SpudFiles

so i'm currently half way through designing my new advanced combustion, and i do have access to a machine shop that can do CNC machining for me, so most of the parts i'm planning to have custom made.

the problem I have run in to is that i don't know the tolerances for a good fit of the fixed fittings to be glued to pipe, and whether or not the fittings need to be tapered.

also, i have the bolt sliding inside the chamber, so i was planning to use o-rings to make a seal, same deal with a vent port that opens by sliding and aligning 2 holes. for that, are there standard sizes of o-rings that are readily available? and also how tight should they fit to be able to move but still make a good seal?

I am new to solidworks but it seems that it has a library of standard o-rings and oring grooves. I guess that autoCAD has them too

One of the best resources for this is RL Hudson O-Ring Design & Materials Guide. It covers the common sizes, dynamic seals, and common clearances used. The guide is complimentary.
http://www.rlhudson.com/publications/pub_orings.html

You only probably need 1 o-ring

Google for "oring size chart"

Depending on what you actually want to accomplish, you could possibly get away with just a tight, lubricated fit.

Ah sweet. I'll probably just do that and groove it for o-rings later, the plan is I'm going to use shells with o-rings as well, and use a burst plate at the back of the shell so I could use it as a hybrid as well.

cfb_rolley wrote: i do have access to a machine shop that can do CNC machining for me

are there standard sizes of o-rings that are readily available? and also how tight should they fit to be able to move but still make a good seal?

I'm sure your machinist has a copy of Machinery's Handbook. In it are tables for static and dynamic o-ring selection and installation. The machinist can quickly determine the bore, gland and o-ring size required for a dynamic o-ring install.