Keith Larrett

June 28, 2013June 17, 2017

Cast and Threaded Pewter Collar and Finial

The following are my demonstration handouts for the “Cast and Threaded Pewter Collar and Finial” demonstration presented at the 2013 AAW Symposium in Tampa, FL.

Pewter is a non-ferrous metal alloy primarily made up of tin (85 to 99%), with the remainder consisting of copper, antimony, bismuth and lead. Modern pewter’s contain no lead and are actually Britannia metal. One noteworthy use of pewter is the Oscar statuettes. They are made of Britannia metal plated with gold. The melting point of pewter is approximately 375 degree Fahrenheit (190 degrees Celsius). The low melting point and non-ferrous nature make pewter a great candidate for incorporating it into turned pieces. A regular propane torch can melt it and it can be cut, drilled and turned with regular woodworking and woodturning tools.

Pewter can be purchased from online metal stores where you can expect to pay around $20 per pound. The frugal among us can also find it sold in ingot form on eBay, where you can typically win with a bid of about $12 per pound. The eBay sellers are normally selling melted down pewter mugs, plates etc. As such you take your chances regarding the lead content, although many claim the pewter is lead free and include pictures of test results.

Molten pewter being poured into wooden mold, using a “bottom pour” electric melting pot.

While pewter can be melted in a metal ladle, I use a small electric furnace or melting pot made by Lee Precision. This is the same pot used for reloading or casting fishing weights. They cost around $60 and are available from most hunting or sporting goods websites. One of the advantages of using this melting pot, aside from not having open flames in the workshop, is the pot is a “bottom pour”. Molten pewter contains a fair amount of “dross”. These impurities float to the top of the mix. With a “bottom pour” pot, when you lift a handle the molten metal flows from the bottom of the pot into your mold, leaving the “dross” in the pot. I have found the spout clogs occasionally, so I keep a propane torch on hand to melt the solid pewter clogging the spout. A casting thermometer is also very useful.

Molds can be made from a variety of materials. I use both wood and silicone to make molds. The silicone I use is sold by Smooth-On. It is called Heat Resistant Mold Max® 60 Silicone. I use this when I have spent time and effort creating a master and want to be able to cast a number of collars from the same mold. For one off collars I will typically just make a wooden mold. They are cheap, quick and easy to make and the collars poured in them can easily be embellished at the lathe. The wooden molds have a limited life span as the heat from the molten pewter causes them to warp. I use kiln dried maple for my wooden molds. The moisture content of the wood needs to be low in order to minimize the possibility of it turning into steam and expanding.

When casting and pouring the pewter make sure you take all safety precautions.

Never leave the melting pot unattended while plugged in.
Place the melting pot on a ceramic tile.
Wear thick gloves and safety glasses.
Allow the pewter to cool fully before trying to de-mold it. Sometimes it can appear solid on the surface but still be liquid inside.

I typically make my collars between 2 and 2 1/2” in diameter. This size works well for a hollow form from six to 12 inches tall. More important it allows me to easily mount the poured collar in my chuck for further work on the lathe. The first step is to drill a ¾” hole through the collar using a Jacobs chuck in the tailstock. Technically, for the size tap I use the hole should be 47/64”, but a ¾” drill bit is more readily available and being off by 1/64” doesn’t seem to make much difference.

Once the hole is drilled I use a NPS 1/2-14 tap to tap the threads in the collar.

Side note: NPS refers to Nominal Pipe Size. This is different to NPT which will produce a tapered thread. The ½” description can be a bit confusing as well, especially as we have just drilled a ¾” hole! It refers to the internal diameter of the schedule 40 pipe that this size thread is used on. The 14 refers to the threads per inch.

The tap is held on the lathe by means of a Lathe Tap Holder. These are available for purchase, but they are relatively easy to make. I made mine from a section of 1 1/8” aluminum rod which I drilled on the lathe. The idea behind threading on the lathe is to keep everything centered on the centerline axis of the lathe. The first collar I threaded, I did by hand holding the collar in the vise on my workbench. When I put the collar on the hollow form the finial was not plumb and stood at an angle!

