Size a reversible edge from the mouldboard geometry and the existing mounting pattern, not from the nominal plow width. Measure the bolt circle, the centre-to-centre hole spacing, the edge height and thickness at the wear line, and the bolt diameter and grade. Then match those dimensions against the published specification for the cutting edge, confirming hole count and countersink orientation before ordering.
Start from the mounting pattern, not the plow width
The mouldboard dictates what an edge can be. Two plows sold as the same nominal width can carry different bolt patterns, different edge heights, and different bolt sizes, so the width figure on the machine is only a starting reference. The pattern on the existing edge is the constraint that matters.
Record the following before opening any catalogue:
- Number of bolt holes per edge and their arrangement (single row, staggered, or grouped).
- Centre-to-centre hole spacing along the edge, measured between adjacent holes and across the full pattern.
- Hole diameter and the bolt diameter currently fitted, including whether the holes are countersunk.
- Overall edge height from the top mounting face to the ground contact line.
- Edge thickness at the mounting face and at the worn end.
- Bolt grade and torque value currently used, taken from the plow manual rather than from habit.
Where the existing edge is worn unevenly, measure the pattern on the mouldboard itself. A distorted edge can shift hole positions enough to mislead a measurement taken from the old part.
Reading height and thickness against wear allowance
Reversible edges are consumables, and their service life depends on how much material sits below the mounting face. A taller edge gives more wear allowance but adds weight and changes the approach angle slightly; a shorter edge reduces both. The correct height is the one the mouldboard was designed around, not the tallest edge that will physically bolt on.
Thickness behaves the same way. A thicker section resists deflection and extends the interval between changes, but it also changes the clearance between the edge and the shoe or skid, and it can interfere with trip-spring travel on some mouldboards. Where the plow uses a trip mechanism, confirm that the chosen thickness does not reduce trip clearance below the manufacturer’s figure.
Carbide-edged variants carry a hard facing or insert at the wear zone. Because the carbide section is not intended to be machined or re-drilled in the field, the hole pattern must be correct as supplied. Dimensions and hole spacing follow the product page specification, so cross-check the drawing against the measured pattern before committing to an order.
Reversible geometry: what “reversible” actually requires
A reversible edge only delivers its second life if the hole pattern is symmetric about the horizontal centreline and the wear profile is compatible with flipping. An edge with an asymmetric hole layout, or one with a relieved section on one face only, may bolt on upside down but will not seat correctly.
Check three things before specifying a reversible part:
- Whether the hole pattern mirrors about the centreline, allowing the edge to be rotated 180 degrees and still align with every hole.
- Whether both long faces are flat and parallel at the mounting zone, so the clamping load is distributed evenly after flipping.
- Whether the wear indicator, chamfer, or carbide placement is positioned so that the second orientation still presents a functional scraping edge.
Rules for when flipping is acceptable and when it is not are covered in the discussion on whether a cutting edge can be flipped. In practice, the decision depends on remaining section thickness and on whether the bolt holes have elongated.
Bolt sizing, torque, and hole condition
Bolt selection is part of edge sizing, not a separate purchasing decision. The hole diameter in the edge sets the maximum bolt size, and the bolt grade sets the torque that the mouldboard and edge can accept. Plow bolts with a square or countersunk shoulder are common because they resist rotation under load and sit flush against the mouldboard face.
| Parameter | What to record | Why it matters |
|---|---|---|
| Hole count and spacing | Number of holes, centre-to-centre distances | Determines whether the edge will bolt to the mouldboard at all |
| Hole diameter | Measured bore, countersink present or absent | Sets bolt size and head seating |
| Edge height | Top face to ground contact line | Controls wear allowance and approach angle |
| Edge thickness | At mounting face; at worn end | Affects clamping, clearance, and trip travel |
| Bolt grade and torque | From plow manual, not from the old bolt head | Prevents loosening and hole elongation |
| Carbide section | Position and extent of hard facing | Confirms the part cannot be re-drilled in the field |
Torque values vary by bolt diameter and grade and should be taken from the plow manufacturer’s manual. Over-torquing distorts the edge and can crack carbide; under-torquing allows movement that enlarges the holes. If bolts are failing repeatedly, the pattern of failure is worth documenting — see the notes on why plow bolts break and how to record it.
Wear life, cost, and what depends on the site
Expected life for any cutting edge is a range, not a figure, and it depends on surface type, down-pressure, operator technique, and how much of the season is spent on abrasive material. Carbide-edged parts generally last longer than plain steel in abrasive conditions, but the multiplier depends on the same variables and cannot be reduced to a single number.
Cost per season should be compared on the same basis: purchase price divided by the expected number of changes, allowing for the second life of a reversible edge. A cheaper edge that requires more frequent changes and more labour may cost more per kilometre plowed, particularly where downtime is expensive. Where one end of an edge wears faster than the other, that pattern usually points to mounting or alignment issues rather than to the edge itself; the checks in one end of the edge wearing faster are a reasonable starting point.
For carbide-specific dimensions, hole patterns, and thickness options, refer to the carbide snow plow blade specification page and match it against the measurements taken from the mouldboard.
Quick summary
Size a reversible edge from the mouldboard’s bolt pattern, edge height, thickness, and bolt specification, then confirm the reversible geometry mirrors correctly about the centreline. Life and cost are ranges that depend on surface, down-pressure, and operating practice, so compare options on cost per season rather than purchase price alone.
Sources checked on 2026-11-08: SENTHAI Tools product specification page for carbide snow plow blades; plow manufacturer mounting and torque guidance; field measurement practice for bolt patterns and wear profiles.
Three more perspectives
Workshop: The bench check is a straightedge across the mounting face and a tape across the hole pattern. If the old edge is bowed or the holes are elongated, measure the mouldboard instead, and keep a sketch of the pattern on file so the next order does not depend on a worn part.
Purchasing: Specify by hole count, spacing, height, thickness, and bolt grade rather than by plow model name. Model names change and overlap between years, and a part ordered on name alone is the most common source of fitment returns.
Field: Check bolt torque after the first few hours on a new edge and again at intervals through the season. A loose edge elongates its holes quickly, and once the holes are oval the reversible second life is lost.
Limits
This page describes how to measure and specify a reversible edge; it does not provide torque tables, approval for mixing bolt grades, or guidance on modifying holes in a carbide-edged part. It is not a substitute for the plow manufacturer’s mounting instructions or for the product page specification, which governs dimensions and hole spacing.
