The 6R12, 6R82 and 6R13 are Soviet knee-type milling machines that for decades milled faces, shoulders, slots and housings. They are replaced because of worn feed screws and nuts, play in the knee, a worn gearbox, or when digital readouts and an accuracy the old machine no longer holds are needed. Unlike drilling machines, the match here is not literal: the size range of modern machines has shifted, and it is worth knowing that before buying.
What to take from the old data sheet
- Table size — set by the last digit of the model: the "2" in the 6R12 and 6R82 means a 1250×320 mm table, the "3" in the 6R13 means 1600×400 mm.
- Travels — 800 / 250 / 420 mm on the 6R12 (longitudinal, cross, vertical), 1000 / 300 mm in X and Y on the 6R13. The length you can mill in one setup is limited by the travel, not by the table.
- Spindle taper — 7:24 No. 50, the same size as ISO 50. It decides whether your arbors and milling chucks move to the new machine.
- Main drive power — 7.5 kW on the 6R12 and 6R82, 10–11 kW on the 6R13 depending on the year. This is the ceiling for a face mill on a roughing pass.
- Spindle orientation — the 6R12 and 6R13 are vertical, the 6R82 is horizontal, with a table that swivels ±45°. A horizontal spindle is needed for side-and-face cutters and gang cutters on an arbor.
Table: old machine to what to look for in the catalog
| Old machine | Table | X / Y travels | Power | Closest in the catalog |
|---|---|---|---|---|
| 6R13, vertical | 1600×400 mm | 1000 / 300 mm | 10–11 kW | LUNA Perseus U5750: 1600×500 mm table, 1200 / 700 mm travels |
| 6R12, vertical | 1250×320 mm | 800 / 250 mm | 7.5 kW | no direct equivalent: the larger Perseus U5750 or the compact FPS 500M-hydro |
| 6R82, horizontal | 1250×320 mm | 800 / 250 mm | 7.5 kW | FPS 500M-hydro: vertical-horizontal, 500 mm X travel |
All the models are side by side in the universal milling machines.
6R13 to LUNA Perseus U5750: the closest match
The LUNA Perseus U5750 table is the same length, 1600 mm, but wider: 500 versus 400 mm. The travels are larger: 1200 versus 1000 mm in X and 700 versus 300 mm in Y. The ISO 50 taper is the same size as 7:24 No. 50, and the weight is similar at 4200 kg. The feeds come from servo drives on all three axes, a digital readout shows the position, and the table carries up to 1800 kg. For longer parts there is the Perseus U5750 MAX with a 2000×500 mm table and 1400 mm X travel.
One difference is worth knowing in advance: the Perseus main motor is 7.5 kW, while the 6R13 has 10–11 kW. That is usually enough for finishing and semi-finishing passes, but heavy roughing with a large face mill should be recalculated: we set the width and depth of cut for 7.5 kW at commissioning.
6R12 and 6R82: no direct equivalent — two routes
The catalog has no machine with a 1250×320 mm table and 800 mm X travel, and we will not stretch an equivalent. The work of the 6R12 and 6R82 is covered in two ways.
- A larger machine. LUNA Perseus U5750 takes everything the 6R12 took and more: a 1600×500 mm table and 1200 mm X travel. It makes sense if long parts come up and the shop has the space.
- Compact and more accurate. FPS 500M-hydro is a German knee-type vertical-horizontal machine: an 800×480 mm table, 500 / 400 / 400 mm travels, 7 kW, a stepless 25–3000 rpm drive and a Heidenhain POSITIP readout. Its X travel is shorter than on the 6R12 (500 versus 800 mm), but the cross travel is longer (400 versus 250 mm), and the head works both vertically and horizontally — one machine replaces both the 6R12 and the 6R82 on parts that fit the travel.
- For a tool room. If the parts are small, there is the compact FPS 300M with a 600×210 mm table and a head that swivels ±90°.
Taper 50 and taper 40: what happens to the tooling
The 6R12, 6R82 and 6R13 have a 7:24 No. 50 taper. The Perseus U5750 has ISO 50, the same size, but arbor shanks and the way they are drawn in differ between standards, so check the drawbar and drive keys before ordering. The FPS machines have an ISO 40 taper: Soviet 50 arbors will not fit, and the tooling has to be bought. For a machine of this class that is a separate budget line, so plan it from the start.
When you need a different type, not a replacement
- Batches of identical parts — cycle-controlled milling machines: the FPS 500M-digital and 630M-digital, 14.1 kW and a Heidenhain control with cycles.
- Contours and 3D machining — CNC milling machines.
- Occasional milling next to drilling — drilling-milling machines.
What to check before the replacement
- Longest part and X travel. The length machined in one setup is set by the travel, not the table.
- Horizontal work. If side-and-face cutters on an arbor were used on the 6R82, you need a horizontal spindle — the FPS 500M-hydro has one.
- Tooling on taper 50. List your arbors and chucks: they may fit the Perseus after the shanks are checked, but not the FPS.
- Power for roughing. If the 6R13 ran at the limit of its 10–11 kW, recalculate the cutting data for 7.5 kW.
- Space and foundation. The Perseus U5750 weighs 4.2 t and takes up 2425×2860 mm — check this before delivery, not after.
We covered replacing Soviet lathes and drilling machines.
Equipment from the catalog
