Archive for the 'Woodturning' Category

Turning a pill box—pt. 2

Published on September 18, 2011 in Woodturning. Closed

Starting the lid

Again I apologize for the delay between posts. Our little start-up company is just porting its software to production servers, and some things are breaking in the process. We’re spending a lot of time testing and talking to the programmers. Our beta test is coming up!

Anyway, I parted the base off the blank and removed the remaining piece from the chuck. I had turned a tenon on the end of the blank which would become the top before parting it off, so it was a simple matter to grip it in the chuck and hollow the top out. The only precision required was in getting a nice suction fit to the base.

I used a digital caliper to measure the little rabbeted ridge on the top of the base, then turned the lid to that diameter. Using a side-cutting scraper, I carefully removed a few thousandths of an inch at a time of wood until I had a tight fit.

Lid holds the base

Since I had a good fit to the base, I could use the lid as a jam chuck to turn the outside of the box and contour the bottom. I tapped the base onto the lid, then turned. Afterward, I sanded and finished the outside of the box and set the base aside.

The next step was to cut the tenon off the top. I removed the lid and put the waste block back in the chuck. Then I turned a rabbet so the lid would fit onto it, making another jam chuck.

Finishing the lid

I didn’t have quite as tight a fit as I would have liked, I wanted to use the tailstock to hold things together. I ran it up to push on the tenon, then turned almost all of the tenon away with a spindle gouge. When there was just a tiny piece remaining, I removed the tailstock and carefully trimmed the last bit off while holding the lid on with my hand. Then I sanded and finished it.

Finished box

That’s it—thanks to the magic of jam chucks. That’s what people used in the days before woodworking chucks, and they were a great solution here.

Turning a pill box — pt. 1

Published on September 6, 2011 in Woodturning. Closed Tags: .
Turned box
The finished, turned box

Little boxes are quick and easy to make, but they offer some interesting challenges in the work holding department. Here’s how to turn one.

This box is about 1.5″ in diameter, so I started with a scrap of mahogany a little larger than that, and longer than needed. I mounted it on the lathe between centers and turned it round.

Rooughout with tenons
Rooughout with tenons

Here I’ve grabbed a Stebb drive center in the jaws of a chuck so I didn’t have to unscrew the chuck, then screw it back on later. I get a little runout (off-centeredness) this way, but not enough to make any difference with this kind of turning. (I wouldn’t do if for a competition top, however). Once I turned the blank round, I cut a tenon on each end.

Parting off the lid

Parting off the lid

With tenons cut, I could put away the Stebb center and grab the piece in a chuck—a necessity for hollowing out the insides of the box. The tenon gives me something to grab onto, and the tenon shoulder serves as an accurate reference against the top of the jaws. This latter part is critical. If I just grabbed the rough blank in the chuck without referencing the shoulders, it would almost certainly move under the stress of turning. And when I unchucked one end and grabbed the other, the two turning axes would almost certainly not line up. An extra minute now saves endless headache later (a lot like the rest of life, I think).

I wanted to preserve the grain match where the top and bottom would come together, so I used my narrowest parting tool—a 1/16″ Chris Stott design (rather like this one), to cut a fine kerf at the dividing line. Here you see it almost cut through.

The box base

The box base

The last steps before unmounting this piece were to hollow the inside to a depth of about 3/8″, and to turn a lip on the edge, so the top of the box would have something to grab. An easy way to hollow end-grain boxes such as this is to use Soren Berger’s Berger tool, which he designed for just such work. After turning, I sanded the inside and finished it with friction polish.

Next time—turning the top, and then the tricky part of blending them together.

Lathe Spindle lock — pt. 2

Published on August 6, 2011 in Tool making and Woodturning. Closed Tags: .

Cones have voids

As I turned, I began to appreciate the difference between a cone and solid wood. Cones have voids, where the little seeds fall out. Even with super sharp tools, I couldn’t keep them all in place. They left pits about 3/16″ in diameter, and I wanted to fill them with something.

The cone had a lot of dark red tones, so I thought some padauk dust would be just the ticket. All I needed was a few tablespoons full of nice clean dust. I sure wasn’t going to generate that with sandpaper in any reasonable amount of time. Sterner measures were called for. A bandsaw seemed like the perfect dust generator.

