Hitachi Seiki CNC Lathe and Sae Morse Lathe: One Program, Two Machines

• 1
  Why a Hitachi Seiki CNC lathe and a Sae Morse lathe can share G-code at all
• 2
  Five conditions that decide whether one program runs on both lathes
• 3
  Offsets, tool data and the parameters that do not travel with the file
• 4
  Where program sharing breaks down, and what it costs
• 5
  Cutting data does not transfer, even when the G-code does
• 6
  Why we keep the same program on both lathes at GreatLight
• 7
  How to release one program to both lathes, step by step
• 8
  When one program for both lathes is the right call

Most lathes built after 1985 speak a dialect of ISO 6983. A Hitachi Seiki CNC lathe with a Fanuc or Seicos control and a Sae Morse lathe with a similar control read the same G71, G76 and G92 blocks in the same order. The words are the same. The meaning of a few words is not.

The difference is not in the G-code itself. It sits in the machine data: work offsets, tool offsets, turret geometry, spindle orientation and the axis limits that decide whether a rapid move is legal. Two lathes can read identical code and cut two different parts.

So the useful question is not "can they share a program". They can. The question is which parameters must be normalized first, and which of them cannot be normalized at all. That is what the rest of this page covers.

We run 127 high-precision CNC machines across three wholly-owned plants in Dongguan and Singapore. Program portability is a daily production decision, not a theory exercise.

• 1
  Same code, different offsetsG54 and tool offset values live in the control, not the program.
• 2
  Same code, different geometryTurret station height and X reference point rarely match between models.
• 3
  Axis limits are hard stopsA legal move on one lathe can trip an overtravel alarm on the other.

Program sharing is a checklist, not a switch. If all five conditions below are true, one file will run on both machines with only a work offset change at setup. If any one is false, you need a post-processor variant or a manual edit before the first part.

Control family comes first. A Fanuc 0T, 16T, 18T or 21T block set transfers between machines cleanly. Seicos controls on older Hitachi Seiki lathes handle most standard cycles but differ on canned cycle return planes and on how they read certain M-codes.

Turret and tool geometry comes second. Twelve stations on one lathe and eight on the other means every T-word needs a map, and any grooving or boring holder that sits at a different center height will cut off-center on the second machine.

Third is the coordinate convention. Diameter programming for X is standard on both, but some older controls accept radius values when a parameter is flipped. One flipped bit turns a Ø40 mm turn into a Ø20 mm cut. Check the parameter, not the drawing.

Fourth is spindle and feed behavior. Constant surface speed, spindle orientation for bar feed, and thread chamfering at the end of a G76 cycle all depend on parameters that live in the machine, not the file.

Fifth is the axis envelope. The two lathes may look similar on the floor and still differ by 100 mm of Z travel.

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  Control familyFanuc to Fanuc transfers cleanly. Seicos needs a read-through.
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  Turret mappingStation count and holder center height must be reconciled.
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  X conventionConfirm diameter programming before the first rapid move.

A G-code file contains geometry, not machine state. Everything a machinist touches at setup, the work offset, the tool offset, the wear value, the turret index reference, stays inside the control. That is good news for portability and bad news for the first article.

Work offsets are the easy part. Measure the same datum on both machines, write the same G54 values, and the program will position the tool correctly on both. This is the only offset most shops need to change between the two lathes.

Tool offsets are the hard part. A tool that touches off at 210.4 mm on the Hitachi Seiki CNC lathe will touch off at a different value on the Sae Morse lathe, often by several millimeters, because the reference point of the turret is a physical property of the casting.

Wear values are the quiet failure. If an operator on machine A adds 0.03 mm of wear compensation to hold a tolerance, that correction sits in machine A. Machine B will cut 0.03 mm off nominal until someone measures the first part.

The practical rule: never trust a tool offset table across machines. Re-touch every tool on the second lathe and record the values in a setup sheet that names the machine.

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  Work offsetUsually the only value you must change between machines.
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  Tool offsetAlways re-measure. Turret reference points differ.
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  Wear compensationStays with the machine and is invisible in the file.

Two failures show up again and again on the floor. The first is a thread that pulls out at a different chamfer angle on the second machine. The G76 cycle reads a parameter for chamfer amount. If that parameter differs, the thread still gauges correctly but the entry looks different, and on a sealing thread that difference matters.

The second is a turret collision during a rapid approach. The program was proven on the Hitachi Seiki CNC lathe, where station 7 sits clear of the tailstock. On the Sae Morse lathe, the same station is 12 mm closer. The rapid move is legal in the file and illegal in the machine.

Both failures share a cause. The program was validated against one machine and assumed valid against another. Simulation catches some of this, but only if the simulation uses the second machine's kinematic model, not a generic lathe.

The engineering answer is a machine-specific verification pass. Run the first article on the second lathe in single block with rapid override down, measure the critical dimensions, and only then release the program for production. On a 500-piece batch that pass costs less than an hour.

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  Thread chamfer parameterDiffers between controls and changes the thread entry.
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  Turret clearanceStation positions are physical, not programmed.
• 3
  Single block first articleCheapest insurance before a production run.

Feeds and speeds in the program are a starting point tied to one machine's rigidity, spindle torque and toolholder stiffness. A Hitachi Seiki CNC lathe with a heavier bed will accept a deeper cut than a lighter lathe running the same insert.

For aluminium 6061-T6 and 7075, the difference is usually small enough to ignore on roughing and large enough to matter on finishing. Surface speed around 300–500 m/min holds on both, but depth of cut should drop on the lighter machine if chatter appears.

Stainless 304, 316 and 17-4PH behave differently. These grades work-harden, so a light pass on a less rigid lathe can rub instead of cut and raise the surface hardness under the insert. If you see Ra climbing between parts, increase feed per revolution rather than reducing depth of cut.

Titanium TC4 (Ti-6Al-4V) and Inconel punish any rigidity gap. Keep surface speed low, around 40–60 m/min, use high-pressure coolant, and treat the second lathe as a different process window rather than a copy of the first.

A program that shares G-code across two lathes should still carry a per-machine cutting data table. The geometry travels. The speeds do not have to.

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  Aluminium 6061-T6Speeds transfer well; watch depth of cut on light lathes.
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  Stainless 304 / 17-4PHWork-hardening punishes light passes.
• 3
  TC4 and InconelTreat each lathe as its own process window.

Part of our turning work runs across mixed lathes because the batch size needs the capacity. Keeping one proven program and changing offsets is faster than maintaining two files that drift apart after every engineering change.

The version control matters more than the time saving. When a drawing revision lands, one program is edited, proven, and released. Two programs mean two edits, two first articles, and a real chance that one file keeps the old dimension.

We hold ±0.005 mm on turned features and inspect 100% of parts before shipment, with raw material checks, in-process monitoring and final inspection. Reports are available on request. Certification covers ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022.

No minimum order quantity applies, from one prototype to 10,000+ part runs. Quotation and free DFM analysis come back within 12 hours, and production can start within 24 hours. Parts ship in 3–5 days.

• 1
  One file, one revisionA drawing change is proven once, not twice.
• 2
  Offset-driven setupMachine differences live in the control, not the program.
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  Documented first articleEvery machine pair carries its own signed-off setup sheet.