Quote Originally Posted by bigtoe01 View Post
Dave I do not feel a taper reamer will be tapered enough, Im thinking something like 5mm down to 3.6mm over 3.5mm length then 1mm at 3.6 opening out for the last 1.5mm, a tapered reamer will just not have enough angle to it unless you have a seriously tapering reamer to hand?

The radius cutter...yep what ever you have to hand.

After you do this one I have another idea on a longer port..so save one back, im thinking of adding in the Bernoulli effect also to see if we can gain some extra air for free...much like filling a 6ft long paper bag with 1 breath however it may need a valve of some kind which I will chat to you about first.
Oh no! thinking this is going to hurt!

Quote Originally Posted by Rich View Post
Seven degrees of divergence is about 1mm expansion in a length of 10mm. So if the part of the TP that is to be taper bored is say 3mm diameter and 3mm long then it will need to be opened out to 3.3mm dia at the exit. You're probably right, this is more than a taper reamer would give you.

How about turning a piece of silver steel with the desired taper, file it off to half diameter, harden and temper. Hey presto a D bit in no time.
Can you remember how difficult it was to do a taper? I really had trouble with this! HANGS HIS HEAD, SLOPES HIS SHOULDERS & WALKS TOWARDS THE DOOR SHAKING HIS HEAD MUTTERING WORDS UNREPEATABLE!

Okay gone on then I'll do it!