Exploding Suns

I’ve had reason to dive into the inner workings of the Teknatool SuperNova2 (SN2) lathe chuck, having experienced some weird results from what is meant to be a precision machined tool. The runout I was getting from a brand new chuck was both unacceptably high and much higher than the G3 chucks I have (which are also Teknatool fwiw).  The SuperNova2 is unquestionably a good chuck, so my experience is definitely an aberration.

I have exchanged the chuck for another SN2, and one who’s jaws are no where near as sloppy as the first chuck – hopefully that is a sign of the main point of difference between them.  To qualify my experience, I tried a number of jaws on the SN2 and two G3 chucks, using the same insert and it was only the SN2 that had an issue.  The body is probably fine – it is the moveable jaws that will be where the fault lay.

In the meantime, we (some of the staff at Carbatec and I) had a look under the hood of the SN2.  I was very surprised with what I found!  I’m not sure what I was expecting – some significant point of difference in the operation to the G3 perhaps.

SuperNova2 and G3 chucks

SuperNova2 and G3 chucks

The SN2 (on the left) is a larger chuck, with quite a bit more weight with the extra material, and a cover to discourage dust from entering into the mechanism.  It takes a hex key to adjust the jaws.

The G3 on the right seems a lot more primitive – no dust guarding, and the key to operate has teeth to mesh with the geared ring inside the chuck through two holes.

However, when the circlip was removed and the plastic cover popped off, inside the two chucks looked remarkably similar.

SuperNova2 internals

SuperNova2 internals

The plastic ring keeps two small gears captive, that once removed results in the SN2 looking exactly like a slightly larger G3.  Got me thinking!  Just how interchangeable are the components?

SuperNova & G3 Part Swap

First, I tried the gear from the SN2 in the G3.  It fitted, although protruded about 5 mm.  The black plastic cover which keeps these gears captive also fitted….sort of – it protruded around the circumference for obvious reasons.  The hole left in the SN2 where the gear came from looked very familiar, which got me wondering if the G3 handle could be used on the SN2.

Interchangeable Handles Lathe Chuck

Interchangeable Handles Lathe Chuck


Guess the moral of that story is, if you have both the G3 and SN2, you can use the same G3 handle for both chucks if necessary.  Parts can also be scavenged from one to repair the other. Wish I could have a look at a Titan now!

SuperNova2 Disassembled

It did convince me of one thing.  Given the parts are the same, the method of operation is as well, then both the G3 and the SN2 should have the same amount of jaw movement (when slack), and the same maximum amount of runout.  Seeing as the original SN2 I had was significantly worse than both G3s, then it definitely made sense to exchange the unit.

Look forward to testing the new chuck, and hopefully this can be the end of the mini-drama, and I can get back to focusing on the turning!

I also feel a LOT better about the G3 – given it is a near identical (although shrunk) sibling of the SN2, I don’t feel owning them is a real compromise – both are equally competent lathe chucks.

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