Dr Bob QF Purging from Reg

[Scott]

I started a new thread rather than turning Stuart's excellent threat into a support column.

Last year I bought a Dr Bob QF & Gauge and a 400cc bottle for my MFR, unfortunately it purged all the air through the push-pin disk set screw hole in the Reg housing as soon as I started filling it.
I spoke with Bob who was great, but as my head was in a bad place I didn't really understand what he said, so I had an oldmantrum boxed it up and tossed it all into the loft and continued with the old setup...

Time to deal with it now as things have moved on and I sadly need to move the MFR on too as Im changing calibre due to recent problems with my only eye,
I can't judge distances anymore so Im just wasting lead lobbing bricks in the air and so Im switching to .177 in the hopes that I can shoot the tin chickens a bit longer.

Anyways enough of my crying and pity party,, I asked Stuart about it and he advised the push-pin disk seal may need replaced.
I bought a full seal kit from Bagnall & Kirkwood and set about it...

It was leaking from the indicated hole:


I swapped out the yellow seal and replaced it with the one that seemed to be most correct.
The new O ring has more of an interference fit than the old yellow one which could only be described as slack:


I put it all together feeling pretty confident of the tighter seal working, filled the bottle to 150bar and to my frustration it was still purging through the same hole,,
I let it empty the bottle and stripped it all out again.


I noticed that the seal on the bottom of the disc was missing, it turns out it is still inside the Reg body.
But it was at this point I remembered what Bob said last year and it made sense now,, he said "it probably needs an extra O ring"
so Im wondering if this is what he meant and if putting another O Ring on the bottom of the disc would stop the air purging out though the set screw hole.
(Perhaps O ring "I" from the above picture)

Im at a total loss here gents, can anybody tell me what I'm doing wrong or not doing at all please?

Many thanks
Scott

[Ca_Varminter]

Hi Scott,

Great Photos... It helps a lot to see what is going on....
Like I said, if the leak was coming from that disk setscrew securing hole. It needs to be sealed..
I was thinking about this more.. Another possible cure is a second grub(set)screw!
Now twirl a little Teflon tape into string... insert into the hole.
Now screw the second screw in the hole... the Teflon tape will be smashed between the two screws
So the Teflon will act as Packing!!

Good luck
Stuart

[KevG]

you need a very small rod of delrin.around 1.5 mm diameter and 2mm long.remove grub screw from hole.pop delrin in then tighten screw down.that should cure it.
KevG

[KevG]

the oring that should seal it will not work with a qf set up.
KevG

[Scott]

Thank you both for the excellent replies and help, and as simple as that its not leaking anymore...

I didn't have any Delrin, but I did have a rubber stopper that I pared down to an interference fit cut to about 5mm length then I pushed it down the hole, added some PTFE for a belt and braces approach, tightened the grub screw up and filled it to 175 bar (mental note: I need to get my bottle filled)

it's holding pressure and no leaks,, to say that Im over the moon is an understatement

[KevG]

nice one Scott m8.
KevG

[KCE]

Nice to see you got it all sorted out.
keep us updated as to how it performs in the field.
Regards Kev.

[Ca_Varminter]

Great Job Scott!!!!
The enginuity of All of the Serious Rapid owner is quite astounding....
We need more owners like You!!

Great job,
Stuart

[Dr Bob]

As a quick fix cut a small section of O ring and pop it in before the grub screw

Bob

[Ca_Varminter]

I Knew the Doctor had a cure for it!!
Well the Doctor is in the House!!

Hey Dr Bob!!

Stuart

[Scott]

As a quick fix cut a small section of O ring and pop it in before the grub screw

Bob

Thanks Bob, wish Id thought of that before I got all medieval on a rubber stopper 
The great news is that after a couple of weeks its still holding pressure 
(not like me to do something right  [size=78%])[/size]

[Buzz20]

Glad you got it sorted Scott
Happy shooting fella
🐝