Grease Nipples Compatible with Hiwin Guideways
These grease nipples fit specific Hiwin linear guideway block sizes and mounting positions. Selection depends on the block series, size, access angle, and thread installed in the end cap or side face. HIWIN is a trademark of HIWIN Technologies Corp. These grease nipples are aftermarket parts, not manufactured, sponsored, or endorsed by HIWIN. Hiwin part numbers are for cross-reference identification only.
Each nipple body is machined from free-cutting steel with a zinc finish for corrosion resistance in normal machine shop air. The thread forms match the fine metric or pipe thread cut into Hiwin block lubrication ports. Choosing the wrong thread can damage the block port or prevent the grease gun from sealing. The table below separates sizes because one series can use different threads at different rail sizes.
Block size drives the thread selection more than series name. For example, HG_15 uses M4 x 0.7P while HG_20 to HG_35 use M6 x 0.75P. Checking only the series name without the size leads to incorrect nipple orders. The full block designation, such as HG_20 or RG_45, should always be read before ordering.
The most common fitment trap is the M6 x 0.75P fine pitch. A standard M6 x 1.0 nipple will not fit these blocks. The fine pitch has a smaller thread helix angle and a different minor diameter. Attempting to force a standard M6 nipple damages the first threads and can block the grease path.
Threads and Dimensions by Size
| Thread and angle | Total length | Thread length | Hex | Block series | Hiwin part no. |
| M3 x 0.5P, 0 degree | 11 mm | 5 mm | 5 mm | MG_15, MGW_15, CG_20, WE_17 | 34310010 |
| M3 x 0.5P, 67.5 degree | 11 mm | 5 mm | 5 mm | MG_15, MGW_15 side access | – |
| M4 x 0.7P, 0 degree | 12.8 mm | 5 mm | 5 mm | HG_15, EG_15, QE_15, RG_15, RG_20, CRG_15, CRG_20 | 34310002 |
| M4 x 0.7P, 67.5 degree | 12.8 mm | 5 mm | 5 mm | HG_15, EG_15 side access | – |
| M4 x 0.7P, 90 degree | 12.8 mm | 5 mm | 5 mm | HG_15, EG_15 overhead clearance | – |
| M6 x 0.75P, 0 degree | 16.5 mm | 5.5 to 6.5 mm | 7 mm | HG_20-35, EG_20-35, QH_20-35, CG_25-35, WE_21-35, RG_25-35, QR_25-35 | 3431003 / 34310008 |
| M6 x 0.75P, 67.5 degree | 16.5 mm | 6.5 mm | 7 mm | HG_20-35, EG_20-35, QH_20-35, RG_25-35 side access | 34320001 / 3432000E |
| M6 x 0.75P, 90 degree | 16.5 mm | 6.5 mm | 7 mm | HG_20-35, EG_20-35 overhead clearance | – |
| 1/8PT, 0 degree | 15.2 mm | 6.3 mm | 8 mm | HG_45-65, QH_45, RG_45-65, QR_45, WE_50 | 34310008 |
| 1/8PT, 67.5 degree | 15.2 mm | 6.3 mm | 8 mm | HG_45-65, RG_45-65 side access | 34320003 |
| 1/8PT, 90 degree | 15.2 mm | 6.3 mm | 8 mm | HG_45-65 overhead clearance | – |
Straight bodies have a 0 degree shank-to-thread line. Angled bodies put the grease entry point at 67.5 or 90 degrees to the mounting face. Total length is measured from the sealing shoulder to the outer end of the nipple head. Hex sizes apply to the wrench flats used for installation and removal.
For more thread form detail, see the grease fitting types guide. A cross-reference of available fine metric nipples appears on the DIN-style grease nipples page.
Block Series Compatibility Map
| Series | Size | Front thread | Side or alternative |
| MG and MGW | 15 | M3 x 0.5P | none (sizes 2/3/5/7/9/12 use syringe or spray grease, no nipple) |
| CG | 20 | M3 x 0.5P | M6 x 0.75P on CG_25 to CG_45 |
| WE and OW | 17 | M3 x 0.5P | M4 or M6 x 0.75P on WE_21 to WE_35, 1/8PT on WE_50 |
| HG and QH | 15 | M4 x 0.7P | none |
| HG, QH, EG, QE | 20-35 | M6 x 0.75P | M6 x 0.75P side |
| HG, QH, RG, QR | 45-65 | 1/8PT | 1/8PT side |
| RG and CRG | 15-20 | M4 x 0.7P | none |
| RG, CRG, QR | 25-35 | M6 x 0.75P | M6 x 0.75P side |
The side or alternative column shows where a second lubrication port exists. Some blocks accept a straight nipple in front and an angled nipple on the side. The side port thread usually matches the front thread for the same block size. Always verify the actual port thread before installation.
