SI-MTFNR 28-3 — boring bar, 1.75" bar diameter, 2.030" minimum bore, 14.0" overall length. Made in the USA by RMC Tooling.
0° End Cutting Edge Angle for Negative Triangle TNM_ Inserts.
Steel-shank indexable boring bar from RMC Tooling, machined in the United States. Ground shank, standard indexable geometry, and a rigid clamping system sized to the bar diameter — the combination that keeps chatter down at the depths where boring bars usually give up.
Sized by minimum bore, so start there: pick the largest bar diameter your bore will clear. Every clamp, lock pin, seat and screw in this bar is a stocked RMC service part, listed below.
These are the service parts RMC lists for this exact model — not a generic cross-reference. Every one is stocked.
| Insert | TNM_-322 — 3/8" I.C. · 1/8" thick · 1/32" nose radius or TNM_-332 (e.g. TNMA 332) — 3/8" I.C. · 3/16" thick · 1/32" nose radius |
| Seat / shim |
ITSN-333 or ITSN-322 |
| Lock pin | NL-34L |
| Clamp | CL-7 |
| Clamp screw | XNS-36 |
| Seat screw | S-34 |
This tool is listed for more than one insert size. The seat has to match the insert you pick — tell us which size you are running and we will pair it for you.
See all RMC spare parts & hardware →
Not sure how to read an insert code? Turning insert designation explained.
Dimensions as published in the RMC 2020 catalog, page 49.
