Troubleshooting guide
Cut Lengths Drifting on a Full Spool: Pay-Off Tension, Straightener Bearings and Misfeed
Why a cut-and-strip machine that held length on a loose coil walks 10–20 mm once a heavy reel goes on, how misfeed detection works, and how to check reel tension, straighteners, feed grip and encoder calibration.
Technically reviewed by: Lao Xiaoyu (劳晓宇) · Senior Engineer
Content updated:
Review confirmed:
A full spool can increase payout drag and change wire tension, causing feed slip and cut-length drift even when the machine recipe is unchanged. Compare lengths on full and partly used reels, then isolate pay-off tension, straightener resistance and measuring-roller slip before recalibrating. Measure each sample with the same method.
The most common complaint about a bench cut-and-strip machine after the first week is not stripping quality. It is that pieces that measured right on Monday measure 10–20 mm short on Thursday, and the difference is a full reel of wire on the input side.
This guide checks three possible mechanical causes before reviewing feed calibration, encoder behavior and the measurement method. A change after loading a reel is a diagnostic clue, not proof of one cause.
How the machine measures length
Many cut-and-strip machines infer length from feed-wheel or drive rotation; some use a separate measuring arrangement. Confirm how your machine measures travel. If the wire moves less than the wheel because it slips, or more because it overruns, the count is still correct and the piece is not.
Check upstream and downstream forces alongside feed grip, length calibration and the method used to measure the cut pieces.
Fault 1 — reel drag
A 30 kg reel on a free spindle has to be accelerated by the feed wheels on every piece and stopped by friction at the end of every piece. Drag varies with reel diameter, bearings, acceleration and brake setting as the reel unwinds. The feed wheels start to slip a little on start, the piece comes out short, and the shortfall grows through the day. Operators describe “the machine dragged the whole reel across the bench” — that reel was doing the feeding.
Fix: a powered pay-off between the reel and the machine. It can supply a buffer of cable and reduce the pulling load on the feed wheels when correctly matched and adjusted. Choose it by reel weight and line speed:
- Bench reels to 25 kg, bench cutters: WM-9154 — 180 W motor, dancer arm, ten speed steps.
- Reels to 60 kg on a fast cutter: WM-9153 — up to 4 m/s, proximity-switch loop control.
- Coils to 150 kg and Ø700 mm, cable to Ø16 mm: WM-9152 — 3+2 dancer, inverter follows the cutter.
The dancer is the part that matters. It keeps a loop of slack between pay-off and cutter and drives the pay-off from the loop length, to help buffer changes in demand. Verify the resulting tension and stop response on the complete line.
Fault 2 — a straightener that is fighting the feed
Straightener rollers are there to take the set out of coiled wire before the guide. If the roller bearings are gritty or the rollers are set too tight, the straightener becomes a brake that varies with wire position. The symptom is the same as reel drag but does not go away when you add a pay-off.
Check: with the machine safely isolated according to its instructions, pull a metre of wire through the straightener by hand. It should run with light, even resistance. Roll each roller with a finger; any roller that does not spin freely is a bearing to replace. Then back the rollers off until the wire just leaves straight.
On belt-fed machines such as the WM-1420, the belts spread the clamping load. Its specification lists a length-related tolerance of 0.002 × L; this does not establish the cause of a particular error or guarantee that a pay-off will remove it. Agree the cable, cut length, measurement method and acceptance limit, then check actual pieces.
Fault 3 — misfeed the machine did not see
If the wire runs out, jams in the guide or slips completely, a basic feed keeps cycling: the blade closes on nothing, the counter still counts. Ten short pieces at the bottom of the tray are the sign.
Fix: a wire-presence or jam sensor downstream of the wheels that stops the cycle. Ask on the inquiry which faults a machine detects — presence, terminal presence, jam and air pressure are listed on our automatic crimping stations; on bench cutters the presence check is what stops a misfeed from becoming a batch of scrap.
Order of diagnosis
- Unspool a few metres by hand so the cutter sees slack wire; run ten pieces. If length improves, investigate upstream tension and the pay-off setup; repeat the comparison before drawing a conclusion.
- Pull wire through the straightener by hand; free any roller that does not spin; back off pressure.
- Check the guide tube diameter against the wire; a loose guide lets the wire walk sideways in the cut and reads as length and strip variation together.
- Only then look at the wheels: worn knurl or a glazed belt slips even on free wire, and that is a wear part on every quote.
If length still drifts after these checks, review drive calibration, encoder or measuring-wheel condition, and the measurement method with our engineering team. Confirm the correction on a representative batch rather than assuming one adjustment resolves every case.
Send your cable details and the operation you need to improve through our quotation form. We will review the application and recommend the next step.
See the process in action
Demonstrations from the machines referenced in this guide. Click to watch the operation, then request a trial with your own material.
Questions engineers ask
Length was fine on a small coil and drifts on a full reel. Is the encoder faulty?
An encoder fault is one possibility, but incoming tension and feed slip should also be checked. On a system measuring feed-wheel rotation, slip can make the wire travel less than the indicated distance. Compare a safely supplied slack-wire trial with the full reel, then check feed grip, calibration and the measurement method.
Do I need a pay-off for a 25 kg reel?
Reel weight alone does not decide this. Check reel inertia, cable stiffness, acceleration, braking and the cutter's permitted inlet tension. A compatible powered pay-off with loop control can reduce the load on the cutter; verify start-stop behavior with the actual 25 kg reel and cable.
What is a dancer, and why does it matter more than reel size?
A dancer is a weighted or sprung arm carrying a loop of wire between the pay-off and the cutter. When the cutter takes wire the loop shortens and the dancer signals the pay-off to turn; when the cutter stops the loop fills and the pay-off stops. It helps buffer demand changes; actual tension and response must be checked across the working reel range.
Why did the machine keep running after a misfeed?
A basic feed has no wire-presence check downstream of the wheels; it will happily cut air or cut short pieces until the batch count runs out. Machines with a presence or jam sensor stop on the miss. Ask on the inquiry which faults the machine actually detects.