I may have made a big project out of a simple task yesterday, but at least I left things in much better shape than the last guy to work on it. It started the other day at church with a dripping faucet, maybe a Gerber washerless one. I paid $7 for a new cartridge at the hardware store. Afterwards I could only get a trickle of water out of either the hot or cold. The hot stop really didn't shut the water off completely, and the cold, the handle turned and turned either way and didn't do anything. Decided to come back yesterday afternoon when turning the main shutoff off would b less disruptive. Instead of angle stops, they were soldered in gate valves. Removed the guts and found the stem was twisted off and the gate gone. Work my way back to the wall unscrewing a 3/8 pipe to 3/8'' tubing adapter. I knew it was 3/8, because it said 3/8 on the old valve. Made a trip to the hardware store and picked up a 3/8 threaded ball valve, nipple, and street ell. Installed them giving me a nice stop for the cold, just needing connected to the copper tubing running to the faucet. I then took out the guts of the hot stop, scraped the lime off, and then discovered how easy it was to twist off the stem putting it back together. Looking a head a little before going to the hardware store again, I realized I would have to solder the tubing into the adapter with it already screwed into the valve. I was afraid I might melt the plastic seats in the valve, or not be able to get the valve back together without leaking. I decided my best bet was a pipe to compression adapter. Picked up two 3/8 to 3/8 ones along with another valve, nipple, and street ell. Got the hot stop done and was able to turn the main water valve on. I made sure the line was clean from the faucet back to the stops. Now, just make the compression to tubing joint, and it should be done. While studying the alignment and length, I discovered the 3/8 compression fitting was for 3/8 OD tubing, and the tubing was 3/8 ID. It was getting late, I had a meeting to go to. The more I thought about being pressed for time, the tubing not quite long enough, needing bent to align right, and having to put the compression fitting over the end tinned from the soldered joint, the less confident I was in the compression joint not leaking. Nuts with it. Since I had to make a third trip to the hardware store for the day, for $7 each, I picked up 4' lengths of the stainless steel braided flex, half inch pipe like the faucet one end and the same 3/8 compression fittings as I had at the other. This also eliminated a galvanized coupling between the brass faucet and the copper tubing adapter. Still couldn't get much water out until I cleaned the aerator.

The angle stops have their uses, but I can't see using the gate valves. The ball valves are much easier to use, and will shut the water off completely even after years of service in hard water.

I may have made a big project out of a simple task yesterday, but at least I left things in much better shape than the last guy to work on it. It started the other day at church with a dripping faucet, maybe a Gerber washerless one. I paid $7 for a new cartridge at the hardware store. Afterwards I could only get a trickle of water out of either the hot or cold. The hot stop really didn't shut the water off completely, and the cold, the handle turned and turned either way and didn't do anything. Decided to come back yesterday afternoon when turning the main shutoff off would b less disruptive. Instead of angle stops, they were soldered in gate valves. Removed the guts and found the stem was twisted off and the gate gone. Work my way back to the wall unscrewing a 3/8 pipe to 3/8'' tubing adapter. I knew it was 3/8, because it said 3/8 on the old valve. Made a trip to the hardware store and picked up a 3/8 threaded ball valve, nipple, and street ell. Installed them giving me a nice stop for the cold, just needing connected to the copper tubing running to the faucet. I then took out the guts of the hot stop, scraped the lime off, and then discovered how easy it was to twist off the stem putting it back together. Looking a head a little before going to the hardware store again, I realized I would have to solder the tubing into the adapter with it already screwed into the valve. I was afraid I might melt the plastic seats in the valve, or not be able to get the valve back together without leaking. I decided my best bet was a pipe to compression adapter. Picked up two 3/8 to 3/8 ones along with another valve, nipple, and street ell. Got the hot stop done and was able to turn the main water valve on. I made sure the line was clean from the faucet back to the stops. Now, just make the compression to tubing joint, and it should be done. While studying the alignment and length, I discovered the 3/8 compression fitting was for 3/8 OD tubing, and the tubing was 3/8 ID. It was getting late, I had a meeting to go to. The more I thought about being pressed for time, the tubing not quite long enough, needing bent to align right, and having to put the compression fitting over the end tinned from the soldered joint, the less confident I was in the compression joint not leaking. Nuts with it. Since I had to make a third trip to the hardware store for the day, for $7 each, I picked up 4' lengths of the stainless steel braided flex, half inch pipe like the faucet one end and the same 3/8 compression fittings as I had at the other. This also eliminated a galvanized coupling between the brass faucet and the copper tubing adapter. Still couldn't get much water out until I cleaned the aerator.

The angle stops have their uses, but I can't see using the gate valves. The ball valves are much easier to use, and will shut the water off completely even after years of service in hard water.

Welcome to the world of repair plumbing . Where a simple repair job can balloon into a plumbers nightmare. Let me clear up the ID verses OD thingy.
Why OD even enters the vocabulary of plumbing is beyond me but it's there now and it still makes me ask,WHY?? Hey! It's not the plumbers that are concerned with OD, it's the AC guys. Let me explain. Plumbers only care about what a pipe will contain and supply hence, ID. AC guys are concerned about what a pipe will radiant, with or withour fins hence, OD.
Back, a million years ago, when I was out in the field plumbers measured a pipe by what it would carry, ( Are you taking notes, Labman? There will be a quiz later) but AC guys would "morph" 1/4" tubing into 3/8", 1/2" into 5/8" and so on. That's about the time t6hat pipe sizes became confusing to the average do-it-yourselfer.
If I understand you correctly when you removed the supply stops, that were installed with gate valves instead of angle stops you were left with 3/8" (ID) male threads coming out of the wall.
I think I would have bushed up from 3/8 to 1/2" (ID) with a 3/8 X 1/2" bushing and installed chrome 1/2" X 1/4" thread to compression angle stops.
That would have cleared the way to install 1/4" (ID) chrome over copper nose cone supplies or the stainless steel braided flex supplies that you ended up using. I still bristle a bit when I walk into a hardware store to pick up a 1/2" fitting and the clerk corrects me, " Oh! You mean 5/8's" No! I'm a plumber not a air conditioning repair man, I mean 1/2"." Perhaps time has passed me by but it seems to me that the old way of determining a pipe size was best. When was the last time you heard 2" PVC referred to as 2 1/4" PVC? I guess drainage will be next. Tom aka "The Speedster"

I have fought this ID/OD nonsense a long time. I just got burned with the hardware store labeling 1/4 compression fittings 3/8. Since the stops were in a sink cabinet, I saw no reason to use the chrome angle stops. Back when I had a factory to run, and a boss that wouldn't tolerate a bucket hanging on a valve, a good salesman gave me a 1/2 ball valve at a Christmas party along with more liquor than was good for me. Lunkenheimer was using newer technology to sell ball valves for about what the cheapest gate valves did. From then on, we started throwing away all the gate and globe valves using ball valves on 2'' and down, and butterfly valves on the big stuff. Under my predesessor, they never learned to adjust stem packing and replaced ones that leaked. We couldn't thread anything bigger than 2'', but I had a guy that could do leak proof welds. Butterfly valves are much cheaper than a flanged gate valve, seal better, are faster to open and close, and take up less room. I prefer valves that nothing goes through or out the stem when they are shut off.

Note, somebody left a new sweat solder gate valve under the sink that said 1/2'' in it.

Mechanics do OD too. Hydraulics are ID.