The pewter collar being threaded on the lathe.

It is important to use some form of lubrication when threading or tapping metal. Although the pewter is a soft metal and threads/taps very easily, you will get a far better finished surface using lubricating oil. In lieu of actual threading oil I just use some regular 3 in One oil.

Now that the collar is tapped, wipe it down and soak it in some acetone or denatured alcohol to get rid of the excess oil. We now need to mount it to the lathe in order to turn a tenon on the underside and shape the top. I use a “27 cent chuck” I get from the hardware store to do this. A ½” PVC male adapter is held in my chuck and then the collar is threaded onto this.

The underside of the tenon being turned. It is threaded on a ½” PVC male adapter which is held in a chuck.

I turn the underside of the tenon first. I turn a tenon which is slightly larger than the hole in the hollow form. (I find it is easier to size the hole in the hollow form to the tenon than the other way around.) I then reduce the bulk of the collar by shaping the underside. Because the collar is held to the lathe by means of a PVC adaptor, I can cut right to the threads and into the PVC collar without worrying about damaging the gouge.

I then remove the collar from the PVC adapter and rotate it so I can turn the top. Wear gloves when removing the collar from the PVC adapter! The collar will have become pretty tight on the adaptor and the metal edges can cut you. Once the top of the collar is shaped it needs to be sanded/polished before embellish. Any embellishing tool you would use on a box top or spinning top can be used on the pewter. Chatter tools, Wagner texture tool, Sorby spiral tool and the Decorating Elf can be used, and the embellishments outlined with the tip of a skew chisel. These embellishments can also be further enhanced by applying India Ink, allowing it to dry before wiping it off.

The top of the collar being decorated using the Decorating Elf.

India Ink being applied to enhance the embellishments.

When I turn the hollow form I use a faceplate and I do not part the hollow form off initially. I typically hollow end grain and so do not experience a lot of movement as the piece dries. Now that the collar is complete I mount the hollow form back on the lathe and size the opening to fit the lathe. Once I have achieved a snug fit, I attach the collar to the hollow form while it is still on the lathe. I use 5 minute epoxy and put it around the opening of the hollow form. I then insert the collar and lightly clamp it using a 60 degree live center in the tailstock.

The next step is turn finish turning the bottom of the hollow form. Ideally I will allow the epoxy to cure overnight, but if you are careful the epoxy is strong enough to allow the next step within about half an hour. After removing the faceplate from the hollow form, mount the ½” PVC adapter in the chuck and then screw the hollow form onto it. Place a live center in the tailstock and bring it up to support the hollow form. Part the hollow form almost through, just leaving a little nub. Shape the underside of the hollow form and sand. Slow the lathe down and cut through the last of the nub. If you have allowed the epoxy time to cure the hollow form will be secure enough on the PVC adapter that you can finish sanding the underside. Keep the lathe speed slow though!

We now need to turn the finial and attach a threaded ring to it. A simple mold for the pewter ring can be made by drilling a 7/8” hole in a block off wood a couple of inches deep. The pewter is then poured into that. Allow the pewter time to cool. This might take a while as it is a pretty large volume of pewter. To remove the pewter from the mold, drill a hole in the block of wood from the underside and use the knock out bar from your lathe to knock the pewter free. It is then mounted in pin jaws in the chuck; drilled with a ½” drill, turned to 53/64” diameter and then threaded using a Round NPS ½-14 Die held in a Lathe Die Holder. Don’t forget to use some form of lubrication.

You will not be able to thread the entire column as the die will stop at the pin jaws, but thread at least ¾”. What is not used can always be melted and used again. Turn the exposed end of the column true and then part off ½” of the threaded column.

The base of the finial needs to be at least 7/8” diameter or it will just screw right into the hollow form! I leave a tenon on the finial which is about ¾” long and exactly 1/2” diameter before parting it off. The threaded pewter ring is then attached to the tenon on the finial using 5 minute epoxy. Apply the tenon to the inside of the pewter ring and not to the finial tenon. By doing so any excess will get pushed out the ring where it will be turned away later.

