The 'D2W' Research and Development Lab.


    Here in the 'Designed2Wind' R & D Laboratory, the 'D2W Stepper Traverser' (from the 'Possibilities' page) has undergone further development
to become the control centre of my latest winder - 'The Model 8' (also pictured in 'The Gallery').


Above: Monochrome shot of the Model 8 in action.

The evolving 'stepper traverser' modifications explained -

Prior to the modifications outlined below, the traverse speed and the winder speeds were set separately. The traverser's onboard circuitry generated pulses for the stepper motor at a rate set by the speed control pot.
However, after some trials and experimentation, the following helpful innovations have been devised and executed by a professional engineer and friend.

a) New 'Synchronized Mode' -
It was determined that winder and traverser could be synchronized (with a fixed pitch ratio applied) if the pulse from the flywheel's magnet and reed counting setup could be harnessed as an alternative trigger to the stepper's own pulse generation. With careful planning, to avoid adverse interaction between both traverser and counter, and attention to gearing, a very useful 'sync mode' was arrived at.
In the early stages of development, it was realised that, with the prevailing mechanical gearing, each step of the stepper motor caused the carriage to move a little over twice the target (desired) pitch. So a flip-flop circuit was used to halve the reed pulse rate fed to the traverser and thus cause ONE step of the traverser for every TWO winder faceplate revolutions.
*Update note: Further engineering of the electronic circuitry has enabled 'half-stepping' of the stepper motor. It can now be operated with a 'full step' per TWO rotations of the faceplate, OR switched to 'half-step' per ONE rotation. Either way, pitch and winding outcomes remain much the same. The main benefit in half-stepping is the visibly smoother travel of the carriage.
Pleasing outcomes are readily achievable with a variety of wire gauges (AWG 42 through to AWG 44 tested).

The traverser can now be used in either 'synchronized' OR 'separate' (non-sync.) mode via a newly-added selector switch (topmost red switch at left). Synchronized mode means the traverse starts, stops, slows, or speeds up in direct response to the winder's rotation. When the selector switch is assigned to 'sync' mode, the 'separate' (non-sync) traverse mode is overridden. Switching between modes can be done 'on the fly' during winding for added versatility. Such toggling between modes could be used to introduce more 'scatter-winding', or be used to operate or speed up the carriage with or without winder rotation in the set-up phase prior to winding ( i.e. setting of traverse limits 'under power' so to speak). The white middle switch  toggles left and right to instantly change the traverse direction by over-riding the auto-traverse (see point 'c' notes below). The lower red switch offers 1) a 'set-up mode' (LEDs 'on'/ stepper 'off') where the carriage can be moved by hand to trigger the LED's to set 'limits', 2) 'all off' at centre position, and 3) auto-traverse 'on' at the lowest switch position.




b) Traverse speed Range (in non-sync mode).

A capacitor value in the original traverser's clock pulse circuit was increased to lower the overall speed range available at the speed control when used in non-sync mode (independent functioning of traverser and bobbin rotation rates).

c) Manual Option - for varying traverse limits (turnaround points) 'on the fly'
The limits of traverse are usually established by the setting of the micro-switch equipped adjustable arms.
However, further flexibility was achieved by the addition of a *3-way momentary/centre-off toggle switch to the control console (see mid-placed white knob switch above).* meaning  momentary left and right activation with return to centre 'off' position.
This is simply connected in parallel to the 'arm' micro-switches, but has the effect of  intervening in the auto-traversing process at the operator's choosing by way of a manual over-ride.
Where would this feature be used?
Consider a coil that is winding unevenly due to deformed bobbins, poor initial setting of traverse, or other reasons.
The manual toggle-activated over-ride allows the operator to lay up winds at any particular point of the coil then revert back to auto-traversing. Elsewhere this feature might be used to scatter wind with non-sync mode.
Note the speed of traverse remains 'as set' elsewhere (be it sync. or non-sync.), but manual 'toggle control' allows for the freedom of altering traverse limits 'on the fly' - it might be thought of as 'semi-auto' traversing!

d) Secret Wiring channels
While not a grand technical innovation, the Model 8 has numerous 'secret (unseen) wiring channels' to present as neat a layout as possible. Channels travel through the roof and walls of the motor box, across the baseboard, through the winding tension turret, and under the adjustable traverser arms. These channels feed dc. power to the counter, send a pulse signal from the flywheel magnet to the counter and traverser, carry wires from the traverser arm micro switches and turret LEDs, and provide for the wiring loom from the stepper.

e) Wire feed and faceplate detail
 
wire guide A recent upgrade, not shown elsewhere, shows the thinly slotted wire feed guide now
made from 'Teflon'(TM). At left of shot, is the calibrated wire tensioner and black speed knob which makes for easy referencing of tension  A closer look also reveals a past innovation on the faceplate - the quick fitting cut-down brass 'shelf stops' (see 'Gallery' notes). The 'stop' is inserted snugly against, and half under, (due to the pin's profile) the bobbin plate to prevent free-spinning of the pickup. The locking effect of the stop's twin radii, shape and firm fit make for a secure fixing. The routed faceplate offers relief (if req.) to the pickup eyelets enabling flush 'seating' of the mounted bobbin.



f) Speed control
- a robust custom-built variable speed control (not shown above) provides set-and-forget speed settings via a rotary knob.

g) Additional comments -
With the exception of my trusty electronic counter (which can be moved from machine to machine), and the tailstock, this is an entirely new home-built machine, though it embodies many ideas from my previous models. Apart from the extensive features described above, I note some other departures in the design from its forerunners.
 
The Model 8 drive is accomplished via a stepped timing belt and toothed cogs/pulleys, not the '0' rings I have previously used. This was a case of what I had on hand and does not imply any dissatisfaction with other drive systems. The headstock is once again a 'found object' machined and fitted with bearings to carry the shaft and faceplate. As always, it is essential that the latter components rotate smoothly and truly. As noted above, the speed control is a custom-made device with dial-up control (not a PWM device) and not the sewing machine foot pedal of the past. The counter reed and  flywheel magnet used on past machines is again repeated here but given the dual function of providing a pulse to both counter and traverser (in 'sync' mode). A measuring scale has been added to each traverse adjustment arm to assist with set-up. Certainly another level of automation could be invoked with the fitting of an automated downcounter, where the machine automatically switches off after counting down from a preset number of turns. This has not been implemented to date. 

Conclusion
The above traverser and its matching winder operate beautifully in providing versatility in both automated and 'hands-on' control of the winding process. Minimum traverse distance is less than 1/8", with max. - about 1.25" in practical terms, though it could be configured for longer travel. It is quite capable of winding speeds in the approx. range of  450 - 2000+ r.p.m. though my preference is to wind at lower, rather than higher, speeds in this range to allow greater attention to detail with the building coil.
I readily admit that much of the electronic design is beyond my own ability, therefore I cannot provide a trained analysis of the circuit (or diagrams). Such credit belongs elsewhere. Even so, I have made a general outline of the 'concept' here for those with qualification, experience and a specific bent for exploring their own solutions at the more technically advanced level.
 
*All text and photos above are copyright property of spinner@designed2wind.alphalink.com.au - 2003, and may not be redistributed, or otherwise copied/ published, or reproduced for mass-circulation without written permission of the author.

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