Resawing for dust

I began by completely cleaning my bandsaw. Then I raided the scrap shelves for a bit of padauk that I could resaw to generate the dust. Since I also teach a veneer class, I figured on killing two birds with one stone: get some slices of veneer and a lot of red dust.

Cone covered with padauk dust in epoxy

The idea worked like a charm, and I wound up with red dust only slightly contaminated with specks of other colors. I dumped it into a plastic cup and picked out the detritus with tweezers. Then I mixed part of the dust with 5-minute epoxy to make a stiff paste and forced it into every void I could see on the surface. I kept the rest of the dust in reserve, in case I needed more later.

As I turned, I uncovered a few more voids, so I was glad to have the extra patching material. Even though it looks gloppy and gross in the photo, almost all of it was turned off, leaving just a tight filling in each of the voids.

Cone, ready to accept the tool shaft

Turning a cone is different from turning wood in an important way—the “grain” follows the petals of the cone. In the photo, it runs from the center of the turning outward and to the left at a very shallow angle. That means I had to turn everything from right to left. I could turn both sides of a bead or cove moving in the same direction—something that’s not very successful with solid wood.

Here you see the cone turned and sanded, ready to have the tool shaft inserted. My plan was to polish the tool shaft, accurately glue It in, then turn the project around on the lathe to complete the bottom of the handle.  More on that next time.

Lathe spindle lock with Pinecone handle – 1

Published on July 31, 2011 in Tool making and Woodturning. Closed Tags: , .

I teach woodturning classes at The Sawdust Shop, where they use 12″ Jet lathes. These lathes lack a spindle lock, which I need when unscrewing chucks and faceplates from the spindle. Jet supplies a screw-in tapered pin for spindle locking and indexing, but it’s a separate little piece. You probably know what happens to separate little pieces in a workshop full of wood chips. Now imaging how fast it happens in a public shop.

The result is that every time I teach a class, i have to go looking for a 1/4″ bolt to serve as an impromptu spindle lock. I decided to make my own, and make it big enough that it wouldn’t get lost in the chips. I also wanted to have some fun with the idea, so I turned the handle out of a pine cone. That decision posed some interesting technical challenges.

You can’t turn just any cone (unless you first want to cast it in plastic). You need one that hasn’t started to open up. That means harvesting it from the tree at an early stage. Mine came from a branch broken by a winter storm.

Cone reversed and mounted by its tenon

There’s no reference surface, so I started by mounting the cone between centers and turning a tenon on the end I though would show the most interesting pattern—the base (to the right in the top  photo). Then I put a chuck on the lathe and mounted the cone in it using that tenon.

As I started turning, I discovered an off-center hole in the cone that would cause a problem as I drilled a hole to mount the brass spindle locking rod, so I filled the hole with epoxy.

Epoxy to smooth the end of the cone

The epoxy was just to give a smooth surface so I could get a centered hole started. I planned to turn it away. However, if the epoxy is to be left for show, it’s important to get rid of any bubbles that get entrained when mixing it up. I used 5-minute epoxy, which I mixed and slathered onto the end of the cone, filling the hole. To eliminate air bubbles, I briefly blew air from a hot air gun onTo the glue. That makes the air bubbles rise to the surface and pop.

Starting the tool hole with a center drill

Once the epoxy had set, was time to drill. To insure a centered hole, I chucked a large center drill in the drill chuck, mounted it in the tailstock, and bored a pilot hole, a little smaller than the final 1/4″ hole. That let me drill an accurately-centered hole for the brass rod, right down the center of the cone.

Next, the special challenges of turning a cone.

Turning a Shaving Brush—part 3

Published on July 7, 2011 in Uncategorized and Woodturning. 2 Comments Tags: .

