# Turning Capacity: Diameter, Swing and Part Length

> Size a turning RFQ correctly: distinguish swing, cutting diameter, part length and workholding, with ATM's documented machine capacities.

Canonical page: https://appalachiantool.com/wiki/turning-capacity.html

Updated: 2026-11-06T01:55:48Z

A part fits a lathe only when the stock, fixture, cutting tools and required operations fit together. Start with separate dimensions for diameter and length, then check the machine and setup that will actually make the part.

## Read the capacity terms separately

Manufacturers publish swing, turning diameter, distance between centers and working length as separate specifications. Okuma's lathe documentation illustrates that these numbers can differ on the same machine. Swing describes rotational clearance over a named machine feature; it does not automatically establish the diameter that a tool can cut through the required working length. A table or faceplate dimension describes another part of the setup. Always retain the original label beside the number. [[2]](https://appalachiantool.com/wiki/turning-capacity.html#source-2)

For an RFQ, describe the largest incoming stock diameter, finished diameter, overall stock length and finished length individually. Include any flange, casting boss or lug that extends beyond the nominal body. Where the drawing contains a large flange and a smaller shaft, identify both instead of summarizing the part with a single diameter. That makes the first capacity review much more useful.

## Use the documented ATM machine figures

The following values come from ATM's owner-supplied capability brief and equipment register. They reproduce the manufacturer-specification values recorded there; this guide does not represent a new inspection of the individual machines. [[1]](https://appalachiantool.com/wiki/turning-capacity.html#source-1)

Recorded turning capacities; all dimensions in inches

| Machine | Swing | Cutting or workpiece diameter | Length or other limit |
| --- | --- | --- | --- |
| Ikegai VT1100 · #219 | 51 | 45.3 maximum workpiece diameter | 49.2 faceplate; 8,800 lb table load |
| Doosan VT900 · #202 | 39.4 | 35.4 turning diameter | 33.4 turning length |
| Okuma & Howa 2SP-V80 · #203 / #204 | 39.37 | 31.5 cutting diameter | 33.07 length |
| Monarch manual lathe · #114 | Confirm for the part | Confirm for the part | 96 between centers |
| Wacheon manual lathe · #115 | 22 | Confirm for the part | 80 between centers |

The 80-inch and 96-inch manual-lathe figures are lengths between centers. Neither is a swing diameter. Likewise, the Doosan's 39.4-inch swing and the Okuma's 31.5-inch cutting diameter belong to separate machine entries; they should not be combined into one machine specification. [[1]](https://appalachiantool.com/wiki/turning-capacity.html#source-1)

## What the 70-inch fleet claim means

ATM's owner and brochure state a fleet-level turning capability of approximately 70 inches in diameter. The machine responsible for that envelope has not yet been identified in the verified per-machine records supplied for this website. The listed Ikegai, Doosan and Okuma VTL specifications do not establish a 70-inch cutting diameter. An inquiry near that size needs a named-machine and workholding review before a machining commitment. [[1]](https://appalachiantool.com/wiki/turning-capacity.html#source-1)

Send the actual blank dimensions, weight, center of gravity if known, and the surfaces that need cutting. Ask the quotation to identify the proposed machine and any conditional setup requirements. A diameter statement becomes useful purchasing evidence when it is connected to a particular part and a workable process.

## Check the setup as well as the blank

Tool interference drawings show why the nominal envelope is only the first check: the toolholder, turret and workpiece must occupy compatible positions throughout the cut. Okuma publishes separate interference diagrams for different holders and turret arrangements. Those diagrams are a useful example of the review needed, not a specification for ATM's listed machines. [[3]](https://appalachiantool.com/wiki/turning-capacity.html#source-3)

Provide a section view for deep bores, recesses or shoulders. Call out surfaces where gripping marks are prohibited and any areas available for temporary clamping. If your supplied stock has already been partially machined, explain what must remain untouched. These details help the shop plan the gripping sequence and identify missing information before committing material.

For long internal features, tool support also matters. Sandvik identifies boring-bar overhang, clamping stability, cutting-force direction and chip evacuation as important contributors to turning stability. A bore that is physically reachable may still require a different tooling plan from a shallow bore of the same diameter. [[4]](https://appalachiantool.com/wiki/turning-capacity.html#source-4)

## Do not combine separate process envelopes

ATM's published 5-axis envelope is Ø19.7 inches × 11.8 inches, and its large milling table is 86.6 inches × 41.3 inches. These are separate capability statements, not dimensions that can be added to a lathe's cutting range. A table size alone also does not establish a finished-part envelope. Use the [equipment register](https://appalachiantool.com/equipment.html) with the [machining capabilities overview](https://appalachiantool.com/capabilities.html) to identify which operations require further review. [[1]](https://appalachiantool.com/wiki/turning-capacity.html#source-1)

A turned housing with side ports, for example, needs a plan for both its rotational features and its off-axis features. Highlight the datum relationships between them on the drawing. Do not assume that separate capacity figures prove that the entire component can be completed in one setup.

## Build an RFQ that answers the fit question

Send a controlled drawing and solid model, with matching revisions and stated units. Add the stock form, alloy and condition, approximate blank weight, quantity, required delivery and whether you or the shop will provide material. Mark the critical diameters, lengths, bores, surface requirements and inspection deliverables. If this is repair work, distinguish measured wear from the intended finished geometry.

For an envelope-edge part, request written confirmation of the incoming blank size, proposed machine, workholding allowance and any operation exclusions. Share photographs of a casting or existing component when they explain geometry absent from the model. Then [send ATM the turning envelope for review](https://appalachiantool.com/contact.html); a complete part definition is the shortest path from a broad capacity claim to a dependable quotation.

## Questions before you quote

### Does swing equal maximum cutting diameter?

No. Swing is clearance over a specified machine feature; the cutting diameter must be checked separately with the tooling and setup.

### Which listed ATM machine verifies 70-inch turning?

None of the per-machine specifications supplied for this guide establishes that diameter. The owner/brochure fleet claim requires confirmation of the actual machine and setup.

### Is the Monarch 96-inch figure a diameter?

No. It is the recorded distance between centers, a length specification.

## Sources and technical basis

1. [ATM equipment register and owner-supplied capability brief (reviewed November 5, 2026)](https://appalachiantool.com/equipment.html)
2. [Okuma LU35II / LU45II manufacturer specifications: distinct capacity terms](https://www.okuma.com/files/documents/LU35II_45II-E_3.1a_Non_Feb2021.pdf)
3. [Okuma LB35III / LB45III: tool interference drawings](https://www.okuma.com/files/documents/LB35III_45III-E_5a_300_Aug2018.pdf)
4. [Sandvik Coromant: Silent Tools turning application guidance](https://www.sandvik.coromant.com/en-gb/tools/silent-tools/what-is-silent-tools/application-guide-silent-tools/turning-appl-guide)

## Related guides

* [Vtl vs horizontal boring](https://appalachiantool.com/wiki/vtl-vs-horizontal-boring.html)
* [5 axis machining](https://appalachiantool.com/wiki/5-axis-machining.html)
* [Gdt tolerances](https://appalachiantool.com/wiki/gdt-tolerances.html)

[Request a part-specific machining review](https://appalachiantool.com/contact.html?intent=wiki-turning-capacity)