Linear rail can usually be cut to many custom lengths, but not every possible length is equally practical or desirable. The finished length must work with the rail’s mounting-hole pitch, the distances from the rail ends to the first and last mounting holes, the required carriage travel, the carriage footprint, and the manufacturer’s maximum available one-piece rail length.
Manufacturers such as THK publish standard rail lengths, mounting-hole pitch, recommended end dimensions, and maximum rail lengths for specific guide families. THK also recommends that special rail lengths maintain end dimensions close to the published values because excessively large end sections can become less stable and negatively affect accuracy.
The basic rule is:
Linear rail can be custom cut, but the best finished length is determined by the machine geometry and mounting-hole pattern—not by overall length alone.
Yes, Linear Rail Can Be Custom Cut
Profile rail is routinely supplied in custom lengths. Linear Automation USA, for example, provides cut-to-size linear rail processed locally for industrial applications.
That means you are not necessarily limited to the standard lengths shown in a manufacturer's catalog.
If a standard rail is 2,000 mm long but your machine needs a shorter rail, it may be possible to cut the rail to the required dimension.
However, there is an important distinction between:
“Can this rail physically be cut here?”
and:
“Is this the correct place to cut this rail?”
The second question is much more important.
Mounting-Hole Pitch Is the Main Constraint
Profile rail normally contains mounting holes positioned at a repeating pitch.
A simplified relationship is:
L = G1 + nP + G2
where:
L = finished rail length
G1 = distance from one rail end to the center of the first mounting hole
G2 = distance from the final mounting-hole center to the opposite rail end
P = mounting-hole pitch
n = number of pitch intervals between the first and last mounting holes
This relationship explains why two rails with slightly different finished lengths can have very different end geometry.
Suppose the mounting holes are spaced every 60 mm. Cutting 20 mm from the end changes the distance between the new rail end and the nearest mounting hole, but it does not move the mounting holes themselves.
The result may be perfectly acceptable, or it may create an undesirable end dimension.
The Mounting Holes Do Not Move When You Cut the Rail
This sounds obvious, but it is one of the most important concepts in custom rail cutting.
Suppose you have a rail with mounting holes positioned at a regular pitch.
If you remove:
37 mm
from one end, the rail becomes 37 mm shorter.
The mounting-hole pattern remains exactly where it was.
You have simply changed the distance between the new rail end and the nearest mounting hole.
That resulting dimension needs to be checked.
This is why you should calculate the hole pattern before selecting the exact finished rail length.
What Are G1 and G2?
For custom-cut rail, it is useful to think of the two end dimensions as:
G1 = first-hole end distance
G2 = last-hole end distance
Terminology varies by manufacturer. THK, for example, commonly uses G and g in its rail-length tables.
The concept is the same: there is a distance between each end of the rail and the nearest mounting-hole center.
These dimensions matter because the rail needs adequate mounting support near its ends.
Do G1 and G2 Have to Be Equal?
No.
A rail does not universally require:
G1 = G2
There are applications where unequal end dimensions are completely appropriate.
For example, an existing machine may require a replacement rail with:
20 mm at one end
35 mm at the other
because those dimensions match the existing machine base.
For a new machine, however, a balanced mounting-hole arrangement may be desirable when the geometry allows it.
The important point is that G1 and G2 should be intentional rather than accidental.
Why Excessively Large End Dimensions Can Be a Problem
The section of rail extending beyond the final mounting hole is not supported by another mounting fastener.
If that section becomes excessively long, it can become less stable.
THK specifically states in its current LM Guide documentation that for special rail lengths, values corresponding to the published G and g dimensions are recommended. THK further warns that as those dimensions increase, the unsupported portion becomes less stable and accuracy performance can be adversely affected.
That means you should not choose a custom length that leaves a very long rail section beyond the last mounting hole simply because the overall dimension fits the machine.
Instead, evaluate whether a nearby finished length would create better mounting geometry.
Example: Why the Exact Cut Length Matters
Suppose your machine needs a rail approximately:
1,500 mm long
and the rail has:
60 mm mounting-hole pitch
You might initially assume:
1,500 mm = cut length
But before making the cut, determine where the mounting holes will fall.
Perhaps 1,500 mm produces an awkward end dimension.
A nearby finished length such as:
1,480 mm
or:
1,520 mm
might create a much better relationship between the rail ends and mounting holes.
