RG Roller Series — Technical Reference
This page collects what the catalogue publishes for the RG roller series: the body types, the accuracy grades, the preload bands, the dust protection codes and the rail bolt sizes. Block dimensions and load ratings for each size are issued on the signed drawing — they are not published here, because a roller rating taken from a similar size would be wrong in the direction that matters.
Body types
| Type | Body | Sizes | Height range | Rail |
|---|---|---|---|---|
| RGH-CA | Square block, top tapped | 25 / 30 / 35 / 45 / 55 / 65 | 40–90 mm | RGR, cut 100–4,000 mm |
| RGH-HA | Square block, extended body | 25 / 30 / 35 / 45 / 55 / 65 | 40–90 mm | RGR |
| RGW-CC | Flange block, bolted above and below | 25 / 30 / 35 / 45 / 55 / 65 | 36–90 mm | RGR |
| RGW-HC | Flange block, extended body | 25 / 30 / 35 / 45 / 55 / 65 | 36–90 mm | RGR |
The square body bolts through the block; the flange body spreads the pattern wider for thin carriage plates. Both run on the same RGR rail of that size, and neither is interchangeable with an HG ball guide — the roller and the rail are a matched pair.
Rail bolt sizes
| Rail | Size | Rail bolt |
|---|---|---|
| RGR25 | 25 | M6 |
| RGR30 | 30 | M8 |
| RGR35 | 35 | M8 |
| RGR45 | 45 | M12 |
| RGR55 | 55 | M14 |
| RGR65 | 65 | M16 |
Accuracy grades
RG is catalogued in H, P, SP and UP. The height tolerance and the running parallelism are quoted per size and per rail length on the datasheet rather than printed here: a running-parallelism number depends on the rail length it is measured over, so a single figure copied onto a page would be wrong for most machines. What matters for selection is that the interchangeable limit sits at P, and SP and UP are supplied as matched block-and-rail sets.
Preload bands
| Grade | Preload force | Behaviour |
|---|---|---|
| Z0 | 0.02–0.04C | Light preload — the lowest the roller series is offered at |
| ZA | 0.07–0.09C | Medium preload — the usual choice for cutting axes |
| ZB | 0.12–0.14C | Heavy preload — maximum rigidity, matched set |
These letters do not mean what they mean on the ball series. On HG, Z0 is a clearance band, effectively no preload. On RG, Z0 is already a light preload, because a roller guide with clearance would lose the line contact that justifies it. A quotation that says only “Z0” is ambiguous: on HG it is a free-running block, on RG it is a preloaded one.
Dust protection and accessories
Standard wiping is fitted as supplied. The catalogue lists the double and triple seal codes (ZZ, KK, DD) and the heavy-duty set (SH, ZH, KH, DH) for abrasive dust. RG also offers a metal scraper for hot chips and cast-iron dust, bolt caps to keep swarf out of the counterbores, and replaceable wipers. Wiper drag is quoted per size because it adds to the axis load at the ends of the stroke.
Where RG is used
Heavy cutting machines, gantries with long overhangs, wire EDM, press frames and grinders — axes where the deflection of a ball guide would show in the part. The trade is friction and heat: a roller guide at speed runs warmer than a ball guide of the same size, so the decision is made on the load case, not on the impression of quality.
Mounting a roller guide
A roller guide is less forgiving than a ball guide about the surface under the rail. Line contact does not absorb a bowed rail the way point contact does, so the mounting face is checked along its full length before the rail goes down, and the rail is checked with a dial gauge after bolting. Bolts are tightened from the middle outwards in two passes; a rail pulled down from one end keeps a bow in the middle that shows as a tight spot at mid-stroke.
Preload is set at the factory on the matched pair, so there is nothing to adjust on site. What can be adjusted is the rail alignment and the block mounting: if the axis binds after assembly, the cause is almost always the two rails not being parallel or not at the same height, not the preload.
What to send with an enquiry
Model and quantity, accuracy grade and preload written with the series — for example ZA (RG, 0.07–0.09C) — the rail length and hole count if the machine is already drilled, and the mounting orientation. If the machine is a replacement, send the block height and the rail hole pitch from the old part: RG is not a drop-in for an HG rail, so the drawing has to be checked before the size is chosen.
FAQ
| Why does Z0 feel different on RG and HG? | Because the letters are defined per series. HG Z0 is a clearance band, so the block moves freely; RG Z0 is 0.02–0.04C of positive preload, so the block has drag from new. Both are correct for their series — quoting “Z0” without the series is not a specification. |
| Why are there no dimensions on this page? | Block height, width and length and the C / C0 ratings are issued per size on the signed drawing. We do not copy a number from a similar size: for a roller guide that would be a guess, and a wrong guess here is a warranty claim. |
| Can I fit an RG block to an HGR rail? | No. RG runs on RGR rails; the roller and the rail are matched. |
| Is SP or UP available? | Yes, as matched block-and-rail sets only. Up to P a block can be replaced on its own. |
Datasheet for a size, or a drawing against your own machine: RG series overview · ball guide comparison · preload bands by series · request a quote.