Multi-Start Trapezoidal Lead Screws: Lead Up to 100 mm per Turn, 2 to 36 Starts, Screw and Nut Made Together

Need a multi-start trapezoidal lead screw: more travel per turn than a single-start thread gives, with the nut that runs on it? Catalogue Tr bar is single start, a few sizes two-start, and stops there. We make multi-start lead screws from 2 to 36 starts, leads up to 100 mm per turn, in the Ø4 to Ø24 range and to drawing above it, cut to length with the ends machined and the bronze or plastic nut cut to the same lead, from one piece. No drawing needed: a photo with a rule, the measurements in a message, the old part or its part number is enough; we draw it, you approve, we machine. Get a quote →

Lead, pitch, starts: the arithmetic every callout hides

EKINSUN LTD is a custom parts manufacturer that makes trapezoidal lead screws and the nuts that run on them to the buyer's drawing, from one piece. On a single-start screw the nut moves one pitch per turn. Cut a second thread between the turns of the first and the pitch stays the same, but the nut now moves two pitches per turn: lead equals pitch times starts. A Tr20×4 screw moves 4 mm per turn; the Tr20×16P4 four-start screw from our range moves 16 mm per turn on the same thread depth, so it is as strong and four times as fast. German calls such a thread mehrgängig, French à plusieurs filets, Italian a più principi or multiprincipio. Multi-start is how a hand-turned slide crosses a table in a few turns, how a valve stem opens in a quarter turn, and how an actuator gets speed out of a slow motor.

Written as	Outside Ø	Lead per turn	Pitch	Starts	In our range
Tr12×3	12	3 mm	3	1	Ø12 × 3
Tr12×6P3	12	6 mm	3	2	Ø12 × 6, two starts
Tr12×9P3	12	9 mm	3	3	Ø12 × 9, three starts
Tr12×18P3	12	18 mm	3	6	Ø12 × 18, six starts
Tr12×45P3	12	45 mm	3	15	Ø12 × 45, fifteen starts
Tr12×45P1.25	12	45 mm	1.25	36	Ø12 × 45, thirty-six starts
Tr18×100P5	18	100 mm	5	20	Ø18 × 100, twenty starts

Multi-start sizes in our range

The rows below are every size in the range with more than one start, taken from the size chart; single-start rows are on the chart. Efficiency is given with a plastic and with a bronze nut.

