Why receipts jam, and what to do about it
A jam is not a random event. The sheet that stopped is a piece of evidence, and where it stopped plus what it looks like afterwards will usually tell you which of about five things went wrong. Getting the jam rate down is a matter of preparing the paper and replacing worn parts, not of buying a better machine.
Read the jam before you clear it
Note where the sheet stopped and what shape it is in. Before you yank it out, look. A sheet that never entered, still sitting in the tray with its leading edge nudged up against the rollers, is a pick failure. A sheet crumpled just past the entry point is a separation failure. A sheet that made it most of the way and then concertinaed is a transport failure downstream, usually an obstruction. A sheet that came through torn along one edge has snagged on something.
Then clear it the way the manual says, which almost always means opening the path and lifting the paper out rather than pulling it against the rollers. Pulling backwards through a closed path drags the sheet across the pick roller under load, which is one of the faster ways to glaze the rubber.
Curl is the most common single cause
Receipt paper spends its life on a roll and does not forget. A curled leading edge meets the pick roller at an angle instead of flat, so the roller has less contact area and either slips or grabs one corner and skews the sheet.
The fix is mechanical and takes seconds. Flex the stack the other way, or press each slip flat under something heavy for a while before a batch, or fold the very top edge over by a couple of millimetres so there is a stiff flat lip for the roller to grip. Loading with the curl facing the direction the mechanism expects also helps, and which direction that is depends on the device — it is worth finding out by experiment on paper you do not care about.
Long till rolls are curl with extra steps, and have enough of their own problems to be worth handling separately: see scanning very long receipts.
Things that should never enter a feed path
Some jams are not jams so much as damage in progress. A short list of what to remove before a stack goes in:
- Staples and paperclips. A staple in a feed path scratches the glass in front of the sensor, and a scratch produces a line on every page you scan thereafter, permanently.
- Sticky tape and glued-on labels. Adhesive picks up dust, transfers to rollers, and turns a grippy surface into a tacky one that grabs two sheets at once.
- Anything folded. A fold is a stiff ridge travelling through a mechanism designed for flat paper. Unfold and flatten first, and accept that a hard crease will show as a dark line in the image.
- Anything torn most of the way through. A partial tear becomes a complete tear under roller tension, in the middle of the machine, in two pieces.
- Anything wet, greasy, or still slightly damp. It will not feed and it will contaminate everything it touches on the way.
Items on this list are exactly what a flatbed or an overhead camera is for. That is not a workaround; it is what the other mechanisms exist to do, as set out in sheetfed, flatbed, or overhead.
Mixed stacks fail more than uniform ones
A separation mechanism is a compromise tuned for a range of paper weights, and every item outside the range makes life harder for the items around it. A stack that alternates stiff card invoices with limp thermal slips gives the pad a different problem on every pick.
Sorting the pile before scanning feels like extra work and generally is not, because it reduces both jams and the silent multi-feeds that cost you far more later. Rough groups are enough: thermal slips together, ordinary paper together, card and anything unusual set aside for the flatbed. If your device supports saved settings for different paper, sorted stacks also let you use them properly.
Wear presents as jamming
A machine that jams more than it used to has a worn part, not a mood. The pick roller and the separation pad are rubber, they polish with use, and a polished pick roller slips — which reads as pick failures — while a worn separation pad stops holding back the second sheet, which reads as multi-feeds. Both symptoms arrive gradually enough that people adapt to them rather than noticing.
If jams have crept up over months on paper that used to be fine, clean the rollers first and replace them second. This is routine and cheap relative to a device, and it is covered in scanner cleaning and consumables. It is also the single most useful thing to check on a second-hand purchase, since you have no idea how many sheets have already been through it — see buying a scanner second-hand.
The jam you should worry about is the one that is not a jam
A jam stops the machine and tells you. A multi-feed does not: two slips travel through together, one gets imaged and one does not, and the batch completes looking perfectly healthy. You find out weeks later when the item you need is not there.
The defence is a count. Know how many items went into the tray, check how many files came out, and reconcile the two before the paper goes anywhere. It takes a few seconds per batch, it is the only check that catches this class of failure, and it is worth building into the habit from the start. If your device has a double-feed sensor, turn it on and let it interrupt you.
Whether the paper can be disposed of once the scan exists is a separate question with a jurisdiction-specific answer. Retention rules vary by country and by the kind of entity keeping the records, so confirm the requirement with your own tax authority or accountant before anything goes in the bin — and until you have, keep the slip.