Does anyone have the exact specs for the barbed fitting used in the E3D Kraken?
I believe RC 1/8"-28, as dimensioned in the drawing, is actually 1/8" BSPT or G1/8. Though it might also be BSPP aka straight thread. He mentions using teflon tape which makes me think tapered, and I didn’t see an o-ring in his prior videos but that could have been removed.
The barb end looks to be 3/8" barb but I can’t tell for certain.
There’s no O-ring, I suggested it a couple times. A small countersunk ring around where the flange sits to keep an O-ring in place, would make that whole connection point a breeze, but likely just switching to the “proper” threads is just as good. According to some comments in the E3D Kraken tester community, the blocks that went out for testing were M8 but they were considering some different thread profiles.
The newer revisions are only going to have 1 side with a grub screw, and it’s going to be installed and sealed prior to shipment from what I can remember.
I sealed mine with teflon tape and it’s been perfectly fine. Though, I put so much on it the tip looked like a mini marshmallow.
Put an o-ring around the threads with a printed collar around it to keep it from swishing out too far. Something will be necessary to keep the threads from loosening, since you won’t be able to fully tighten it. Maybe thread lock, or something in the hole for the bottom of the fitting to tighten on.
Or, tape and tighten it once and be done with it. Sealing thread fittings are some of the simplest to manufacture, and probably the lightest.
You may be able to use a copper crush washer, as used on banjo fittings for hydraulic systems such as automotive brakes. Google DIN7603 or head to the auto parts store. Printed ABS washers may work in this application.
@ThantiK I agree. Oring seal or face seal (like JIC) would have been better. Tapered pipe thread seal is cheap and easy… But an inferior practice. I engineered and installed fluid handling and dispense automation equipment for 10 years. You are always going to fight leakers even in low pressure applications with low viscosity liquids like water glycol.
get out thecalipers and goto parkers or eaton and double check it looks like 1/8straight to3/8 barb. But always measure. Also straight pipe use pipe dope like locktite or equivilent to seal if that is what you are using them for. I would use NPTF threads and alsopipe dopefor extra security if in a liquid or gas application. good luck
I’m pretty certain these fittings will be factory installed with an industrial grade thread sealant from what @Joshua_Rowley mentioned in the Kraken testers group. I recall they will also have a larger hexagonal flange to allow the use of an o ring and better tightening.
interesting enough Fastenal has a universal pipe threat in 1/8. didnt believe it til I tried it myself on their 4 thread 4 way demonstration fitting.
Thanks for all the advice on this. I should have noted that I don’t actually own a kraken yet but rather I’m working on a solidworks model to share on thingiverse and grabcad so I want to make sure it’s as accurate as I can make it before I release it.
If anyone has one and can measure I’d be greatly appreciative
on my current water cooled hot end A high temp thread locker was used to seal the barbs, then i just put some zipties over the tube to prevent them from slipping off. I would stay away from o rings, you basically have a 160 watt max heater hooked up to an aluminum block the o rings wont last long in that environment. obviously you would always want to run the water cooling but If you forget or it gets unplugged a bad o ring could cause a leak and start a problem.
@David_Farmer_Digital good point about the temperatures. Hopefully the water cooling keeps everything relatively cool, but the material of any o-ring used should be selected to cope with potentially elevated temperatures. Usually, that means Viton. If the water allows high enough temps to damage even a nitrile o-ring, you probably have other problems too.
Seems like they took my advice.