Home made coil winder.

[glowinganode]

With the recent withdrawal of VVT from the valve transformer market, I decided it was time I was capable of winding my own.
I'd seen advertised a number of cheap but basic, Chinese made winders. I thought this would make a good starting point so settled on this one. I ordered it on Christmas eve and it arrived by new year's eve, which is a credit to both Royal Mail and the seller who is based in the UK. No connection, just a satisfied customer.
When it arrived I was really quite impressed with it. The only thing that let it down was casting flash on the base, but was soon dressed up with an angle grinder.
A sheet of 3mm aluminium was selected for the base plate and the winder mounted.
Next I needed a mount for the spool. The axle was made from an M8 bolt with a coned hub pinned and locktited in place. This runs on 2 off 6201-zz roller bearings which are located in the rectangular aluminium housing. This axle is currently free-running, I intend to add a tensioning brake later.
The wire guide was designed around some small brass pullies I acquired. These run on 5mm diam steel rods, and are guided by a machined brass yoke. This is tapped M6 x 1 for the leadscrew.
I have up-loaded a video of it in action here.
Still to come are wire tensioner, brake and linkage and then rotary encoder coupled to the output shaft controlling a stepper motor driving the leadscrew. Add an Arduino for good measure.

Cheers,
Rob.

[Wendymott]

Nice start. It will be interesting to see the next phase, motorising the traverse.

[joebog1]

As you have access to a lathe, all you need is a spring tensioned drum brake about 2" diameter for the spool tension. The springs can be different strengths for different guages.
The "brake drum" obviously rotates with the spool and the brake band ( lined with ordinary cork floor tile) is a piece of bent alloy/steel that sits over about 1/3 of the brake drum. An extension of the brake band has the tension spring attached and variable tension is achieved by compressing to a greater or lesser degree, the aforementioned spring. Costs two bob and works a million quid!!
Its how my Glow winding machine operates, and is capable of superb control. Even if its a little slow.
Joe

[glowinganode]

Originally Posted by joebog1

Its how my Glow winding machine operates, and is capable of superb control.

Thanks Joe, any chance of some photo's?

Cheers, Rob.

[joebog1]

I will do my best!! Most is packed up, BUT I believe I have some spool holders and brake assemblies ( in very poor condition) but easily observable for reproduction standards.
I have actually packed most "junk" up as I am trying to move some 2000 kliks south,
where I will setup everything I have ( LOTS of rubbish and junk, but my lifetime of collecting) Bear with me, I do have a few brake assemblies!!.
You will need 20 of em if you get serious!! to pack up the 30 gauge wire, and use the same brake setup for 25 gauge wire is hopeless, and will take weeks of "swapping" the wire rolls and brake assemblies over.
Im not talking of making 100 transformers!!! JUST one, BUT if all the windings use the same gauge I want your design criteria

I have the "spool holders" on quick release mechanisms, read two slightly different sized small exhaust pipes that slip over one another, so its easy to leave the brakes on,
pick up the spool, brake and spool holder, and move it "to the back of the winding table"
Then I simply move the heater wire ( say 18 gauge) to the front and roll out the wire over your "grain breakers" small brass pulleys, and keep winding after rolling on paper/plastic/tape insulation, between winding layers.
Sounds complicated, but its cheap and highly productive for a "lone wolf" I mean "lone winder". Cost is very small!!! I "read" your photos and see you have the "gist" of it!!.
Brake photos tomorrow!! Promise!!

Joe

[FRANK.C]

Great work Rob. You have a very useful piece of kit there.

I used one of those Chinese made winders for several years and found it very good for its price.
I found its bearings needed constant oiling to keep it running smoothly but that's not a problem.
I often wondered would it be worth while to tap the oiling holes and fit grease nipples.

Self adhesive felt pads (the type made to fit to the bottom of table and chair legs) which can be got in sheets will also make a good liner for your back tension brake.

