WS39 casing tooth
JM cutter tooth
B47K22 bullet toothIdentify the mounting already on the barrel before choosing replacement parts. A weld-on leg, a separate holder and a crossbar with bolts require different matching parts and service access. Similar cone shapes do not establish fit.
Compare the interface, access and replacement scope
| Mounting reference | Interface and service access | Replacement scope |
|---|---|---|
| MH-3 · weld-on leg | Match the leg profile to the ring opening and selected cutter position. Allow access for preparation, positioning and the agreed welding procedure. | Roller-bit assembly; identify any separate cutting-ring repair work. |
| MH-3C · separate holder | Match the holder opening and fixing details. Check space to remove the cutter and confirm the selected weld arrangement. | Replacement cutter only, or cutter with holder and required retaining parts. |
| MH-3B · crossbar and bolts | Match the crossbar, two bolts, locknuts and mounting dimensions. Check access to remove and fit these parts. | List the roller bit and which crossbar, bolts and nuts must be supplied. |
The documented MH-3C arrangement combines mechanical retention with welding. Confirm the selected holder and weld arrangement rather than treating “replaceable” as a promise of a weld-free change. For any mounting, identify what will be retained, repaired and supplied new.
If the model is unknown, start with the existing connection photographs. See the three mounting references and supply scopes.
Will the welded leg fit the cutting ring?
Check the leg profile against the opening, then confirm radial position, projection and orientation from the selected layout drawing. A worn opening is a condition to inspect, not a reliable template for the replacement.
Agree the installation sequence and welding heat controls before work starts. The bearing, seal and lubricant are part of the assembly that the installation procedure must protect.
Is the replaceable assembly matched to its holder?
For a holder-mounted roller bit, identify both the bit and holder and confirm the seating interface and retention method.
For a bolted assembly, check access with the parts in their installed positions. Seeing the bolt head does not establish that the specified tool can engage it and operate beside the crossbar, ribs or guides. Check access at the bolt head and any nut that needs to be held. Separately check the clearance to withdraw the fixing parts and to remove the roller-bit assembly.
Record the fixing parts as one set: bolt designation, overall length and threaded length, plus the washer and nut or locking arrangement. Keep the two lengths separate, with their measurement references identified on the selected drawing. Confirm the complete set against the assembly drawing or parts list before ordering replacements.
Compare mating dimensions between the same reference faces. A height measured from the top of a mounting plate and one measured from its underside are different measurements; identify both endpoints on the drawing or marked photo. Do not assume interchangeability between holder, bolted and weld-on families.
If the selected mounting requires welding
A weld-on choice also requires suitable positioning and welding controls. The checks below protect both the joint and the assembled bearing. Use the selected drawing, qualified welding procedure and assembly limits; see the installation guide for the photographed positioning sequence.
| Step | Work to complete | If it is missed |
|---|---|---|
| 1. Prepare the joint | Remove old weld, slag, rust, oil and paint from the intended joint and work-clamp contact. Dry-fit the leg against the specified opening; do not bridge an oversized cut-out with an improvised filler. | Poor seating changes the cutter position; contamination can contribute to pores, inclusions or poor fusion. |
| 2. Establish the current path | Connect the welding work-return clamp to clean bare metal on the stationary component being welded, close to the joint. Keep the return path out of the cone and bearing contacts. | Current crossing a bearing contact can cause local electrical erosion, separately from heat damage. |
| 3. Tack the complete layout | Set the centre and reference plane. Position the first inner and outer bits, tack them, then tack and measure the whole set before final welding. Recheck the centre after moving the barrel. | A tilted first bit or displaced centre can be copied around the ring and locked in by final welding. |
| 4. Distribute the weld sequence | Follow the specified run sequence across the assembly. The workshop method alternates portions of weld between positions instead of finishing one leg continuously. Remove slag between passes where the process requires it. | Local heat accumulation and contraction can shift the layout and heat the bearing assembly. |
| 5. Measure the relevant temperatures | The welding procedure must state steel preheat and interpass limits; the bit manufacturer must define any separate assembly-temperature limit and its measuring point. Take readings before the next run. | A satisfactory weld temperature at the joint does not establish a safe temperature at the seal and lubricant. |
| 6. Cool and recheck | Use the specified cooling method. After the assembly reaches the stated inspection condition, clean and inspect the welds, remeasure cutter positions and check cone movement. | Distortion, a changed cone feel or a visible weld defect may otherwise reach the first drilling shift. |
Fill in the controls before welding: process and consumable; current (A); voltage (V); wire feed (m/min), where applicable; travel speed (mm/min); preheat/interpass limits (°C); assembly-temperature limit and measuring point; pass sequence; cooling method. These values come from the applicable procedure and assembly design. An unspecified “low current” or a wet cloth is not a measurable temperature control.
Technical references: Miller on joint preparation, SKF on electrical bearing damage, and TWI on tack welding and weld sequence.