The final step is to clean up the underside of the tenon on finial. I do this by mounting a length of 2” PVC pipe using my chuck jaws in expansion mode. In the open end of the PVC pipe I place a piece of scrap wood with an appropriately sized tenon. The wooden insert has been drilled and threaded in the center so that the finial can be screwed into it. It helps if you cut a slit with a bandsaw from the edge of the wood to the center, making a “collet” chuck. The wood is then friction fit into the PVC pipe with the finial inside the pipe and the underside of the tenon exposed allowing you to turn it true.

June 21, 2013June 22, 2013

2013 AAW Symposium ~ Tampa, FL

Things have been quiet on my blog the last two couple weeks as I have been getting ready for the 2013 AAW Symposium being held in Tampa, FL at the end of this month. I will be demonstrating at the Symposium and all of my spare time lately has been devoted to preparing for this.

I’m really looking forward to the Symposium. As well as a great line up of very talented demonstrators there is so much else to see and do. The instant gallery, billed as the largest display of turned wood objects under one roof, is a sight to behold and I plan on spending a couple hours there. There is also the juried exhibition, this years theme is “Currents”. Not to forget the Vendor area where you can pick up that last tool that stands between you and greatness! You can read more about the symposium at the AAW website or download the Symposium Planning Guide.

My demonstration will be on casting and threading a pewter collar and finial for use in a hollow form. I will be doing two rotations, one on Saturday and one on Sunday. If you’re a reader of my blog feel free to say hi and introduce yourself. It would be great to meet you and talk a bit about turning.

Hope to see you in Tampa!

May 31, 2013June 6, 2013

Tissue Box Cover – Part 2

Last week I covered the cutting of the four sides and the top for the tissue box cover. This week I will be showing how I embellished the sides and top with some wood turning.

The first step was to lay the parts out in the order in which they would be assembled.

I then laid out where the opening for the tissues would be and also drew some decorative circles to indicate where the embellishments would go. The center of the 6″ circle falls directly at the intersection of two sides and the top. The center of the 4″ circle falls at the intersection of two sides and the center of the 5″ circle is offset from the intersection of two sides.

The idea is to have the turned embellishments wrap around the sides and top of the assembled box. The layout for the embellishments that fall on two faces is not that critical, however if the embellishment falls on three faces then it is critical that the center of the circle is exactly at the intersection of the three faces, or the embellishments will not flow around all three faces.

I started with the 4″ circle and put double-sided tape on the back of the two faces that it fell on.

I then stuck the two pieces on a 12″ plywood circle which was attached to a face plate. I lined the two pieces up so that the center of the circle was at the intersection of the two pieces.

A couple of notes about the plywood backing. I used two pieces of 3/4″ plywood laminated together and rough cut to 12″ diameter. The double thickness helps to stiffen the piece and reduce vibration and flex at the circumference. The laminated plywood was then screwed to a face plate mounted to the lathe and turned true. It is important to use a face plate with set screws and tighten the set screws to the lathe spindle once the face plate is mounted on the lathe. If you don’t use set screws there is a danger of the plywood continuing to turn after the lathe is shut off, and it will then unscrew itself from the lathe!

Once the pieces are in position I like to apply pressure to the double sided tape for a couple of minutes. I place a scrap piece of wood over the parts and applied pressure with the tail stock. I also applied pressure to the corners of the scrap wood with some clamps. A couple of minutes under pressure makes the double sided tape stick much better.

After removing the clamps, scrap wood and tail stock, I turned the lathe on at a very slow speed and standing off to one side slowly turned up the speed. I let it run for a couple of minutes and then checked to see that the pieces were secure and had not moved. Once I was satisfied they were secure I turned a hemisphere in the center and some further embellishments with a texturing tool and skew.

While turning I kept the speed fairly low, around 1000 rpm.
Don’t skimp on the double sided tape.
Apply pressure to the tape for a couple of minutes to increase the adhesion strength.
Rotate the plywood before turning on the lathe to make sure nothing comes into contact with the tool rest etc.
Keep your hands and fingers behind the tool rest!
Take care removing the parts from the plywood. Slow, gentle and constant pressure will cause the tape to slowly give.

