Smitty Two wrote in message
news
In article ,
"N_Cook" wrote:

The spool must be wound in a radial sense at manufacture, so I assumed
it
was best to take it off radially.
If mounted vertically and pulled off vertically then its not just the
uppermost take-off rubbing against the spool end but at the lower end,
on
every other layer, you are pulling against the remaining lay of wire.

My method is not ideal , hence this thread. I chose mounting vertically
and
pulling off horizontally for minimum pull off variable tension.
Mounting the spool on a pair of good quality ball races and then adding
an
ex-VCR slip clutch pair over the top. One runs with the spool and the
other
sprung tied back to frame and small weight added to activate the
braking/slip.
That works very well but it leaves the problem of variable lay pull-off
tension from the spool at these small wire gauges.

I see I have to probably increase to 3 slip/brakes. Existing exVCR slip
with
very little weight , little more than a brake, and the main back-tension
governed by a mix of your felted clothes pegs and lightly sprung felted
discs, separated as far apart as practical to employ inherent slight
stretching in the wire, to even things out, as well as my existing
dancer
arm and pulley.

Another minor problem is the final small pulley that delivers the wire
to
the bobbin. Plenty of pulleys with good quality bearings salvaged from
kit.
But they all the good quality ones have a groove at the join of the V of
the
pulley, just the thickness of this wire, so useless for this purpose. I
assume as they are for rubber drive band use it is something to do with
air
being trapped between pulley and rubber if no such groove. I may swap to
just a small piece of PTFE with a groove in it , extended on a moveable
rod,
instead of a pulley for final delivery.

I'm not quite following your last paragraph, here. Why are the good
quality guide pulleys useless? Isn't the guide groove just what you
want? Sounds like what we have at the bobbin end. What do you mean by
them being for rubber drive band use?

BTW, how are you handling the traverse motion to lay the wire neatly
along the bobbin's length?

Most of the pulleys , that have high quality bearings, ie run true have come
from tape players or VCRs. It seems that along with the high quality
bearing, they have this very small groove, that honestly I've never noticed
before.

The pulley rim is V in section but instead of coming to a point at the
bottom of the V they have a tiny slot perhaps 0.1 to 0.2mm which grabs on
wire of 0.07mm diameter, due to slight imperfections or whatever.

The traverse speed and change direction is automatic and works very well
once the infinitely variable gearing is set and end settings positioned.
There is a bit of a kick due to the PTO change-over action but a kick to
slacken wire supply, rather than tighten which would be disastrous, and I
can compensate for that , as manual , by slowing the rotation down just
prior to flip over and hand brake slightly..


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/