Cutting internal threads with a machinist's tap

The brush blank was already mounted in the chuck, so this was a good time to turn the outside profile. I could see the brush tuft hole in the end, so it was a simple matter to create a nice shape with adequate wall thickness around the hole. Because this Dymondwood is so tough and abrasive, I had to sharpen several times. The saying in turning is, “if you even think that maybe, possibly, you should sharpen, you should”.
Now it was time to cut threads in that 5/6″ hole, so I could turn the brush around and remount it. Getting taps to cut straight in is always an issue. If the tap’s a thin one and you start at an angle (easy to do if you’re holding the tap in your hand), you’ll often break the tap. The 3/8″–16 tap won’t break in the Dymondwood, but it would easily strip out the threads it’s cutting if I went in off-axis. So I used the lathe to help me.
In the photo you see the tap in a home-made tap wrench (the knurled handles sticking out to each side. That gadget to the right of it is key to the job. It’s a spring-loaded tap guide, held in a Jacobs chuck in the tailstock. Taps often have a slight depression in the tail end, centered on the axis. If you align the spring-loaded center with the tapping axis, put its point into the end of the tap, and bring up a little spring pressure, that will hold the tap on axis as you begin cutting threads. Every few turns you can bring up the spring pressure again as the tap advances into the workpiece. It’s less than $10 and has saved many a threading job for me.
Once the tapping was done, I screwed a Beall Collet Chuck onto my lathe spindle, pushed a piece of 3/8″-16 threaded rod through a collet, and clamped everything securely. Then I screwed the brush blank onto the stub of threaded rod and snugged it up tight against the collet face. Notice, in the photo, the little bit of blue shop towel sticking out around the left end of the brush. That protects the finished rim from the metal collet.

Finishing the end

Once the brush was remounted, it was a simple matter to clean up the end. That’s when I realized it was a little too plain. Fortunately, a friend had given me a little bag of 1/4″ mother-of-pearl dots, the kind luthiers inlay into the necks of guitars. You can find them at Stewart MacDonald, a luthier supply house. I drilled a shallow 1/4″ hole with a Forstner bit (for super clean edges), epoxied the dot in place (slightly proud of the surface), and leveled everything.
I wet-sanded to #12,000 with 3M MicroMesh, which left a high-gloss, waterproof surface. Then I finished by epoxying the brush tuft into place.
I’ve been using the brush for three weeks now, and I really like it. This is a good, fast project that yields something really useful. Now my son is asking for one.

Turning a shaving brush–part 2

Published on July 4, 2011 in Woodturning. Closed Tags: .

Drilling the mounting hole

I hope you all are enjoying this beautiful (and hot) 4th of July weekend. I’m taking a break from all matters corporate and enjoying friends and a little recreational writing.

So, the problem is how to mount our shaving brush on the lathe. We can’t turn it between centers because we don’t want to wind up with a visible hole in the end  from the tail center. We need to mount it from one end, and there are a couple ways to do that. One is by leaving it in the chuck as you see it here, turning everything, then parting the piece off and hand-finishing. But this Dymondwood is HARD, and the prospect of finishing the parted-off stub without power assist wasn’t appealing. So I hid the mounting hole in plain sight.

Once I’d drilled the hole for the brush tuft, I drilled a 5/16″ hole right in the middle of it, about an inch deeper than the bottom of the main hole. 5/16″ is just the right size to accept a 3/8″-16 tap. That tap cuts threads which will screw onto a piece of 3/8″ all-thread, and that’s the stage-two mounting strategy. If this were a softer wood, I could use the mounting screw to cut its own threads, as wood screws normally do. But this stuff is much harder than natural wood.

Cleaning up the rim

With both holes drilled, I cleaned up the rim and trimmed it perpendicular to the turning axis. Now’s the time, while the piece is thick, to do this, as there’s always a danger of pushing a splinter off either the inside or the outside wall when you run the tool across the rim. With material to remove on both inside and outside, I could clean up any problems so no one would ever see them.

Rough-sizing the hole

Now it was time to make the hole fit the brush tuft.

Tufts never seem to be an exact size. The knot of epoxy that binds the hairs together is usually slightly irregular, and it was bigger than my Forstner bit (intentionally). So I trimmed out the inside of the drilled hole to rough size.

Some people do this with a scraper, but Dymondwood is so abrasive it takes the edge off a scraper in seconds. I used a Viking tool, by Soren Berger, which is designed just for hollowing end grain. I got the top of the hole to final size with that tool, stopping frequently to check the hole against the brush tuft. It’s easy to take more wood out of the hole, but a lot harder to put it back, so a go-slow approach pays dividends here.

