DRS, Accelerator Wheels, and Low Grist Yarns

Many of the commercial double drive wheels come with a differential rotation speed of ~1.6. this would seem to make them ideal for making singles for worsted weight 2-ply yarns.

However, such thick yarns rapidly change the effective diameter of the bobbin as they accumulate on the bobbin.  Changes in the effective diameter of the bobbin change the DRS,  To keep grist/twist within ~10%, DRS need to be kept within  ~10%.  When you accumulate 1/4" of yarn on the bobbin, the diameter changes by 1/2" and the DRS changes by a lot and one needs to either change flyer whorls or wind off or allow slippage.  Slippage is the easiest, but why go to the effort of having a DD system, if you are just going to let the drive band slip?  I mean, at these grists we do not have to worry about breaking fine singles.

My first choice for spinning a single with grist of less than 2,500 ypp is single drive, bobbin lead (Irish tension).  These yarns do not require at lot of twist, so one does not need the very high rpm that requires 2 drive bands.  With these yarns, two thousand rpm will produce 10 yards per minute, which is about as fast as you can draft quality yarn.  With 90 rpm as a comfortable treadling cadence, that means a good ratio is ~1:24.

Whorls less than 2" (50 mm) in diameter tend to slip, so if you really want 2,000 rpm, then you need a whorl of 2" and a drive wheel of  48"!!  Forty-eight inch drive wheels are a big pain.

Enter the accelerator wheel.

When I first went looking for more speed for fine singles, I went to higher ratios by decreasing the size of my whorls. It was more an education than a success.

Today, I use the Ashford Jumbo flyer in Scotch Tension mode with the accelerator wheel for plying, and I routinely ply at more than 2,000 rpm.  I could just as well be spinning singles at (more than)  9 yards per minute. I have done samples and tests but no production spinning with that plying setup. Since with Scotch tension, worsted yarn does not self assemble as it does with DRS, it is all long draw woolen, rather than worsted. The speed is limited by my drafting, rather than the speed of the equipment.

Since low grist worsted tends to be harsh, when I want thick worsted yarns, I ply them up from fine worsted singles and have no interest in trying to figure out how to use DRS to spin low grist yarns.  On the other hand, this means that I have a great desire for fine singles.

Bottom line -- DRS for low grist yarns is a waste of effort.  DD without DRS is a waste of effort.  The only reason that people do it is that they have heard myths about the power of  double drive wheels  And, DD does have power.

DD with DRS can do things that SD simply cannot.  DD with DRS is a very powerful tool for spinning singles in the range of 2,500 to 45,000 ypp (5 m/gram to 90 m/gram). With DRS, true worsted and true woolen can be spun with almost the same drafting technique - what differs is the fiber preparation. Woolen is spun from a pile of carded rolags and worsted is spun from a distaff of combed sliver.  In particular, DRS allows spinning true worsted singles faster than long draw woolen singles of the same grist can be spun. (Woolen requires more twist than worsted of the same grist.) With DD/DRS, true worsted 5,600 ypp singles (10s) can be hand spun at 10 yd/minute on a sustained basis.  However, this puts very high demands on fiber preparation to avoid "twittering", which is variation in thickness of a single as a result of variation in the density of the sliver being spun.  Even with minor twittering, DRS allows spinning 560 yard hanks that are consistently within 5% of the desired weight.

And now you know why I have such respect for Clemes and Clemes.  Better fiber preparation is at the core of better and faster spinning.

On the other hand, minor twittering will not affect the final quality of 5-ply sport weight yarn.  The folks who say it does do not make enough of such yarn to make many objects from it.

RPM update

The new geometry is faster, and it took me months to learn to use it.  Net drive ratio is on the order of just over 58. so with my normal treadle cadence of 90, I should get just over 5200 rpm of spin insertion. I have not even come close.

Drive band(s) slip was on the order of 20%, meaning actual twist insertion was only about 4,200 rpm.

However, 4200 was as fast as I could spin for months.  Now, I am more comfortable with that kind of speed.

Thus, last night, some more tension on the drive bands, (using a pair of 8 oz weights with a spring between them), and this morning twist insertion is up around 4,800 rpm.

