil sandwiched in the middle.  Unsure if that will help with anything or just be a pain.

Now, from what I gather, after people see the money shot, it's time for cuddling.  Here's Paisley and Bob laying on my organic duvet, enjoying quality time together.

Paisley and Bob