Cox cylinder/head tap
05-24-2014, 11:47 PM
#26
Join Date: Jul 2005
Location: Upper HuttWellington, NEW ZEALAND
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I had been thinking of doing some needle valves like the KirnKraft remotes too, but I will likely never find a #2 or 3 x 128tpi tap and button die.* I think a 2mm x .25 is pretty good too.* If they were a common standard size they are sometimes reasonable, but no one likes to carry stock any more, then they can get a special order price.
ChrisM
'ffkiwi'
05-25-2014, 12:11 AM
#27
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
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Such rod when cut to a taper is likely the source used by a lot of the fairly common generic replacement needle valve and spray bar setups that were sold for older control line and free flight engines. Many of those had really small needle valves.
05-25-2014, 07:29 AM
#28
I've only had one cup of coffee, so the brain is only about half power. It's pretty obvious that locating suitable fine thread stock, dies or taps can be difficult.
How about experimenting with changing the taper on the standard NV's. A long thin taper on a standard NV might give a similar effect to a fine thread NV. Tip may need to be cut off to avoid running the needle too far into the seat, but a little testing could identify a sweet spot along the taper. Sorry for the hi-jack.
Before you toast my coattails too much, just remember the coffee comment.
How about experimenting with changing the taper on the standard NV's. A long thin taper on a standard NV might give a similar effect to a fine thread NV. Tip may need to be cut off to avoid running the needle too far into the seat, but a little testing could identify a sweet spot along the taper. Sorry for the hi-jack.
Before you toast my coattails too much, just remember the coffee comment.
Last edited by Andrew; 05-25-2014 at 07:31 AM.
05-25-2014, 01:13 PM
#29
I made a couple of NVs from 2:56 threaded rod, and they worked fine. I just used threaded stock from the hobby shop and ground the point on my belt sander to the angle while turning it by hand. The lathe didn't like turning it, it would just flop around. I don't think the needle would work too well on a bladder. I used stainless steel threaded rod which I could not solder a washer to, but could not find any brass or steel material. Hijacking is sometimes more fun than a regular post.
05-29-2014, 08:23 PM
#30
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I made a couple of NVs from 2:56 threaded rod, and they worked fine. I just used threaded stock from the hobby shop and ground the point on my belt sander to the angle while turning it by hand. The lathe didn't like turning it, it would just flop around. I don't think the needle would work too well on a bladder. I used stainless steel threaded rod which I could not solder a washer to, but could not find any brass or steel material. Hijacking is sometimes more fun than a regular post.
ChrisM
'ffkiwi'
05-30-2014, 08:04 AM
#31
I tried a few kinds of flux with no luck. I think my threaded rod may have been the Dubro or whatever the hobby shop carried near the Dubro rack. Non magnetic anyway. I just made a couple of lock nuts and a thumb tack with a hole for adjustment. I think I should just turn a smaller dia, and bend it next time. I could shorten the whole thing a bit too like the Fora, so it doesn't bend in a crash. I am not sure I want to go to the trouble of splitting the spraybar and making up a collet nut. I also made a few longish nipples for a remote needle system, but they still need a needle valve.
