A lever arch clip hole size must match the diameter of the rivet or screw barrel that passes through it, and it is constrained by base plate thickness (60C, 65C or 70C) and by board thickness. JXY produces lever arch clips with 3.8 mm, 4.2 mm or 4.5 mm holes. Choose the size that gives a light interference fit on the mating fixing, then state the hole diameter and its tolerance as a separate dimension on the drawing.
What does the hole size on a lever arch clip actually control?
It controls one interface, and everything about the folder follows from it: the fit between the clip and the fixing that ties the clip to the board.
A lever arch clip is not a self-contained part. It is riveted or screwed to a pre-punched board, and the holes in the base plate are the only place where the clip and the board meet. If that fit is right, the mechanism sits flat, the lever stroke is clean, and the arch lines up with the punched paper. If it is wrong, no amount of plating quality or lever design will rescue the finished folder.
This is why “75 mm lever arch clip” on its own is not a specification. Spine width tells you how much paper fits. Hole size tells you whether the clip can be assembled to your board at all.
Which rivet or screw barrel is each hole size expected to accept?
The hole serves the barrel, not the other way around. A 3.8 mm hole is intended for a smaller-diameter barrel than a 4.5 mm hole, and the correct approach is to bring the mating fixing to the conversation rather than to pick a hole size first.
JXY supplies the mating hardware in the same catalogue, which makes the pairing easier to close:
Hollow rivets
- in a range of lengths and head colours, used to tie the base plate to the board.
Double-head rivets
- , where a decorative two-piece head is wanted.
Chicago screws (screw posts)
- with a 9.5 mm head diameter, stocked in 3 mm, 4 mm and 5 mm, with post lengths of 3, 4, 5, 6, 7, 8, 9, 10, 12 and 15 mm. A screw post is the natural choice when the folder may need to be re-opened for repair, because it can be taken apart and re-tightened.
A 3 mm post and a 5 mm post cannot share a hole. That single fact is why the hole size has to be locked before the punching die is cut, not after.
Hole size selection table: hole diameter, plate thickness and fixing type
Use the table below as selection logic, not as a stock list. All three hole sizes and all three base plate thickness codes are available; the pairing that ships is the one fixed by your rivet sample and your board.
| Hole size | Base plate thickness code | Fixing type it usually suits | Board thickness it tolerates | What goes wrong if chosen blindly |
| 3.8 mm | 60C (lightest of the three codes) | Small-diameter rivet barrel; 3 mm screw post | Thin board stock | Cannot be driven over a heavier barrel; forces the assembler to ream, which damages plating |
| 4.2 mm | 65C (mid code) | Standard rivet barrel; 4 mm screw post | Mid-range board stock | Tolerates the widest range of stock boards, but is oversize on a small barrel and lets the clip rotate |
| 4.5 mm | 70C (heaviest of the three codes) | Larger rivet barrel; 5 mm screw post | Thick board or double-wall construction | Too loose on a small barrel; the arch will not stay square to the spine |
The logic in the right-hand column is the part buyers get wrong. A generous hole feels safer because the rivet “always goes in”, but a generous hole is exactly what produces a clip that spins on its fixing after three weeks in the field.
How do base plate thickness and board thickness constrain the choice?
Total grip length is the sum of everything the fixing has to pass through: base plate, board, and any washer or reinforcement the design adds. That sum is what selects the rivet or post length, and it is also what limits how small the hole can be.
Two effects run in opposite directions:
Thicker plate, thicker board, longer barrel.
- Moving from the 60C code to 70C adds steel to the plate. Add a thicker board and the barrel has to reach further, which usually means a larger-diameter fixing and therefore a larger hole.
Harder stack, tighter tolerance.
- A heavy-gauge plate plus a hard board leaves no room for the rivet to deform its way in. The hole has to be right the first time, because there is no compressible material to absorb the error.
This is the reason the hole size and the thickness code belong on the same line of the drawing. A drawing that says “4.2 mm hole” but does not state the plate thickness code has left half the fit undefined.
Why does an undersized hole crack the board?
Because the rivet has to displace material that has nowhere to go.
