So i bought some weinmann dp18s for the conversion ive been working on. I was planning to ride the bike fixed with only a front brake but the more I have been thinking about it, I feel like I am going to want to ride it single speed some of the time. Should I return the wheels for a set that are machined or should I just let my brakes do the machining and keep rocking the dp18s?

return em. brakes do take the paint off of rims and 'machine' their own surface, but it takes a while and will never look as clean as machined rims. you won't regret returning them.

So, if I read this correctly, I'm assuming you got a machined front wheel already? If so, just stick with the front brake when riding it SS "some of the time" and dont worry about about mismatching front and rear rims (M and NM). If you DIDNT get the front wheel machined, it'll still stop with the painted sidewall Just hit the front brake a few times pretty moderately so to get some wear on the sidewall... it'll wear evenly and stop just fine. BUT, it will look crappy. It would be better if you get a properly machined wheel for which you'll be using a brake on.

neither of the rims are painted so im not worried about that. should i still return them?

I guess I misunderstood a little. When you said you were planning to ride the bike fixed with only a front brake, are you saying you DIDNT get a machined front rim for brake use? You're best to get a machined wall for brake use. It gives a perfectly flat surface for the brake pad.

The way you made it sound is you got one front machined, a non-machined rear and since you were thinking of riding SS some of the time, you were thinking of adding a rear brake and were worried about the rear wheel not being machined. If you are only riding SS some of the time, just keep a front brake with a front machined wheel. If youre worried about matching wheels, I guess return the both for 2 machined wheels? I guess we dont know what you currently have LOL. 2 non-machined wheels? 1 machined front and NM rear?

If they arent painted, just ride em, in a matter of a few weeks they will machine and be fine.