Just picked up a Sullivan, and It’s snapping strings within 3-6 throws 
It snags up weirdly almost like the string got stuck, then it snaps.
I sanded the area of the threaded axle with high grit sand paper to try and smooth things out, yet it still snaps them the same.
Any advice? Do I just need a new threaded axle?
If it needs a new axle it’s on me. I didn’t have issues with the Sullivan and only through the Irving like twice. I through the pants off that Sullivan came apart a bunch of times in the beginning but never snapped a string.
Let’s wait to hear from Dr. Haponik
Edit: bat-signal to @edhaponik
That’s very kind of you man, but I really tend it doubt it’s the axle, especially if it wasn’t giving you any troubles.
What type of strings did you use with it? I used some poly, and standard 100% cotton and both snapped 
Maybe I’m assembling it incorrectly?
It’s almost like the string is getting caught in something, and then snapping the next throw, it’s very strange.
The Irving works great though! No sweat there.
Cotton 10 is all I used. Maybe pull a “burn in” I think that’s what Ed calls it but will search. Although I did that first thing what I got the Sullivan. Is it snapping at the loop or higher? If it’s higher than maybe the axle needs to be more flush.
What’s a burn in?
It’s breaking right at the loop unfortunately.
I had the same thing happen with my new Morrow. Turns out one of the axle threads, which are very sharp, was exposed just enough to cut the string. After going through four strings I took it apart and reassembled it taking extra care to make sure everything lined up flush. No problems after that.
Found the instructions, start with no string on the axle, wrap the string (cotton) around axle once and slowly pull it so it rubs the axle. Also I’d wax it, bees not chapstick.
Thanks so much guys! I’m gonna try this in a bit, I’m optimistic 
As am I but if it’s not sorted by tomorrow (provided Ed has chimed in) then I’ll order a new one to your door. My BST’s come with a warranty!
That certainly won’t be needed either way man. That’s an extremely kind thing to do, but especially since it wasn’t giving you any trouble I’m sure the problem is somewhere on my end.
You’re a real stand up guy!
In my experience you just need to ensure that the wall of the axle is flush with the wall of the yoyo. After that, I do “prep” axles by basically wasting a cotton string to make sure they are free of any hidden burrs. Really haven’t had an issue with snapping following that algorithm with any yoyo. Granted lately I haven’t been throwing for distance lol.
I seem to have remedied this by making sure it was perfectly flush
Thanks to all who reached out, I’m enjoying this thing thoroughly!