Keystone Engineering & MFG. LLC

11 patents currently held · Updated Nov 14, 2026

Held is read from USPTO's recorded assignments; a transfer never recorded there does not appear.

Ending by 2030

Jan 2029

Next term end

When these terms end

5 yrs10 yrs20 yrs

Held patents by the year their term ends

20262027202820292030203120322033203420352036203720382039204020412042204320442045

Fee deadlines

Maintenance fees fall due 3.5, 7.5 and 11.5 years after grant. A missed fee ends a patent at the end of the six month grace period that follows, not on the due date.

1 fee due May 5, 2027
The maintenance fee for Tapered cutter bit and mounting block for the same (US 10,465,513) comes due May 5, 2027. Unpaid by Nov 5, 2027, it lapses early.
1 fee due Jul 19, 2027
The maintenance fee for Tooth and retainer for a milling drum (US 9,238,893) comes due Jul 19, 2027. Unpaid by Jan 19, 2028, it lapses early.

Which patents, and when each one lapses · Pro

Recent changes

Nothing was recorded against this company's patents in the last 90 days.

Patents held now

Soonest term end first. Each date below is computed on that patent's own page, which shows the rule, the adjustments and the fee history it was derived from.

Patent	Title	Status	Expires	Confidence
US 8,528,990	Cutter with diamond bit tip In force Term ends Jan 22, 2029 · From the USPTO record	In force	Term ends Jan 22, 2029	From the USPTO record
US 8,573,885	Road surface planar In force Term ends Sep 1, 2031 · From the USPTO record	In force	Term ends Sep 1, 2031	From the USPTO record
US 9,631,490	Tooth and retainer In force Term ends Aug 26, 2033 · From the USPTO record	In force	Term ends Aug 26, 2033	From the USPTO record
US 9,238,893	Tooth and retainer for a milling drum In force Term ends Sep 23, 2033 · From the USPTO record	In force	Term ends Sep 23, 2033	From the USPTO record
US 9,394,787	Wear resistant insert for diamond abrasive cutter In force Term ends Dec 20, 2033 · From the USPTO record	In force	Term ends Dec 20, 2033	From the USPTO record
US 9,890,635	Tapered cutter bit and mounting block for the same In force Term ends Dec 20, 2033 · From the USPTO record	In force	Term ends Dec 20, 2033	From the USPTO record
US 10,465,513	Tapered cutter bit and mounting block for the same In force Term ends Dec 20, 2033 · From the USPTO record	In force	Term ends Dec 20, 2033	From the USPTO record
US 9,382,794	Wear resistant insert for diamond abrasive cutter In force Term ends Dec 28, 2033 · From the USPTO record	In force	Term ends Dec 28, 2033	From the USPTO record
US 10,787,774	Milling cutting element system In force Term ends Jul 14, 2036 · From the USPTO record	In force	Term ends Jul 14, 2036	From the USPTO record
US 11,408,135	Milling cutting element system In force Term ends Jul 14, 2036 · From the USPTO record	In force	Term ends Jul 14, 2036	From the USPTO record

10 of 11 patents shown.

Pro members see all 11.

Pro members: see all 11 patents

Also on record, not counted in the 11: 2 ended at full term. List them

Sources and methods

Compiled from the USPTO record, grants, published applications and recorded assignments, not yet reviewed by hand. How this record was built

Computed patent terms end on the dates shown. Related patents and pending applications may cover overlapping subject matter.

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