Whether either alternative is acceptable depends on the machine's required stroke and available space.
The correct sequence is therefore:
required stroke → required rail length → mounting-hole calculation → final cut length
rather than:
desired overall length → cut immediately
Required Stroke Also Limits How Short the Rail Can Be
The rail must be long enough for the carriage or carriage group to complete the required travel.
This is where another common mistake occurs:
required stroke is not the same thing as required rail length.
Suppose a machine requires:
1,000 mm travel
That does not normally mean you need:
1,000 mm rail
because the carriage occupies physical space on the rail.
A useful preliminary relationship is:
Rail Length ≈ Required Stroke + Carriage-Group Footprint + End Allowance
Example With One Carriage
Suppose:
required stroke = 1,000 mm
carriage length = 100 mm
desired end allowance = 40 mm at each end
The preliminary rail length would be:
1,000 + 100 + 80 = 1,180 mm
You would then check 1,180 mm against the rail's mounting-hole pitch and end dimensions.
The final rail might remain 1,180 mm, or a nearby dimension might produce better mounting geometry.
Two Blocks Require More Rail Length
Many industrial profile rail systems use:
two rails
two blocks per rail
If two blocks are used on each rail, the complete carriage group occupies more rail length than one carriage alone.
Suppose:
block center-to-center spacing = 300 mm
individual block length = 100 mm
The approximate carriage-group footprint is:
300 + 100 = 400 mm
If the required stroke is:
1,500 mm
and total end allowance is:
100 mm
the preliminary rail requirement becomes:
1,500 + 400 + 100 = 2,000 mm
Again, the mounting-hole pattern should then be checked before the finished rail length is finalized.
Block Spacing Should Not Be Sacrificed Just to Shorten the Rail
It can be tempting to move the blocks closer together so that a shorter rail will work.
That may be a poor tradeoff.
Block spacing contributes to the system's ability to resist:
pitch
yaw
moment-induced carriage loading
Reducing block spacing may increase the reaction forces required to resist the same moment.
So do not shorten the rail by compromising necessary carriage spacing unless the resulting guide loads and rigidity have been recalculated.
Is There a Minimum Linear Rail Length?
There is no single universal minimum length for all profile rails.
The practical minimum depends on:
manufacturer
guide family
nominal size
carriage length
number of carriages
required travel
mounting-hole pitch
end dimensions
mounting support
A very short rail still needs enough mounting geometry to support the guide appropriately.
If an unusually short rail section is required, verify it against the dimensional information for the exact rail family.
Is There a Maximum Linear Rail Length?
Yes.
Every guide family has practical manufacturing limits.
THK, for example, publishes maximum rail lengths for its individual LM Guide families. These values vary by model and size, and THK notes that maximum available length can also vary with accuracy grade.
For example, THK's current SHW documentation shows maximum lengths ranging from 1,230 mm for one smaller model to 3,000 mm for several larger sizes.
Other guide families have different limits.
Therefore:
Do not assume that every size-15, size-25, or size-35 rail has the same maximum available length.
Always check the exact manufacturer and series.
What If the Rail You Need Is Longer Than the Maximum?
If the required rail length exceeds the manufacturer's one-piece limit, the application may require:
jointed rails
a different guide family
a revised machine design
manufacturer consultation
THK specifically states for multiple current guide families that jointed rails may be used when the required length exceeds the maximum one-piece rail length.
This makes extremely long travel possible without requiring one continuous rail.
Jointed Rail Is Different From Two Cut Rails
Do not assume you can take two ordinary pieces of profile rail, cut the ends, butt them together, and create a proper precision joint.
A carriage must transition smoothly from one rail section to the next.
A properly engineered joint may require:
specially prepared rail ends
matched sections
controlled joint alignment
correct mounting-hole geometry
installation procedures specific to the guide
If the application requires a rail longer than the manufacturer's maximum one-piece length, ask for a manufacturer-supported jointed-rail solution.
Can You Cut a Standard Rail Shorter?
Usually, yes, provided the selected rail can be appropriately processed and the resulting geometry is acceptable.
For example, suppose you have:
2,000 mm stock rail
but the machine requires approximately:
1,740 mm
The rail may be cut shorter.
Before cutting, however, check:
required usable stroke
carriage-group footprint
mounting-hole pitch
G1
G2
whether the cut intersects a mounting feature
whether the finished rail has adequate mounting support
That is much better than simply measuring 1,740 mm and making the cut.