This was the 5″ circle which was offset from the intersection of the two sides. I added a scrap piece of maple to help counter balance the offset weight.

Last, I turned the embellishments that would flow over two sides and the top of the tissue box cover. It was critical that I align the center of this circle with the intersection of the three pieces. I also added a scrap piece of maple in the one corner to counter balance the weight and also to help provide support to the cuts I was making.

I then moved to my scroll saw and cut out the opening in the top for the tissues.

The five parts laid out again.

I laid some clear packing tape across the four sides, flipped them over, applied a thin bead of glue to the four sides, then rolled the parts up into a box …

… and taped it together. The tension created as the tape is stretched when rolling the sides up is more than sufficient clamping pressure for this assembly.

I then applied a thin bead of glue to the four bevels of the top …

… and taped it in place.

The finished tissue box cover.

May 24, 2013June 6, 2013

Tissue Box Cover – Part 1

This week I will be covering the cutting of the four sides and top for the tissue box cover I am making for my wife. The panels are laid out so that the grain will be continuous around the box and the cuts are made on the crosscut sled with the blade set at 45 degrees.

The top and sides are first cut slightly oversize. They need to be clearly marked. I have labelled the pieces with chalk, 3 will butt to 3, 4 will butt to 4 etc. As a lot of the work in this project is set up, I deceided to make two tissue box covers at the same time, hence the A label indicating it is the first of two boxes.

The first cut made on each of the side is the vertical or upright joint on the left. This establishes a 45 degree miter cut that runs at right angles to the base of the cover.

The same is done on one of the sides of the top piece.

A stop block is clamped to the fence of the cross cut sled and the vertical right hand joint is cut on each of the side pieces. While the stop block is in this position, cut the other three sides of the top piece. The top is square and it is important that the length of each side of the top be exactly the same as the width of each side.

The stop block is now moved and each side piece is rotated 90 degrees and the horizontal joint cut. This also establishes the height of the tissue box cover.

To test the accuracy of the joints it is a good idea to do a dry run prior to glue up. The four sides are laid out in order against the fence with the show side up. Some tape is stretched across the pieces …

… and the box is rolled up and taped closed.

The top piece is then taped in place. All the joints look good, so I can proceed to the next step which will be embellishing the sides and top with some wood turning. I’ll cover that in the next post.

May 17, 2013May 17, 2013

Quick and Easy Crosscut Sled

I built a crosscut sled many years ago and it has seen a lot of use. However, I have always wanted another crosscut sled set up with the table saw blade tilted to 45 degrees. Although the blade is titled, the principles behind the crosscut sled and its making are exactly the same if the blade were set at 90 degrees. It is a quick and easy project and will provide a jig which you will use in projects over and over again. A very useful addition to your workshop.

The image above shows the materials needed for construction of the crosscut sled.

A sheet of 1/2″ MDF cut to 2′ x 3′.
Two strips of hard maple sized to fit snugly in the miter gauge slots.
A piece of hard maple approximately 1″x 3″ x 12″ for the bridge. This will not really act as a fence, it is solely there to help keep the two halves of the sled together at the front.
A piece of hard maple approximately 1 1/2″ x 2 x 24″ for the fence. It is important that this piece is jointed so that it is perfectly straight.

Set a couple of washers in the miter gauge slots so that the runners are raised slightly above the surface of the table saw. Set the table saw fence at 18″ and lower the blade completely.

Run a thin bead of glue on each runner. Then butt the MDF against the table saw fence and slowly lower it down onto the runners. Using appropriately sized nails, tack the MDF sheet to the runners in a couple of spots.

The MDF sheet can know be lifted up with the runners in place and flipped upside down. Drill, countersink and screw the runners to the sheet from the underside.

Drill and countersink pilot holes for the bridge and the fence. Drill the holes for the fence slightly oversize. Be careful to position these holes so that they are well clear of the table saw blade!

Clamp the fence to the front edge of the sled and attach it with the screws. Also screw the bridge in place at the front of the sled.

