Which tap size?

[Zax]

Hi,

I'm new to this forum and this is my first post but I have been reading alot of the previous threads and I have to say there are some really amazing people here and I really appreciate the fact that they have shared their work and experience with others, keep it up please!
I have a couple of questions, I'm making my first block, Rotor style with a polycarbonate top. I have these fittings;

http://www.koolnquiet.co.uk/index.ph...=221&cat_id=53

My question is, which size tap do I need to tap the holes in the polycarbonate?
Also, I'm thinking of using "Instant gasket" to seal the block, it's an rtv silicone used in engines, is this stuff good enough, in some parts of my block the sealant will have about a 3mm wide contact zone between the copper and polcarbonate, however there will be 4 small bolts sealing the block aswell.

All advise would be much appreciated, thanks.

[krazy]

I'm almost certain that those fittings use a straight thread. Somewhere else around here recently, someone mentioned that the Innovatek-style fittings (like what you link to) use a standard size pipe thread, but they are a special variety that does not have a taper to it, so they usually rely on an O ring or gasket to make the actual seal instead of ever-tightening threads.

Here's the type of thread you're dealing with compared to a standard 1/4"NPT threaded barb fitting:


I would look for a tap specified as 1/4"M instead of the usual 1/4"NPT and see how you fare.

If I've got this wrong, someone with more wisdom is more than welcome to step in and correct me.

[Zax]

Thanks for the prompt reply Krazy, you're right about the straight thread and o-ring bit. You're probably right about the tap size too but I just need someone to confirm this. I don't want to end up with another useless tap , these things are expensive.

I'm in the UK so what would the standard be here? I've looked at http://www.tapdie.com/index.html for the tap you mentioned but got completely confused with all the different standards (Well I suppose we were all Noobs once, it's just my turn at the moment )
Nice piccy by the way.

[|kbn|]

What you need is a 1/4" BSPx tap then. X is either T for tapered threads (ever tightning threads) or P for parrelell (straight threads).
You should find that threads using parrelell are ok to use with tappered barbs, theres not that much difference between the too. Idealy though you would use a non-brittle plastic for the top, so overtigtning etc.. wont crack it. Polyethelene is ideal... but if you already have polycarb that shoudl work well too... (though iirc its brittle still).

You can get taps here, http://www.chronos.ltd.uk/acatalog/catalogbody.html which is cheaper (tapdie is about £30 inc for a tappered tap!) but they dont sell BSPT ones.

Get the 1/4" BSPP Taper tap from there. When using parrelell taps, there are usually 3 kinds. the first one is called taper, becuase its tapered slightly, to help it start cutting, the second is less tapered, and the third is not tappered atall.

If using parrelell tap you might also want to get parrell barbs.. I find it costs less to get parelell ones and a parrelell tap, than to just get a BSPT tap...

[Zax]

Thanks for the help guys, thats really cleared things up alot.

[Zax]

Just a quick question to add to that, which drill bit size should I use for this size tap?

[|kbn|]

for the 1/4" BSPP Taper?
Mine says on the side "11.8 Drill"although anything bigger than 11.4 should do (this is what I was going to use).

[Zax]

Thanks to you guys I now have all the info I need to continue with my project (to water cool my radeon 9800 pro)

[|kbn|]

btw for a gfx card wb you might prefer to use a copper top. you can get 1/2" (12.54mm) copper pipe from chronos. You then need a 1/2" drill bit, and a drill with a big enough chuck (which was my mistake, hand drill upto 6mm and cordless upto 10mm. My dad had to do it at work for me). cut the pipe to length and solder it in, and you canuse copper elbows aswell which is usefull.

Copper soldered barbs - Smaller, look better (imo), easyer to do, less restrictive, wont leak (if soldered properly) and wont crack the top. Elbows for gfx blocks
Barbs - holes need to be tapped, taps cost money, looks worse, barbs are 3x longer than they need to be, and most annoying - noone ever tapps holes fully, instead only half tap the hole so the barb is half hanging out. 90degree barbs cant be used on the same face unless spaced far apart.

So now I have £12 worth of 1/2" barbs, a 1/2" bspp tap and tap wrench and a 11.4mm drill that i will probably never use