Can You Order Nonstandard Rail Lengths?
Yes, depending on the manufacturer, guide family, and supplier.
THK specifically discusses special rail lengths in its current technical documentation.
The important point is that a special length should still be selected with the manufacturer's:
mounting-hole pitch
end dimensions
maximum length
accuracy requirements
in mind.
Custom length does not mean dimensional rules disappear.
Can Linear Rail Be Cut to Any Millimeter?
Physically, a supplier with appropriate cutting equipment may be able to create many different overall lengths.
But that does not mean every millimeter increment produces equally good mounting geometry.
For example, imagine that:
1,423 mm
fits your machine envelope.
The rail might physically be cut to 1,423 mm.
But if:
1,420 mm
produces much better end dimensions while still satisfying the required stroke, 1,420 mm may be the better engineering choice.
This is why Linear Automation USA's rail-cut planning considers more than overall length.
Can Linear Rail Be Cut to Any Inch Dimension?
The same principle applies to inch dimensions.
A customer might request:
72 inches
because the machine was designed in imperial units.
But the rail itself may use:
metric mounting-hole pitch
metric end dimensions
The requested inch dimension should therefore be converted and checked against the actual rail geometry before cutting.
Do not assume that a convenient imperial dimension automatically produces a convenient mounting-hole arrangement.
Does Cutting a Rail Change Its Load Rating?
Properly shortening the rail does not inherently change the published basic load rating of the carriage.
The carriage still has its manufacturer-defined:
basic dynamic load rating
basic static load rating
However, shortening the system can indirectly affect performance if it changes:
block spacing
mounting support
available stroke
carriage arrangement
For example, if shortening the rail forces two blocks closer together, the system's resistance to moment loading can change substantially.
So while the carriage's catalog rating may remain unchanged, the machine's guide geometry may not.
Does Cutting Linear Rail Affect Accuracy?
A correctly executed end cut should not inherently change the accuracy of the remaining raceway.
But poor cutting can create problems.
Potential issues include:
excessive heat
burrs
raceway damage
contamination
poor end support
The finished rail must also be mounted correctly.
The rail's accuracy specification cannot compensate for an inaccurate machine base or poor installation.
Accuracy Grade Can Affect Maximum Available Length
This becomes particularly important when ordering long precision rails.
THK notes that maximum rail length can vary with accuracy grade.
That means a rail may be available at a particular length in one accuracy grade but require manufacturer consultation in another.
For long, high-precision axes, confirm:
guide family
accuracy grade
required rail length
before finalizing the machine design.
Can You Cut Through a Mounting Hole?
Avoid creating an accidental partial mounting hole at the rail end.
A cut that intersects a counterbored mounting hole can leave an undesirable feature at the end of the rail.
Instead, calculate the cut location from the existing mounting-hole pattern.
Often, changing the overall rail length slightly can avoid the problem completely.
Can You Add New Mounting Holes?
Do not treat profile rail like ordinary mild-steel bar stock.
Linear guide rail incorporates hardened precision raceways, and additional machining may require specialized equipment and procedures.
If a machine requires an unusual mounting-hole arrangement, discuss the requirement with the supplier before attempting to drill or machine the rail.
Possible alternatives may include:
manufacturer-supported special machining
modifying the machine mounting plate
an engineered adapter arrangement
depending on the application.
Replacement Rails Require Extra Attention
Suppose you are replacing an obsolete linear rail.
Matching only:
overall length
is not enough.
Measure or identify:
rail width
rail height
mounting-hole pitch
mounting-hole diameter
counterbore dimensions
G1
G2
carriage mounting dimensions
manufacturer and series
Nominal rail size alone does not establish interchangeability.
A size-25 rail from one family should not automatically be assumed to replace another size-25 rail.
Custom-Cut Rail for Two-Rail Systems
When two parallel rails are being cut for the same axis, the finished geometry should be coordinated.
Typically, you will want to verify:
matching overall length
appropriate mounting-hole patterns
intended rail orientation
corresponding end dimensions
This is especially important if the machine mounting plate has already been drilled.
A mismatch that seems minor at the cutting stage can become a major installation problem.
Long-Stroke Applications Need Special Planning
For long-stroke applications, the question changes from:
“How short can we cut this rail?”
to:
“Can this entire rail be supplied in one piece?”
