THK4RSR15VM+430LMiniature LM Guide Assembly — Two Size-15 V-Type Stainless Carriages on One 430 mm Rail, Normal Clearance

Product Description

What this part is

A THK miniature LM Guide assembly from the RSR series: two model RSR15VM LM blocks supplied on one 430 mm LM rail. The RSR is THK’s miniature four-way equal-load linear guide — two rows of balls at a 45° contact angle circulate through the block, so one block carries load in the radial, reverse-radial and both lateral directions.

Decoding the order code

Read 2RSR15VM+430L field by field. The leading 2 is the number of LM blocks used on the same rail. RSR is the miniature LM Guide series. 15 is the size, which fixes the rail width at 15 mm. V is the block form — the short V-type block with four tapped mounting holes taken from the top face, as opposed to the longer N-type block. M means stainless steel: on RSR-VM the LM block, LM rail and balls are all stainless, which is why this is the series THK offers for corrosive and washdown duty. +430L is the LM rail length in millimetres, so the rail supplied is 430 mm long. No accuracy letter is present, which is normal grade; no clearance letter is present, which is normal radial clearance rather than the C1 light preload option. Normal clearance and light preload are not interchangeable — C1 raises stiffness and repeatability and also raises drag.

Scope — what is in the box

This is a matched assembly, not a bare carriage: both RSR15VM blocks and the 430 mm rail are included. That matters because on a linear guide the rail is usually the larger part of the cost and the harder part to source, and because a block cannot simply be dropped onto a rail of another brand. In THK’s own terms one set of a single-rail unit is one rail plus its blocks — if your machine runs two rails in parallel, you need two of these.

Published ratings and mounting data

Model: RSR15VM, size 15, V-type block, stainlessBlock height M: 16 mmBlock width W: 32 mmBlock length L: 42.9 mm (body length L1 25.7 mm)Block mounting holes: 4 x M3, 4 mm deep, on a 25 mm x 20 mm pattern (B x C)Block shoulder dimension K: 12 mm; N: 3.5 mm; H3: 4 mmRail width W1: 15 mm (0 / −0.025)Rail height M1: 9.5 mm; W2: 8.5 mmRail mounting hole pitch F: 40 mmRail bolt holes: 3.5 x 6 x 4.5 mm (for M3 socket screws)Rail length supplied: 430 mmBasic dynamic load rating C: 4.41 kN per blockBasic static load rating C0: 6.57 kN per blockStatic permissible moment MA: 23.7 N·m one block, 63.1 N·m two blocks in close contactStatic permissible moment MB: 21.1 N·m one block, 55.6 N·m two blocks in close contactStatic permissible moment MC: 38.8 N·mBlock mass: 0.069 kg each; rail mass 0.925 kg/mGreasing: PB107 grease nipple provisionStandard maximum RSR15 rail length: 1600 mm

What these specs mean in practice

At 16 mm tall and 32 mm wide this is a genuinely small guide, and the stainless construction is the reason to choose it — food, medical, semiconductor wet process and any wash-down axis where a bearing-steel RSR would rust. The V-type block is the short one, so moment capacity per block is modest; the published figures show why THK quotes two blocks separately, since two blocks in close contact take roughly 2.7 times the MA moment of one. Running them spaced apart on the 430 mm rail rather than in contact gives far more moment capacity again, limited by the block load rating rather than the moment table. Normal clearance suits general positioning; if the axis is cantilevered or reverses under load and you need repeatability in the low microns, that is what the C1 preload variant exists for.

Fitting notes

The rail is bolted down through 3.5 x 6 x 4.5 mm counterbored holes on a 40 mm pitch using M3 socket screws; check that your hole pattern matches the 40 mm pitch before machining. Mount the block from the top face with M3 screws no deeper than 4 mm of thread engagement in the block. The mounting surface for a miniature guide needs to be flat and burr-free — RSR blocks have very little capacity to absorb a wavy mounting face, and a high spot shows up immediately as varying drag. Do not slide a block off the end of the rail: the balls are retained by the endplates only while the block is on the raceway, and a dropped block usually loses balls.

Interchange guidance

Miniature linear guide blocks are not cross-brand interchangeable. The RSR rail profile and ball diameter are specific to THK, so an IKO, NSK, Hiwin or generic size-15 miniature block will not run correctly on this rail even where the nominal rail width also happens to be 15 mm. Within THK, the same size in the longer block form is RSR15N and the wide-rail form is RSR15WV / RSR15WVM — those are related sizes with different footprints and different ratings, not substitutes. The number is also written RSR 15VM, RSR-15-VM, RSR15VMUU and RSR15VM1UU depending on whether the seal and block-count fields are spelled out.