Outside Ø	Lead	Pitch	Starts	Root Ø	Efficiency, plastic / bronze nut
4.2	2 mm	1	2	3.2	56 % / 43 %
5.4	5 mm	1.25	4	3.6	70 % / 58 %
5.71	10 mm	2.5	4	4.29	76 % / 65 %
4.71	15 mm	2.5	6	3.29	76 % / 64 %
6	20 mm	1.25	16	5	77 % / 64 %
6	3 mm	1.5	2	4.1	58 % / 46 %
6	5 mm	2.5	2	4.02	68 % / 56 %
6	9 mm	2.25	4	4.02	76 % / 64 %
6	10 mm	2.5	4	3.97	77 % / 66 %
6	18 mm	4.5	4	4.02	77 % / 64 %
7.4	25 mm	1.25	20	6.3	—
8	4 mm	2	2	5.5	—
8.2	10 mm	2.5	4	5.5	75 % / 62 %
8	12 mm	3	4	5.6	77 % / 64 %
8.2	15 mm	2.5	6	5.5	77 % / 66 %
8	24 mm	4	6	5.6	76 % / 64 %
8.6	30 mm	1.25	24	7.5	77 % / 64 %
10	3 mm	1.5	2	—	45 % / 33 %
9.53	4 mm	2	2	—	55 % / 42 %
10	5 mm	2.5	2	—	59 % / 46 %
9.53	6 mm	1.5	4	—	61 % / 48 %
10	10 mm	2.5	4	—	71 % / 59 %
10	10 mm	1.25	8	—	70 % / 58 %
10	12 mm	3	4	—	73 % / 62 %
10	15 mm	3	5	7.1	75 % / 64 %
10	20 mm	2.5	8	—	77 % / 66 %
10	25 mm	2.5	10	—	77 % / 65 %
9.53	35 mm	1.25	28	—	76 % / 70 %
10.1	50 mm	5	10	—	71 % / 55 %
12	4 mm	2	2	9.34	47 % / 35 %
12	5 mm	2.5	2	8.9	53 % / 41 %
12	6 mm	3	2	8.5	58 % / 45 %
12	9 mm	3	3	8.16	66 % / 54 %
12.62	10 mm	2.5	4	9.19	67 % / 55 %
12.2	15 mm	3	5	9.2	73 % / 62 %
12	15 mm	2.5	6	8.7	74 % / 62 %
12.7	16 mm	3.2	5	9.5	73 % / 62 %
12	18 mm	3	6	9	75 % / 64 %
11.9	25 mm	5	5	8	77 % / 66 %
12	25 mm	2.5	10	9.2	77 % / 66 %
12	45 mm	3	15	9.6	76 % / 62 %
12.8	45 mm	1.25	36	11.4	76 % / 64 %
14	6 mm	3	2	10.5	54 % / 41 %
14	8 mm	4	2	9.7	61 % / 48 %
13.62	10 mm	2.5	4	10.37	65 % / 53 %
14	12 mm	4	3	9.7	68 % / 56 %
14.3	18 mm	3	6	11.4	73 % / 62 %
13.9	30 mm	5	6	10.1	77 % / 66 %
16	5 mm	2.5	2	12.2	46 % / 34 %
16	8 mm	4	2	11.5	58 % / 45 %
16	16 mm	4	4	11.5	71 % / 59 %
16	16 mm	2.29	7	12.6	70 % / 58 %
16.5	21 mm	3	7	13.6	73 % / 62 %
16	25 mm	5	5	11.5	76 % / 64 %
15.9	35 mm	5	7	12.1	77 % / 66 %
17	90 mm	5	18	14.3	71 % / 55 %
18	8 mm	4	2	13.5	54 % / 42 %
18	16 mm	4	4	14.3	68 % / 56 %
18	18 mm	4.5	4	14.4	70 % / 58 %
18.7	24 mm	3	8	15.7	73 % / 62 %
17.9	40 mm	5	8	14.1	77 % / 66 %
18	60 mm	6	10	13.9	76 % / 64 %
18.8	100 mm	5	20	16.2	71 % / 55 %
20	8 mm	4	2	15.5	52 % / 39 %
20	12 mm	3	4	15.8	61 % / 48 %
20	16 mm	4	4	15	67 % / 55 %
20	18 mm	6	3	13.66	69 % / 57 %
20	20 mm	4	5	15	70 % / 59 %
20	45 mm	5	9	16.1	77 % / 66 %
21.54	6 mm	2	3	19.63	41 % / 30 %
22	8 mm	4	2	17.5	—
22	10 mm	5	2	16.5	55 % / 43 %
22.23	10 mm	2.5	4	18.82	54 % / 41 %
22.23	16 mm	4	4	18.82	64 % / 51 %
22	20 mm	4	5	18.3	68 % / 56 %
22.23	24 mm	4	6	18.82	71 % / 59 %
22	50 mm	5	10	18.1	77 % / 66 %
24	10 mm	5	2	18.5	—
24.3	40 mm	5	8	19.8	76 % / 66 %
24	55 mm	5	11	20.1	—

The 50 % line: fast travel or holding, rarely both

Efficiency rises with the lead. A screw and nut under 50 % efficiency hold a load when the drive stops; over 50 % the load can turn the screw back. The Ø12 group shows the whole climb: the single-start 3 mm lead is at 30 % with a bronze nut and holds, the two-start 6 mm lead is at 45 % and still holds, the three-start 9 mm lead is at 54 % and back-drives, and the fifteen-start 45 mm lead is at 62 %. A lifting or clamping screw is therefore chosen under the line; a positioning slide, a fast return or a hand-turned feed is chosen over it and given a brake where the load must not run away. The plastic nut sits about ten points higher than bronze on every row.

Ø12 size	Starts	Bronze nut	Plastic nut	Use it for
Ø12 × 3	1	30 %	41 %	Jacks, clamps, slow feeds: holds under load
Ø12 × 6	2	45 %	58 %	Feeds that must hold with a bronze nut
Ø12 × 9	3	54 %	66 %	Fast slides, back-drives, brake if needed
Ø12 × 18	6	64 %	75 %	Fast hand traverse, actuators with a brake
Ø12 × 45	15	62 %	76 %	Quarter-turn and few-turn mechanisms

Left-hand and multi-start together

Left-hand is a matter of which way the threads wind, not how many there are, so any multi-start row is made left-hand to order; the six left-hand sizes stocked in the range are single start. A screw that carries right-hand thread on one half and left-hand on the other moves two nuts toward each other, the way a vice with two jaws or a centring device works; both halves are cut on one shaft in one setting.

