Linear rail for a CNC router
Updated: October 2026
You are building a gantry or a slab sled, and the rail in the basket is the one a 3D printer used. A linear rail for a CNC router has to take a side load from the cutter, and the dust is a separate problem the carriage will not solve. The [linear guide comparison](/hub/workshop/linear-guide) lists the kits and the amazon.co.uk prices from 19 October 2026. A qualifying purchase can earn us a commission at no extra cost to you.
You are building a gantry or a slab sled, and the rail in the basket is the one a 3D printer used.
You are building a gantry or a slab sled, and the rail in the basket is the one a 3D printer used. A linear rail for a CNC router has to take a side load from the cutter, and the dust is a separate problem the carriage will not solve. The linear guide comparison lists the kits and the amazon.co.uk prices from 19 October 2026. A qualifying purchase can earn us a commission at no extra cost to you.
Our top picks
| Badge | Product | Family | Rail length | Blocks | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  GooEquip GooEquip HGR20 700 mm rail set | Profile rail | 700 mm | 4 x HGH20CA | 7.4 | about £41.05 | View offer |
 CNCMANS CNCMANS SBR20 800 mm rail set | Supported shaft | 800 mm | 4 x SBR20UU | 9.2 | about £43.33 | View offer | |
| Best value |  CNCMANS CNCMANS SBR16 600 mm rail set | Supported shaft | 600 mm | 4 x SBR16UU | 7.9 | about £34.33 | View offer |
On this page
A router is not a 3D printer
An MGN12 rail is a miniature profile. In this set the DTGN pair is two 200 mm rails and two MGN12H blocks at £26.99. Printer rails are short, the moving mass is a head, and the load is mostly along the carriage. A router pushes sideways, at the end of a gantry or at the edge of a sled. Copying a 200 mm miniature pair onto that job runs out of travel as soon as you subtract the blocks.
Hobby builds often treat HGR15 as a floor and HGR20 as the common size once the cutter and the span grow. The amazon.co.uk reviews in this comparison show SBR kits bought for sleds, not for mills. The mechanism, profile against round shaft, is the whole argument on HGR20 or SBR20.
Sled on a supported shaft, gantry on a profile rail
A slab sled wants two supported shafts, a deck, and a router that slides. The CNCMANS SBR16 set is two 600 mm shafts and four blocks at £34.33, with 4.1 from 36 reviews that are mostly that job. The SBR20 set is two 800 mm shafts and four blocks at £43.33, with 4.7 from 40 reviews. SBR16 reviews include ball races that broke or were missing. SBR20 blocks arrive gritty until they are oiled. Sight the shaft before you build the deck. A slab sled can live with SBR. A gantry should not inherit a twisted shaft.
A router gantry wants a profile pair so the carriage cannot rotate around the rail. The GooEquip HGR20 set is two 700 mm rails and four HGH20CA blocks at £41.05, and the only review text is Thanks. Choose HGR20 as the geometry if you will check the steel. Do not treat those stars as a straightness test. Separating a stage from a bare rail is the linear guide buying guide.
Make the rail longer than the cut
The length in the title is the steel, not the travel. Subtract the carriage and a margin at each end so the block never becomes the bumper. A 600 mm SBR16 does not give you 600 mm of sled movement. A blog's extra 200 to 300 mm is a rule of thumb, not a standard. Measure your own carriage.
Run a pair, not a single shaft, under a router. One SBR rod lets the sled rock. On a gantry, set one profile rail as the datum and align the second to it. The rail will not straighten a twisted beam. If the first powered move is still ahead of you, limit switches and grease are the procedure on how to install a linear rail.
The rail does not collect the dust
A smooth carriage does not reduce wood dust. HSE treats hardwood and softwood dust as a health hazard, with nasal cancer among the hardwood risks, and points the workplace limits to EH40. At work, extract at the tool. HSE says to enclose the cut or use on-tool extraction, and to clean up with a Class M or Class H vacuum rather than a sweep or compressed air. PUWER 1998 applies to that work equipment, not to a private hobby bench, and the dust is still a hazard at home.
At home you still extract, and you still do not blow dust off the rails into the room. Seals on a profile carriage are not an extractor. Wiring the spindle and the drivers to 230 V, if you are not already competent to do it, is the point to stop and get help.
Common questions
Is MGN12 enough for a wood router?
No, not as the default. The DTGN pair in this set is two 200 mm miniature rails at £26.99, a printer-scale part. Travel collapses once the blocks are subtracted, and a cutter's side load is not a print head. Use it for a light head on a short axis, not for a gantry or a slab sled.
HGR15 or HGR20 on a gantry?
HGR15 is the smaller profile and a common floor when the frame flexes first. HGR20 is the usual step up for a heavier cutter and a longer span. Here the HGR15 pair is £48.05 with two reviews, and the cheapest HGR20 pair is £41.05 with no descriptive review text. Choose the size for the load, then check the rail, because the stars do not certify either length.
Can I flatten slabs on SBR16?
Yes, that is what many of the 36 reviews describe, on the £34.33 pair of 600 mm shafts. Inspect the ball races first, because broken or missing races are in those reviews, and remember that 600 mm is the rail, not the full travel of the sled. Step up to the SBR20 pair at £43.33 if you want the larger shaft and the stronger star line.
Do I still need extraction if the rails are smooth?
Yes. HSE treats wood dust as a health hazard whether or not the carriage feels smooth. At work, use on-tool extraction or an enclosure, and a Class M or Class H vacuum for clean-up, not a brush and not an airline. At home, extract as well. Seals on a profile rail are not a dust system.
Does PUWER apply in my garage?
PUWER applies to work equipment, not to a private hobby bench. You still do not blow dust through the shed, and you still stop if you are wiring 230 V without the competence. Selling a finished machine on the Great Britain market is a different set of duties under the machinery regulations.
Will a twisted SBR ruin a sled?
It will put a rock or a tight spot into the travel. A slab sled may tolerate a milder bow if the cut is not a precision joint. Roll the block the full length before you build the deck, and return a rail that is clearly bent rather than shimming one bolt.
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)