For 9 tpi worsted, that is ~14 yards per minute, which is faster than I can pull fiber off the distaff, so I am working on a new distaff design and geometry.

On the other hand it will do 17 tpi shirting singles at ~ 8 yards per minute, which is a nice pace.

When I first sat down at the Traddy some years ago, it felt like a race car that wanted to go faster. Now, it feels like a race car that is running near its design speed. It is like an old Ferrari,  tuned by the factory race team, running time trials at Sebring.  It is going almost as fast as it can go.

http://www.sebringraceway.com/sebring-events/12-hour-race/12-hour-race-information

Spinning oil

(applied frequently)

Commercial cap  and later ring spinning frames ran at about 5,000 rpm.  My best guess is that 5,000 rpm is about the maximum speed for flyer/bobbin spinning to run on a routine and sustained basis.

Do I  think Scotch tension systems can run this fast - not likely.  Single drive, bobbin lead (Irish Tension) is mechanically more like the  cap spinning devices.  On the other hand there were hundreds and hundreds of patents for bearings and geometries before the commercial cap spinners were able to run that fast,  and then the technology was only used for a few years, before better spinning devices came along.  I think an Irish tension is a hard way to get to 5,000 rpm.  That said, I do use Irish Tension for plying with jumbo bobbins, and it runs at - 3,000 rpm using a ratio of 33:1.  Irish Tension at 3,000 rpm is easy.

A note on ergonomics.  If you do not have to spin as long to get a project done, then there is less  total stress on the body.  And, DRS hugely reduces the stress of spinning - particularly on the drafting hand, drafting hand wrist, and drafting hand forearm. I could not spin as much as I do, if my drafting hand had to resist the ongoing tension of Scotch tension.

My lazy kate has a tension box so there is essentially no stress on my hands while plying.  I just sit there and treadle, pausing every so often to move the flyer heck, and place new bobbins of singles on the lazy kate. 

Cross check

When I make a change to my wheel, I go back and check how it performs Scotch Tension and Irish Tension (single drive, bobbin lead).

Thus, I setup the new mother of  all  for Scotch Tension. RPM was about 65% of what I get with DRS, but net productivity was only ~ half for the 5,600 ypp woolen weft I am currently spinning.

Productivity for single drive, bobbin lead was better, and in the range of 70 % of  DRS. It must be noted that productivity was not as high as I would had expected for the achieved bobbin rotation speeds.

With the accelerator wheel and large whorls,  there was not as much difference between the performance of the #1 and #0 fliers as there is without the accelerator wheel and large whorls. The moral of the story is that: Small whorls have large slippage!

A second moral to the story is that gravity is a very good way to tension the drive belt, and that when the flier/bobbin assembly can move, vibration in the system is reduced.

However, the uniformity and grist control from DRS was distinctly better.  This may have just been a function of my spending more time spinning DRS recently, but given the higher productivity and better grist control of DRS, I am not going to put the effort into keeping my long draw and inch worm skills sharp.

Is the extra effort (and math) for DRS worth while? It means that I can spin/ply a hank of  5-ply gansey yarn in a day.That means I can spin the yarn for a sweater in a week and have a couple of days of knitting rather than spinning.  And, for big projects where I budget a thousand hours for spinning, it means that I have an extra 300 hours for weaving rather than spinning.    That is almost 8 weeks,  That is enough time to weave the yarn from (700 hours of fast spinning) or (1000 hours of spinning slow).  Thus, by spinning 30% faster, my weaving time is free. And, the quality of the yarn that I produce with DRS is much better, so my cloth is better.

The greatest comparative advantage in textiles is in better spinning.

More on spin count

The distaff is dressed with 60 count flock-run long wool, and the task at hand is 40s (150 wpi) for weaving warp. I need a good bit of the warp, and I am working on it diligently.

However, spinning 60s from 60 count wool is so easy and so relaxing that I do find myself accumulating bobbins of 60s - and this is only with flock run fiber -  and not well graded fiber. After "working" on the 40s for a while, I flip the drive band over to the 20 tpi whorl and spin 60s for fun.  I may just change my mind, and just spin the warp from 40 count wool.  I had intended to spin the weft as 22,400 woolen singles from 80 count Rambouillet.  Samples of woolen singles of from 40 count fibers are not that soft, but they are faster and easier to spin.    Frankly, at this point, I find worsted singles in these grists easier to handle than woolen, and singles management is becoming a big deal.  