A very interesting project, keep up posted.
Frank

[Diabolical Artificer]

Nice engineering Rob. Here's my attempt at a brake/tensioner made out of a mounting bracket of a PC monitor, and a few bits out of the tat pile. Used pear for the pad.

Andy.

[Andrew B]

How about an infinately variable eddy current brake, just a copper disk with a couple of them new fangled super magnets either side?

[glowinganode]

I did consider that Andrew, but need a brake that will maintain reasonably constant tension over a range of speeds (including zero).
An eddy current brake will give a braking torque proportional to speed and will creep at zero speed.
I have settled for a cast iron drum brake, with tufnol shoes. Will add some pictures in the near future.

Thanks for the suggestion and your interest.

Rob.

[glowinganode]

I've made some progress on the brake mechanism.
A drum was turned from an old cast iron 1" flange and loctited to an aluminium hub.
The brake shoes were made from a scrap of 1/4" tufnol, turned as a ring and divided into four.
The operating arm is drilled in several places to allow a range of tensions.
A horizontal rod mounted on radius arms carries a third pulley. This is spring loaded and designed to smooth out the jerkiness caused by winding onto a square former.
It also has a second function of controlling wire tension.
A soft spring connects the radius arm to the brake arm. As the tension increases, the radius arm moves and backs off the brake tension.
It certainly displays the characteristics of a feedback mechanism, at some settings it run really sweetly, at others it's very jerky or else fails to tension.
I'm still getting my head round the subtleties of operation, although find myself comparing it to (a rather low performance) op-amp.
Photo's attached of various stages of fabrication.
Thanks for your interest,
Rob.

[glowinganode]

More photo's.

Rob.

[Diabolical Artificer]

Well thought out Rob and built like a tank. Almost worthy of Heath Robinson. Are you going to drive the wire guide of use your finger?

Have you wound any trial bobbins yet?

Andy.

[jonmiller]

Heres some pictures of my Avo winder brake, for ideas.

[ms660]

Not sure if this would apply to your winder, but as has been mentioned in an earlier post a lined band brake works well, a la reel to reel tape recorder.

As an aside, if you want a small shaft to stop rotating PDQ then a centrifugal clutch and an over centre unlined steel band band brake takes some beating, a la chainsaw brake.

Lawrence.

[glowinganode]

Thanks Andy, as mentioned earlier the wire guide will be actuated by a stepper motor and lead screw.

Cheers, Rob.

[glowinganode]

Still ticking along with this.
I've fitted the rotary encoder to the winder which rotates at spindle speed, driven by a tufnol gear.
Spent a bit of time getting acquainted with the Arduino. Can't help but feel I could have built it quicker in hardware, but anyhow good excuse to have a play and get to grips with it.
Photo's attached.

Cheers, Rob.

[Diabolical Artificer]

Wondered how you were getting along Rob. Could'nt see how you'd attached the encoder at first, in pic one it looks like it's stuck on, neat job. As you had to drill into the cast, what sort of quality is the cast iron? Looks a bit roughly cast and machined.

Never used an encoder before, I suppose it counts the revolutions. Was programming the Arduino pretty straight forward and intuitive?

Andy.

[julie_m]

A rotary encoder has 2 pairs of contacts that open and close in turn as the spindle rotates: A, both, B, neither, A, both, B, neither ... going one way and A, neither, B, both, A, neither, B, both ... the other way. Every time A closes, you count one step; and the state of contact B at the moment A closes tells you the direction of rotation.

The "all-in-one" knob on many cheap car stereos is a rotary encoder. Posher versions may use optical sensors instead of actual contacts, and count more steps per full turn, but the principle is exactly the same.

This may be egg sucking time, for very thin wire it is pulled off the end of the reel.

[glowinganode]

The casting is a bit rough but is quite fine grain and drills and taps ok.
I used a 1,000 step optical encoder which should allow down to 0.01mm winding pitch. The tufnol gear was cut on the lathe.

Cheers.