What to send for a multi-start quote

You have	Send	We confirm
A drawing	The PDF or STEP; the callout with lead and pitch or starts, the ends with keyways to DIN 6885	Lead, pitch, starts, hand, before the quote
The old screw	A photo with a rule across ten crests, and the end face showing the thread starts	Pitch from the crests, starts from the end face, lead from both
Only the travel you need	Millimetres per turn, the load, the diameter you have room for	A size from the chart under or over the 50 % line as the job needs
The nut too	Nut form and how it mounts	Nut cut to the same lead and starts, run on the screw before shipping

Materials: screw and nut

Material	Where it is used	Note
Bearing steel 100Cr6 (GCr15, SAE 52100)	Standard screw material for every size in the Ø4 to Ø24 range	Machine tools, semiconductor equipment, instruments, conveyors
Stainless steel 304 (1.4301)	Screws in wet, washdown, food and lab equipment	On request; the screw with the plastic nut in the photos
Carbon steel C45 (1.0503)	General machinery and large screws to drawing	On request
Aluminium 6061	Light hand-feed and instrument screws where weight matters more than wear	With a bronze or plastic nut
Bronze CuSn12 nut	Load, heat and long machine-tool duty	The bronze column of the chart
Plastic nut (POM)	Quiet, self-lubricating, light load, higher efficiency	The plastic column; anti-backlash version with a spring

Price, lead time, delivery

There is no list price for a lead screw made to your length and ends; a single piece starts from €25 and is quoted within 12 hours from the callout: outside diameter, lead, pitch, starts, hand, length, the ends, and whether a nut goes with it. One to a few dozen pieces ship in 5 working days, 50 to 500 in 15 working days, delivered DDP to your door with duties in the quote. The first piece is the sample; repeat orders run to the same drawing, and 500-piece and 1,000-piece runs are priced lower per piece. The screw is bearing steel unless the order says stainless 304 or carbon steel C45; the nut is bronze unless the order says plastic; the grades go on the drawing.

Where the catalogue stops

What you need	In the catalogue?	What to do
Single-start Tr bar	Yes	Buy it there, or ask us
Two-start Tr bar in a common size	Some sizes	Ask us; in the range from Ø4 up
Three-, four- or six-start screw	No	In the range: see the table above
Ten to 36 starts	No	In the range: Ø10 × 50, Ø12 × 45, Ø16 × 90, Ø18 × 100, Ø24 × 55
A multi-start screw with journals, keyway, square drive	No	Made to drawing
The nut for a multi-start screw	No	Cut to the same lead and starts, with the screw
Ø60 to Ø300 multi-start	No	Made to drawing

Related lead screw pages

Frequently asked

What is a multi-start lead screw?

A screw with two or more separate threads wound side by side. The nut then travels the pitch times the number of starts in one turn: a Ø20 screw with a 4 mm pitch moves 4 mm per turn with one start and 16 mm per turn with four. The thread depth stays that of the pitch, so the screw keeps its strength while the travel multiplies.

How do I read Tr20×8P4?

Outside diameter 20 mm, lead 8 mm per turn, pitch 4 mm, so 8 divided by 4 gives two starts. When only one number follows the diameter, as in Tr20×4, the screw is single start and lead equals pitch. LH after the callout means left-hand.

Which multi-start sizes do you make?

From two starts up to 36 in the Ø4 to Ø24 range: Ø10 × 50 with ten starts, Ø12 × 45 with 36 starts, Ø16 × 90 with 18 starts, Ø18 × 100 with 20 starts, Ø24 × 55 with eleven, and the two-, three-, four- and six-start rows in between. Larger multi-start screws, Ø60 to Ø300, are made to drawing.

Will a multi-start screw hold a load when the motor stops?

Usually not. A four-start Ø12 screw with a bronze nut is at 62 % efficiency and a load can turn it back; the single-start Ø12 × 3 at 30 % holds. If you need fast travel and holding, the drive gets a brake or the screw is sized so the efficiency stays under 50 %.

Can you make a multi-start screw with a square drive, a knurl and an end thread from my drawing?

Yes. The thread section is made from the chart size or to your callout, and the ends carry what the drawing shows: a square or hex drive, a knurled grip, a metric end thread for a locknut, journals and keyways to DIN 6885. Lead, pitch and starts are confirmed from the drawing before the quote, because a callout such as Tr24 × 6 can mean a 6 mm lead as well as six starts.

Who makes multi-start trapezoidal screws in small numbers, and what do they cost?

EKINSUN, from one piece; a single screw starts from €25 and is quoted in 12 hours from the callout. Starts do not change the price much; length, the ends and the nut do.