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How to use a flex shaft: Part 7 of 7

Loose ends and tricky business

Each Sunday for seven weeks, we will be posting a different part of our series "How to use a flex shaft"

Well, we’ve reached the end of this series, and this seems like a good place to attend to things that didn’t fall neatly into previous installments, and to trot out a few tricks: nifty things they don’t teach you in school — or in books!


Here are a few doodads that make your shaft more, er, flexible. These rely on the #30 or a similar-style handpiece. 

Drill press

Foredom makes two models: the DP30 and the DP39. Both have stops to allow for preset hole depths; the more expensive DP39 sports a depth-indicator dial. Foredom units are nice and rigidly built.  

2-in. (51 mm) Angle grinder

When I began to work on larger projects (home remodel, sculpture), I came to depend on a 5-in. (12.7 cm) angle grinder, a tool that welders and body shops use. After years working with the flex shaft, that tool just made sense to me. Wouldn’t it be great if someone made a smaller version for the flex shaft, with the grinding disk offset 90° to the handpiece? Turns out that Foredom does. This is great for stone carving, woodwork, and all sorts of projects. A word of caution: Never use it in reverse! 

Belt sander

Two makes of flex-shaft belt sanders translate the advantages of a woodworker’s belt sander to jewelry scale — with the added benefit of variable speed. You can switch and replace belts on each. The Foredom requires a #30 handpiece and uses a belt that’s 9⁄32 in. (about 7 mm) wide. The standard model comes without a handpiece; a kit version includes one along with an assortment of belts. Since the Foredom connects with the handpiece rather than straight to the shaft, it will work on either U.S. or European (slip-joint-style) shafts.

The Kate Wolf sander is a complete unit. It is the handpiece — you simply snap it on or off the flex shaft as you would any handpiece. This sander is designed to work only on U.S.-style key-tip flex shafts and is the more expensive of the two, but it features a wider, 1-in. (25.5 mm) belt. The Wolf also comes with a bench clamp (adjustable to any angle) and belts and is available with the GRS (benchmate) mounting cleat — very nice!


Matt wax trimmer

A good tool if you are carving waxes, this trimmer consists of a flat, adjustable-angle platform that clamps to a #30 handpiece. Set a bur (a large cylinder for trimming ring blanks, for instance) in the handpiece chuck, and rest the wax on the stable plat-form. Then slide the platform up to the spinning bur to provide a consistent cut. It’s like a minature version of a router table. You can use a variety of bur shapes, and I imagine you can use other soft materials, such as wood and plastic, as well.

Mounting clamp

Mounting clamp 

A clamp immobilizes the handpiece so that it becomes a stationary workstation. You can find several handpiece clamps out there, usually two blocks of plastic that grip a #30 handpiece. Some have hardware that clamps to the bench, while others are themselves clamped between the jaws of a bench vise.  

More handpieces!

It’s tempting to start adding attachments to your flex-shaft arsenal and not buying more handpieces. After all, you only really need one #30, right? But in practice, disconnecting the handpiece from one attachment and attaching it to the next can be a pain, especially in the heat of the metalsmithing moment. It’s ideal to have a flex-shaft consigned to each attachment, but who can lay out the cash? (Although, I highly recommend dedicating a machine to the drill press.) A decent compromise for the mobile attachments — angle grinder, wax trimmer, etc. — is to have a #30 hand-piece for each; the assembly can be switched out like you would any handpiece. To the light user, this may sound excessive; but for a professional, where time means money, it’s a good investment. 

Shared foot-control panel 

If you do have more than one flex shaft, and you’re using multiple foot controls, this gizmo is calling your name. You can use up to five machines (one at a time), all with the same pedal. Pull one handpiece/shaft from its slot in the switch panel, and that one goes “live.” No more searching blindly with your foot for the right pedal. Any motor that can be used with a foot pedal will work with this switch. Otto Frei’s the only supplier I can find who carries it.


It doesn’t seem right not to mention the tool that could be seen as the evolutionary legacy to the flex shaft. With the motor contained in the handpiece and no shaft to weigh you down, the micromotor is similar to a Dremel. Different makes and models will vary, but in general, the handpiece is light, agile, and well balanced. It runs smoother, truer, and much faster, and the power supply/control unit can run several handpieces. Most micromotors offer reverse, dial speed or foot-pedal control, and adjustable chuck and quick-release handpieces. Some offer hammer and specialty handpieces — even belt-sanding attachments. Performance varies widely, so do your research!

Cotton swab

Flex-shaft tricks

Swabs and skewers

Cotton swabs, toothpicks, and bamboo skewers make neat little finishing aids for tight places. Use cardboard or wood-shafted swabs; the hollow plastic ones collapse. Snip the swab mid-shaft, and chuck the stump. You can charge the cotton end with tripoli, rouge, etc., and use it as a tiny buff. Or, snip the cotton off entirely, spin the shaft against a separating disk to shape it, charge it, and use it like a hard felt buff. Round wooden toothpicks and kabob skewers can be cut to size, shaped, and used as micro finishers.

Miniscule but mighty

The smallest members of the versatile ball-bur family can be the handiest.

  • Sign your work with a 0.4 mm ball bur. It takes practice and a steady hand, but gets you into places a stamp won’t go. Vary the motor speed for each letter.
  • Use a 0.4 mm or so bur to restore a texture, such as reticulation, that has been compromised by an accidental solder spill or finishing slip.
Pilot mark
  • Use a 1 mm or smaller bur to grind a “kernel” (pilot mark) prior to drilling into a tube or hollow object. Try doing that with a center punch!

