What the FAA Handbook says
| Topic | What the Handbook says | Source |
|---|---|---|
| Hole duplicator | Also called a hole finder. The peg on the bottom leg fits the existing rivet hole; drill through the bushing on the top leg to match it in the new sheet. A separate duplicator is needed for each rivet diameter. | Handbook pp. 4-7, 4-8 |
| Rivet spacer | Makes a quick, accurate rivet pattern on a sheet, with marks for 1/2, 3/4, 1 and 2 inch spacing. | Handbook p. 4-4 |
| Dividers | Transfer a measurement from a part to a scale. Set one point on the 1-inch mark and measure from there. | Handbook p. 4-4 |
| Edge distance | From the centre of the first rivet to the edge of the sheet: not less than 2 nor more than 4 rivet diameters, recommended about 2-1/2. Minimum is 2 diameters for universal rivets and 2-1/2 for countersunk. | Handbook pp. 4-34, 4-35 |
| Rivet pitch and rows | Smallest pitch 3 rivet diameters; usually 4 to 6, sometimes up to 10. Two-row layouts need at least 4 diameters; rows at least 2-1/2 diameters apart. Copy the original spacing where possible. | Handbook pp. 4-34, 4-35 |
Layout tools, as listed
| Tool | Type | Listed spec | Where |
|---|---|---|---|
| 6" Standard Hole Finder, 5 Piece | Hole finder, standard | #40, #30, #21, #10, 1/4"; 6" long; tapered ends for prying sheets apart | US · Yardstore |
| 6" Standard and Inverted, 10 Piece | Hole finder, standard and inverted | Five standard plus five inverted, #40 to 1/4"; 6" long | US · Yardstore |
| Hole Duplicator, Bushing Type (AT532-61 to -65) | Hole duplicator | Pilot and drill .098" (#40), .129" (#30), .159" (#21), .194" (#10); AT532-61 about 8-5/8" long | US · Aircraft Spruce |
| Strap Duplicator, Inverted Type (12-01505 to -01514) | Inverted hole duplicator | #10, #21, #30, #40, 1/4"; 6-1/4" or 13-1/4" long; locates a hole from the back of an overlapping sheet | US · Aircraft Spruce |
| Economy Blind Hole Spotters | Hole spotter | 1/8" (12-01771), 3/16" (12-01773), 1/4" (12-01774), 5/16" (12-01775); marks the centre for the opposite hole | US · Aircraft Spruce |
| Adjustable Rivet Spacer (12-00184, 12-11700) | Rivet spacer | 10-hole: 17-1/2" at full extension; 20-hole: 36"; 301 stainless; about 9/16" centre to centre closed, about 1" at most open | US · Aircraft Spruce |
| Edge Marker Block (12-00630) | Edge marker | Adjustable stop for variable edge distance; Delrin; takes a Pilot marking pen; range not stated | US · Aircraft Spruce |
As the sellers list them, no prices. Yardstore names link to our catalogue page with its source (checked 29 September 2026). Aircraft Spruce names link to the seller's own page, read 28 October 2026. A blank spec means the listing does not state it.
How to choose, per the FAA Handbook
One duplicator per diameter. The Handbook is explicit: a separate duplicator for each rivet diameter. Size them to the rivets you use most: #40, #30 and #21 are the hole drills for 3/32, 1/8 and 5/32 in rivets (chart); the sets add #10 and 1/4 in.
Standard when you can pry, inverted when you cannot. A standard finder slides between sheets. Where the sheets cannot be pried apart, the hole must be located from the back.
The pattern comes from the original. The Handbook's first rule is to match the existing edge distance, spacing and row distance; the numbers above are for new sections. Compute with the edge distance and rivet spacing calculators.
The edge marker block is not in the Handbook. It is a marker holder with an adjustable stop, listed below; the Handbook's rule for edge distance is the one to set it to.
Questions people actually ask
What is a hole finder used for?
To copy an existing hole into a new sheet or patch. The peg sits in the old hole and you drill through the bushing above it, so the new hole lines up.
What is the minimum edge distance for aircraft rivets?
The Handbook says not less than 2 rivet diameters from the centre of the hole to the edge, not more than 4, with about 2-1/2 recommended. The SRM or repair data comes first. The edge distance calculator gives the numbers.
How far apart do I space the rivets?
At least 3 rivet diameters in one-row and three-row layouts and 4 in two-row layouts, typically 4 to 6, per the Handbook. Match the original pattern where you can; the rivet spacing calculator does the sums.
Do I need a different hole finder for every rivet size?
Yes. The Handbook says a separate duplicator is needed for each diameter, which is why the sets come in #40, #30, #21, #10 and 1/4 in.
Limits of this guide
A comparison of published figures and FAA guidance.
- No tool was tested. Fit of the peg in the hole, and the accuracy of the spacing, are not in a listing. The site has no named technical reviewer yet, so there is no shop verdict.
- The Handbook does not describe an edge marker. Only the edge distance rule it should be set to.
- Adjustable spacers are not in the Handbook. It describes a rivet spacer with marks for 1/2, 3/4, 1 and 2 in, not an expanding one.
- Listings change. The seller's live page is the current one.
Sources
- FAA-H-8083-31, AMT Handbook — Airframe, Volume 1, Chapter 4 — pp. 4-4 (dividers, rivet spacer), 4-7 to 4-8 (hole duplicator), 4-34 to 4-35 (rivet spacing, edge distance, pitch).
- Seller listings — every figure in the table: Yardstore through the linked catalogue pages, and Aircraft Spruce through the linked product pages.