Turning captive rings on a baby rattle
A captive ring is a ring turned from the same blank as the spindle it rides on, then cut free underneath so it slides along the shaft but cannot come off. On a baby rattle the rings are the noisemaker. The whole project comes down to one rule: everything beyond a ring must stay larger than that ring's inside diameter.
Quick answer: Turn a 1 5/8-inch cylinder from dry, tight-grained hardwood such as hard maple or cherry. Cut a band for each ring with a parting tool, round its outside with a spindle gouge, sand it, then undercut it from both sides until it drops free. Keep the ends larger than each ring's inside diameter. If you sell the rattle in the US, it must pass the federal rattle rule, 16 CFR 1510.
Dennis Daudelin's photo walkthrough below shows the whole job on a cherry rattle. Before it, I have pulled together the parts his photos cannot show: how to size the rings, the three ways to undercut them, and the safety rules. Two rattle articles in Fine Woodworking #19 (1979), by Richard Starr and John C. Townsend, fill in most of the details.
The sequence at a glance
- Round the blank and size it with calipers. Dennis takes a 3 x 3 x 6-inch cherry blank down to 1 5/8 inches. Set the speed for that diameter with the lathe speed calculator.
- Lay out the rattle. Dennis shapes the headstock end and a tailstock bead first, then marks a band for the rings.
- Cut a parting-tool groove on each side of every ring band, down to the stem diameter. Starr leaves each band a little wider than the finished ring.
- Round the outside of each ring with a spindle gouge or a beading tool.
- Sand every surface you can still reach. Starr sands each ring before he frees it, with 220 and 400 grit wet/dry paper kept wet with mineral oil.
- Undercut each ring from both sides until it drops free. Make the inside diameter as large as you can.
- Hold or tape the freed ring out of the way, clean up the stem under it, and repeat for the next ring.
- Sand the inside of each ring on an abrasive strip wrapped around the stem, then shape the ends and part off.
Ring sizing: the one rule that keeps the rings captive
| Dimension | Rule | Why it matters |
|---|---|---|
| Ring inside diameter | As large as possible (Starr) | More travel along the stem, more rattle |
| Stem under the rings | Smaller than the ring's inside diameter; bring it to final size after the rings are free | The ring has to slide |
| End beyond the last ring | "Just a little larger" than that ring's inside diameter (Starr) | This is what holds the ring on |
| Widest point of the rattle | No less than 1 inch (Townsend), and it must pass 16 CFR 1510 | Choking risk |
Starr adds a design trick: graduate the ring diameters so the middle ring looks as if it should fall off, held only by the smaller rings on either side. It costs nothing and it is the detail adults notice first.
Why captive rings break: The grain of a spindle runs along its axis, so a ring cut from it has short grain all the way around its circumference. Give each ring enough cross-section to survive being dropped, and check every ring for cracks before the rattle goes to a child. A ring that breaks off becomes exactly the kind of small part 16 CFR 1501 tests for.
Three ways to undercut a ring
| Tool | How it cuts | Strength | Weakness |
|---|---|---|---|
| Toe of a 1/4-inch skew | Paring cut from each side, edge horizontal, handle down (Starr) | No special tool needed | The toe catches if the handle rises |
| Ground dental picks, left and right | Round-headed scrapers made from hardware-store picks (Dennis, below) | Cheap; fits small rings | Slow, light scraping cuts |
| Paired captive-ring hooks | Commercial left and right HSS hooks, sold by turning suppliers such as Lee Valley | Repeatable ring section | Extra cost; each pair suits one range of ring sizes |
I would start with whichever of the first two matches your skew control. Buy the hooks only if you plan to make rings regularly. Keep any of them sharp: a dull hook tears the inside of the ring, and that surface is the hardest one to sand.
Sanding the inside of a captive ring
The inside of a freed ring is hard to reach, so you let the lathe drive the abrasive. Dennis wraps a strip of 100 grit around the stem, grit out, and holds it with blue masking tape. With the lathe running, he holds each ring against the strip and turns it by hand. Starr does the same and adds two details. He wraps the strip clockwise so it does not unwind in use and holds it with a rubber band. He also tilts the ring to round its edges, working up to 400 grit wet/dry paper wetted with mineral oil. If the inside of a ring comes out ragged, Starr starts at 100 grit.
