How to enlarge or align a hole in metal

Geposted von Adam Smith am

misaligned holes

Enlarging holes or aligning mismatched holes in metal is the job of a tool known as a reamer.

The process by which this is done is called Reaming and differs from traditional drilling as it requires an existing hole, or holes, as a starting point. A reamer cannot create a hole from scratch, only increase the size of current holes.

Below you will find a step-by-step guide to reaming along with technical recommendations, best practice advice and information on the range of HMT reamers available and the best situations in which to use them.

 enlarging a hole in metal

How to enlarge or align (Ream) a hole in metal:

  • Firstly, ensure that your workpiece is securely fixed and isn’t going to move.
  • Secondly, assuming you already have a hole you wish to enlarge or align choose the most appropriate reamer for the size of hole you need. For example, if you are wishing to go from an 8mm hole to a 16mm hole it is not advisable to do that in one operation. For best results, and to prevent tool breakage, enlarge the hole in small increments of 2-3mm at a time, using the appropriate sized reamer to do this.
  • Fit the reamer to your drive tool.
  • When using a Holemaker Technology VersaDrive reamer in an Impact wrench, magnet drill or SDS drill choose the correct adapter, fit to the drive tool and insert the reamer.
  • When fitting an ImpactaMag reamer to a magnet drill simply insert into the arbor and tighten grub screws.
  • Insert reamer into the hole to be enlarged. VersaDrive and ImpactaMag reamers are Tapered reamers, otherwise known as Bridge reamers, and will self centre thanks to their sloping, tapered sides. (Reamers used in a magnet drill can only self centre with the magnet turned off so the drill can move to the correct position.)
  • When ready, slightly withdraw the reamer so it is not in contact with the sides of the hole and start it spinning.
  • Start the cut, applying steady feed pressure throughout the operation.
  • Once the reamer has reached its widest point the cut is complete, and the reamer can be stopped and withdrawn.

Best Practice advice:

  • Check the minimum torque requirement for the tool in use.
  • Apply firm, steady feed pressure throughout the cut, applying the feed very slowly and cautiously during the first 1mm of cut.
  • To maximise tool life do not attempt to increase the existing hole diameter beyond 2-3mm. If a larger, finished hole size is required, then the next size reamer should be used to ‘step up’ until the finished hole diameter is reached.
  • Avoid lateral movement or tilting which can cause damage to the tool
  • Ensure regular application of quality cooling lubricant, especially when drilling thick or hardened materials.
  • Flame cut, laser cut or punched holes may not be possible to ream with an impact wrench. In this situation the hole can be reamed out with a slow speed Magnet Drill with an ImpactaMag or VersaDrive reamer.
  • Follow guidelines to set correct RPM speed. Incorrect RPM can lead to poor life or tool breakage.
  • Ensure a debris free surface of sufficient steel thickness for strong magnet hold when Magnet Drilling.
  • Regularly check that Magnet Drill slides, handles, arbors and movable parts have not vibrated loose over time.
  • For fastest performance use on impact wrenches and impact drivers.
    For extensive technical information on recommended speeds and feeds see the end of the article.

    Now you know how, why would you want to ream a hole?

    There are many reasons why holes need to be modified after they have been created – most commonly these can include specification changes, a change in the type of fixings to be used, or even simply a measurement mistake at some stage of the process.

    Whatever the reason for enlarging a hole though, it has traditionally been difficult to do accurately on site and away from static, precision milling and drilling machines, especially in hard materials such as steel.

    The question of 'how to do this quickly and correctly' then became a real challenge.

    It was a desire to provide a solution to these challenges that led us to create two brand new products - Enter the VersaDrive and ImpactaMag range of construction and fabrication reamers.

    VersaDrive Impact Reamers

    HMT versadrive reamer

    VersaDrive reamers are the perfect hole alignment and enlarging tool for metalworkers & steel erectors for keeping the job moving when a hole is misaligned or the incorrect size for the fixing.

    Featuring a specially designed 6 flute cutting geometry and Titanium coating, VersaDrive™ Reamers are fully Impact rated and perform fastest when used with an Impact wrench providing ultimate cutting performance with virtually no powertool kickback.

    VersaDrive Reamers have a patented non-slip, Hex shank suitable for use in any standard 1/2” drill chuck for cordless or pistol drills or used with a VersaDrive Rapid Lock adapter for use in a wide range of powertools such as Magnetic Drills.

    • Precision 6-flute design for smooth cutting
    • Safer reaming with minimal kickback
    • Specially hardened for impact wrench use
    • High grade tool steel for high accuracy and long life
    • Goldmax low-friction titanium coating to stop burn-out
    • High strength, non-slip shank design
    • Use on Impact or Rotary

    Technical Quick guide

    • For fastest performance use on impact wrenches & impact drivers
    • Impact driven reamers are not recommended for Flame or Plasma cut holes. Use with a Magnet Drill
    • Reamer should be rotating before starting the cut & steady feed pressure should be used through the cut
    • For materials thicker than 20mm use of ImpactaMag reamers is recommended


    HMT ImpactaMag Reamer

    HMT ImpactaMag Reamer

    The ImpactaMag™ HSS reamer is a unique double-use reamer for enlarging and aligning holes in metals and hard materials.

    Specially designed cutting geometry allows the tool to be used in an Impact wrench or a Magnet drill. When used in an Impact wrench it is secured into a special adapter meaning the tool is easier to control, apply correct feed rate, and withdraw from the finished hole, enhancing tool life. This reamer will also fit into a standard Weldon magnet drill arbor.

    The tapered design allows the narrow end of the ImpactaCut reamer to be entered into the existing hole and accurately centred.

    The rotary/percussion impact cuts precise shavings off each side of the hole, up to the widest dimension of the reamer.


    • Ideal for steel erection & bridge work
    • Ideal for modifying & enlarging holes
    • Secured directly to the Impact Wrench
    • Can be used with any standard Magnet Drill
    • Available in intermediate sizes
    • Unique 6 flute design for faster, smoother cut
    • Prepare holes ready for installation of TCB & friction grip bolts


    So how do you know which one is for you?

    The correct tool for the job will depend on the drive tool you are able to use, the size of the final hole required and the material you are reaming.

    When VersaDrive reamers are the best option:

    When using a portable power tool like an Impact Driver or Impact Wrench and the final hole size required is below 26mm the VersaDrive Impact Reamer would be the recommended option. This tool quickly and easily fits the VersaDrive range of quick-change, rapid-lock adapters and can be used to enlarge a hole in materials up to 20mm thick.

    VersaDrive reamers can also be used with cordless drills and magnet drills or pillar drills so for applications requiring holes up to 26mm diameter in materials up to 20mm thick VersaDrive reamers are still perfect for the task.


    When ImpactaMag reamers are the best option:

    If you are using a magnet drill without an adapter, require a hole size between 26-39mm or have material greater than 20mm thick then the ImpactaMag Reamer would be the recommended option.

    With it’s Weldon shank the ImpactaMag reamer will fit directly into a standard 19.05mm arbor whilst it’s construction makes it perfect to tackle thicker materials, over 20mm in depth.


    Many building and construction professionals will testify. A job on-site or in the workshop can be going fine until a small problem like a misaligned hole, a poorly drilled hole, or a connection hole that is too small, can put a very expensive spanner in the works.

    Having a set of VersaDrive or ImpactaMag reamers on hand means this potential problem can be quickly overcome.


    Speeds and feeds

    reamer technical data

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