Soldering Issues on Heatbed MK1 & MK2

Hi All,

We are in the middle of building our first reprap (SAE Prusa Mendel w/ Gen6 electronics). We've had a few things print, but we're still in the tweaking stage before things will really run smoothly.

One of the biggest problems we've run into is keeping the dang heatbed wires attached to the board. We started out w/ a PCB Heatbed MK1 with 12 gauge wire. However even if it seemed we had a really good solder connection, if we looked at the dang board funny one of the wires would disconect from the solder point. We did have the solder points on the underside of the heatbed & they were reinforced w/ kapton tape. We've resoldered each wire at least 6-8 different times. It is very frustrating. We don't want to use a smaller gauge wire and we finally killed the MK1 by soldering the wires back on too many times. So we finally bought a PCB Heatbed MK2. (note that we tried a few diff kinds of solder, but all of our other connections for everything else are still functioning perfectly)

We do not want to make the same mistakes, obviously, that we made with the MK1. What I'm looking for is any type of connector that anyone knows about that we can screw, crimp, etc the wire into and then put that into the MK2. Again, we are using 12 gauge wire & don't want to go smaller as this was recommended by several sites and fellow reprappers. Thanks for any help you can give.

Lindsay

You need to have some strain relief on the cable. I.e. only use the solder for an electrical connection not a mechanical one. Something like a cable clamp to attach the wires to the Y carriage and then have a small loop so the solder joints are not under tension and free from any slight movement.

You also need something to enforce a minimum bend radius on the thick wire, otherwise it will fracture one strand at a time until it catches fire. I use ribbon cable and a polypropylene strip to to achieve that on Mendel90, see [reprap.org]. The ribbon cable is lots of fine wires that add up to make up the current, but are flexible in one plane.

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[www.hydraraptor.blogspot.com]

Silicone wire like this is very flexible: [www.cheapbatterypacks.com]

But I found the wire from computer ps is holding up ok.

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Thingiverse ID Alan1279

Hi nophead,

The ribbon cable idea is definitely appealing. However, I can't seem to find what they use for the heatshield for the cable (looks like red plastic from the pictures) on that wiki post. Would you be able to spread some light on that? Thanks!

I use polypropylene 0.5mm thick. It isn't a heat shield, it is there to force the ribbon into a U shape with a rolling curve at the front so it always has the maximum bend radius.

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[www.hydraraptor.blogspot.com]

I used a dab of epoxy on the edge of the pcb where the wire exits. I holds well and maintains all of the strain of movement - and isn't that hard to remove if you need to.

For 10 amps, there is no way you need 12 gauge wire.