Good Afternoon All,
I now own an Ambition Mods Bi2hop, and I love the unit - great flavor, easy to build, gravity feed keeps contamination out of the tank, and it’s the best wicking RTA I own - MTL or DL.
However, there is a problem noted by others that I can confirm - the deck o-rings. Despite the fact that I liberally lube all the o-rings in the unit following every wash, the o-rings have already started to shear and destroy themselves after only a couple of months. Those who have a Bi2hop (or it’s predecessor, the Bishop V1) will know that the decks are constructed such that you cannot gently twist the tank onto the deck - it must go straight down, and the fit is extremely tight.
Here’s my question: The Ambition Mods page for the Bi2hop calls these NBR o-rings which I assume are metric. Does anyone know:
What size are these?
What would be the next size down of the o-ring cross section?
Reduce the diameter, or reduce the cross section size?
How can I accurately measure NBR o-rings for replacement?
There is a company called Allorings.com, located at:
To measure you can either get a tool or use calipers to get the ID (inner diameter). From there it’s just a matter of matching the sizing of no calôipers you can get things to print out online a sheet that has the sizes and you plop the oring on top and match it up. The next will be finding the durometer which should be firmer, but going a size smaller while maintaining the thickness has always worked for me. It will thin out as it stretches
Every oring spec I’ve seen posted by mfgrs has been metric, and whole numbers. Ordering really comes down to 3 main things. The ID (inner diameter), the thickness, and the material it’s made from.
I use my digital caliper to measure the thickness first, then the OUTER diameter and subtract 2X the thickness to get the ID. The material is important as that (apart from other things) determines the squishiness of the oring. As an example my Taifun GT5 (stupid f’ing tank) uses 3 different materials overall. *only time I’ve ever seen that.
Good Afternoon All,
I just wanted to post a follow-up on this because I have good news. As I had mentioned, when I measured the spare o-rings from my Bi2hop kit, I came up with 16 mm outside diameter, 14 mm inside diameter, and 1 mm cross section from the spares. I didn’t even bothering measuring the o-rings that were already installed because they are stretched and damaged.
I found NBR (nitrile?) o-rings on Amazon, and ordered 15 mm outside diameter, 13 mm inside diameter, and 1 mm cross section replacements that arrived today, and I wasted no time installing these with liberal lubrication with VG. I’ve not yet wicked and filled the unit, but I can tell already that the fit is MUCH better. The tank section slides onto the deck SO much easier and is still snug enough that the tank does not come off when picking up the unit by the tank. Removing the tank from the deck used to be an absolute fight - now it’s an easy but still snug pull. The improvement is night and day so I can whole heartedly recommend this upgrade to Bi2hop owners. Thanks again to @JoelSq and @Wayneo for their helpful suggestions - the size-down has worked an absolute treat! Here’s the link for the o-rings I ordered!
