Option 1: zero-point pallet plus a standard vise
Cheapest and most flexible. A 100 mm zero-point pallet takes a standard vise, and the vise takes the part. Changeover between jobs is minutes, and the pallet repeatability (typically 0.005 mm) is better than what most parts need.
Where it fails: a vise holds the part from the sides, which is exactly where the tool wants to be for the fourth and fifth faces. On a 200 mm cube, the vise jaws and the handle occupy 30–40 mm of the working envelope on two sides. If your finishing pass runs around the perimeter, the vise is in the way.
Option 2: dovetail blank holder
The part is machined from a blank that is dovetailed at the base, and the dovetail is held in a low-profile clamp. The part is gripped from below, so all five faces are free and the tool can reach the bottom edge of the part without a clamp in the way.
Where it fails: the dovetail has to be cut into the blank, which costs material and a preparation operation. On expensive material (titanium, Inconel) the wasted stock is a real number. It is also less rigid than a dedicated fixture, so deep pockets at long overhang will chatter.
Option 3: dedicated trunnion fixture
The part is located on its own datums, clamped from points that the tool will never need, and mounted between centres or on a faceplate. Access is designed rather than inherited, and stiffness is the highest of the three.
Where it fails: cost and lead time. A trunnion fixture is 6,000–28,000 USD and 7–10 weeks, and it only pays back if the part runs for years or the batch is large. It is also specific: a design change of 20 mm may mean a new top plate.
The decision rule that actually works
Ask how much of the part the tool needs to reach, not how accurate the fixture is. If the answer is “five faces plus the perimeter”, the vise and the dovetail both fail for different reasons: the vise blocks the sides, the dovetail wastes material. If the answer is “three faces and a bore”, a vise on a zero-point pallet is correct and everything more expensive is over-engineering.
| Option | Cost | Lead time | Free faces | Changeover |
|---|---|---|---|---|
| Zero-point pallet + vise | 2,000–4,500 USD | 2–4 weeks | 3 of 5 | 5–10 min |
| Dovetail holder | 3,000–6,000 USD | 3–5 weeks | 5 of 5 (from below) | 10–15 min + blank prep |
| Dedicated trunnion fixture | 6,000–22,000 USD | 7–10 weeks | 5 of 5, designed access | 20–30 min |
Questions
Can I use a standard vise for 5-axis work at all?
Is dovetail clamping safe for a heavy part?
What repeatability does a zero-point pallet really give?
Published by Liuzhou Dongben Machinery Equipment Co., Ltd. · More notes