This rather upsets things as I have a lot of fine (80 count) wool ordered for this project- all based on the conventional wisdom that it would be easier to spin 22,000 ypp singles from finer wool. As I get into this, what I find is that it is easier to spin 22,000 ypp/150 wpi from 40 count wool (34 micron)  than from 80 count (20 micron) wool - - if you have the correct equipment.  And this goes for both worsted and woolen singles.

Let me say this over and over.  If you have a single drive wheel, then yes, it is easier to spin 40s/22,000ypp/150 wpi from finer fiber.  If you are working on a DRS controlled spinning wheel then is is easier to spin 40s from 40 count wool, and 80s from 80 count fiber.  And, a DRS wheel will let you spin 40s about 5 to 8 times faster than a single drive wheel.  NOT twice as fast, but more like 5 times faster -- or even more.  This is spinning.  Why do not the "experienced" spinners / teachers talk about it?  Because it takes some math and skill in setting up the wheel.  I think spinning 8 or 9 times faster is worth a little math.

The bobbin core on the AA#0 flier is 0.95", the bobbin whorl is 45.00 mm in diameter, and the flyer whorls for 40s, 60s and 80s are 45.9, 45.72, and 45.63 mm respectively..   These must be calculated, and not guessed. And then, a bit of dirt on whorl can spoil everything.  These combinations insert approximately 18, 20, and 23 twists per inch to produce 22,000, 30,000 and 45,000 ypp singles. That flier runs at over 4,000 rpm. The bobbin whorl on the AA#1 flier is 50.00 mm, and its flyer whorls produce 10s, 20s, and 40s. That flier runs at over 2,500 rpm.

I need a quarter million yards of 22,000 ypp (40s) singles.  I need easy!!  I need fast. Last winter, before the improvements on the wheel, I thought the path to fast and easy was finer wool.  Now, I know better. If I am going to write a check for $1,500 for the fiber for one project, I want to make sure I am buying the correct fiber.

The extra speed of from the new accelerator and the additional precision from the larger ~(50) mm DRS seem to facilitate the spinning.  Over all DRS as a technology resolves most of the difficulties enumerated by other authors discussing the spinning of fine singles. I am going to revisit this real soon.

However, watching the fine thread slipping through the fingers at 3 or 4 yards per minute does tire the eyes and ultimately bring on vertigo.  This can be avoided by spinning by feel.

I can watch DVDs while spinning.  The only thing is that I must limit wood working to retain sensitivity in the finger tips to allow spinning with minimal looking. However, with limited woodworking, I can spin even 80s (200 wpi) mostly by feel.

Spinning productively

Why, Oh Why, comb top, and then knock the fibers out of alignment before spinning?  It is doing the work twice.  No professional does the same job twice, unless they did a poor job the first time.  No the comb/diz did their job, but the spinner destroyed the alignment when held the fiber to keep the flyer/bobbin assemble from pulling the whole top into the orifice all at once, like a hungry grizzly bear eating a Big Mac.


Silly!! The spinner that knows their craft simply keeps the fibers straight, and aligned parallel all the way through the process. The combs /diz can align the fibers better than fingers hurriedly inch-worm drafting.  More, better, faster drafting to realign the fibers is not the answer. The Answer is: Do not mess the fiber up!

The answer is use differential rotation speed (DRS) so that fiber is drawn into the orifice only as fast as twist is added..When, I am spinning 10s at 9 tpi, my flier/bobbin assembly draws in 1/9" of fiber stream and inserts 1 twist.  I do not have to pull back on the fiber stream to retard its entry into the orifice, because it is only going to take in as much fiber as is needed for the twist that is being inserted.

Alden Amos and others have tried selling such wheels but there was no market.  Modern spinners do not have the skills to operate such wheels.  That is stupid because the concepts and math are fully explained in the spinning manuals from the beginning of the 20th century.  And, Alden Amos in his Big Book of Handspinning walks us through the math and concepts.

