coil winding traverse data?

mm

from the table at the top of http://136.159.225.44/AlliedData2.pdf then it would seem that for

35 AWG = 5.715 mil = 0.14mm ~= 38.5 SWG increase is 17 percent 40 AWG = 3.145 mil = 0.8mm ~= 44.2 SWG increase is 13 percent

46 AWG = 1.57 mil = 0.04 mm ~= 48.1 SWG increase would be ? that table only goes up to 40 AWG. I would have expected the percentage increase would increase with finer gauge wire. And there does not seem to be a straightforward AWG to SWG conversion either

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

I am not sure if an allowance was made? Looking at the table for travers on the Avo Douglas machine on page 21 of this pdf:-

Taking, for example, a 10 thou traverse, the table gives gears of 30,40 and

48,36 which fit precisely into the formula at the bottom of the table for 10 thou wire diameter. Similarly for 20 thou wire diameter.

--
Geo

but arguing with myself - there is a table of allowances on page 6 of the older instuction manual which gives 0.2 though for 46 to 50 SWG.

--
Geo

older

g.co.uk/pdf/avocoil.pdf

The big unknown is the thickness of the insulation in 1930 when the manual was produced and the thickness of the insulation on the wire that Norm is proposing to use. THe actual copper thickness should be the same.

mm

this

and

10

Useful info there

You must have some excess traverse, for all the previous mentioned reasons plus back tension variability , non linearity of traverse and dirt, as the winding will eventually upset and overwind otherwise, just a matter of gauging how much.

Following on from a previous discussion here on back tension etc, this is now what I use on my ETA machine, mechanics much like the Douglas For very fine wire I use a small PTFE thru chassis terminal as final delivery point, passin wire thru the where the pin was. ptfe squashed and then mounted on adjustable metalwork for the best angle/ work closeness. With as straight as run as possible between mandrel , PTFE and supply spool. To give some slack in the wire, to allow for snatching/ uneven slip-clutch, by allowing the supply wire to stretch , I mount the supply spool about 10 or 12 feet away with slip clutch and adjustable weight and then a felt clutch about 2 foot from the spool, far enough for up and down motion along the spool. Felt clutch made from a strip of felt wrapped a few turns around the wire and then held in the clothes line notch of a sprung clothes peg , fixed to a support.

Where I used to work and a had use of a Douglas the most accomplished, radio man, had created a 3 way plot for this info. Gauge v back tension v traverse and some allowance for diameter of former.

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

mm

this

and

10

I will go with that Avo/Douglas data, going on the conservative side

50 swg 20 percent 46 swg 8% 38 swg 6.5 % 30 swg 5% 25 swg , 4%

Incidently I think the ETA reversing mechanism may be better than the Douglas one, for fine wire anyway. I seem to remember that if everything was not just perfect then sometimes with the Douglas there would be too much of a kick on the traverse arm and so break the wire, at reversal. I discovered that the kick I was getting on my ETA one (in the right sense of slackening rather than stretching, in both directions of traverse) was just due to a slack end bearing of the leadscrew. The ETA uses a rubber rimmed cam that engages with a flywheel to flip a synchronised? dogclutch across to engage , meshed I think, cleanly with the reverse set of cogs.

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

Haven't been on this board for a while so I'm late with this reply. Maybe you sorted it out already.

There is no gap between wires. Wire manufacturers publish minimum, nominal, and maximum diameters for every flavor of wire they make. Use the maximum. Just divide the bobbin length (traverse length) by the diameter to get turns per layer. Then the only space you'll have between wires is the amount by which your wire deviates from the maximum.

If you don't have and can't get the spec, you're best off with a toolroom micrometer measurement of the wire in hand. The operative adjective here is "toolroom." A standard shop mic is woefully inadequate for this task with wires that small.

We buy coil wire from MWS. Lots of good technical data on their website. Note that the Allied table you linked is for bare copper. Coil wire is insulated, which adds to the diameter.