Set the table saw blade to 45 degrees. If you are making a regular cross cut sled, then check the blade is at 90 degrees at this point.

Run the sled through the blade and establish a kerf. If you always use the same blade with the sled then this will be a zero clearance kerf supporting the work on the underside and preventing tear out.

The screws on the fence are now loosened slightly and the fence is set so that it is straight and at right angles to the saw kerf. As you can see, my wooden mallet has been well used since I made it.

This was just a test piece from some scrap plywood. It shows how I will be making the tissue box cover. I was pleased with the results. The vertical cuts were all square to the base of the box and all the miter joints fitted together perfectly.

I mentioned in the previous post how I planned on decorating the tissue box cover with some wood turning. The image is a teaser shot showing where I’m going with that.

May 11, 2013May 11, 2013

Continuous Grain on a Box

I’m going to be doing some woodworking on the next couple of posts. My wife asked me to make her a tissue box cover. Considering how understanding and supportive she is of the time I spend in my workshop it is always nice to have the opportunity to make something for her. I plan on making a tissue box cover with mitered joints. I also have an idea to embellish the sides and the tops of the cover with some wood turning.

The situation does remind me of a joke I saw a while back. Two ladies were talking and the one asked “How is your husbands new woodworking hobby coming along?” The second lady replied, “Great! Can I interest you in a $5000 paper towel holder?”

While not technically a box, as the cover has no bottom, I did want to try and ensure the grain flowed around the sides of the box. Getting the grain to flow across three of the four corners is pretty easy. However to get the grain to flow around all four corners does require an additional step. You need to start out with a piece of wood that is equal in length to the front or back and one of the sides. Further, the board needs to be twice as thick as you need the final sides to be.

Here I have a piece of walnut which I have jointed on one face and edge and then planed. It is about an inch thick.

The next step is to resaw the board in half.

Then each board is cut in half.

I have now reassembled the four boards in the configuration they were before the board was resawn. I’ve also labelled each corner. The next two images show how the box is “opened’ and it should be clear how the grain will flow continuously around the entire box.

Please Note: I am making a square box, which is why I cut each resawn board in half. If you are making a rectangular box you will need to adjust the cuts accordingly. Each resawn board should be crosscut in order to yield the front or back of the box and a side. The diagram below illustrates this.

In closing I want to remind readers that you can have these blog posts delivered to you automatically via email. Just go to https://syzygywoodworks.com/news/ and in the right hand column you will see a box to subscribe to the blog.

May 3, 2013April 28, 2013

Remote Switch for Powermatic 3520B

One of the first modifications I made to my Powermatic 3520B was a remote switch. I had one on my previous lathe and had grown comfortable with it. I like to keep the switch on the lathe bed by the tail stock, so I don’t have to reach through the “line of fire” if I need to switch the lathe off in a hurry.

Most of the instructions you find on the internet for making a remote switch involve relocating the on/off switch only. I wanted to relocate both the on/off switch and the variable speed dial. Being somewhat “electronically challenged” I also needed a simple method that didn’t involve a lot of rewiring. After much searching I finally found the following set of instructions on the AAW Forum.

http://www.aawforum.org/vbforum/showthread.php?p=51600#post51600

It was pretty simple to do. Once I had sourced the various parts it took me about an hour to assemble everything. In essence all you are doing is putting a longer wire between the control panel that holds the on/off switch and speed dial ant the wires in the head stock. I have been using it for over a year now and have not experienced any problems.

I removed the control panel from the head stock and took a couple pictures with my cell phone so that I would have a reference of which wire went where.

Then I went shopping in the electric department at Home Depot.

Conduit box.

Male and female disconnects.

Spade terminals and snap connectors.

Next stop was NAPA auto parts.

10 feet of trailer wire. They did not have 5 conductor wire, so I got some 6 conductor and didn’t use one of the wires.

Total cost was around $35. $15 at Home Depot and the trailer wire cost $2 a foot.

Push the wire through the hole at the back of the head stock. Remove the grommet from the hole first. It’s a very tight fit. I couldn’t get the grommet back in the hole fully, you might have better luck.

Connect all the wires at the headstock side.