Still modern spinners insist on messing up their top by using Scotch Tension wheels, and in the discussion of what kind of wheel to buy there is no discussion of  DRS.Even Alden does not discuss the advantages of DRS in his big blue book.

When, I started using DRS, I thought that it was faster because there were 2 drive band contact areas, and hence more friction to drive the flyer/bobbin assembly faster.  And, that is certainly part of the story, but it does no explain the full increase on productivity.  The other side of the story is that DRS speeds spinning by making fiber in take much more efficient.  And, instead of a fiber drafting process there is a very efficient top/roving attenuation process.

So here is the deal. A DRS wheel is inherently faster than single drive wheel - and that includes e-spinners.
A double drive wheel that does not use DRS is somewhat faster than a single drive wheel, but not nearly as fast as a true DRS wheel.  And the difference between a not DRS DD wheel and a true DRS wheel is only millimeters - you cannot tell without measuring unless you work with DRS all the time.

My take is that any spinner that wants to spin productively, will put the effort into learning DRS; the concepts, the math, the tools, and the technique.  How productive is DRS?  Well, it will let me spin 560 yards of lace weight worsted spun single in ~70 minutes.  How long does it take you?  Yesterday, I was tuning my whorls, and running back and forth between the wheel and the lathe.  In the process, I spun a couple of thousand yards of lace weight singles.  How much did you spin yesterday?

Spinning more Hanks

I am in this for the yarn.  I want better yarn.  That means hand spun.

From the start, I wanted my yarn fast.  I was in this for the yarn, not as a way to pass time.  I was willing to put in the time that the chore of spinning demanded, but I did not want to put any extra time into spinning.

I came to spinning knowing how construction professionals worked. They had good tools, they knew how to use them, and they worked rapidly with no wasted motions. They did the job, and then they went on to the next job.  Spinners on the other hand seemed intent on slowing the work process.  Spindles were designed with large whorls so they spin slowly.  Spinning wheels were designed to spin slowly.

Spinners are in denial.  They say, "No, my wheel is fast."  However, they do not stop an think that flyer/bobbin speed is limited by power transfer through the drive band and Scotch Tension systems brake the flyer/bobbin assembly, and thereby reduce the over-all rate of twist insertion.  Then, they have double drive systems that inherently require drive band slippage.  If there is slippage, then the flyer/bobbin assembly is not going as fast as it would without slippage.  For the last 50 years, spinners have been favoring wheels that had SLOW built into them, and wheel makers built what the market demanded.

Spinners say, "These are traditional designs!"  Ok, traditional designs for what?  Linen! The long fibers of flax need a slower speed, and there were a lot of old linen wheels around.  People assumed that a spinning wheel was a spinning wheel, and used old linen wheels as the design prototype for wool wheels.  So what is the difference between the design of a good linen wheel and a good wool wheel?  The linen wheel wants less speed, and the wool wheel wants more speed.  Scotch Tension systems are a logical engineering choice for a wheel designed for linen. They are less logical for a wool wheel. They are not at all logical for spinning cotton.

A traditional wheel design for woolen spinning is Irish Tension. There is no additional braking to slow the flyer/bobbin assembly.  There is no drive band slippage to slow the the flyer/bobbin assembly. The mechanism is simple to make and inexpensive. If you wan to spin medium woolens (30,000 yd/lb and less), bobbin lead is a very good and traditional approach. It is simple and easy to set up. And yet, I remember the feeling of rebellion, when I first tried IT.  Everyone was telling me that most spinners were much happier with ST.  And, yes, IT with the big Ashford flyer does have a very strange feel to it. The sudden increase in take-up at higher speed is very disconcerting for the beginner who is not forewarned.   The beginner (with a big flyer) says WTF, and abandons the concept. The beginner with a small flier feels no take-up and says, WTF and abandons the concept. The ST friction brake provides a steady take-up pressure as speed increases that is easy for the beginner.  While the IT takeup is a cube function that is small at lower speeds, and then increases very rapidly at high speed.   With the big Ashford  fliers, IT does produce excessive take-up pull when one tries to spin fast (more than ~800 rpm).  However, a small flier such as AA's #1 flier produces very reasonable take-up tensions at speeds in the range of 1,800 - 2,200 rpm. On the other hand take-up at speeds less than 1,500 rpm is negligible. At slow speed, one can spin very fragile yarns or make pig tails. For conventional yarns, one either spins fast or it does not work. The AA #0 flier running in IT generates reasonable take-up at speeds in the range of  2,400 - 3,200 rpm.