Scraping the hole to final size with square inside corners

Finally it was time for the scraper. I used a 1/2″ tool with an 80º corner ground on the left side. This way, I can put that point right into a 90º inside corner in my turning and cut either the side or the bottom individually. That makes for a much more controllable, less grabby cut. Since the top of the cut was already the right size for the brush tuft, I just had to extend the walls down to the bottom cleanly. The scraper did it in seconds.

Next comes turning the outside, tapping the hole, and remounting to finish the piece.

Turning a shaving brush – pt. 1

Published on June 26, 2011 in Woodturning. 2 Comments Tags: .
SAMSUNG DIGITAL CAMERA

Summer’s here, and it’s sometimes hard to leave the sunshine and spend time in the shop. But recently my shaving brush died, and I needed to replace it. Meanwhile, some students at the high school where I volunteer also wanted to make such brushes, and the question of how to mount them for turning without leaving holes came up. That was all the excuse I needed to turn a brush and talk about the process.

The parts for brush and stand

Shaving with a brush and razor is a vanishing pleasure in this age of electric everything. But it’s very satisfying—a meditative ritual of whirling up a lather in the soap cup and daubing it on. A nice brush is essential to the experience. So start with good parts.

Several places sell the badger hair tufts at the heart of the brush. I got mine from The Golden Nib, which carries a selection of sizes and qualities. The one in this brush is a 22mm “Super Silvertip”. I also ordered a chromed brush stand and a turning blank for the handle.

Shaving brushes get wet. A lot. If you apply a film finish to a solid wood handle, it will eventually fail with water penetrating small cracks. Varnish lasts longer than shellac or lacquer, but it’s not waterproof. That’s why I opted for a Dymondwood cocobolo blank, also from The Golden Nib. This is a manmade product that looks like cocobolo, but is impregnated with plastic so it requires no finish to look beautiful.

First, turn a tenon

Let’s turn it.

We’ve got to grab one end of the blank in a chuck so we can drill the brush tuft hole in the other, and you can build a problem into your project right at this stage if you go about it wrong. The blank will certainly fit into chuck jaws as is, but it won’t be very stable. Also, since the end may not be square to your turning axis, you may wind up mounting the block at an angle. So the first thing to do is to mark the center at each end, mount the blank between centers on the lathe, and turn a small tenon on one end. The chuck will grab this tenon, and the tenon’s shoulder will bear against the tops of the jaws to provide stability.

Drilling the brush tuft hole

The next step is to drill the hole for the brush tuft. Look at the epoxy button on the base of the tuft and drill your hole deep enough that it won’t show. As I recall, this was about 5/8″ deep. I used a Forstner bit, running the lathe slowly, to get a perfectly round, flat-bottomed hole with a small pit in the center.

Next post—mounting so you don’t wind up with a hole you don’t want in the other end of the blank.

 

Finishing and using the pin chuck

Published on March 7, 2011 in Jigs and Fixtures, Machines and Woodturning. 1 Comment Tags: , .

Grinding the flat

Once the shaft slid smoothly into a 7mm pen barrel, it was time to cut a flat for the locking pin. I clamped the shaft in a vise and removed most of the metal with a grindstone in a Dremel rotary tool. Just as in hand sharpening, I locked my arms to my body, then used my legs to traverse the tool back and forth, about 75% of the way along the shaft. I got a fairly even cut.

The shaft, with its locking nail

Once I’d removed about a third of the diameter of the shaft with the grinder, I filed the cut flat. For this job I used a 10″ single-cut mill file. File teeth are graded relative to the length of the file, so a fine-tooth 10″ file has smaller teeth than a fine-tooth 12″ file, and leaves a nicer finish. A double-cut file cuts faster, but rougher. About 15 minutes of work got me a relatively flat surface along most of the shaft, as you see at left.

The nail I’d originally selected as a locking pin proved too large, so I used a #4 finishing nail instead, nipping off its head first. Here is the complete tool, almost ready for use.

Magnetizing

I say “almost” because, if your shop is like mine, having a little loose part such as the pin is a recipe for grief. It’ll get lost in no time, probably falling into the chips under the lathe the first time I pull a pen blank off it. So I ran the pin and shaft through a magnetizer. It doesn’t make them grip tightly—the pin can still roll so it locks, but it keeps the nail from sliding off the shaft.