The smallest MG and MGW sizes do not use threaded grease nipples. Those blocks use syringe or spray grease applied through open ports. Fitting a nipple to those sizes can crack the end cap or block the recirculation channel.
Body Angles and Access
0 degree straight nipples mount in front end caps where the grease gun approaches along the rail axis. These are easiest to reach on machines with open rail ends. The straight body also has the lowest installed height.
67.5 degree angled nipples are for side access where 45 degrees is too shallow and 90 degrees is too tight. They are common behind machine guards and where way covers limit the gun swing. The body angle places the gun coupling slightly upward and outward.
90 degree right angle nipples allow top-down or perpendicular access. They work behind way covers where only vertical clearance exists. The gun locks on from above rather than along the rail.
For installations with tight guards, compare the total length plus grease coupler height before choosing a body angle. A straight nipple can block a cover that an angled nipple clears. Machine guard clearance determines workable access.
Grease Gun Adapters
| Nipple | Hiwin part no. | Adapter |
| M3 x 0.5P | 34310010 | A2 or A31 from the Hiwin GN-80M set |
| M4 x 0.7P | 34310002 | A2 or A31 |
| M6 x 0.75P straight | 3431003 / 34310008 | A1 or A21 |
| M6 x 0.75P angled | 34320001 / 3432000E | A1 or A21 |
| 1/8PT | 34310008 / 34320003 | A1 or A21 |
The adapter table maps common Hiwin nipple part numbers to grease gun couplers from the GN-80M set. Coupler selection uses the nipple head shape, not the thread size. A hard seal at the coupler prevents grease bypass during the stroke.
For gun and line planning, see the grease line tubing fittings selection guide. Pump selection options appear on the grease pump page.
Initial Lubrication and Care
Linear guide blocks must never run without initial lubrication. Factory rust-preventive oil is not a running lubricant. Grease must be pumped into the block until clean grease exits the seals before first motion.
Regreasing intervals follow the machine manual and duty cycle. Short stroke, high speed, contamination, and heat reduce the interval. A fixed number of hours does not apply across all machines.
Use a grease compatible with the existing charge in the block. Mixing incompatible thickeners can harden the grease and block the return tubes. When changing grease type, purge the old charge completely.
Inspect nipple threads during each service. Bent shanks or rounded hex flats make future removal difficult. Replace damaged nipples promptly to avoid introducing debris into the port.
For specific M6 fine pitch nipples, see the M6 grease nipple page. For inch thread alternatives, see the 1/4 UNF grease nipple page. Contact the team for cross-reference help through our quote page.
Frequently Asked Questions
Will these nipples fit my Hiwin block?
Fit depends on the complete block designation, including series and size. Check the thread form and body angle against the port before ordering.
Are these original Hiwin parts?
These are aftermarket grease nipples, not manufactured or endorsed by Hiwin. Hiwin part numbers are used only for cross-reference identification.
What thread does an HG15 block use?
The HG_15 block uses M4 x 0.7P grease nipples. Larger HG blocks from HG_20 to HG_35 use M6 x 0.75P instead.
Why do larger blocks use 1/8PT instead of metric?
Larger Hiwin series such as HG_45-65 use 1/8PT for stronger port walls. The pipe thread handles higher grease flow without splitting small metric threads.
What is the 67.5 degree body for?
The 67.5 degree body fits side access where 45 degrees is too shallow and 90 degrees is too tight. Machine guards often force this angle.
Do new blocks need initial lubrication?
New blocks ship with rust-preventive oil that is not a running lubricant. Grease must be pumped until clean grease exits the seals before operation.
Which grease gun adapter fits?
Adapters A1 and A21 fit M6 fine and 1/8PT nipples in most cases. Adapters A2 and A31 fit the smaller M3 and M4 nipples.
Can I use a standard M6 x 1.0 nipple instead?
No, Hiwin blocks using M6 fine pitch require M6 x 0.75P exclusively. A standard M6 x 1.0 nipple will cross-thread and damage the port.
How often should guideways be regreased?
Regreasing intervals follow the machine manual and duty cycle, not a fixed number. Short strokes and contamination reduce the safe interval.
Who builds these nipples, and how do I get a quotation?
IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, builds and supports every unit. Email inquiry@isohitech.com for specifications and a quotation.
Ask for a cross-reference check and a written quote. Contact the team.
