when 3/8" is not 3/8"

[BuddyHolly]

I was working on the pieces to install 3/8 inside diameter tubing on my Innovatek cooling system. It has the little 1/4 inch stuff, and I can never leave anything well enough alone. Well, I got some 3/8 barb fittings with the proper 1/8" thread. I noticed that the inside diameter lookd awful small. Well, I measured it, and it was only about 11/64", which is less than the 1/4" I was trying to move up from. Of course, the stock 1/4" was still smaller, but I was not pleased. So, I drilled the barb out to 9/32, which was much better. I roughly guessed it was around 30% greater in diameter than when I started. These are brass fittings, but two of the plastic fittings that I had seemed to be just as bad. Anyone else noticed this? If nothing else, it is something else for everyone to fine tune..I did not have quite a good enough bit to go much closer to 3/8"..drilling up to 9/32" was tough enough..

[frostmeister]

Yeah. I bought some BSP fittings (nickel plate brass) and 3/8ths braid re-inforced clear hose. The hose goes on fine and dandy, but the I.D. on the fittings is only 7mm or 8/32". Personally, Id like my fittings to be that much harder to fit on the hose, and be 3/8ths inside diameter, so there's no restriction anywhere in the system. That's why I use 10mm O/D copper pipe on my waterblocks which is a nice stretch for the 3/8ths hose. Dagnabbit.

[BuddyHolly]

Yes, I was really suprised to find that I was putting the larger hose in place while at the same time installing 4 brand new bottlenecks in the system. It would be nice to have the inside diameter 3/8" and streach the hose. I do understand why, to a point. The barb is meant to have hose clamps and a good bit of pressure. If the walls were too thin, than it would crush the fitting. I have thought about going with the reinforced hose, but may try the flexi flyer tygon stuff first..

[UnLoadeD]

You can get less restricive fittings like THESE. (http://www.usplastic.com/catalog/category.asp?catalog%5Fname=USPlastic&category%5Fname=Eldon+James+%28tm%29+PVDF%2C+Nylon +and+Polypropylene+Tubing+Fittings&Page=1)
edit: if link doesnt work goto www.usplastic.com and use drop down menu to Tubing and Fittings then hit Eldon James fittings.

peace.
unloaded

[FIZZ3]

Originally posted by BuddyHolly
I was working on the pieces to install 3/8 inside diameter tubing on my Innovatek cooling system. It has the little 1/4 inch stuff, and I can never leave anything well enough alone. Well, I got some 3/8 barb fittings with the proper 1/8" thread. I noticed that the inside diameter lookd awful small. Well, I measured it, and it was only about 11/64", which is less than the 1/4" I was trying to move up from. Of course, the stock 1/4" was still smaller, but I was not pleased. So, I drilled the barb out to 9/32, which was much better. I roughly guessed it was around 30% greater in diameter than when I started. These are brass fittings, but two of the plastic fittings that I had seemed to be just as bad. Anyone else noticed this? If nothing else, it is something else for everyone to fine tune..I did not have quite a good enough bit to go much closer to 3/8"..drilling up to 9/32" was tough enough..

Weird, my Innovatek came with 10mmOD tubing. That's slightly more than 3/8" OD, the inner diameter is slightly less than that.
I have looked around to see whether there are larger stock sizes for sale anywhere, but I didn't see any, only smaller ones.

[Daemonfly]

I bought 1/2" x 1/4" NPT barbs and just drilled them out. MOST barbs I've seen have very thick walls, which aren't really needed for a computer watercooling application. I just took a drill bit, popped it in my drill & opened up that hole :D , then put a chamfer/taper on the edges. You might need a decent drill, as the brass will want to draw the bit into itself, much like copper. Weaker drills will just stall out.

[BuddyHolly]

Yea, I drilled mine way out on my drill press. It really seemed to help. Good point, weak drills need not apply. I even stalled my drill press out once..