Doff a spinning frame by stopping the drive, locking the belt on the loose pulley, waiting until every flyer has visibly halted, then lifting off all the full bobbins and fitting empties; it takes 2-3 minutes on an 8-spindle frame. That is 0.24-0.36% of the 13.8 hours an assumed bobbin takes to fill, so changing a bobbin on a moving frame to save the stop gains almost nothing and is how hands are lost.
Part of Spinning Frame
Removing full bobbins from a stopped spinning frame and replacing them with empties.
The Stop Costs Almost Nothing
The overview says that when bobbins are full the frame is stopped and all bobbins are removed together, empties are placed and spinning resumes, and that on an 8-spindle frame doffing takes 2-3 minutes. Per spindle that is 2 × 60 ÷ 8 = 15 s to 3 × 60 ÷ 8 = 22.5 s. Scaled to 20 spindles (an assumption that time is proportional) it is 5 to 7.5 minutes.
How often? With the assumed bobbin of this tree (barrel 25 mm, full 45 mm, length 100 mm; Winding On) a bobbin holds about 2.1 km, 62 g of Ne 20 yarn, and takes 13.8 hours at 152.4 m an hour, which is 828 minutes. The stop costs 2 ÷ 828 = 0.24% to 3 ÷ 828 = 0.36% on 8 spindles, and 5 ÷ 828 = 0.6% to 7.5 ÷ 828 = 0.9% on 20. The pressure to doff on a running frame is therefore a saving of a fraction of one percent against a hazard of losing a hand.
Why Frames Are Doffed All At Once
The bobbins fill at nearly the same rate because every spindle delivers the same length per minute (Twisting). Doffing together keeps the frame in one cycle, and gives a natural moment to take a sample bobbin for testing (Twist Testing).
What You Need
- A stop that can be locked: a belt shifter with a pin or tie, so the belt cannot be thrown back on while hands are in the row (Drive System).
- A rack or tray for full bobbins.
- A supply of empty bobbins matched to the spindles.
- A second person to watch the shifter, or a tag on the lock.
Method: Doffing A Frame
Step 1: Call “stopping” so everyone in the shed knows.
Step 2: Throw the belt to the loose pulley, then fit the lock.
Step 3: Wait until every flyer has stopped, judged by eye, not by sound. Remember the frame coasts for a few seconds on the assumed figures in the drive article, and the line shaft behind it is still turning.
Step 4: Break or cut the yarn at each flyer, lift off the full bobbins in one pass along the row, and set them in the rack.
Step 5: Fit the empties, draw each yarn end through the spindle top and the flyer eye and fix it to the new bobbin, as the start-up of the hand wheel in Spinning Wheel does.
Step 6: Take one sample bobbin and mark it with the frame and spindle number.
Step 7: Remove the lock, call “starting,” check that nothing is in the row, and then throw the belt on.
Worked Example
A frame with 20 spindles runs for 13.8 hours before a doff. In an 8-hour shift it is doffed about once every 1.7 shifts. The doff, 5 to 7.5 min, is 0.6-0.9% of running time. If a worker tried to doff each spindle in turn while the frame runs, to avoid the stop, he would reach among 19 other turning flyers for the whole 5-7.5 min for a gain of under 1%.
Common Mistakes
- Doffing a “slow” frame after the belt is shifted, before the flyers have halted.
- Forgetting the lock, so someone throws the belt on again.
- Leaving the weights on the rollers when the frame will stand for a long time (Roller Weighting).
- Mixing bobbins from different frames, which hides a twist fault.
Safety
Doffing and piecing are the jobs that maimed children, and they are adult jobs here
In historical spinning rooms the doffer’s and piecer’s jobs, changing bobbins, tying broken ends and crawling under the frame to clear waste, were given to children because small bodies fit between the machines, and they were hurt exactly there. The corpus rule is the opposite: keep children away from running machinery at any age until trained, hand a task over in stages with an adult within arm’s reach, and treat handing a hazardous job to a child because adults are short of hands as a mistake (Task Assignment by Age, Child Development & Welfare After Collapse, Avoiding Exploitation). This guide gives no age for doffing because none is sourced, and it relaxes no part of those articles. A learner may practise on a stopped, locked frame with an adult beside them; nobody learns on a moving one. Never doff or clear under a running frame, keep the stop within reach, and never rely on the frame having “stopped” without looking. For a crushed or severed hand, press firmly on the wound (Bleeding Control) and shut the water gate first if anyone is still caught.
What’s Next
- Learn next: Thread Quality Control — testing the sample bobbin
- Combine with: Frame Layout — leaving the space to doff