22, 40 or 48 — what each one makes, which yarn to use, and why stitches drop
Sentro sells three machines and the only thing that changes between them is how many needles sit in the circle. That single number decides the one measurement you cannot change: the circumference of the tube. Everything on this page follows from it — what each machine can actually make, which yarns run through it, and why stitches drop.
Finished tube measurements are for worsted (#4) at 2.6 stitches per inch, relaxed off the machine.
about $36 — the impulse-buy one
8.5"tube circumference
about $50 — the children's one
15.4"tube circumference
about $55 — the one to buy first
18.5"tube circumference
Prices are the brand's own direct-sale figures as of August 2026 and move constantly — "Sentro" is a name several resellers use, so the same machine appears at several prices. addi Express King (46 needles) and Jamit (48) are the same maths with a different badge.
The needle circle is fixed, but the knitted fabric relaxes, and how much it relaxes depends on how thick the yarn is. Each cell shows the relaxed circumference and how far it stretches before it goes sheer.
| Yarn weight | Typical gauge | Finished tube circumference | |||
|---|---|---|---|---|---|
| sts/in | rows/in | 22 needle | 40 needle | 48 needle | |
| Sport / fine (#2) | 3.00 | 8.0 | 7.3" to 9.9" | 13.3" to 18.0" | 16.0" to 21.6" |
| DK / light (#3) | 2.80 | 7.5 | 7.9" to 10.7" | 14.3" to 19.3" | 17.1" to 23.1" |
| Worsted / medium (#4) | 2.60 | 7.0 | 8.5" to 11.5" | 15.4" to 20.8" | 18.5" to 25.0" |
| Chunky / bulky (#5) | 2.35 | 6.2 | 9.4" to 12.7" | 17.0" to 23.0" | 20.4" to 27.5" |
The needles on a circular knitting machine are a fixed distance apart and the hooks are a fixed size. A yarn works if it is thick enough to be caught reliably and thin enough to pass through the yarn guide and round the hook without dragging. That is a question about thickness, which is what yarn weight measures. It is not a question about what the yarn is made of.
Worsted / medium (#4) is the right answer for almost everything. It is what these machines are built around, it gives roughly 2.6 stitches and 7 rows per inch, and it is the gauge every published Sentro row count assumes.
DK and sport (#3, #2) run fine but produce a thinner, looser fabric with more stitches per inch, so the tube comes out narrower and you need more rows for the same length. Two strands of sport held together behave roughly like one worsted.
Chunky (#5) is the practical ceiling. It works, it is fast, and it jams if your tension is even slightly tight. Super bulky (#6) and above does not fit — it will not pass the yarn guide cleanly and it grinds the gears.
Fibre only matters through friction. Smooth, plied, springy yarns feed best: standard acrylic, acrylic-wool blends, plied cotton. What causes trouble is anything that grabs — mohair and other haloed yarns, chenille, bouclé, thick-and-thin singles, and anything with slubs or sequins. Those drop stitches not because of what they are made of but because the hook cannot slide through them. Cotton is a special case: it has no stretch, so it feeds fine but the finished tube will not spring back, which makes it a poor hat yarn and a good bag yarn.
The honest test is cheaper than the theory: crank twenty rows. If it feeds without a single dropped stitch, the yarn works.
Same machine, same needle count, three different hats. Which is why "how many rows for a Sentro beanie" has no single answer until you say which yarn.
A dropped stitch is always mechanical. Something failed to catch, or something failed to let go.
This is the cause behind most dropped stitches and almost nobody mentions it. A knitting machine needs downward tension on the finished fabric to pull the old loop off the latch. On the first few rows there is no fabric hanging yet, which is exactly when stitches drop.
Fix: hold the cast-on tail and pull it steadily downward for the first ten rows, or clip a small weight to the tube. Once six inches of tube are hanging, the problem disappears on its own.
At speed the needle hooks reach the yarn feed before the yarn has settled into them. Every troubleshooting guide says the same thing: crank the first three rows needle by needle, stopping to check each one catches, then at half speed to about row five.
After that you can go as fast as you like — the fabric weight is doing the work.
Too loose and the yarn sags below the hook so the needle passes over it. Too tight and the yarn cannot be drawn through, which shows up as grinding or popping gears rather than a clean drop.
The yarn should run with light, even resistance — enough that it does not loop or sag between the guide and the needles, no more.
Each needle has a hinged latch that closes over the hook. If one is bent, gummed with fibre or held open by lint, that needle drops its stitch on every single row — which is how you recognise it: a ladder running straight up the tube in one column.
Fix: take the needle out, clean the latch, flick it with a fingernail to check it swings freely, and replace it if it is bent. Sentro sells replacement needles; keep a couple spare.
Mohair, chenille, bouclé, thick-and-thin singles, sequinned or slubby yarn all grab the hook instead of sliding round it. Cotton and other non-springy yarns are a milder version of the same problem. The machine is not faulty; the yarn is wrong for it.
Fix: use a smooth plied worsted. If you must use the fancy yarn, hold it together with a smooth strand so the smooth one does the feeding.
A skein sitting on the table rolls, catches, and jerks; a cone tips over; the yarn wraps the guide arm. Every jerk momentarily starves a needle, and that needle drops.
Fix: feed from a yarn bowl or a bottle, keep the yarn path straight from the ball to the guide, and pull off a couple of yards of slack before you start a long run.
If stitches drop in one column, it is a needle. If they drop randomly all over, it is tension or fabric weight. If the machine grinds instead of dropping, it is tension or yarn that is too thick.
Only the number of needles, and therefore the circumference of the tube. In worsted the 22 makes an 8.5 inch tube, the 40 makes 15.4 inches and the 48 makes 18.5 inches. That is the whole difference: same mechanism, same yarn, same speed. The 48 makes adult hats, the 40 makes children's hats, and the 22 makes cozies and cuffs.
The 48, unless you only want to make things for babies. It covers adult hats, cowls, bags and pillow covers, and you can knit narrower pieces on it in flat mode by taking needles out of work. You cannot do the reverse: nothing makes a 40-needle machine bigger.
Anything that is a tube or a flat rectangle: hats, cowls, leg warmers, bags, pillow covers, cozies, scarves, blanket strips, and sweater panels to seam by hand. What you cannot make is anything with shaping knitted in — no armholes, no raglan lines, no waist. Those are done off the machine by gathering, seaming and hand-finishing.
Smooth plied worsted (#4) acrylic or acrylic-wool. Weight matters far more than fibre: #2 to #5 all run, super bulky does not fit, and anything fuzzy, slubby or sequinned drops stitches because the hook cannot slide through it. If it feeds cleanly for twenty rows, it works.
Six mechanical causes, in order of how often they are the answer: not enough downward weight on the fabric, cranking too fast in the first rows, the tension arm set too loose or too tight, a bent or sticky needle latch, yarn that grabs instead of sliding, and yarn snagging on its way to the machine. A ladder in one column is a needle; random drops are tension or weight.
Mechanically yes, in build quality no. The addi Express King has 46 needles rather than 48, is several times the price, and has a reputation for dropping fewer stitches. All the arithmetic on this page applies to both, and to Jamit and the various rebadged Sentro clones — substitute the needle count and the numbers follow.