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How to Use Transfer Screws to Locate Holes
Guide · Updated October 28, 2026
Transfer screws thread into tapped holes and leave a sharp point just above the surface. Press the mating part down on them and each point marks where to drill the clearance hole. They are the tapped-hole version of transfer punches.
Check the spacing
Measure the hole spacing after marking. The free Gage Block Calculator builds the stack.
Step by step
- Pick the thread size: Match the screws to the tapped holes.
- Thread them in: Thread each screw in until the point sits a little proud of the surface; keep heights equal.
- Position the mating part: Locate it against stops or by eye.
- Press or tap: Press the part down or tap lightly with a soft mallet.
- Lift and check: Each point leaves a dimple. Check spacing.
- Punch and drill: Center-punch, spot drill, then drill the clearance size.
- Remove screws: Unthread with a screwdriver or hex key.
Worked example: 1/4-20 holes, 2.000 in apart
Two 1/4-20 tapped holes 2.000 in apart. Thread in 1/4-20 transfer screws and mark the cover plate. Drill clearance: ASME B18.2.8 lists 0.266 in (17/64) close fit and 0.281 in (9/32) normal fit for a 1/4 in screw, with 0.297 in (19/64) for loose fit; the table gives these as minimum hole sizes, with maximums of 0.272, 0.290 and 0.311 in. A close-fit hole gives (0.266 − 0.250) ÷ 2 = 0.008 in radial slop, so the marking must be good to within about 0.008 in, or bolts will bind. Normal fit allows (0.281 − 0.250) ÷ 2 = 0.0155 in.
Height matters
If one point sits higher, it marks first and the part can tip, shifting the others. Keep points equal; check with a straightedge.
When to use transfer punches instead
For through holes or clearance holes, use transfer punches sized to the hole. Transfer screws are for blind or tapped holes.
Better accuracy
For precise work, mark with transfer screws, then pick up the marks on the mill with an edge finder and drill by coordinates.
Common problems
Holes off: mating part slid during marking; clamp it. Faint marks: points dull. Bolts bind: drilled close fit with imperfect marks; use normal fit.
Tips
- Punches: transfer punch sets.
- Transfer: transferring hole locations.
- Tap drill: tap drill chart.
FAQ
What are transfer screws?
Pointed screws that thread into tapped holes to mark a mating part.
Transfer screws vs punches?
Screws for tapped holes; punches for open holes.
What clearance hole for 1/4 in?
0.266 in close fit or 0.281 in normal fit (ASME B18.2.8).
How do I keep the marks accurate?
Equal point heights and clamp the mating part.
Can I reuse them?
Yes; keep points sharp.
Related guides and calculators
- How to Use a Transfer Punch Set
- How to Transfer Hole Locations
- Tap Drill Chart Explained
- How to Use a Center Punch and Prick Punch
- How to Tap on a Mill
- How to Use Jack Screws to Support a Setup
- All free machinist calculators
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