Valve/tube screening can problem

[N_Cook]

Mesa Nomad 55 with one of the 12AX7 snow capped and a neat ring around the
top of the glass envelope. Obviously due to the bed-spring gauge of spring
inside the can. 2Kg to halve the spring length, probably 2/3 compression in
use.
No point in replacing without changing all the springs or something. How to
reform a weak straight compression spring (easily available) to conical or
otherwise fit inside the can and the glass touching end be centrally
posistioned. ?
Secondly there is no dedent to stop the cans rotating other than use of
heavy springs - catch 22. What to do, retrofit, without taking the amp apart
to get to the inside of the chassis. So far I've discovered a working , but
not elegant solution. One of those brass-eyelet hand pincer/dies pushing the
die pin outwards to deform a pip in the aluminium, outwards, 1/4 way round
so it locates in one of the 2 chassis cutaways. Needs some rubber padding on
the outside so the other anvil half does not excessively damage that local
area. Any other solutions anyone else has found, particularly forming or
re-forming spring metal to something like conical My attempts are very
wonky.

 

[N_Cook]

Mesa Nomad 55 with one of the 12AX7 snow capped and a neat ring around the
top of the glass envelope. Obviously due to the bed-spring gauge of spring
inside the can. 2Kg to halve the spring length, probably 2/3 compression in
use.
No point in replacing without changing all the springs or something. How to
reform a weak straight compression spring (easily available) to conical or
otherwise fit inside the can and the glass touching end be centrally
posistioned. ?
Secondly there is no dedent to stop the cans rotating other than use of
heavy springs - catch 22. What to do, retrofit, without taking the amp apart
to get to the inside of the chassis. So far I've discovered a working , but
not elegant solution. One of those brass-eyelet hand pincer/dies pushing the
die pin outwards to deform a pip in the aluminium, outwards, 1/4 way round
so it locates in one of the 2 chassis cutaways. Needs some rubber padding on
the outside so the other anvil half does not excessively damage that local
area. Any other solutions anyone else has found, particularly forming or
re-forming spring metal to something like conical My attempts are very
wonky.

This is a work-around for the springs. May have gone too far the other way
200gm rather than 2Kg. Expanded aluminium mesh (for continued ventillation
through the central hole in the can) cut to a square to squash inside the
can. Straught 12mm diameter compression spring. One end , the last 2mm ,
bend to point axially. Thread that end through a suitable hole inthe mesh
and push around for a near circle and feed back through the mesh with the
return poking through the adjascent hole. Curl back the corners of the mesh
enough to push into the can. Use a din connector cover to go over the spring
and push the mesh into the can. Then with din cover in place , use a
screwdriver to push the mesh down to wedge into the can top. The spring then
stays centrally and axially located .

The eyelet pliers fudge works quite well for dedenting the cans, combined
with the existing "O" ring antivibration ring.

rarp added as probably relevant

 

[Kirk Johnson]

Mesa Nomad 55 with one of the 12AX7 snow capped and a neat ring around the
top of the glass envelope. Obviously due to the bed-spring gauge of spring
inside the can. 2Kg to halve the spring length, probably 2/3 compression
in
use.
No point in replacing without changing all the springs or something. How
to
reform a weak straight compression spring (easily available) to conical or
otherwise fit inside the can and the glass touching end be centrally
posistioned. ?
Secondly there is no dedent to stop the cans rotating other than use of
heavy springs - catch 22. What to do, retrofit, without taking the amp
apart
to get to the inside of the chassis. So far I've discovered a working ,
but
not elegant solution. One of those brass-eyelet hand pincer/dies pushing
the
die pin outwards to deform a pip in the aluminium, outwards, 1/4 way round
so it locates in one of the 2 chassis cutaways. Needs some rubber padding
on
the outside so the other anvil half does not excessively damage that local
area. Any other solutions anyone else has found, particularly forming or
re-forming spring metal to something like conical My attempts are very
wonky.

Maybe give this a try lad

http://www.imagefap.com/image.php?id=1988478267

Always works wonders for me!

Kirk Johnson
"EXTREME Stretching Specialist"