For the expert with a flyer that has a low aerodynamic cross section,  that low take-up at low speed and high take-up at high speed is a very powerful tool.  The expert can adjust take-up by altering the bobbin rpm by treadling slower or faster. The take-up adjust is precise over a wide range, fast, and does not require the hands to leave the yarn.  All of which  is important when yarn is running through your fingers at 10 yards per minute. However, the spinner much be prepared spin fast, and know that slowing down will stop take-up before the bobbin stops.  This is a set of skills that have fallen out of spinning lore.

Now look at the literature.  Do the experienced spinners warn the beginners? Why not?

What if one wants to spin worsted fines (30,000 to 48,000 ypp)? Fines require some 20+ tpi. Scotch Tension systems will get you there, but it is clumsy and very, very slow.  IT is faster, but it gets very delicate as the flyer is pulled by a fresh yarn of only 20 fibers.  Modern double drive with slippage is a fraction better than ST. Differential Rotation Speed Double Drive is the best engineering design for spinning yarns in this class, but one must prepare and fabricate a specific engineering design for the grist. This is worthwhile if you plan on spinning many miles of a particular grist. Then, these yarns can be spun as fast as they can be drafted, and well prepared fiber can be drafted very fast.  Traditionally, hand spinners did spin fines as a commercial product.  Here, "commercial product" means the yarns were spun by hand rapidly.  Differential Rotation Speed Double Drive has no equal for hand spinning worsted fines.

I spin yarn as I need it. I benchmark how fast I spin, so that I can evolve and improve my spinning.  I do not care how fast you spin, but I do care how fast I spin. I want to make sure that I am spinning at a reasonable rate.  If others are mired in myth and cannot believe what I do, that is not my problem.

My problem is to make the yarn that I need, in the time that I have.

DRS Revisited

I have been plying yarn for my Shetland gansey.  Some of the singles were spun last winter before I built the Hot Rod and some after. 


Running the singles through my fingers, I am impressed by the consistent fineness of the singles spun using the Ashford high speed whorl and bobbins with whorls that provide the proper DRS (differential rotation speed) for the grist of yarn being spun.  While the Hot Rod certainly allows me to spin faster, singles spun on it tend to drift in thickness.  For example, singles that I intend to be ~9,000 ypp end up with portions being closer to 7,000 ypp or 11,000 ypp.  I think this is because with the small whorls, a small change in anything changes the DRS.  While the standard Ashford high speed whorl is twice as large, so the same change in that system makes only half as much change in its DRS. 


Anyway, I am going to move toward larger whorls so that I have better control of my  DRS.  I have not decided if I am going to do that by putting an accelerator wheel on the Traddy or if I will buy a 30 inch wheel.  


Most of last week, I had the Ashford Lace Flier (ST) on the wheel.  First and foremost, I do not think that there is any question that a good bumpless driveband (per Amos) delivers more power than the Ashford Turbo driveband (clear stretchy plastic).  2)  Fluorocarbon leader material (fishing line) makes very good brake band material for spinning very fine yarns. 


As long as we are talking about spinning fine, see the Bothwell Spining results at http://www.bothwellspinin.com/spinin/files/LongestThreadResults_2011l.pdf   The winners are spinning singles up in the range of 100,000 ypp or 176 hanks/ lb. The winner, Jan Zandbelt, currently uses a Louet Julia, but in 2007, he used a Majacraft Suzie with 1 gram of brake tension and custom made ultra-light weight spinning bobbins.  Of course, that contradicts my thoughts about DD being better for spinning fine.  Or, does it?


I do not spin that fine.  I do not try to spin that fine.  I do not need singles finer than about 27,000 ypp.  I aim to spin my finest singles at ~90% of  their spinning count.  Thus, Polwarth has a spinning count of ~ 62, so I would aim to spin it at ~ 31,000 ypp.  Zandbelt spins it at 88,400 ypp.