When a rivet barrel is driven into a hole that is smaller than the barrel, three things happen in sequence. The fibre of the board is crushed and pushed outward, which can lift the printed surface or delaminate a laminated cover. The plating around the hole edge in the base plate stretches, and once it stretches past its limit it micro-cracks. And the rivet seats at a slight angle, so the clip does not sit flat.
The crack is the expensive part, because it is a corrosion initiation site rather than a cosmetic defect. Corrosion testing such as the neutral salt spray method described in ISO 9227 will find that crack faster than the visible face of the clip, and if the substrate is exposed then nickel release becomes a compliance question under REACH Annex XVII entry 27 rather than a purely cosmetic one.
An undersized hole is also the most common cause of “board cracks at the rivet” claims that arrive months after shipment, because the crack propagates slowly under lever load.
Why is an oversized hole just as bad as an undersized one?
Because the clip is held by friction and geometry, and both disappear when the hole is too large.
With a loose fit, the mechanism can rotate about the rivet. The arch then sits slightly off-square to the spine, which shows up as punched paper that does not run parallel to the arch, and as a lever that feels vague at the end of its stroke. The board wallows out around the hole as the clip is actuated, so the looseness increases with use rather than settling in. The rivet head no longer clamps the plate, so the plate can stand proud of the board surface, and folders no longer stack or lie flat.
In short: an undersized hole fails at assembly and in service, while an oversized hole passes assembly and fails in the field. Both are fit problems, and both are solved on the drawing rather than on the line.
How do you state the hole size and its tolerance on a drawing?
State the diameter as its own dimension, give it its own tolerance, and separate diameter from position.
The cleanest approach is to use a published general tolerance system so that the factory and the buyer are arguing about the same numbers. ISO 2768-1 general tolerances for linear and angular dimensions is the usual reference for stamped and plated sheet parts. A workable drawing then carries:
Nominal hole diameter
- written as a diameter callout, for example “3-hole pattern, hole diameter 4.2 mm”.
Dimensional tolerance on the diameter
- , either as an explicit limit pair or by invoking a general tolerance class, so the punch and the plating thickness are both accounted for.
Position tolerance
- for the hole pattern, referenced to a stated datum edge, so that centre-to-centre distance and edge distance are both defined.
Base plate thickness code
- (60C, 65C or 70C) on the same view as the holes.
Material and finish
- so that the plater knows whether the hole is measured before or after coating.
The mating fixing
- , quoted by part number, or a physical sample of the rivet or screw post supplied with the enquiry.
One practical note: plating adds material inside the hole. A hole that measures perfectly before plating will measure smaller afterwards. Say on the drawing whether the tolerance applies to the pre-plate or post-plate condition, because that single sentence prevents most fit disputes.
How do you verify the hole match during first-article inspection?
Measure the hole with a pin gauge, not with a caliper, and assemble the real clip to the real board.
Calipers measure a chord across a hole, so a burr or a slight ovality is invisible. Go / no-go pin gauges measure the feature that actually matters. A first-article inspection plan for a lever arch clip should include:
| Check | Method | Why it matters |
| Hole diameter | Go / no-go pin gauge at the stated size | Confirms the barrel will pass without being forced |
| Hole roundness | Pin gauge in two axes, 90 degrees apart | Catches oval holes from a worn punch |
| Hole position | Centre-to-centre and edge distance measurement against the datum | Confirms the clip drops onto the pre-punched board |
| Assembled fit | Build the clip onto the production board with the production fixing | The only test that predicts field behaviour |
| Plating at the hole edge | Visual inspection at magnification | Finds cracks before they become corrosion sites |
| Corrosion | Salt spray to the agreed hours | Confirms the plating survives the hole-forming operation |
Sampling for this inspection should follow an agreed plan, typically the attribute sampling approach set out in ISO 2859-1, with the acceptable quality level written into the purchase order rather than agreed after a dispute. The inspection record should state the pin gauge sizes used, because “hole size OK” on a report is not evidence that a specific barrel fits.
What is the fastest way to lock the hole size?
