This page is about choosing. How each kind of clamp works, and the difference between force and pressure, is in the clamps guide.
Note— How this guide was made
It compares kinds of clamp and their published specifications. No clamp was tested for it, no product is ranked, and no price or rating appears.
Clamps by the work you do
| Work | Clamps | How many |
|---|---|---|
| Holding work to cut, drill or rout | One-handed bar clamps or C-clamps | A pair, so work is held at both ends |
| Small glue-ups and repairs | Spring clamps and small C-clamps | Several of each; they are used in numbers |
| Edge-gluing panels and tabletops | Bar, pipe or parallel clamps long enough for the widest panel | Enough to space along the longest joint and alternate — see the worked example |
| Boxes, cases and cabinets | Parallel-jaw clamps | At least two per side being closed, plus cauls |
| Picture frames and mitred boxes | A band or strap clamp, or corner clamps | One band clamp, or one corner clamp per corner |
| Tapered, angled or finished parts | Hand screws | One or two to start |
Buy for the next project’s largest glue-up; add clamps as projects need them rather than as a set.
How many clamps a panel needs
In an edge-glued panel, the clamps squeeze every joint in turn, so each joint carries the full clamp force. The number of clamps therefore depends on the area of one joint and the pressure you want on it, not on how many boards there are.
Worked example: a 36 in hardwood panel
Area of one joint
Boards 3/4 in thick, 36 in long: 0.75 × 36 = 27 sq in.
Force for the stated pressure
Titebond gives 175–250 psi for hardwoods: 27 × 175 = 4,725 lb at the low end of its range.
Clamps at full rating
At Jorgensen’s 1,000 lb heavy-duty rating, five clamps; at the Cabinet Master’s 1,500 lb, four; at the 300 lb of IRWIN’s SL300, sixteen.
Adjust for reality
Clamps tightened by hand rarely reach their rating, but well-fitted joints also need less — the USDA notes flat, well-planed surfaces bond at lower pressures. Titebond’s own test is pressure enough to close the joint tightly.
Check the spacing
Whatever the count, you need a clamp near each end and enough in between, alternated, to keep the panel flat. For a 36 in panel, four to six bar clamps is a practical set; light one-handed clamps are not the tool for it.
What to check
| Specification | Why it matters |
|---|---|
| Opening (length) | Sets the largest work. Buy for your widest common glue-up; Jorgensen’s E-Z Hold clamps can be joined end to end for more. |
| Reach (throat depth) | How far from the edge the pad presses: 3-1/4 in on IRWIN’s SL300, 3-7/8 in on Jorgensen’s Cabinet Master. |
| Jaw style and pads | Large faces spread force; small pads need blocks. Removable pads or caps (IRWIN, Bessey) can be replaced when worn. |
| Stated force | Useful for comparing clamps from one maker; makers state it in different terms (nominal, sustained, maximum), so it is less useful across makers. |
| Parallel jaws | Parallel-jaw clamps push squarely on cases and panels; F-style and one-handed clamps do not hold their jaws parallel under load. |
| Bar stiffness | A bar that flexes lets the jaws tilt; IRWIN uses an I-beam bar to reduce flexing and bowing. |
| Weight | Heavy clamps tip small work: Bessey’s K Body REVO runs from 4.76 lb at 12 in to 13.21 lb at 98 in. |
| Spreading | Reversible clamps push outward for dry-fit adjustment and repairs. |
| Locking and parts | A clutch or lock that holds anywhere on the bar; screws, pads and fixtures available as parts. Jorgensen advises cleaning glue off promptly. |
Bar clamps and corner clamps
- Bar clamps. For panels on a budget, pipe clamp fixtures on lengths of pipe; for cases and cabinets, parallel-jaw clamps; for holding, one-handed clamps. The kinds are compared in the bar clamp guide.
- Corner clamps. Useful for screwed or nailed butt joints; for glued frames, a band clamp closes every corner at once. Neither checks the whole frame — the corner clamp guide shows the diagonal check.
- Short-reach clamps. Spring clamps, C-clamps and hand screws are covered in their own guide.
What matters less than it seems
- The highest force rating. Past the point where a joint closes, more force does not help; a clamp you can set quickly and squarely matters more.
- A matched set. Clamps are used in mixed groups; buy the kinds and lengths your projects need.
- Every length. A few long clamps close short work too; very short clamps cannot close long work.
Checklist
Before buying clamps
- You know the next project’s largest glue-up and its widest part.
- The clamps open wide enough for it, with reach enough to press where needed.
- You have enough to space along its longest joint and alternate them — worked out, not guessed.
- Jaws or pads will not mark the work, or you have blocks and cauls ready.
- For cases, at least some clamps hold their jaws parallel.
- They are light enough to set quickly and not tip the work.
- Pads and parts are replaceable, and the clamp can be cleaned of glue.
Sources
This guide is specification-based: it compares kinds of clamp and what makers state, and no clamp was tested for it. Ratings are the makers’ own, in their own terms. The worked example uses Titebond’s stated pressure; how many clamps a job needs is bench practice.
- 1.
Product Catalog, Spring 2024. Pony Jorgensen.
Used for: Steel bar clamps at 600 lb and 1,000 lb heavy duty; one-handed E-Z Hold clamps from 50 to 600 lb that join end to end; pipe clamp fixtures used on any length of pipe 7 in longer than the work; spring clamps, C-clamps, hand screws and band clamps.
- 2.
Jorgensen Cabinet Master Medium-Duty 90° Parallel Jaw Bar Clamp. Pony Jorgensen.
Used for: 1,500 lb; a 3-7/8 in throat; parallel jaws; a reversible head; removing glue from the clamp promptly.
- 3.
K Body REVOlution parallel bar clamps (KRE). BESSEY Tools North America.
Used for: A nominal 1,700 lb; weights from 4.76 lb (12 in) to 13.21 lb (98 in); removable, glue-repellent pressure caps; spreading without tools.
- 4.
SL300 One Handed Bar Clamps / Spreaders. IRWIN.
Used for: 300 lb of sustained force; removable pads; conversion to a spreader; an I-beam bar that reduces flexing and bowing.
- 5.
Titebond Original Wood Glue. Franklin International (Titebond).
Used for: Clamping pressure enough to bring joints tightly together — generally 175–250 psi for hardwoods.
- 6.
Charles R. Frihart and Christopher G. Hunt. Wood Handbook, Chapter 10: Adhesives with Wood Materials — Bond Formation and Performance. USDA Forest Service, Forest Products Laboratory — Wood Handbook, FPL-GTR-190, 2010.
Used for: Small areas of flat, well-planed surfaces bonding satisfactorily at lower pressures.
About this buying guide
Written by BenchRoot Editorial. How BenchRoot sources, checks and corrects its pages is set out in the Editorial Policy. If something here is wrong or unclear, the contact page explains how to tell us.