I hope this isn't a repeat.
Where the heck do I find parts to build a custom 7 speed cassette?
I've looked every place I can think of, I'd like to build a 14-34 and can't corner the parts. Suggestions?

Is a 14-32 acceptable?
https://harriscyclery.net/product/shimano-hg-50-7-speed-cassette-14-32-quotfquot-728.htm

I don't believe you can get a 34T cog in 7 speed, so you'd have to use a 34T off an 8 or 9 speed.

The slightly thinner cog won't be a problem since it's on the end of the "stack".
The problem basically is that it appears the only 7 speed cassette with a 14T top cog is the one listed above.
That means you'd be spending a lot of $ to gain 2 teeth on ONE cog.

The era of the "cog board" and the ability to build nearly any possible tooth combination has been over for decades. Between proprietary spacing and the matching of the ramps and shaped teeth needed for indexing, manufacturers limit what they offer to the most popular combinations. You can do a mix and match of 7 and 8-speed cogs (use the 7-speed spacers) within reason but it will necessitate buying two or more cassettes or choosing from the few individual cogs still available.

The first issue you'll have is the 14t 1st position sprocket. 1st position sprockets are different from the rest as they must have the spacer built on. This allows the sprocket to overhang the end of the freehub body so the lockring can compress the cassette without bottoming out. If you try to use a loose spacer and mid position sprocket on the outer end, the sprocket will either hang in space, or be hanging by a hair and tear loose under torque.

I don't believe anyone is currently offering 14t 1st position sprockets, but I'm not certain either way so you should check that first before moving forward.

One alternative to using a 14-34 cassette is to go with chainrings about 15% smaller. This will yield similar gearing using a more readily 12-28 or 13-28 cassette.

Here's a 13-34 7-speed cassette: https://www.google.com/products/catal...ed=0CDwQ8wIwAQ

You can take the cassette Bill referenced and combine with the above. But, as he mentioned, that's double the cost for a slight change from stock.

Not sure what happened with my first link??

https://sheldonbrown.com/harris/k7.html#7

Thanks everyone,
I found a whole drawer full off cassettes in the local
Community bike shop...
I'm building my own!

Despite the promise of truly custom sets I don't think I ever saw any single cogs except for a few Dura Ace ones, very early on in the HG/UG cassette era

Custom cassettes cannot be built without sacrificing some of the "hyper" in glide.

The positions of the shift gates are phased with the neighboring sprockets so the shifting chain meets the new sprocket with the spaces lined up with the teeth that have to engage them. When you mix/match you lose this phasing, and a shifting chain may meet the new sprocket with a roller lining up with a tooth rather than the space between them. This can cause some minor delay or skipping when shifted under a bit of load. This isn't a crisis,since we got along without gates for decades, but manufacturers don't encourage it since it's contrary to their marketing message.

"Cog boards" predate cassettes by quite a bit. "Back in the day", every well equipped bike shop had a Sun Tour, a Shimano and the good ones, a Campy cog board that was a large board with pegs and the outlines of evey cog size and configuration they offered. You bought them individually to bulid a custom freewheel or to replace specific worn cogs on your existing freewheel.

Uh, watch out for the smaller cogs especially - likely to be worn.