bikemig 

This is a VAR right? We had one in the shop I used to work at. It's a good truing stand.

savvas

The Preciray is 'self-centering' once the hub is centred in the jig *& the rim width dialled in. No need to flip or do anything else to ensure appropriate dishing. Brilliant design!

jccaclimber

Ignoring the issues of bumping a long sleeping thread, if you have to dial the rim width in it doesn’t sound self adjusting any more than using a single indicator.
How well does the self centering mechanism work? All of the Park stands claim to, but even the TS3 was off just a bit of you used it on multiple wheel diameters and axle spacings.

Big Steve

The Preciray stand is not self-centering. Centering the rim in the center of the hub requires simple arithmetic. Hub width is automatically measured by a permanent ruler on the stand. Rim width is easily measured by a "pop-up" ruler on the stand, which doubles as the ruler measuring the distance between the outside of the left axle nut and the left side of the rim.

Here's a brief description of how it works: Assume the hub is 135mm wide between dropouts. Place hub in stand and slide right "dropout" to snug up hub inside the "dropouts." The permanent hub width ruler will indicate that the hub is 135mm wide. Then use the "pop-up" ruler to measure the rim width. (Alternatively, use a caliper.) For our hypothetical, assume the rim measures 25mm wide. Subtract half the rim width (12.5mm) from half the hub width (67.5mm) to ascertain the distance (55mm) from the edge of the hub axle to the side of the rim.

This is much easier to demonstrate in person than to explain in words. During my years as a shop rat (1975-1980, 1982-83), I taught a dozen or so fellow shop workers the technique, each of them quickly learning the process.

IME, the calculation takes about 30 seconds and reliably produces a centered rim +/- 1mm without using a dishing gauge or flip-flopping the wheel, although IMO one of those should be done before finishing the wheel. In my case, before final dishing, I always checked the dish by flip-flopping the wheel in the jig.

jccaclimber

So, to summarize that, you still have to flip the wheel? It sounds like the math you’re doing is pretty similar to flipping a wheel with an indicator, and the wheel ends up flipped in the end anyways.
While it’s definitely convenient that it’s built in, it still seems substantially similar to throwing a pair of indicators on any stand, which I was thought by a long time wheelbuilder like you.
I agree that having an amplified error reading, either by indicator dial or by lever like this is a substantial improvement over the usual pincer arrangement.

Big Steve

If you do it correctly and can live with a +/- 1mm tolerance, there is no need to flip-flop the wheel or use a dishing tool. IME, every truing stand requires either of those techniques to ensure a proper dish with tolerances tighter than +/- 1mm.

"Throwing a pair of indicators [dials] on any stand" does not get you there, e.g., adding dial indicators does not provide an accurate ruler measuring the edge of the axle to the outside of the rim. That's not as easy as it sounds because axle end and the rim are a fair distance apart. It works with a Preciray because the fixed vertical member holding the left side of the axle is very true and very rigid. (IME, the vertical member on the beefiest Park stand is prone to flexing.) Again, this is much easier to demonstrate than to explain in words.

IME, the big advantages of the Preciray over other stands are: (1) the wheel can be brought to 95%-ish true and 99%+ round with a single rotation of the wheel, which results in faster wheel builds; and (2) it is very rigid, moreso than any other stand I've used. Point (1) is difficult to explain without actually trying it. IME, it takes more than double the time -- often quite a bit more than 2X -- to get a wheel as round with other shop-level stands.

Dan Burkhart 

Just curious to know if you availed yourself of any that were up for offer earlier in this thread or if you are still on the hunt.

Big Steve

I bought a used one in 2011. The seller (NatoPotato, I think) was in Seattle (where I lived at the time) for business, thus I avoided shipping costs. I have built several hundred wheels on it.

ETA: After some thought, I'd estimate the dishing tolerance without flip-flop or dishing tool is more like +/- 0.5mm, assuming proper setup and arithmetic. IME (which includes building 200+ frames) frame rear triangles are often not that precise, even on very expensive frames.