How to clean a drilled hole before installing a chemical anchor
Every major anchor manufacturer tells you to clean the hole before you set the anchor. Dust left in a masonry hole stops the resin bonding to the concrete, and it stops a screw-in or sleeve anchor seating to its full embedment depth. This page explains the cleaning step, and shows which Industrial Printworks drill hole dust extractor nozzle matches the hole size you have just drilled. Every figure below is linked to the manufacturer's own published data sheet.
Why hole cleaning matters
An adhesive (chemical) anchor works by bonding resin to the wall of the drilled hole. Drilling leaves that wall coated in fine masonry dust. Resin injected onto dust bonds to the dust, not the concrete, and the anchor can pull out well below its rated load. Anchor manufacturers publish this as a mandatory installation step, not a recommendation.
- Ramset chemical anchoring: cleaning sequence of blow x 2, brush x 2, blow x 2, brush x 2, blow x 2, or the use of a dustless drilling system.
- Ramset TruBolt stud anchors: "Clean the hole thoroughly with a hole cleaning brush. Remove the debris with a hand pump, compressed air, or vacuum."
- Ramset AnkaScrew screw-in anchors: "Clean thoroughly with brush. Remove debris by way of vacuum or hand pump, compressed air etc."
- Ramset DynaBolt Plus sleeve anchors: "Clean hole thoroughly with brush. Remove debris by way of a vacuum or hand pump, compressed air, etc."
- Hilti HIT-HY 200 injection mortar requires compressed air cleaning for hammer-drilled holes, unless the hole was drilled with a hollow dust-removal bit.
A vacuum is named as an approved dust removal method by every one of those manufacturers. That is what these nozzles do: they seat over or into the hole so your existing site vacuum pulls the dust straight out, instead of a blow pump pushing it into your face.
The cleaning steps
- Drill to depth. Drill the hole to the diameter and embedment depth the anchor's data sheet specifies, plus a little extra for debris.
- Vacuum the hole. Fit the nozzle that matches your hole size, seat it on the hole and pull the loose dust out.
- Brush the hole. Use a stiff wire or nylon hole brush sized for the hole. This lifts the compacted dust off the hole wall.
- Vacuum again. Remove what the brush just released.
- Repeat the brush and vacuum cycle as your anchor manufacturer's instructions require, then install the anchor to their instructions.
Always follow the installation instructions supplied with your specific anchor and adhesive. The information on this page is a general guide, not a substitute for the manufacturer's data sheet or an engineer's specification.
Which nozzle size do I need?
Match the nozzle to the hole diameter you drilled, which is set by the anchor, not by the bolt you are fixing. A screw-in anchor is normally set in a hole the same size as the anchor. A chemical anchor stud is normally set in a hole larger than the stud. Every hole size in the table is linked to the manufacturer data sheet it came from.
| Masonry drill bit / hole size | Anchors set in this hole size | Nozzle |
|---|---|---|
| 8 mm | Ramset TruBolt M8 stud anchor [1] · Ramset AnkaScrew 8 mm screw-in anchor [2] · Ramset DynaBolt Plus M6 sleeve anchor [3] | 8 mm drill hole dust extractor |
| 12 mm | Chemical anchor, M10 stud [4] [5] · Ramset TruBolt M12 [1] · Ramset AnkaScrew 12 mm [2] · Ramset DynaBolt Plus M10 [3] | 12 mm drill hole dust extractor |
| 14 mm | Chemical anchor, M12 stud [4] [5] | 14 mm drill hole dust extractor |
| 16 mm | Ramset TruBolt M16 [1] · Ramset AnkaScrew 16 mm [2] | 16 mm drill hole dust extractor (Milwaukee M18 fitment) |
Not the size you need? Chemical anchor studs start at M8, which takes a 10 mm hole [4] [5], and an M16 stud takes an 18 mm hole. We 3D print to order here in Australia, so if you want a 10 mm, an 18 mm or any other size, email us with the hole size and your vacuum model.
Which vacuum does it fit?