A long axis may encounter:
manufacturer maximum rail length
accuracy limitations
shipping limitations
installation challenges
If the required length exceeds the one-piece capability, jointed rail may be required.
Plan this before building the machine base.
Why Ordering Cut-to-Size Rail Can Be Better
If the finished rail dimensions are already known, having the supplier process the rail can eliminate several field-cutting risks.
These include:
incorrect finished length
poor mounting-hole end dimensions
damage to hardened raceways
cutting debris
inadequate cutting equipment
additional shop labor
Linear Automation USA currently provides cut-to-size linear rail processed at its local warehouse for its supported product lines.
For many industrial applications, the simplest approach is to provide:
manufacturer
guide series
rail size
quantity
desired overall length
required stroke
desired end dimension if critical
and have the rail supplied ready for installation.
A Practical Custom Rail Length Selection Process
Step 1: Determine Required Stroke
How far must the carriage actually move?
Step 2: Determine the Carriage-Group Footprint
Account for:
block length
number of blocks
block spacing
Step 3: Add Appropriate End Allowance
Ensure the carriage remains fully supported throughout the required travel.
Step 4: Calculate Preliminary Rail Length
Use:
Rail Length ≈ Stroke + Carriage-Group Footprint + End Allowance
Step 5: Identify the Exact Rail
Determine:
manufacturer
family
nominal size
Step 6: Find the Mounting-Hole Pitch
Obtain P from the manufacturer's dimensional information.
Step 7: Calculate the End Dimensions
Use:
L = G1 + nP + G2
Step 8: Adjust the Finished Length if Necessary
A small change in overall length may produce better:
G1
G2
mounting support
Step 9: Check Maximum Rail Length
Verify that the requested length is available for the selected:
series
size
accuracy grade
Step 10: Specify the Finished Rail
Only after those checks should the rail be cut or ordered.
Common Custom Rail Length Mistakes
Assuming Any Physical Cut Length Is Equally Good
The mounting-hole pattern still matters.
Cutting Before Checking Hole Pitch
This can create poor end geometry.
Making Rail Length Equal to Stroke
The carriage footprint also requires rail length.
Ignoring Block Spacing
Shortening the rail can force blocks too close together.
Assuming G1 and G2 Must Always Be Equal
They do not, although their values should be deliberate.
Leaving Excessive Rail Beyond the Last Mounting Hole
Manufacturer guidance warns that excessive end dimensions can reduce stability and affect accuracy.
Assuming Every Rail Has the Same Maximum Length
Maximum length varies by family, size, and sometimes accuracy grade.
Butting Two Ordinary Rails Together
Long jointed systems require appropriate rail-joint preparation.
Assuming Nominal Size Establishes Interchangeability
A size-25 rail is not automatically interchangeable with every other size-25 rail.
Cutting First and Designing the Machine Around the Result
The machine requirement should determine the rail geometry—not the other way around.
Linear Automation USA's Perspective
At Linear Automation USA, we believe the answer to “Can linear rail be cut to any length?” is best expressed this way:
It can often be cut to the length you need, but we should first determine whether that is the length you actually want.
When planning custom-cut rail, we look at:
required stroke
carriage length
number of blocks
block spacing
total rail length
mounting-hole pitch
first-hole end dimension
last-hole end dimension
manufacturer maximum length
This is particularly important because Linear Automation USA provides custom-cut rail from its local warehouse.
The goal is not simply to cut steel to a number on a purchase order.
The goal is to provide a rail length that makes sense as part of the complete linear-motion system.
Linear Automation USA supports profile rail products from SBC Linear, WON Linear, and other supported linear-motion product lines, along with custom rail processing and replacement/interchange assistance.
Our rule is:
Choose the finished rail length from stroke and carriage geometry first, then verify it against the rail's mounting-hole pitch, end dimensions, and manufacturer length limits.
Frequently Asked Questions
Can Linear Rail Be Cut to Any Length?
Linear rail can often be supplied in many custom lengths, but not every arbitrary length produces desirable mounting-hole and end geometry. Check the exact rail's hole pitch and recommended end dimensions first.
Can I Cut a Linear Rail Shorter?
Yes, provided the cutting process is appropriate and the resulting rail still provides the required travel, mounting support, and acceptable end dimensions.
Can I Order Custom-Length Linear Rail?
Yes. Custom-length rail is commonly available. Linear Automation USA currently provides cut-to-size rail processing for supported product lines.
