What are Threaded Drop In Anchors?
Threaded drop-in anchors, also called machine screw anchors, are flush-setting anchors for solid concrete. After you set the anchor with a drop-in setting tool, it leaves female threads in the hole so you can install or remove threaded rod, bolts, or studs.
Why choose threaded drop-in anchors?
- Flush mount keeps the surface clean for overhead work and trim plates
- Reusable internal threads let you adjust or remove hardware later
- Strong holding power in solid concrete when set correctly
- Available in zinc-plated steel and stainless steel for corrosion resistance
Where do threaded drop-in anchors work best?
- Pipe supports and strut
- Light fixtures, cable tray, and suspended ceilings
- Equipment hangers and safety lines
Use only in solid concrete. They are not recommended for brick or hollow block.
How do threaded drop-in anchors work?
Each anchor has a pre-installed expander plug. After drilling the hole, insert the anchor flush with the surface and strike the plug using the correct setting tool. The sleeve expands against the hole wall and creates durable internal threads.
Installation tips
- Drill the exact hole size listed for the anchor
- Drill to the required depth so the anchor sets fully and sits flush
- Brush and blow out dust before setting
- Use the matching drop-in setting tool and strike until the tool shoulder meets the top of the anchor
Drill sizes and hole depths
Match your anchor size to the hole size and depth below for quick, error-free setup.
| Anchor Size | Hole Size | Hole Depth |
|---|---|---|
| #6-32 | 5/16 in | 1/2 in |
| #8-32 | 5/16 in | 1/2 in |
| #10-24 | 3/8 in | 5/8 in |
| 1/4 in | 1/2 in | 7/8 in |
| 5/16 in | 5/8 in | 1 in |
| 3/8 in | 3/4 in | 1-1/4 in |
| 1/2 in | 7/8 in | 1-1/2 in |
| 5/8 in | 1-1/8 in | 2 in |
How do you size threaded drop-in anchors (inch and metric)?
- Pick an anchor with internal threads that match your rod or bolt size
- Confirm the hole size and depth from the table above
- Choose zinc-plated for dry interiors and stainless for wet or corrosive areas
Best practices and safety
- Wear eye and hand protection
- Keep the drill perpendicular for a straight, full-depth hole
- Do not use in cracked or crumbling concrete unless the product is rated for it
- Test a sample installation if you are unsure about concrete strength
FAQs about Threaded Drop-In Anchors
Clear answers to common questions on use, sizing, and installation.
- What is a threaded drop-in anchor used for?
Creating female threads in concrete to hang threaded rod, bolts, or studs for supports and overhead work.
- Can I use threaded drop-in anchors in brick or hollow block?
No. These anchors are designed for solid concrete only.
- What tool do I need to set them?
A matching drop-in setting tool. Strike it until the tool shoulder meets the top of the anchor.
- What size drill bit should I use?
Use the hole size listed in the “Drill sizes and hole depths” table for your anchor.
- How deep should I drill?
Drill to at least the depth in the table so the anchor sits flush and expands fully.
- Do I need to clean the hole?
Yes. Brush and blow out dust before placing the anchor to improve holding power.
- Can I remove the threaded rod later?
Yes. The anchor stays in the concrete and the internal threads let you remove or replace the hardware.
- Which finish should I choose?
Zinc-plated for dry interiors. Stainless steel for wet, coastal, or chemically exposed areas.
- Do these anchors work in cracked concrete?
Some models are rated for cracked concrete, but many are not. Check the product rating.
- How strong are threaded drop-ins?
Strength depends on size, embedment, and concrete quality. Follow the manufacturer’s load data for your specific product.