Put the connectors on the remote side of the cable. I made the red plug from some scrap rubber. Cut it to fit the conduit box and drilled a ½” hole in it to accept the cable.

I cut the back outlet thingy off the conduit box at the band saw. Then I cut a piece of scrap wood the size of the conduit box. Epoxied six ½” x 1/8” rare earth magnets into the wood and then screwed the wood to the backside of the conduit box. You need some strong magnets. The on/off switch on the control panel takes quite a bit of force to pull out and if the magnets are not strong enough you will pull the remote box off the lathe trying to turn the lathe on.

The back of the box.

I gave the conduit box and cover a coat of appliance paint and let it dry overnight. Before I painted the cover plate I drilled the holes with a ¼” bit and kinda elongated them by pulling them against the bit. The spacing on them is a little close to fit over the holes on the headstock and so some tweaking was needed.

The headstock with the conduit cover in place of the control panel.

The remote switch. It sticks in the horizontal position better than in the vertical position due to the curved sides of the lathe ways.

April 26, 2013April 21, 2013

Custom Live Center Cones

After my last post on turning a sphere using the Soren Berger Sphere Calipers, I received some queries on making the live center cup that holds the sphere during the final stage of turning the sphere. Custom live center cones are easy to make and open up many possibilities for supporting the work piece on the tail stock side. I have the Jet live center that came with my Powermatic and it has 3/4 – 10 threads on it. This is the same size as the threads on the popular Oneway live center.

To make custom live center cones you will need a 3/4 – 10 tap, a 5/8 drill bit and a 3/4 – 10 bolt around 2 1/2″ long.

Mount a block of wood in a chuck, turn it round and true up the face. It is best if the wood is mounted in a face grain orientation, as if you were turning a bowl. The threads that are tapped into the wood will be stronger with the grain orientated like this. Once trued up, drill a hole around 1 1/2″ deep with the 5/8″ drill bit.

To tap the block of wood on the lathe I use the following procedure. First lock the spindle on the lathe. Then position the tap at the mouth of the drilled hole and support the other side of it using a 60 degree live center. Most taps have a hole or dimple on this end allowing you to do this. Then comes the part that requires a bit of co-ordination 🙂 Using a wrench turn the tap and as it threads into the lathe turn the wheel on the tail stock to help drive and support the tap. It is actually a lot easier than it sounds.

You will need to tap the blank deep enough that when threaded onto the live center it bottoms out and the blank makes contact with the live center. This will help to support the live center cone, in much the same way that a blank held chuck jaws is supported by the shoulders of the jaws as well as gripped by the jaws. Check that this is the case before proceeding.

With the head removed from the 3/4 – 10 bolt, mount it in the chuck with a set of pin jaws. Now would also be a great time to release the spindle lock on the lathe!

Screw the blank onto the 3/4 -10 bolt. You did remember to release the spindle lock on the lathe, didn’t you?

The blank can now be turned to whatever shape you need. This custom live center cone will be used to support a goblet while the stem of the goblet is being turned.

The image below shows the finished custom live center cone mounted and ready for use.

A variety of custom live center cones for a variety of purposes. From left to right:

A cone to fit in the mouth of a hollow form and support it.
A cup to support a sphere.
A convex shape to support a goblet.
A cylinder to support a pepper mill.

April 19, 2013April 19, 2013

Using the Soren Berger Sphere Calipers

The gifted among us can turn a sphere by eye. For the rest of us some system is necessary to turn a spherical object. I’ve written previously about a method Al Hockenbery demonstrated on how to turn a sphere. Since then I have acquired a set of Soren Berger Sphere Calipers. They use the same principle as the previous method, but take out the math. The calipers consist of a large set of jaws, which when set to the diameter of the sphere, will automatically set two smaller “birds mouth” jaws to the correct spacing to enable you to turn the cylinder, into a square first, then an octagon and finally a sixteen sided shape, from where it is relatively easy to smooth out the sphere. The image below shows the Soren Berger Sphere Calipers. You can see the large jaws towards the bottom of the picture and the two “birds mouth” jaws toward the top of the picture. The smaller set of “birds mouth” jaws are nearly obscured by my thumb.