Pull it true

I always plan for the worst. If I need to drill a 2 mm (5⁄64-in.) hole dead center in a rectangular sheet, I always start small, below 1 mm, to allow for mid-course correction. A small hole drilled awry can be “pulled” to center with a narrow cylinder or Krause bur. Thread the bur into the hole and grind the side of the hole, enlarging it until the hole is more or less centered. Then, use a larger drill bit to clean up the slightly irregular hole, and finish with a 2 mm (5⁄64-in.) bit.


Make it safe

There are times when a bur with a safe, noncutting side can save the day. Grind the side of a cylinder or inverted cone bur smooth by slowly spinning the teeth against a separating disk until they are gone. Since only the teeth on the end remain, you can use this “improved” bur to refine the bottom of a hole, channel, or bezel without harming the side walls. Also, try “safing” the bottom of the bur or other bur shapes. But remember: There’s no going back!

The lowdown

I have my flex shaft hanging fairly low so that I can hold the handpiece, chuck facing up, steady against my bench pin without over-bending the shaft. This way, I can bring work to the spinning chuck. I can use the side of a separating disk as an abrasive turntable or lap against which I sharpen tools, or I can file a point on a piece of wire by spinning it in my fingers against the disk. The possibilities are endless.

Tube and rod

Tube and rod

Filing a perfect, true end on a tube or rod isn’t rocket science, sure, but it can be done more efficiently if the rod or tube fits in the chuck of a #30 handpiece. Chuck a short length of rod/tubing — under 2 in. (51 mm) long (too long and it will wobble) — and hold the handpiece chuck facing up against your bench pin. Step on the pedal so that the shaft spins forward at a relatively slow speed. Now here’s the tricky part: Hold a flat file flat on the face of the tube nearest you, with the teeth of the file facing into the spin. (If you hold the file in your right hand, the teeth will be pointing to the left. Because the tube is spinning into the file teeth, you will plane the whole face of the tube. No harm will be done if the file is held on the opposite side of the tube; it just won’t cut. Like many flex-shaft techniques, this takes practice.

Ear post

Ear posts

Sometimes it pays to make your own ear posts. The tricky bit is how to get that little safety groove near the end of the post. Using the same basic tech-nique above, chuck the proper length of post wire into the handpiece. As the wire spins, pinch it about 2 mm (5⁄64 in.) from the free end with a pair of slender roundnose pliers, using firm (but not insane) pressure. Lube the pliers’ jaws with wax or bur lube. As the wire spins, the pinching pliers will swage (compress) a necked-in groove into the wire without removing any material and weakening it. File the end of the post true, and then hold the appropriately sized cup bur against it, moving your wrist in a little circle to cut a nice dome on the post end. Finally, flip the wire around and file the solder side flat.

Separating disks

Separate disks

Ah, the old separating disk — great for so many things, like cutting slots or grooves. Stack them on a screw mandrel to produce a wider cut. For cutting multiple, parallel grooves, slots, or tabs, stack two disks with a small spacer between them. The spacer doesn’t have to be fancy: Just drill a hole the same diameter as the mandrel screw in a small piece of metal sheet. The spacer doesn’t even have to be round, just small and even in gauge. The thicker the spacer, the further apart the slots that the disks will cut. And don’t forget that ultra-thin, .006-in. (0.2 mm) separating disks are a great way to cut jump rings. No “accordion action,” and a neat, narrow kerf (width of cut).

Eye screw

Pit pounder

Got a little casting porosity or a pit in a solder seam? Take a trip to the hardware store and buy a small steel eye screw (machine thread, not wood), maybe 1⁄2 in. (13 mm) in diameter. Take a minute to polish the zinc plating off the end, leaving the steel shiny; don’t worry about the threads. Chuck the threaded end into the handpiece and, with it spinning at low speed, firmly hold the loop end of the eye screw against the offending porosity, moving back and forth across it. As it spins, the two sides of the loop act as hammers, pounding the metal and closing the pits. You will still have to finish the metal. I have also used this to upset (edge forge) or thicken the rim of a raised cup -— or any edge, for that matter. The hole in the middle of the eye becomes transparent as it spins, so you can see the work. Sweet!

Cratex hammer

One of the first things I learned in my first post-school bench job was how to put a hammer finish on a wide band. Now, I thought I already knew how to do this, so I cockily stepped forward, thread-ed the band onto a ring mandrel and, wielding my domed hammer, I put a nice, deep planished finish on the band. My seasoned co-workers looked on, jaws agape, as I pulled the band from the man-drel: I could fit my leg through it. Merci-fully, and without further humiliation, they showed me how it’s done. Sculpt the edge of a hard-rubber abrasive wheel (like a Cratex brand extra-fine) into a dome by spinning it against something abrasive, like a separating disk, then use the domed wheel to grind the hammer marks one by one into the properly sized band. Maneuver the wheel a little, and dig into the metal until the mark is how you want it. It looks more like a hammer-finished band than a band finished with an actual hammer, and the band isn’t stretched. Wear a mask.

Well, there you have it. It’s been fun and — I hope — informative. I’ve certainly learned a bunch. There is so much the flex shaft can do, but, like any tool, it can take a while to master. In the end, it depends on the skill of the hands using it. It‘s been my job (and pleasure) to open windows into what this tool can do. Now it’s up to you to open more. Be careful, be safe, and try to think outside the box!

Author’s note: Special thanks to John at Otto Frei, Mike at Foredom, Tevel at Allcraft, and the folks at Rio Grande.

FIND MORE: metal , finishing , stone setting

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