Does that invalidate everything that I say?  I want yarns that knit up into fabrics that I like, and I want to produce those yarns with a minimum of effort. Zandbelt wants thin yarn for contests. He says that "Patience"  is important.  We have different goals.   


However, I am arrogant enough to think that if I wanted to spin Polwarth  into a yarn that was too fragile for any practical use, I could.   I would approach the problem by making up a DD spinning bobbin with a DRS of 1.01 and a bobbin core diameter of 0.625".  I think that for that low a DRS, I would use the regular Ashford DD flier whorl, which gives me a bobbin whorl diameter of 1.73". We are talking a bobbin speed of 1,200 RPM.  My bobbin has not gone that slow in ages.  It would take all weekend to spin 10 grams. "Patience" is right. 

Virtues of Scotch Tension

Previously, I noted that Double Drive (DD) spinning wheels can go faster because they have two drive bands to transmit that power from the drive wheel to the flier assemble. However, you may not really need to go that fast.

If you do not have a real need for speed, “Do you want a DD spinning wheel?” I suggest, not likely.

With DD wheel, the ratio between differential rotation speed (DRS) strongly affects the kind of yarn that you spin. A set DRS can help you spin a very consistent yarn if you are working with the same kind of wool and want to spin miles and miles of the same kind of yarn (production spinning).

On the other hand, if you to work with different kinds of fibers/wools, or you want to spin a different kind of yarn, with a DD wheel you need to change the DRS. This means changing your bobbin or changing your flier whorl or both. If you want to spin different yarns with a DD wheel you need a whole set of bobbins and flier whorls.

Now, some of this can be done by working with a partially filled bobbin to fine tune DRS, and some can be done by adjusting belt tension. However, these steps only take you so far. If you do not have a bobbin/flier whorl combination to give you the DRS that you need for the yarn that you want to spin, you are going to have to fight your wheel for every inch of that yarn that you produce. This takes away from the joy of spinning. This is one reason that people have different DD wheels. Each has a (set of) different DRS, and thus different yarns that they spin easily.

DD wheels come with a very limited selection of bobbin/flier whorl combinations that allow the easy spinning of a very limited number of different yarns. If you have an Ashford Traddy with a (Fast) DD kit, you will find it easy to spin lace singles at about 5,000 ypp. However, spinning 11,200 ypp singles leads to cuss words that cannot be said in public – until you get the right whorl (custom made), and then it goes like butter on warm toast. (Oh, yes, it can be done, but it is not as easy as it is when you have the bobbin/flier whorl combination to produce the correct DRS for that yarn.) If you want to spin 22,400 ypp singles (easily), then you need a different (custom) bobbin/flier whorl combination. Thus, if I want to spin a new kind of yarn, I start by going into the shop and turning a new spinning bobbin that gives me the correct DRS for the yarn that I want to spin. And, when I am spinning ST, I put a lot of yarn on my spinning bobbin. When I am spinning DD, I stop and wind off frequently, because as the bobbin fills, my DRS changes.

Scotch tension (ST) on the other hand will allow you to produce almost any yarn that you want from almost any wool. Small changes in drafting technique, or treadle rate or brake tension are all that is required to easily produce a wide variety of yarns. Thus, Scotch tension is better for people that want to work with a variety of different wools/fibers to produce a variety of different yarns. The downside of ST is that it has lower limits on speed and it is harder to produce a very consistent yarn.

The virtues of DD are ease of producing a consistent yarn very rapidly. The vices of DD are the extreme difficulty of producing yarns for which you do not have an appropriate bobbin/flier combination to produce the correct DRS, and the difficulty of obtaining appropriate bobbin/flier combinations for specialty or unique yarns (particularly for old wheels.)

A New Twist on Lace Fliers

I came to spinning not as a spinner, but as a person interested in yarns that I could not get from commercial sources. As a good student, I asked, “What is the best way to spin fine, high twist singles?” The conventional wisdom that I received was to use a “Lace Flier”.

Lace fliers are Scotch tension flier and bobbin assemblies ostensible designed for the rapid production of lace singles. They tend to be “balanced”, and have low friction bearings to allow them to spin at very high speed. They are flier lead and have small whorls resulting in “high ratios” so that they can turn very fast with a limited treadle rate. Or, at least that is the conventional wisdom.

