On Aug 4, 10:59*pm, (Doug Miller) wrote:
In article , Larry Fishel wrote:

On Aug 4, 3:05=A0pm, RicodJour wrote:
I don't know how critical it is to have
the joint bottomed out. =A0Preferable? Sure, but I don't think it
affects things too much.

His concern was that if he carefully measures and dry-fits everything,
then when he applies the solvent the lengths will change and the
assembly will be FUBAR.

That's why you should carefully measure and *not* attempt to dry-fit. Measure
to the bottom of the seat in each fitting, because that's where the pipe is
going to wind up when the solvent is applied and the joint is made properly.
Trying to dry-fit plastic pipe is an exercise in futility: the pipes *never*
bottom in the fittings, so there's no way that the final assembly (with
solvent, and hence with the pipes bottomed) will be the same size as the
dry-fit size.

You can easily measure lengths in most cases. But when you have a
complex series of fittings at angles within a small area that has to
then align with 3 existing fixed pipes, it's not just a matter of
simple measurement. You need to know the angles can come together
correctly together with the various pipe lengths involved.