Linear guide buying guide
Updated: October 2026
You are at the bench with a sled or a gantry half drawn, and the basket already holds a rail whose size code looks familiar. A linear guide buying guide stops you treating the number 20 as a duty rating and the printed length as the travel. The [linear guide comparison](/hub/workshop/linear-guide) holds the amazon.co.uk prices. This page is the order of the decision. Shelf figures are from 19 October 2026, and a qualifying purchase can earn us a commission at no extra cost to you.
You are at the bench with a sled or a gantry half drawn, and the basket already holds a rail whose size code looks familiar.
You are at the bench with a sled or a gantry half drawn, and the basket already holds a rail whose size code looks familiar. A linear guide buying guide stops you treating the number 20 as a duty rating and the printed length as the travel. The linear guide comparison holds the amazon.co.uk prices. This page is the order of the decision. Shelf figures are from 19 October 2026, and a qualifying purchase can earn us a commission at no extra cost to you.
Our top picks
| Badge | Product | Family | Size code | Rail length | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  GooEquip GooEquip HGR20 700 mm rail set | Profile rail | HGR20 | 700 mm | 7.4 | about £41.05 | View offer |
 CNCMANS CNCMANS SBR20 800 mm rail set | Supported shaft | SBR20 | 800 mm | 9.2 | about £43.33 | View offer | |
| Best value |  CNCMANS CNCMANS SBR16 600 mm rail set | Supported shaft | SBR16 | 600 mm | 7.9 | about £34.33 | View offer |
On this page
Four kinds of linear guide
These kits are not one product in four lengths. A miniature rail, a supported round shaft, a profile rail, and a motorised stage solve different jobs, and the first mistake is to pick the family because a forum used the same number.
A miniature rail is the light one. The DTGN pair is two 200 mm MGN12 rails and two MGN12H blocks at £26.99. A wood router is a different side load, so a short miniature rail is the wrong default there.
A supported shaft is an SBR rail: a round rod on an aluminium support, with an open bearing. In this set that is the CNCMANS SBR16 at £34.33 and the SBR20 at £43.33. Neither includes a motor. It does not stop the block rotating around the rod when a cutter tries to twist it. If you are stuck between that shaft and a square profile rail, read HGR20 or SBR20 before you add either kit.
A profile kit is an HGR rail with a square carriage that cannot spin around the rail. GooEquip lists an HGR20 pair at 700 mm for £41.05, with no motor and no stated accuracy class. Cutting, rather than sliding a slab, is the linear rail for a CNC router page. A motorised stage already includes a screw and a NEMA 23. You still buy a driver and limit switches. A stepper voltage is not a BS 1363 plug.
Size, carriages, and stroke
The size code is the width of that family, not the length and not the load. HGR20 is a size-20 profile rail. SBR20 is a 20 mm supported shaft. They share the digits and not the stiffness. Read the block code next. HGH20CA is a square, top-mounted carriage in the heavy-load length for a size-20 rail. It is not an HGW20CC flange block, and it is not an SBR20UU open bushing. Rail length is stroke plus the carriage group plus a margin at each end. A 600 mm SBR16 is not 600 mm of sled travel. Once the kit is the right family, the fitting sequence sits on how to install a linear rail.
What the precision lines do and do not mean
High precision on these listings is an adjective. HIWIN grades its own HG rails as C, H, P, SP, and UP. On an HG15 or HG20, class C allows ±0.1 mm on the height and width assembly dimensions. None of the kits in this comparison states a HIWIN class, and a marketplace HGR title is not evidence of a genuine HIWIN part. You have not bought class P when the bullet says high precision and gives no letter.
Ball-screw grade C7 is a different scale. On THK's table to JIS B 1192, C7 is about ±50 µm over 300 mm. The FUYU listings also print a repeatability of 0.02 mm or ±0.02 mm. Those are not the same measurement, and neither is a test of the finished axis.
What you can ignore on a home bench
A rail and a carriage with no drive are components. The Supply of Machinery (Safety) Regulations 2008 matter when someone places machinery on the Great Britain market, which calls for a technical file, English instructions, a declaration, and the conformity mark. PUWER 1998 applies to work equipment, not to a private garage build.
If you are about to sell a machine, wire a driver to 230 V, or run a powered axis that can crush a hand, that is the point to bring in someone who does that work. For a home sled, the buying job ends when the family, the block code, and the stroke all describe the same part.
Common questions
Do I buy a rail kit or a stage that already has a motor?
Buy a rail kit when you already have a drive, or when the axis is pushed by hand, as on many router sleds. Buy a stage when you want the screw and the NEMA 23 in the same box. The Zeberoxyz, the FUYU FSK40, and the FUYU FSK40J are the motorised rows here. A driver, a supply, and limit switches are still separate. The FUYU contents lines do not list a controller or limit switches.
Is HGR20 the same duty as SBR20?
No. Both codes use 20, and they are different parts. HGR20 is a profile rail with a square carriage that resists a twisting load. SBR20 is a 20 mm round shaft on a support, with an open bearing that can rotate around the shaft. The amazon.co.uk kits in this set do not print a catalogue load, so the shared number is not a shared capacity.
How much longer must the rail be than the travel?
Longer by the carriage group and a margin at each end, so the block does not run off the race. A 200 mm MGN12 rail with two MGN12H blocks has far less than 200 mm of useful travel. A 600 mm supported shaft is the steel you bolt down, not the distance the sled can move. Measure the block, add the stroke, then add a stop margin.
What does HGH20CA mean?
It is a square, top-mounted carriage for a size-20 profile rail, in the heavy-load body length. The GooEquip and iMetrx HGR20 kits name four of those blocks. It is not a flanged HGW block and not an SBR20UU. If a listing mixes HGH15, HGH15CA, and HG150CA, as the GooEquip HGR15 page does, the block in the box is not fully specified.
Does high precision mean HIWIN class P?
No. Class P is one of HIWIN's own grades, tighter than class C. Class C on an HG15 or HG20 allows ±0.1 mm on height and width. None of these marketplace listings states class P or any HIWIN grade. A similar-looking HGR title does not make the rail a HIWIN part.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Updated October 2026.
- HIWIN HG series catalogue (retrieved 19 October 2026)
- HIWIN linear guideway assembly manual (retrieved 19 October 2026)
- THK ball screw accuracy, JIS B 1192 (retrieved 19 October 2026)
- CNC4YOU SBR load sheet (retrieved 19 October 2026)
- GOV.UK Supply of Machinery (Safety) Regulations 2008 (retrieved 19 October 2026)
- Supply of Machinery (Safety) Regulations 2008, SI 2008/1597 (retrieved 19 October 2026)
- HSE PUWER overview (retrieved 19 October 2026)
- HSE wood dust (retrieved 19 October 2026)