Theoben Rapid Forum
KevG Lathe work undertaken => kevG section => Topic started by: rsedwards1 on July 09, 2026, 08:45:44 AM
have a Rapid 12/250 the 4BA thread is stripped holding the exhaust valve .it blows out the Grub screw this only happens on firing and no leak otherwise.
I have a hele coil kit , but was told that a new block is the only answer any thoughts appreciated.
I would re-tap the threads one size up..
I believe it would be a 4mm thread....
A couple of members have done this Fix!!
https://rapidforum.co.uk/forum/index.php?topic=4309.0
Good Luck,
Stuart
Quote from: rsedwards1 on Today at 08:45:44 AMhave a Rapid 12/250 the 4BA thread is stripped holding the exhaust valve .it blows out the Grub screw this only happens on firing and no leak otherwise.
I have a hele coil kit , but was told that a new block is the only answer any thoughts appreciated.
Impact Airguns are Norfolk based (iirc), they re-tapped one for me a few years back for not a lot more than buying a decent quality set of Taps would have been, I'd give Chris a call.
As already recommended re-tap a metric fine one size up.
Not that different to a fitting heli-coil and 3mm grub, isn't a lot of metal to work with.