How to install a linear rail
Updated: October 2026
The kit is on the bench, and the carriage looks easier to remove than to bolt down in place. This is how to install a linear rail without dumping the balls and without running on shipping oil. Leave the block on the rail if you can, clean the film, put a service lubricant back, and do not power a screw into a hard stop. Choosing the family sits on the [linear guide buying guide](/hub/workshop/linear-guide/sub/linear-guide-buying-guide). Prices sit on the [linear guide comparison](/hub/workshop/linear-guide). A qualifying purchase can earn us a commission at no extra cost to you.
The kit is on the bench, and the carriage looks easier to remove than to bolt down in place. This is how to install a linear rail without dumping the balls and without running on shipping oil.
The kit is on the bench, and the carriage looks easier to remove than to bolt down in place. This is how to install a linear rail without dumping the balls and without running on shipping oil. Leave the block on the rail if you can, clean the film, put a service lubricant back, and do not power a screw into a hard stop. Choosing the family sits on the linear guide buying guide. Prices sit on the linear guide comparison. A qualifying purchase can earn us a commission at no extra cost to you.
Our top picks
| Badge | Product | Family | Blocks | Rail length | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  GooEquip GooEquip HGR20 700 mm rail set | Profile rail | 4 x HGH20CA | 700 mm | 7.4 | about £41.05 | View offer |
 CNCMANS CNCMANS SBR20 800 mm rail set | Supported shaft | 4 x SBR20UU | 800 mm | 9.2 | about £43.33 | View offer | |
| Best value |  CNCMANS CNCMANS SBR16 600 mm rail set | Supported shaft | 4 x SBR16UU | 600 mm | 7.9 | about £34.33 | View offer |
On this page
Keep the balls in the block
The first failure is pulling the carriage off because the mounting holes are hidden. Recirculating balls are held by the rail. Slide the block off the end and they can leave the circuit. On a profile or miniature block, the plastic keeper in the bag is the temporary rail. The DTGN MGN12 listing tells you to keep the block parallel and push it on gently with the keeper fitted. Do not tip the block, and do not flick it back on at an angle.
If the balls do come out, stop. Forcing them in damages the track. An SBR block fails differently: more than one CNCMANS SBR16 review found a ball race already split or empty. Spin each block before it goes on the shaft. An empty race is a return.
Bolt the rail to a straight datum
The rail copies the surface you screw it to. HIWIN's assembly guidance makes the same point for its own parts: parallelism depends on the mounting datum, and a guideway is not a straightener. Sight the support against a straight edge before the first screw goes in. If you are still choosing between a profile rail and a round shaft, that choice is on HGR20 or SBR20, not in the drill bit.
Tighten from the middle outwards, with the carriage able to pass the screw you just nipped. On a pair of rails, set one rail as the datum and bring the second to it. A carriage that binds in one place and floats in another is telling you the rails are not parallel. Roll the block the full length before you build the deck. If it tightens, slacken the screws and let the shaft sit.
Replace the rust oil
Shipping oil is a rust film. It is not the lubricant you run. HIWIN's manual says not to operate a guideway without initial lubrication, and to move the block until a film shows on the rail. The DTGN bullet says to wipe the rust-prevention oil and fit a linear-guide lubricant. iMetrx parts arrive oily. Free-fall down a vertical rail is gravity, not a smoothness test.
SBR blocks arrived dry or gritty until they were oiled, and one buyer added dry PTFE. A printer-maintenance note warns against PTFE, graphite, and molybdenum disulphide, and prefers an oil or a light EP00 or EP000 grease. This set was not a grease test. Use a lubricant sold for linear guides. Wood dust is separate. Extraction is on the linear rail for a CNC router page. The no-maintenance line on the CNCMANS bullets is the sentence to ignore.
Limits before you energise a screw
A hand sled can stop against a wooden block you chose. A ball screw cannot. The Zeberoxyz and FUYU stages include a NEMA 23 and still need a driver, a supply, and a way to stop. FUYU contents lines do not list limit switches. Do not invent a 230 V connection from a stepper voltage printed as 1.7 V.
Fit the switches, or a hard stop that cuts the drive, before the first powered move. Leave a margin so the nut and the carriage are not the end stop. Stop and get help when the next step is wiring a driver to UK mains, guarding an axis that can crush a hand, or placing a finished machine on the Great Britain market. If the rail is bent and the seller will not collect it, the Consumer Rights Act 2015 is the route for a faulty good, not a shim under one end.
Common questions
Do I take the carriage off the rail to fit it?
Only if you cannot reach the holes with the block parked at one end. If you slide it off, use the plastic keeper and keep the block parallel, which is the DTGN instruction for the MGN12. Catch any loose balls in a tray. A block that was forced on at an angle should come off the machine, not be run in.
What do I do with the shipping oil?
Wipe the heavy rust film if it is contaminated, then put a linear-guide lubricant back before the first working travel. iMetrx parts arrive oily, and SBR blocks in these reviews often arrive dry. Either way, the warehouse coating is not a service fill. Move the block until you can see a film on the rail.
Which grease is safe to name?
None by brand. This set was not a grease test. A light oil or an EP00 or EP000 grease without PTFE, graphite, or molybdenum disulphide is the practice note from printer maintenance, and it conflicts with one SBR buyer who added dry PTFE. Follow the lubricant sold for the carriage you have, and do not copy a single review as the specification.
Why does the carriage feel notchy?
A repeating notch is usually a ball damaged on refitting, dirt in the race, or a screw pulling the rail down. Dry SBR blocks feel gritty until they are cleaned and oiled. A carriage that only feels loose is not automatically healthy. Play and notch are different faults.
When do I fit limit switches?
Before the first powered move on a screw stage. They are not in the FUYU contents line, and reviewers of the 700 mm title say you add them. A hand-pushed sled can use a wooden stop. A ball nut should not be that stop.
When should I stop and get help?
When you are connecting a driver to 230 V mains, when a powered axis can crush a hand and you have no guard plan, or when you are supplying a machine on the Great Britain market. Fitting and greasing a component rail on a home bench is the job this page covers.
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)