Every nozzle is printed for one specific vacuum hose fitment. Pick your vacuum, then pick your hole size.
| Vacuum | 8 mm | 12 mm | 14 mm | 16 mm | 3 piece set |
|---|---|---|---|---|---|
| Milwaukee M18 | Yes | Yes | Yes | Yes | 8+12+14 mm |
| DeWalt 35 mm | Yes | Yes | Yes | Ask us | 8+12+14 mm |
| Bosch GAS 35 | Yes | Yes | In the 3 piece set | Ask us | 8+12+14 mm |
| Ryobi RVC (35 mm) | Yes | Yes | Yes | Ask us | 8+12+14 mm |
The 3 piece sets cover 8 mm, 12 mm and 14 mm, which are the hole sizes behind the most common mechanical anchors and the M10 and M12 chemical anchor studs. All 3 piece sets ship free within Australia.
Common questions
Do I really need to clean the hole before a chemical anchor?
Yes. Anchor manufacturers make hole cleaning a required installation step, because injected resin bonds to whatever is on the hole wall. If that is drilling dust, the anchor's holding power is reduced.
Can I just blow the hole out?
A blow pump is one accepted method, but it pushes silica dust back out into your breathing zone and often leaves compacted dust on the hole wall, which is why manufacturers pair blowing with brushing. Vacuum extraction removes the dust rather than redistributing it.
What size hole does an M10 chemical anchor need?
Ramset and Hilti both specify a 12 mm hole for an M10 threaded stud, and a 14 mm hole for an M12 stud. Use our 12 mm and 14 mm nozzles respectively. Always confirm against your own product's data sheet.
What is the 8 mm nozzle used for?
Mechanical anchors. An 8 mm hole takes a Ramset TruBolt M8 stud anchor, an AnkaScrew 8 mm screw-in anchor and a DynaBolt Plus M6 sleeve anchor, which are among the most common fixings on site. Chemical anchor studs start at M8, which needs a 10 mm hole, so the 8 mm nozzle is for mechanical fixings rather than resin anchors.
What is the best way to clean drill dust out of a masonry hole on site?
Fit a nozzle sized to the hole onto your site vacuum, vacuum the loose dust, brush the hole wall, then vacuum again. It is faster than a blow pump, it keeps the dust out of your breathing zone, and it leaves the site cleaner.
Will these fit my vacuum?
We print separate fitments for Milwaukee M18, DeWalt 35 mm, Bosch GAS 35 and Ryobi RVC vacuums. Buy the one that matches your vacuum. If your vacuum is not listed, email us with the model and we will tell you whether we can print one.
Are they only for chemical anchors?
No. Any fixing set in a drilled masonry hole benefits from a clean hole, including screw-in anchors, sleeve anchors, stud anchors and rebar dowels. They are also useful for keeping dust off a customer's floor.
Sources
Hole diameters and cleaning instructions on this page are taken from the following manufacturer publications. We have linked them so you can check the figures yourself.
- Ramset TruBolt Stud Anchors — Specifiers Anchoring Resource Book, ANZ Ed. 3. Thread size to drill hole diameter, and hole cleaning instructions.
- Ramset AnkaScrew Technical Data Sheet Guide — anchor size to drilled hole diameter, and hole cleaning instructions.
- Ramset DynaBolt Plus Sleeve Anchors — Specifiers Anchoring Resource Book, ANZ Ed. 3. Thread size to drill hole diameter, and hole cleaning instructions.
- Ramset Chemical Anchoring, Anchor Studs — Specifiers Anchoring Resource Book, ANZ Ed. 3. Stud size to drill hole diameter, embedment depth, and the blow and brush cleaning sequence.
- Hilti HIT-HY 200-A/R Injection Mortar Technical Data Sheet — threaded rod size to nominal drill bit diameter, and hole cleaning requirements by drilling method.
Industrial Printworks is not affiliated with, endorsed by or sponsored by Ramset, Hilti, Milwaukee, DeWalt, Bosch or Ryobi. Brand names are used only to identify the anchors and vacuums our nozzles are designed to suit. Always work to the instructions supplied with your own anchor and adhesive.