In use

Here’s the new pin chuck in use. I held it in a Beale collet chuck (they have less runout than scroll chucks or Jacobs chucks), slid the desk pen blank on, and twisted it to lock it in place. I brought up the tailstock to stabilize things for most of the turning, parted off at the end of the bead, and pulled the tailstock out of the way to clean up and sand the part. It worked like a charm.

A pin chuck for desk pens

Published on March 3, 2011 in Jigs and Fixtures and Woodturning. Closed Tags: , .

The parts of a pin chuck

I was asked to turn a couple desk pens for people to use as they signed the guestbook at an upcoming wedding. Now I’ve turned a lot of pens, but never a desk pen, which sits in a “funnel”, rather than being clipped into a pocket.

Desk pens differ from other pens in that the top section is longer, and has a blind hole—it doesn’t go through the top. Instead, there’s a finial there. That means I couldn’t mount the blanks on a pen mandrel as I’d normally do. I needed a mandrel that could grip the upper pen blank from the inside, and support it as I turned it. What I needed was a tiny pin chuck. Today.

Filing the rod to size

Fortunately, they’re easy to make. Since I was building the pens with 7mm components, I started with a nail and some 1/4″ tool steel (O1 or W1 steels are readily available at hardware stores). 1/4″ rod is just a few thousandths of an inch too big to slide inside 7mm barrels. So I cut off a length, mounted it in a collet chuck on my lathe, and filed it to size. Note that when you file on the lathe, you do it left-handed, so the end of the file is off to the right, away from the chuck. You can really get hurt doing it right-handed, if the end of the file catches in the chuck.

Five minutes later, the barrel slid on easily.

I know filing steel rod to size sounds tedious, but it took no more than five minutes to reduce it to the point where the brass barrels slide on smoothly. There’s not much steel to remove. I polished the rod with sandpapers up to #600, and  then I was ready to cut the flat.

A pin chuck projects into a hole just slightly larger than it is. The chuck’s rod has a flat on it, and sitting on that flat is a smaller rod, such as a nail with the head cut off.

The diagram at left is a view from the tailstock of a hollow tube such as a pen tube mounted on a pin chuck. When the lathe spins counterclockwise, the little rod trapped in the flat rolls to the right, jamming the tube onto the pin chuck. It works amazingly well, jamming into blind tenons and tubes with dependability and repeatability.

Next post, I’ll talk about finishing and using the pin chuck.

How to hit the high notes

Published on January 27, 2011 in Jigs and Fixtures, Machines and Woodturning. 3 Comments Tags: , , .

I belong to a woodturning club, and each month we have a President’s Challenge project, to get us to stretch a bit and try something we wouldn’t normally do. This month’s challenge is “Stemmed”.

The note at an early stage, on the lathe.

I think one of the secrets to success is to figure out what everyone else is doing and don’t do it. In this case, I’m betting a lot of people will turn goblets or pieces of fruit. So I wanted to make a musical note.

I mounted a 3″ diameter chunk of osage orange between centers, and turned the stem down to 5/16″ using classic spindle turning techniques. I left a large round piece at the bottom. At this stage, it looked rather like a top.

The next step was to mount it sideways, gripping that large round section between centers. Then I could turn the section down to become the body of the note. I had to turn very carefully, because that long, thin stem whips around in an almost invisible arc. I turned left-handed so I could cut in close to the stem while keeping my hands clear. You can see the note body (that ball on top) is complete, and I next have to remove the rest of that big wooden round. I’ve remounted it along the original turning axis for the photo.

A Porter Cable trim router is the right size.

Now’s the interesting part. I want to attach a “flag” to the stem, like a musical note would have. That means I need to cut a 1/8″-wide mortise in the stem to accept the end of the flag.

I had a little trim router perfect for the job. But I needed to be able to move it in a controlled way along the centerline of the turning. Time to make a jig.

Here are the guts of the jig.

I started with some scrap melamine-coated particle board, 3/8″ carriage bolts, nuts, and washers. Carriage bolts are nice for jigs because once their square shoulders bite in to the wood, they won’t rotate as you tighten bolts on them. By building the jig as a base and elevated platform, fastened by bolts, I eliminated the need for precision cutting and tricky measurements of router bit height. This jig would be adjustable! (That also means I can adapt it to other routers when this one dies.)

Next—turning that pile of stuff into a jig.