Anyone familiar with coil winding machines ?

"N_Cook" wrote in news:g1dt4k$824$ snipped-for-privacy@registered.motzarella.org:

Many sewing machines use a similar system to set the thread tension. You might adapt one from a sewing machine.

Also try looking up the patent applications for such devices, you might finds something helpful.

I think a cross-wired memory effect has come into play. That pair of discs is what I've seen on a sewing machine and memory transfered to coil-winder m/c so probably have no recollection of what that Douglas mechanism was. But I do remember having to use fingers for back-tension as the proper mechanism , whatever it was, was unreliable.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

"N_Cook" wrote in news:g1e7b4$fga$ snipped-for-privacy@registered.motzarella.org:

One or more turns around a shaft might do the job. You might tear up an old hard drive and use the supports and bearing for the platters for the shaft variable drag on the shaft could set the tension for you. Somewhat similar to the drag on a tape machine.

Another idea, how about the variable drag on a fishing reel? Off load your wire onto the reel.

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That would be very helpful. Can you upload to a site somewhere? if by email, I will have to relay an email account/address to you that does not have filters on it.

I've had another google and not found anything useful.

There is nothing wrong with the spool layering , it is just the natural marginal wedging that occurs with on unwinding, not overlaps , but just slight variation of a couple of ounces that would not matter if using 8oz of back tension or more for a thicker gauge, but 2 oz is too critical.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

I don't know about that how ever, at work we deal with small wire and conductor in the area's of 40 AWG etc.. and 2 difference systems are used.. One uses a small lever (catenary) arm with a small disc roller on the end of the arm along with an eyelet to keep it in the roller. When the wire is pulled, it pulls down on the arm which has a spring as part of a strap that goes around a drum that is an integral part of the pay off shaft the supply of wire is loaded on.

The strap has a rawhide pad on it.. the pulling of the arm pivots on a shoulder bolt, the other end opens the strap to release the braking. Putting on a tiny air piston with speed bleeders on both ends help in damping the oscillation.

The other system is just about the same how ever, we have a DC motor attached to the shaft with a dancer circuit. The centenary arm has a small POT on it that drives the DC regen drive to maintain position of the arm which maintains constant tension through out on the take up end.

This works great for very fine wire and all we do is adjust the spring on the arm via a thumb screw and lock nut on the threads.

The motors are 1/10 HP PM units.

The pot's are optical types, so the movement in the shaft has very little drag and are smooth .

The electronics for the Pot sensing has trims on it to adjust for delay, Lead, sensitivity etc..

Many thanks for that. Seems more black arts than science. I assume the black fibrous block under the arm in pic 008 is someone's retrofit damper like the Millenium Bridge in London.

I think I would make the sprung arm out of lighter materials as I would only need it for 40AWG/45SWG type gauges and so less inertia there. Do you find a problem with dirt or grime on the felt pads causing irregularity problems at these light tensions ?

I was wondering if a servo system for spool unloading to zero tension is a way to go. Inductively or optically, somehow monitoring the sag in an unsupported section of the supply wire. When in optimal band then spool rate say 5 second average speed. More sag then proportional down to zero speed and too little sag then proportional up to some system limit.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

With pulling off the spool axially and vertically don't you get problems when the lead-out reaches the top of the supply spool? compared to pulling off axially.

One thing i have learnt is the use of a small force gauge as used in checking slip clutches etc on VCRs. Mine is 0 to 50gm Halda / Haldex of Sweden, just make a loop in the end of the wire to hook into and pull for a bit, to check for tension and consistency on the dial.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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But what happens for the when the spool take-off reaches the very uppermost turn and the wire is rubbing along the internal face of the spool and being pulled through a softened right angle at the the spool rim ?

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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.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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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

"N_Cook" wrote in news:g1ouq3$jsl$ snipped-for-privacy@registered.motzarella.org:

can you run a rattail file along there to widen/remove the groove? How about wrapping a few layers of TFE tape around the pulley and filling in the groove?

Shapelock aka Friendly plastic could be used to mold a 'cover' for the pulley. Heat it with a hot air gun or hot water, it turns clear and mold-able. It sticks to other plastics. When it cools it is nylon hard and opaque white. I have used it to fix broken nylon gears in a printer and a broken slide bracket in my wife's sewing machine.

I tried plumber's PTFE and it failed. Had another hunt through my collection of salvaged pulleys and from about 20 they all had this tiny groove just where I don't need it. Never previously realised, because it is such a tiny groove, that all good quality small pulleys , plastic, brass or aluminium have this groove. Still not found the funtional reason for it.

Took some advice from a proper mechanical engineer on how to best tackle turning my own small 8mm diam x 3mm PTFE pulley with a straight (un grooved) V cut , and will go down that root ;-)

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Just a little speculation about the groove: It may be that if the pulley is transporting something like mag tape this groove is necessary to keep an air bubble from forming and "flying" the tape.

It would not be difficult to round out the bottom of an existing pulley with a lathe-like setup. I save old drill bits to make special tools for that sort of thing.

John Ferrell W8CCW Beware of the dopeler effect (pronounced dope-ler). That's where bad ideas seem good if they come at you fast enough.

You dont want the bottom of a pulley for square section belts to be rounded, the drive comes from the sides of the belt. Like the vee belt on a car alternator, when it wears enough for the belt to bottom out on the pulley, it stops driving.

The slit is there so that the flat sides make correct contact

Ron(UK)