The blank that I am turning is a piece of hickory, just over 4″ long and 3″ diameter. Once the blank has been turned to a cylinder measure the diameter using the large set of jaws. Then transfer that dimension to the blank and turn the blank to that dimension, essentially creating a “square” cylinder whose length is equal to the diameter.

Then, using the large “birds mouth” jaws, make four marks on the blank equal distances from the corners of the blank.

Turn away the wood between these marks in a straight line. There are two “shoulders” which need to be turned away. We are now left with an octagonal shape, which contains the sphere.

Using the small “birds mouth” jaws, once again make a mark either side of each “corner” of the blank. This time we will make a total of eight marks. Sorry, but I forgot to take pictures of the small “birds mouth” jaws in action, but you can clearly see the eight lines that are established using them

Things can start to look a bit confusing at this point, so it can be beneficial to color in the spaces between each set of marks in order to clarify which areas need to be turned away. This time there are four “shoulders” to be turned away. As before, make sure the areas are turned away in a straight line. Any concave lines will bite into the sphere. Once the areas are turned away we are left with a sixteen sided polygon or hexadecagon. Regardless of what you call it, you can see that it started to look an awful lot like a sphere.

The next step is to free the sphere from the hexadecagon. I find light cuts and a slow measured approach are the key at this point.

The tenons are then turned down and then cut off with a handsaw with the lathe turned off. It always surprises me as to how small you can turn the tenons if you take care! When the handsaw cut is made, the blade is angled away from the sphere so that a small nub is left. If the saw cut is made straight down then there will be a small indent in the side of the sphere.

The sphere is then mounted between cup cnenters and the nubs are turned off. For a detailed explanation on how to make the cup centers you can refer back to my previous post on turning a sphere.

Once the nubs are turned away, the sphere is sanded and a coat of wax applied …

… and then into the bowl it goes with the rest of them!

April 12, 2013April 14, 2013

Wooden chuck jaws

I needed to make another set of wooden chuck jaws for a project I am working on. Wooden chuck jaws can be quite useful. They are quick to make, cheap and can be custom made to suit a particular project. They have the added advantage that you can hold a piece without the risk of damage from the jaws. The obvious disadvantage is they are not as strong as metal jaws, so care and thought needs to be used in their application.

With these jaws I needed to hold a sphere around 3″ in diameter, so I needed the useful depth of the jaws to be at least 1 1/2″. I say useful depth, because about 1/2″ of the jaws will be taken up by the screws attaching them to the chuck. With that in mind, the first step was to joint and glue a couple 2×4 lengths together. Once the glue had cured, I cut 4 3 1/2″ sections as shown in the image below. I planned on mounting these jaws to my Vicmarc VM120 chuck and so I also needed some M6 x 1.0 pitch screws, 20mm long, that’s about 3/4″.

Using an appropriately sized transfer punch and the regular metal jaws I marked the locations of the eight holes on the four blanks. I also numbered the blanks.

I then moved to my drill press. I drilled a 1/4″ hole at the marks all the way through the blanks. I did this from the underside of the jaws, the side that would be against the chuck, in order to reduce any alignment issues. I then flipped the blank over and drilled a 15/32″ hole almost all the way through the blanks. I set the stop on the drill press so that the drill would stop about 1/2″ from the underside of the blank. That way when the screws were placed in the hole just over an 1/8″ would protrude out the bottom of the blank.

I then moved to the bandsaw and cut the blanks to form a circle.

The blanks were then screwed to the chuck …

… the chuck mounted to the lathe, and the wooden jaws were turned round and the face trued up. Use caution, a slow speed and light cuts, until you are assured the blanks are secure on the chuck. After you have turned the jaws round, and before you true up the face, remember to transfer the jaw numbers to the outside of the jaws.

A cylindrical hole was then hollowed in the wooden jaws. Again, use caution, especially at the bottom of this hole, to make sure you don’t hit the screw heads with your gouge.

A test sphere for the project I am working on was then held securely in the jaws and hollowed.