In fact, at lower speeds (400 – 800 rpm) this is how lace fliers work. As a beginning spinner starts wanting to spin faster, a lace flier helps them insert more twist into their fine singles, and for the beginning spinner, it seems like a lace flier is the ultimate answer to rapidly spinning fine singles.

At slightly higher speeds, things start to fall apart. At low speeds, it takes very little power to drive the flier and bobbin. Windage is minimal. Energy to accelerate the flier is minimal. Energy going into twisting the yarn is minimal. And, (if you oiled your wheel) friction is minimal. However, windage is proportional to the cube of the speed and acceleration is proportional to the square of the speed, with the power dissipated as friction and going into twist being directly proportional to the speed. Together these represent a power consumption function. All the power to the flier is supplied to the flier and bobbin by the drive belt.

Thus, if “windage” consumes 1 watt at 400 rpm, it will consume 8 watts at 800 rpm, 27 watts at 1,200 rpm, 64 watts at 1,600 rpm, and 125 watts at 2000 rpm. This power must be delivered by the drive band. A piece of kitchen string tied with a square knot can easily transfer 8 watts, even if it is sweeping a small whorl. To get that kitchen string to transfer 125 watts (i.e., 2,000 rpm) you are going to have to ply it up into a cable and douse it in a high-friction belt compound, otherwise that belt is going to slip or break. You will be treadling like like crazy, and you wheel will be making all the noises that say it is going fast, but drive belt will be slipping against that little lace flier whorl, so that the flier and bobbin are not going as fast as you think they are going.

Wheel wrights have put great effort into reducing the windage of their lace fliers, but that cubed function for windage is against them. And, in a Scotch tension system, the bobbin cannot go any faster than the flier. In fact, the bobbin speed (and hence twist) will be between 10 % and 30 % less than the flier speed.

The truth is that a high-speed double drive system will provide higher bobbin speed and hence insert more twist into the yarn, allowing faster spinning than a lace flier. There are several reasons for this. Double drive wheels have more than twice as much contact surface with the drive band to transfer more than twice as much power. In a double drive system the bobbin goes 10 % to 30 % faster than the flier. Thus, if you have a Scotch tension wheel and a double drive wheel with the fliers going at the same speed, the double drive wheel will be putting 20 % to 60% more twist into the yarn. I did not know this when I looked at the ratios of various fliers as I prepared to buy my first wheel.

Last summer, I spun 10 miles of 5,600 ypp singles with a lace flier on my Ashford Traddy, and I guessed much of the above. In December, I got a Neiko Digital Tachometer (NDT). That confirmed my worst fears. I was wasting effort. I was treadling and my drive belt was slipping like crazy. (Despite that fact that I have long experience with drive belts in the power range of 0.5 to 800 hp, and I know how to minimize belt slip.) The bottom line is that the small swept area of the lace flier whorl is not capable of handling the power required to drive the flier at much over 2,000 rpm.

The NDT tells me that if I treadle diligently, I can insert a lot more twist into my yarn using the high-speed double drive (ratio stated as 17:1) than I can using the lace flier that Ashford tells me has a ratio of 40:1. For example, the NDT tells me that the Ashford Turbo dive band starts slipping at ~2,000 rpm. It does not matter how much tension I put on it, the band does not drive the Ashford Lace Flier faster, no matter how fast I treadle. From my treadle pace, I think my flier is flying, but the NDT is there to keep me honest.

The NDT tells me that much of what is tossed around about speed of spinning is not accurate. And, it tells me that much of the conventional wisdom about spinning is wrong.



A faster DD bobbin/whorl set for my Traddy that I made by hand.

Moreover, the industry has a odd way of calculating the ratios for DD spinning wheels.  The actual drive wheel/ bobbin ratio affecting spin insertion for the high-speed Ashford DD bobbin/whorl set is closer to 22:1.  The drive wheel/ flier ratio is ~ the stated 17:1, but in practice the bobbin turns faster than the flier, and thus twist insertion is greater than would be expected by comparing the ratios of the DD kit with the ratios of the lace flier kit.

DD is the smart spinner's way to fast twist insertion.