Does the Rail Length Have to Match the Mounting-Hole Pitch?
Overall rail length does not necessarily need to be an exact multiple of the hole pitch because there are end dimensions on both sides. The hole pitch and end dimensions together determine the finished geometry.
Do the End Dimensions Have to Be Equal?
No. G1 and G2 can differ when required by the machine, although both should be intentionally specified and appropriate for the rail.
Can I Cut a Rail Between Two Mounting Holes?
Potentially, provided the resulting end dimension is appropriate and the cut does not damage the functional rail surfaces.
Can I Cut Through a Mounting Hole?
Avoid leaving an accidental partial mounting hole. Plan the cut location around the existing hole pattern.
Does Cutting Linear Rail Change Its Load Capacity?
Shortening the rail does not inherently change the carriage's published basic load rating, but changes to block spacing or mounting support can change the performance of the complete system.
How Long Should My Linear Rail Be?
A useful preliminary relationship is:
Rail Length ≈ Required Stroke + Carriage-Group Footprint + End Allowance
Then adjust or verify the length using the actual mounting-hole pitch and end dimensions.
Is There a Maximum Linear Rail Length?
Yes. Maximum one-piece rail length depends on manufacturer, guide family, size, and sometimes accuracy grade.
What If I Need a Rail Longer Than the Manufacturer's Maximum?
A manufacturer-supported jointed-rail arrangement or another guide family may be required.
Is It Better to Order Rail Already Cut?
Often, yes. Supplier cutting can simplify installation and reduce the risk of incorrect dimensions, poor end geometry, contamination, or raceway damage.
Need a Custom Linear Rail Length?
Before requesting custom-cut rail, provide:
manufacturer or preferred brand
rail series
nominal size
quantity
required stroke
desired finished rail length
number of carriages
block spacing
mounting-hole pitch if known
required G1/G2 dimensions if critical
For a replacement application, photographs and measurements of the existing rail can also help.
Contact Linear Automation USA for custom-cut profile rail, replacement assistance, or help determining the appropriate finished rail length.
Recommended Reading
How to Cut Linear Guide Rail to Length
Learn how to plan the cut, protect the hardened raceways, account for mounting-hole geometry, deburr the rail, and prepare it for installation.
Publishing note: Replace this temporary homepage link with the final published article URL.
How to Select Linear Rail Length
Calculate required rail length from usable stroke, carriage footprint, block spacing, and end allowance.
Publishing note: Replace this temporary homepage link with the final published article URL.
Linear Guide Selection for Long-Stroke Applications
Learn how maximum one-piece rail length, jointed rails, mounting geometry, alignment, and accumulated travel affect long-axis design.
Publishing note: Replace this temporary homepage link with the final published article URL.
How Far Apart Should Linear Guide Blocks Be?
Understand why shortening a rail should not come at the expense of block spacing needed for pitch and yaw stability.
Publishing note: Replace this temporary homepage link with the final published article URL.
Linear Guide Selection Checklist: What to Know Before Requesting a Quote
Gather the rail dimensions, stroke, carriage arrangement, loading, and application information needed before ordering custom rail.
Publishing note: Replace this temporary homepage link with the final published article URL.
Sources & Technical References
THK — LM Guide General Catalog
THK publishes standard lengths, mounting-hole pitches, recommended end dimensions, and maximum lengths for individual LM Guide families. THK also explains that special rail lengths should maintain appropriate end dimensions and that excessive end dimensions can reduce stability and negatively affect accuracy.
THK — SHW Standard and Maximum Rail Lengths
THK's SHW documentation provides a useful real-world example of why there is no universal maximum rail length. Depending on the SHW size, the published maximum ranges from 1,230 mm to 3,000 mm, and THK notes that maximum length can vary with accuracy grade.
THK — NR-X/NRS-X Super-Heavy Load LM Guide
This manufacturer documentation shows the same relationship between standard rail length, mounting-hole pitch, G/g end dimensions, and maximum one-piece rail length for a different guide family. It also specifies jointed rails when required lengths exceed applicable maximums.
THK — SHS-N LM Guide
THK's current SHS-N documentation again recommends maintaining appropriate G/g dimensions for special rail lengths and warns that excessively large end portions can become less stable and affect accuracy.
Linear Automation USA
Linear Automation USA supplies industrial profile rail guides and currently offers custom-cut rail processed in its local warehouse for supported product lines.