How to find polarity/direction of rim spoke holes?

[Shut Up Legs]

The rims I'm using for my 1st wheel building project, DT Swiss TK540, don't seem to have any polarity for the rim spoke holes! In other words, I can't tell which side of the rim each hole is biased towards. They all seem perfectly centred. Are some rims like this, or am I just checking it incorrectly? I tried hanging a spoke (with nipple screwed on) from 2 of the holes on 1 side of the valve hole, and carefully held this side of the wheel up, and both spokes seemed to drop perfectly centred along the centre axis of the rim. Suggestions, anyone?

 

[TissoT]

Just looked at my Fulcrum R3 ... they are centre pulled with no left or right in the rim !
with a spoke pattern three pull then a 80mm cap . 1. 3. pull to the cog/chainset::.2 (middle) opposite and so on
You need to find the spoke pattern for that particular wheel/hub ? look on line see if you can get a close up ! or try and find a wheel building website/ forum

 

[Spoked Wheels]

First hole on the left of the valve ( drive side) will give you a good starting point.

 

[Poacher]

Seems unusual to have non-directional rims, but the pics I've looked at of TK540s don't show any evident direction, so it looks like you have a free hand to do as you please! Good-looking rims, by the way, but so they should be at those prices!
I hope you're using beefed-up spokes on the rear drive-side; the tension differential can be frightening for a novice!
Have you perused Sheldon Brown's wheelbuilding guide? I've found it clear and reassuring several times!

 

[Davidc]

I've met rims with no spoke direction, albeit a few years back. They weren't DT Swiss rims though (cheap ones). Worked OK. I think I used my usual 2 crosses lace up but can't be sure. It might be more noticeable with 3.

 

[fossyant]

Many rims are non directional. My not cheap CXP33s are not directional.

 

[Shut Up Legs]

No, these rims aren't the cheapest, but they're good quality. I currently have these exact brand and model rims on my Vivente tourer (commuter) bike. I just searched back through my bicycle receipts, and found that these rims were used in a wheel build by a local bike shop on 20th August last year. Since then, I've done about 14,300km on this bike, which thanks to my hilly commutes includes just over 200,000m climbing. This of course, means the rim brakes get used a lot, so more wear on the rims.

I also just checked what I paid for these rims back in August last year: $175 per rim! The ones I just bought from CRC cost $85. I even paid $140 for the labour back then. This motivates me even more to stick with it, and learn wheel building .

Anyway, thanks heaps for the useful comments, people. Just what I expected on these fora!