How to clean a drilled hole before a chemical anchor
Anchor manufacturers require the hole to be cleaned before the anchor goes in. Dust left in a masonry hole stops resin bonding to the concrete and stops screw-in or sleeve anchors reaching full embedment. This page covers the cleaning step and which nozzle fits each drilled hole size. Every figure links to the manufacturer's own data sheet.
Why hole cleaning matters
A chemical anchor works by bonding resin to the hole wall. Drilling leaves that wall coated in fine dust, so the resin bonds to the dust instead of the concrete and the anchor can pull out well under its rated load. Manufacturers list cleaning as a mandatory installation step.
- Ramset chemical anchoring: blow twice, brush twice, blow twice, brush twice, blow twice. A dustless drilling system is an alternative.
- Ramset TruBolt stud anchors: clean the hole thoroughly with a hole brush, then remove debris with a hand pump, compressed air or a vacuum.
- Ramset AnkaScrew screw-in anchors: brush thoroughly, then remove debris by vacuum, hand pump or compressed air.
- Ramset DynaBolt Plus sleeve anchors: brush the hole, then remove debris by vacuum, hand pump or compressed air.
- Hilti HIT-HY 200 injection mortar: hammer drilled holes need compressed air cleaning unless a hollow dust removal bit was used.
Every manufacturer listed accepts vacuum extraction as a dust removal method. Our nozzles seat over or into the hole so a site vacuum removes the dust, rather than a blow pump pushing it toward you.
The cleaning steps
Drill to depth
To the diameter and embedment in the anchor data sheet, with extra depth for debris.
Vacuum the hole
Fit the nozzle that matches the hole size, seat it and extract the loose dust.
Brush the hole
A stiff wire or nylon brush sized for the hole lifts compacted dust off the wall.
Vacuum again
Remove the dust the brush loosened.
Repeat as required
Repeat the brush and vacuum cycle as the manufacturer specifies, then install the anchor to its instructions.
The manufacturer's installation instructions and data sheet take priority over this general guide. Where an engineer's specification applies, follow it.
Which nozzle size do I need?
Match the nozzle to the drilled hole diameter, which the anchor determines, not the bolt you are fixing. Screw-in anchors normally go in a hole the same size as the anchor. Chemical anchor studs normally go in a hole larger than the stud.
| Drill bit / hole | Anchors set in this hole size | Nozzle |
|---|---|---|
| 8 mm | Ramset TruBolt M8 stud anchor [1], AnkaScrew 8mm screw-in anchor [2], DynaBolt Plus M6 sleeve anchor [3] | 8mm nozzle |
| 10 mm | M8 chemical anchor stud [4] [5], Ramset TruBolt M10 [1], AnkaScrew 10mm [2], DynaBolt Plus M8 [3] | 10mm nozzle |
| 12 mm | M10 chemical anchor stud [4] [5], Ramset TruBolt M12 [1], AnkaScrew 12mm [2], DynaBolt Plus M10 [3] | 12mm nozzle |
| 14 mm | M12 chemical anchor stud [4] [5] | 14mm nozzle |
| 16 mm | Ramset TruBolt M16 [1], AnkaScrew 16mm [2] | 16mm nozzle (Milwaukee M18 fitment) |
An M16 chemical stud needs an 18mm hole. Nozzles are printed to order, so for 18mm or any other size email the hole size and vacuum model and we will quote it.
Which vacuum does it fit?
Each nozzle is printed for one vacuum hose fitment. Choose your vacuum first, then your hole size.
| Vacuum | 8 mm | 10 mm | 12 mm | 14 mm | 16 mm | Chemical kit 10+12+14 | Mechanical kit 8+10+12 | Set 8+12+14 |
|---|---|---|---|---|---|---|---|---|
| Milwaukee M18 | $5.99 | $7.99 | $9.99 | $11.99 | $11.99 | $24.99 | $24.99 | $24.99 |
| DeWalt 35mm | $5.99 | $7.99 | $9.99 | $11.99 | Ask us | $24.99 | $24.99 | $24.99 |
| Bosch GAS 35 | $5.99 | $7.99 | $9.99 | $11.99 | Ask us | $24.99 | $24.99 | $24.99 |
| Ryobi RVC | $5.99 | $7.99 | $9.99 | $11.99 | Ask us | $24.99 | $24.99 | $24.99 |
The chemical anchor kit covers M8, M10 and M12 studs. The mechanical anchor kit covers the common TruBolt, AnkaScrew and DynaBolt Plus sizes. All three piece kits post free within Australia.
Common questions
Is cleaning really required before a chemical anchor?
Yes. Manufacturers make it mandatory because resin bonds to whatever is on the wall, and drilling dust reduces holding power.
Can I just blow the hole out?
A blow pump is an accepted method, but it pushes silica dust into your breathing zone and can leave compacted dust behind. That is why manufacturers pair blowing with brushing. Vacuum extraction removes the dust rather than redistributing it.
What hole does an M10 chemical anchor need?
Ramset and Hilti both specify a 12mm hole for an M10 stud and a 14mm hole for an M12 stud, so use the 12mm and 14mm nozzles. Confirm against your product's data sheet.
What is the 8mm nozzle for?
Mechanical anchors, including the Ramset TruBolt M8, AnkaScrew 8mm and DynaBolt Plus M6. Chemical studs start at M8, which needs a 10mm hole, so the 8mm nozzle is not for resin anchors.
What is the best on-site cleaning method?
Fit the correctly sized nozzle to your site vacuum, extract the loose dust, brush the wall, then vacuum again. It is faster than blowing, keeps dust out of your breathing zone and leaves the site cleaner.
Will these fit my vacuum?
We print separate fitments for Milwaukee M18, DeWalt 35mm, Bosch GAS 35 and Ryobi RVC. If your vacuum is not listed, email the model and we will tell you whether we can print one.
Are they only for chemical anchors?
No. Screw-in anchors, sleeve anchors, stud anchors and rebar dowels in drilled masonry all benefit from a clean hole. They also keep dust off the customer's floor.
Sources
- Ramset TruBolt Stud Anchors, Specifiers Anchoring Resource Book, ANZ Ed. 3. Thread size to hole diameter and cleaning instructions.
- Ramset AnkaScrew Technical Data Sheet Guide. Anchor size to hole diameter and cleaning instructions.
- Ramset DynaBolt Plus Sleeve Anchors, Specifiers Anchoring Resource Book, ANZ Ed. 3.
- Ramset Chemical Anchoring, Anchor Studs, Specifiers Anchoring Resource Book, ANZ Ed. 3. Stud size to hole diameter, embedment and the blow and brush sequence.
- Hilti HIT-HY 200-A/R Technical Data Sheet. Rod size to nominal bit diameter and cleaning requirements by drilling method.
Industrial Printworks is not affiliated with or endorsed by Ramset, Hilti, Milwaukee, DeWalt, Bosch or Ryobi. Brand names only identify compatible anchors and vacuums. Follow your own anchor and adhesive instructions.