Safety: what a rattle has to pass
- 16 CFR 1510 (rattles): "No portion of a rattle, when tested in accordance with the procedure of § 1510.4 below, shall be capable of entering and penetrating to the full depth of a cavity in a test fixture." The rattle has to pass before and after the use-and-abuse tests of § 1500.51.
- 16 CFR 1501 (small parts): toys intended for children under 3 may not fit entirely within the small-parts cylinder, in any orientation. Pieces that come off during use-and-abuse testing are tested the same way.
- The fixtures: both rules define pass and fail with physical gauges whose dimensions are drawn in each rule's Figure 1. Read the figures on eCFR, linked in the sources below, before you sell or give away a rattle.
- Wood: hard, tight-grained species such as hard maple, cherry, and Bradford pear work well. Starr warns against toxic or irritating species such as African blackwood, wenge, and cocobolo.
- Finish: Starr and Townsend both used mineral oil, because the rattle will go in the baby's mouth. Leaving the wood bare is the other safe choice.
Two variations from 1979
Townsend's hidden-chamber rattle. John C. Townsend's rattle in the same issue has no captive rings. He glues a block cut from 7-inch-long, 1 1/4-inch-square stock around a short bored dowel holding six or seven popcorn kernels, then turns the body. He keeps the rattle no less than 1 inch across at its widest and names cherry, walnut, and apple among the best woods. The glue line is the failure point, so that joint has to be sound.
Starr's linked-ring puzzle. Starr suggests breaking one ring, interlocking it with another, and gluing the break so nobody can work out how it was done. That one is a puzzle for adults. I would not give an infant a ring held together with glue.
Dennis Daudelin's photo walkthrough
The wood in this project is a hunk of cherry. It is about 3 inches square and 6 inches long. It is dry and has been sitting in the shop for about 1 year.
The first step in all spindle work is to make the workpiece round. Here I am using a 1 1/4 inch roughing gouge.
I am using a set of calipers to check for the 1 5/8 inch dimension that I wanted for the rattle.
In this picture, I have now rounded off the headstock end of the rattle (left side), created a bead on the tailstock end of the rattle (right side) and then decided how much room to set aside to make the captive rings. I used a spindle gouge for the shaping and a parting tool for cutting each side of the captive ring stock.
Here is a close-up of the area set aside for the captive rings.
Making captive rings is relatively easy. The first step is to determine the internal stem size and cut out the ring stock. Here I've decided that I have enough stock for 2 captive rings. So, I've cut down to the stem size on each side of the future captive rings. For this step, I used a parting tool.
I have now rounded off the individual captive rings using a spindle gouge.
This is a dental pick that I purchased a the local hardware store. I have ground the tips into round-headed scrapers; one for right cuts and one for left cuts.
Pardon the poor picture but it shows that I've cut under the ring from both sides and the ring has fallen to the right. The wood remaining under the ring is now exposed.
I have taped the first captive ring to the tailstock hub and have cleaned up the stem of the rattle. I'm now starting to cut under the second ring to release it from the wood.
Now the second ring is cut and the wood underneath the ring is exposed and the final part of the stem is now ready to be cleaned up. Once I cut the stem round, I will sand it.
After sanding the stem, I want to sand the bottom (or underneath) of both rings. To do this, I've taken a piece of 100 grit sandpaper and wrapped it around the stem, sandpaper grit out. I've used blue masking tape to hold the tape to the stem The sandpaper is beneath both rings and is ready for the lathe to be turned on. I will hold each ring in my hand as the lathe is running. The lathe drives the sandpaper and I turn the ring and hold it against the sandpaper to clean it up.
Here is the project after the rings have been sanded underneath.
Here is a close-up of the final rings, all sanded.
This is the project that we've made in this tutorial in its completed stage.
Here's a second example of a baby rattle with a thinner handle and a single captive ring.
For another small spindle project, see the step-by-step tutorial on turning a toy soldier ornament.
Frequently Asked Questions
Written by Vince
Vince is a woodturner and the founder of WoodturningOnline. He writes tool reviews, buying guides, and turning tutorials to help woodturners at every level make informed decisions about their craft and equipment.