In the E3D Kraken cooler block, there is a big, 10 mm grub screw, along the side of the cooler block.

I watched the entire Kraken assembly video:

There was no mention of this very thick grub screw. The E3D Kraken assembly wiki page may refer to this part as the "stainless plug".

Does the depth of the screw inside the Kraken heatbreak affect the effectiveness of the water cooling?

Why was it included in the design at all?

I'm asking because water frequently leaks out of this pore for me, ever since I had to repair some damaged tubing. Additionally I often have to use an extra fan when printing at high temperatures. I'm wondering, before I epoxy this grub screw into place, whether the amount it is tightened into the Kraken has some advantages or disadvantages.

The video shows the part already assembled on the Kraken. This is what the part looks like - it is much larger than the screws used to secure heat throats. enter image description here


This stainless steel plug is necessary because of the fabrication of the cooler block. As this is a water cooled block, cold fluid flows in the inlet brass barb, and hot fluid out of the exit brass barb. The manufactured channel between the two is done through the hole that is later plugged by the stainless steel plug.

From the manufacturers website of the stainless steel plugs you can read that a tapered hole and sealant are required to make a tight seal:

They have a wide range of applications in sealing and require a tapered hole.


Replacing these plugs on the Kraken should only be completed if you are confident in your ability to achieve an adequate seal. We use Threadlock and a measured torque setting.

Be sure the hole has a taper, if you over-tightened if once it may have worn. Epoxy based glue would be able to be used at the cooler block, temperatures are not expected to be too high, but from the comments below it becomes clear that there are specific sealing products available for sealing the plug other than epoxy.

The depth of the grub screw is not likely to affect the cooling properties (it isn't expected to block one of the brass barbs).


The connecting channel between the two brass barbed hose fittings needs to be drilled out. To open that channel, a hole is drilled into the side to connect the two top holes (which have the brass fittings screwed into them). The hole doesn't need to penetrate both sides, but it must get through one side.

The grub screw seals the hole.

Instead of using epoxy to seal in the screw, you could use the PTFE (Teflon) white plumbing tape. It is specifically designed to seal threads.

If I remember, you can thread it in as tightly as you like. It won't interfere with the water channel.

I have a Kraken, and I looked at how to make another one.


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