Please see my page: DIY Jeweler’s Workholding System with a Ring Clamp and my short video on this subject.
*Note: instructions, tools and materials are what I used for creating my ring clamp modification – your requirements may vary.
The reason for performing this adaptation on your ring clamp is because the wedge, that usually comes with the clamp, falls out – usually at the most inopportune time. With this adaptation, your work is held securely in place.
Material sizes listed, are for what I used. You may need differently sized bolts, nuts and washers.
- Ring Clamp – make sure that it’s wood. Plastic may work but, I haven’t tried it. Sources of ring clamps: Amazon, Contenti, Otto Frei, Rio Grande, FDJ On Time, etc.
- Bolt: Length is the most important factor. You don’t want it so long that it gets hung up on everything or so short that you can’t screw on the wing nut or open the jaws. My clamp, (at 1 7/8″ down from the top) is: 1 1/2″ wide so, a bolt that has enough room for two washers and a wing nut would be:
- (thickness of two washers) + thickness of wing nut + thickness of ring clamp = minimum bolt size. Don’t forget to add some extra for opening the clamp.
- For mine: (1.52mm x 2) = 3.04mm (1/8″) + 4.51mm (3/16″) + 37.46mm (1 1/2″) = 45.01mm (1 3/4″) bolt. I used a 2 1/8″ bolt because that’s what I had.
- Easier yet: bring the ring clamp to the hardware store and collect the parts there.
- I used two different bolts (once again, ’cause that’s what I had!): one with a 5/16″ diameter and the other with a 3/16″ diameter: one for the bulbous end and the other for the flat end. Both bolt sizes work, as would any sizes in between.
Here’s a mm to fraction converter to help you with this. I measured in millimeters and converted using this converter. I used my digital calipers to measure with.
- 2 Washers – I used washers that matched the bolt diameter.
- Wing Nut – Make sure that the threads of your wing nut are the same as the bolt.
- Digital calipers or ruler.
- Drill or drill press.
- Drill Bit
These instructions are for the type of clamp that I have.
- Measure and mark a spot, anywhere from 1 1/4″ to 2 1/2″ down, from the top of the clamp. I used a Sharpie. Your mark needs to be at least a 1/2″ (1.5cm) above the hinge so, that the clamp still functions and you don’t weaken the wood.
- Choose a drill bit that is the same size as, or slightly larger, than your carriage bolt. You want the bolt to move smoothly in the holes.
- Either using a drill or a drill press, drill straight through both sides of the clamp – all at once. If your holes aren’t level, don’t panic, the adaptation should still work (mine isn’t level). It’s difficult to hold the clamp flat while drilling – especially with a drill.
- Don’t drill one side at a time or the bolt may not slide through easily – this is important!
- Slide a washer onto one side of the bolt, slide bolt and washer into clamp, slide second washer on and then the wing nut.
- Adjust the wing nut to close the clamp.
- If your bolt sits loosely in the clamp, you might want to glue the head in place. Try a two-part epoxy. Otherwise, you may have to hold the head of the bolt when tightening.
- See the second part of this idea, making GRS-style system, for methods of holding your new, modified ring clamp.
Other Modification Ideas
- GIA: Bench Tip #18. Modifying a ring clamp for a bench pin.