Just built some wheels

.

put them in a bike and spin and check that they don't move

a set of wheels i had did the same thing but they moved up and down, not side to side

When in your fork/frame you should use some markers (tape, cable tie etc) to check if the hub goes off centre.

You need to tie something to your fork that almost comes into contact with the outer edge of the rim.

When you spin the wheel you need to pull the rim in at contact points. If its a lot, you should loosen off the spokes and start again.

Don't sweat it. There could be pins/welding mass around the join. There could be a family of ladybirds nesting in one spot. It really doesn't matter. If it's round and true and fits your frame, just get out there and ride and stop wasting time obsessing :)

^nice.

it's possible that the rim has a heavy spot to counter balance the weight of the air in the tube, that generally is denser around the valve (obvious when you think about it, as that's where the air goes in).

^other way round^

It's lighter by at the valve hole (it's a hole)!

Once the tyres on... all will be well.
I bet you haven't lined the Shimano logo (on the hub body) with the valve though have you?

Oh well.

I've heard that manufactures actually lighten the hub on the logo side as the rim hole/valve is naturally the heavy spot.

I actually thought it was bollocks when I first heard that, but my wheels settle exactly where they would if that was true. And no I didn't get it right, I faced the logos forward.

To muddy the water even further Shimano DA I think is one of the brands that does it the wrong way round... ie Logo facing forward, rather than to the hole (i think).

BTW the logo mentioned is the logo on the hub body, not necessarily the flange.

If it's sunny where you live... forget all of the above and go for a ride.

Great. No logo solves your problem! haha.

I'm putting off my ride into Bristol this afternoon. Bristol Is not nice to ride fixed. And i'll have to take my beater (Sundays in Bristol... you need an electrified ground anchor to keep your bike from being pinched).