When a machine builder asks for a custom slide table, the first email usually says "we need 940 mm of travel". That number is the least interesting part of the request. Any frame can be cut to 940 mm. What decides whether the axis works is the five other constraints around it — and they are usually known, just not volunteered.
The five inputs that define a custom build
- Function. Cutting, transferring, scanning or holding position. This decides rail type, preload and drive before anything else.
- Load case. Mass, centre of gravity offset, acceleration, and whether the load is caught (shock) or merely moved.
- Envelope. Overall length available, stack height available, and where the cable chain can run. These three kill more designs than tolerance does.
- Interface. Mounting hole pattern, motor frame size, control signal type, and whether an encoder or brake is needed.
- Environment. Coolant, swarf, washdown, vacuum, temperature range, cleanroom class.
A sketch with those five items is enough for a quote. A full 2D drawing shortens it to same-day. A sample of the part being replaced is the fastest route of all for a retrofit, because it carries the mounting pattern in physical form.
How tolerance is allocated on a custom frame
Custom does not mean unmeasured. Every build starts from a tolerance budget: what the process needs, what the frame can hold, and where the budget is spent.
| Contribution | Budget | How it is controlled |
|---|---|---|
| Screw lead error | 0.030 mm | C5 ground screw, 0.023 mm/300 mm |
| Rail straightness | 0.010 mm | Rails seated on a machined datum, indicated at assembly |
| Backlash | 0.005 mm | Preloaded double nut, verified per unit |
| Frame deflection | 0.008 mm | Section sized for 1.5× rated load |
| Thermal growth | 0.015 mm | One end free, scale option if tighter |
| Total (RSS) | ≈ 0.037 mm | Reported on the inspection sheet |
If the process needs ±0.02 mm over that stroke, the budget says a scale is required. Saying that on the quote is more useful than promising the number without one.
Why long custom stroke forces a drive change
At 940 mm a Ø16 mm screw is close to its critical speed at 500 mm/s. The usual answer is a larger screw in the same frame format, which pushes the comfortable range out before the same limit returns. At 2000 mm nobody should be using a screw: a belt module or a rack axis is the correct engineering answer, and the repeatability requirement decides which.
Drive selection by length
These are the break points where the drive choice has to change.
- ≤ 600 mm
- Ø16 screw, 500 mm/s
- 600–1200 mm
- Ø25 screw, 700 mm/s
- 1200–2000 mm
- Belt or helical rack
- > 2000 mm
- Rack with jointed sections
First article, then batch
A custom build ships its first article within the lead time quoted on the order with a dimensional report: straightness at three positions, backlash, flatness, and the actual stroke achieved. The customer tests it on the machine. One geometry or preload adjustment is included free of charge, because a first article that needs one iteration is normal and should not be an invoicing event.
Once approved, the drawing is frozen. Batch production runs against that drawing with the same inspection plan, the same datum references and lot traceability on rails and screws. This is what prevents the classic custom-part failure where unit 40 does not fit unit 1.
OEM and ODM arrangements
For OEM customers we mark the unit with your part number, ship in neutral packaging and do not apply our brand. For ODM work we design the frame and the customer owns the drawing, subject to an exclusivity term. Both arrangements include the inspection report and the material certificates, because those are what an end customer asks for when a machine is audited.
What custom actually costs
Within the standard frame limits, a custom stroke or hole pattern carries no tooling charge — the frame is cut to order either way. Above those limits, expect a new base casting or extrusion, a design fee, and a longer lead time. Where a standard frame can be adapted with a spacer plate, we will say so even when the custom frame is the more profitable answer for us.
The custom slide table page lists the capability envelope and the five-step build process. If you already have a drawing, send it; if you only have a constraint, send that instead.
Common questions
No, within the standard frame limits. Above them a new base casting or extrusion may be required, which carries a one-off cost quoted with the design.