Send the rivet. A measured sample of the mating fixing, plus the board thickness and the intended plate thickness code, lets the factory confirm the hole size and the hole tolerance in one pass instead of three rounds of drawings. If a sample cannot be shipped, a drawing of the barrel with its diameter, head diameter, and length is the next best thing.
Then write the confirmed values onto the specification sheet, along with the model, the spine width, the plate thickness code and the lever side, and treat that sheet as the controlled document for the project.
Frequently Asked Questions
What is the standard hole size for a lever arch clip?
There is no single global standard hole size. JXY produces lever arch clips with 3.8 mm, 4.2 mm and 4.5 mm holes, and the correct one is the size that matches the rivet or screw barrel you intend to use. Because a folder is assembled from a clip and a pre-punched board, the hole is a system interface, not an independent dimension.
Is a 3.8 mm hole stronger than a 4.5 mm hole?
Neither hole is stronger in itself. A smaller hole leaves more material around the rivet and therefore a stiffer base plate area, but it only works if the barrel fits through it. The strength that matters is the strength of the assembled joint, which depends on the plate thickness code, the board, and how well the hole diameter matches the fixing.
Can I drill out a lever arch clip hole if the rivet does not fit?
Drilling out a plated hole removes the coating on the hole wall and leaves a raw edge, which becomes the first place corrosion appears. It also turns a controlled fit into an uncontrolled one, so the clip may rotate. The correct fix is to change the hole size at the punch, or to change to a smaller fixing.
What tolerance should I put on a 4.2 mm hole?
Apply a general tolerance system such as ISO 2768-1 and state whether it applies before or after plating, because the coating closes the hole slightly. Then confirm the resulting limits against the barrel you plan to use. If the barrel is at the top of its own tolerance and the hole is at the bottom of its tolerance, the two still have to assemble without force.
Does base plate thickness change which hole size I need?
Base plate thickness constrains the choice rather than setting it. A heavier plate (moving from 60C to 70C) usually pairs with a longer and larger-diameter fixing, which pushes the hole size up. A light plate on a thin board can carry a smaller hole. The plate code and the hole size should always appear together on the drawing.
Do right-hand and left-hand lever arch clips use the same hole size?
Yes. Lever position is a mirror of the mechanism and does not change the base plate hole pattern. Hole size, hole position and plate thickness are shared between the right-hand and left-hand versions of the same model, so a folder tooling project only needs one hole pattern even if both lever sides are ordered.
How do I check hole size on an incoming shipment?
Use go / no-go pin gauges at the agreed sizes, sample to an agreed AQL plan, and keep the pin gauge set with the inspection record so the measurement is reproducible. An assembled fit check, using the production rivet and the production board, is worth more than a dimensional report alone because it tests the interface the customer will see.
Does hole size affect nickel release compliance?
It can. If the hole is undersized and the plating cracks at the hole edge, the substrate is exposed, and exposure is what turns a plating specification into a compliance question under the nickel restriction. A correctly sized hole keeps the coating continuous and keeps the clip well inside the corrosion performance you tested for.
Next Step: Send the Rivet With the Drawing
Hole size is decided in minutes when the mating fixing is on the table and in weeks when it is not. Send JXY the rivet or screw post sample, the board thickness, the intended base plate thickness code and the folder spine width, and ask for the hole diameter and its tolerance to be confirmed in writing. Foshan Jinxinyu Hardware Products Co., Ltd. reviews lever arch clip specifications against the real accessory range, so the hole size, the fixing and the plate thickness are confirmed together rather than one at a time.
About JXY Foshan Jinxinyu Hardware Products Co., Ltd. (JXY) is a stationery hardware manufacturer based in Foshan, Guangdong, China, with a 30,000 m² factory, 25 years of production experience, 300 product types, 500 staff, a monthly capacity of 30 million pieces, and customers in 50 countries. Product range: ring mechanisms, lever arch clips, board clips, jumbo clips, lever clips, snake clips, eyelets, rivets and loose-leaf accessories. Website: https://newworldstationery.com | Email: michelle@jxystationery.com | WhatsApp: +86 18138349832