Heule BSF – Back Spot Facing and Counterboring from One Side

by Bernard Martin

When the back side needs a spotface & the part stays right where it is, the Heule BSF earns its keep.

If you’ve ever had a part where the back side needs a clean spotface or counterbore and you don’t want to flip it over, that’s exactly what the BSF tool from Heule Tool is built for. It lets you machine the back side of the part through an existing hole, in one cycle, from one side.

The BSF runs through a drilled hole with the cutting blade pulled in. Nothing is cutting on the way in. Once the tool reaches depth, the blade opens up and cuts the spotface or counterbore on the back side of the part.

When the cut is finished, the blade pulls back in and the tool comes out the same hole it went in.
That motion is controlled mechanically, so the blade opens and closes at the same point every time. You don’t have to babysit it or worry about it hanging up inside the part.

Blade Activation Options
How the blade opens depends on what your machine can support.

• On machines with through-spindle coolant, coolant pressure is used to push the blade out and pull it back in. That same coolant helps move chips away from the cut.
  
• If you don’t have through-coolant, there are air-activated versions that use shop air instead.
• There’s also a mechanically actuated version for machines that don’t have either option. 

The cutting action is the same in all cases. The activation method just matches the tool to your machine.

What It Can Cut
The BSF can machine a back spotface or counterbore that’s much larger than the hole it passes through. In most cases, you’re looking at a finished diameter more than twice the size of the entry bore.  The cutting blades are replaceable carbide, so when the edge wears out, you change the blade instead of the whole tool. That keeps size consistent and keeps tooling costs under control.

The biggest win is avoiding a second setup. You’re not flipping the part. You’re not re-indicating it. You’re not trying to hit the same bore location again from the other side.

Everything stays in one setup, so the back spotface stays concentric to the hole that was drilled. Cycle time drops, handling drops, and repeatability improves.

This tool shows up a lot on aerospace parts, hydraulic components, housings, and structural parts where bolts or fasteners seat on the far side of a wall. Any time you need a clean, flat surface on the back side of a hole and access is limited, this tool solves the problem without making the job more complicated than it needs to be.