Sunday, 26 October 2014

Checking Spinning Wheel Ratios

Modern spinning wheels usually come with a description that includes whorl ratios.  For example, the Kromski Sonata description says that the standard flyer has 3 ratios: 6.7:1, 12.5:1, and 14:1.   This describes the number of times the bobbin rotates during each full rotation of the drive wheel.   A number of wheel manufacturers round the numbers up for simplicity, and humidity may affect the ratios as well.  The problem is of course that if the ratios aren't exactly as stated, the twist math calculations go out the window when you actually try to spin to a particular tpi (twist per inch).   It's best to check them when you first try out a wheel and then as weather or humidity changes.  With my wheels, once I've checked them a couple of times, I found them to be stable but wood contracts and expands sometimes, so it's better to be sure.

Starting point for checking wheel ratios
The easiest way to check the ratios is with a little bit of tape and a few minutes to hand manipulate the wheel.    I use masking tape because if you remove it right after you've used it, it doesn't leave any residue.   I would normally use the green painter's masking tape, but didn't have any, so the regular masking tape worked just fine.  I put the flyer arms so that they are vertical, just for convenience sake.  It doesn't really matter but I find it an easier visual.  I put a little piece of tape at the top edge of the whorl that I'm testing.   I also put a piece of tape on the drive wheel, directly under the tape on the whorl.  This is the even starting point.  Now it's simply a matter of hand turning the drive wheel and counting the bobbin rotations.

The bobbin will rotate faster than the drive wheel.  The aim is to find out how many times the bobbin rotates completely for one rotation of the drive wheel.  Turn slowly so as not to miss-count.  It's easier on the largest whorl, but on the smallest one, it's much easier to miss counting a rotation.    When you get to the end, there is a good chance that the two pieces of masking tape will not line up for a full rotation.  Then you need to bring the drive wheel back to the starting point, and see how far the bobbin tape has gone past the initial starting point.  This will give you a fraction of a turn.   Then you have to decide what to do with that fraction.  

If the fraction is close to a whole number, I tend to round up because the math with whole numbers is so much easier.  With my Minstrel, I know that the one whorl requires me to add an extra treadle every once in a while to make up for that difference or measure my drafting zone with a scant inch, instead of a full inch.

There are three whorl groves on the regular flyer.  My count for this wheel was 6.5:1, 12:1, 14:1.    I'll have to do some experimenting to see if that half rotation makes a difference to my spinning.   If my drafting length is accurate it could be an issue.  We'll have to see.  As it is, my default ratio on the Minstrel is 8:1, for just general spinning.  The Sonata misses that ratio on the regular flyer, so I'm going to have to make adjustments for that.

Bamboo/Yak on the new Sonata
Are wheel ratios important?  For general spinning it's good to know that the smaller the whorl, the more twist per drive wheel rotation.  For a thin, tightly spun yarn, having a whorl with a higher ratio means less treadles, which is less work.  You can treadle in a calm, relaxing fashion instead of speeding up to add more treadles per drafting zone.  The larger whorl will give you less twists for that same drafting zone, so your thicker, airy yarns also can be done using that same treadling speed.   It's when you want to spin something specific, like duplicating a yarn that you can't find any longer, or making a yarn for a particular purpose, such as a 3 ply sock yarn, where a higher twist per inch will make a more durable pair of socks, that knowing the specifics about your ratios will make a huge impact.

For the DH, who mentioned that I neglected this in my Fibre Festival post - yes, a Sonata followed me home last weekend.   I've been looking for a used one for over 18 months and haven't found one yet.  All that time I've been saving for this.  Finally I figured it was now or never, in order to get familiar enough with the wheel before level 6.  There is a good chance I'll have to travel for my Master Spinner level 6 and neither of my other wheels will do that, certainly not by air.  The smallest, which was my travel wheel doesn't have the versatility for the required spinning.  Twice I've had to switch it out for the Minstrel  when at locally held Master Spinner classes, which is a pain because it doesn't really fit in the little parcel area of the truck. It's just not as versatile a wheel as the others.  The Sonata folds up into a backpack, has a 19in drive wheel and still weighs less than 12 lbs.  It has 3 standard ratios and one can get both a jumbo flyer and a faster flyer for it if needed, which make a total of 9 different ratios from 5:1 - 18:1.

The last time I went to Olds, I used a rented wheel, which was fine, but I didn't have the control that I would want to have for a testing year.   Could I afford it?  Not really, but I tell myself that I really couldn't not to either.  I'm extremely happy with it though.  I can see selling off my Mazurka at some point in time because right now, I can't imagine using it much after this, as pretty a wheel as it is.

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