Syzygy ... » Hints and tips

Threaded wooden dowels

Keith Larrett — Mon, 25 Jan 2010 12:23:12 +0000

I spent some time this weekend organizing my workshop. It often feels like I spend more time organizing my workshop than I do working on stuff. A big part of the problem is I keep on buying stuff and then I have to find a home for it in an already crowded space. A smart person might realize this and quit buying stuff, I prefer to spend my weekends trying to find a place to put it all

Something that has been bugging me for a while is where and how to store my donut chuck. I use it often so it needs to be close to the lathe, but at just under 16″ diameter and consisting of a couple pieces 3/4″ plywood along with a heavy dedicated face plate, it is fairly bulky and heavy. Inspiration struck me and I decided to hang it on the wall behind my lathe using a threaded wooden dowel. The following post shows how I threaded the dowel with 1 1/4″ x 8 threads to match those on the face plate. Thanks to Al Hockenbery for the advice he gave me on the AAW forum.

The first step was to measure the large diameter of the threads on my lathe. Strangely enough that came to 1 1/4″. Who would have guessed that! Now I know why it is called a 1 1/4″ x 8 thread!

I then rounded a piece of scrap wood between centersto the same diameter, tapering one end slightly.

Then, using the faceplate that I had dedicated to my donut chuck, I cut threads in the dowel. Tapering the end of the dowel helped a lot in getting the threads started. I also found that reducing the overall diameter of the dowel from 1 1/4″ helped as well. Once I had done this, screwing the dowel into the face plate and cutting the threads, was a lot easier. Making the dowel about 8 to 10″ long also helped as it gave me a decent place to grip with both hands. The threads did not look as good as those on a metal bolt, nor were they as deep, but they worked just fine.

Once that was done I mounted the dowel in a chuck and predrilled a hole for the screw that was going to be used to attach the dowel to the plywood.

Measured to length and parted the dowel off.

Not trusting the holding power of a screw into plywood, I put some wood glue on the back of the dowel before screwing it to the plywood partition. I was concerned that when I unscrewed the donut chuck from it’s new resting place, that the screw holding the dowel on would unscrew from the plywood. Here is a shot of the threaded dowel mounted.

A shot of the donut chuck screwed onto the dowel. I made the dowel about 2 1/2″ long, giving me room to hang the front section of the donut chuck on the dowel as well.

Excited with my new threading abilities, I made some more threaded dowels, and decorated the wall with my sanding disc and my vacuum chucks as well. I was surprised how well the wooden face plates on the vacuum chucks threaded onto the wooden threaded dowel. They actually threaded on easier than the metal faceplate on the back of the donut chuck. I did find that a dab of paste wax on the threads helped lubricate them.

Spindle and tenon gauge

Keith Larrett — Tue, 15 Dec 2009 22:53:48 +0000

I was getting tired of reaching for my calipers and setting them to my chuck diameter every time I needed to turn a tenon. The alternative was trying to “guesstimate” the diameter needed and very often I would turn the tenon to small. So I made a spindle and tenon gauge.

I have a set of forstner bits and they go from 1/4″ to 2 1/8″ diameter, in 1/8″ increments. I figured that while I was busy making the gauge, I might as well go ahead and include all these diameters.

I used a piece of 1/4″ hardboard. It was thicker than my parting tool, so I ran it through my drum sander a couple of times until it was just slightly thinner than my parting tool. This is probably not necessary for most applications, but I thought it may be useful occasionally when I wanted to make a parting cut in the middle of a piece and not have to widen it in order to insert the gauge.

Then I drew two lines down each side of the hardboard, just over one inch from each edge. I set my drill fence so the center of the forstner bit was positioned over one of the lines. Then, using a scrap piece of wood as a backer board, I started drilling holes, from big to small, down one side and up the other side.

When all the holes were drilled, I set my table saw fence to the line I had previously drawn, and with two passes, cut all the circles in half.

The gauge now hangs within easy reach of my lathe and is perfect for sizing tenons and checking spindle diameters. A quick, easy and cheap solution that makes my work flow at the lathe easier

If you have a hint or tip feel free to share in the comments section.

Uphill and downhill – cutting with the grain on a lathe

Keith Larrett — Sun, 08 Nov 2009 14:33:29 +0000

Uphill or downhill. Cutting with the grain or against the grain. Understanding how the grain is orientated on the lathe and which direction to cut in order to get the smoothest cuts possible can be confusing.

Brian Clifford has a great article on his site The Woodturners Workshop which illustrates these concepts very clearly. Here is an brief extract from the article. To read the full article please visit Brian’s site here.

7.1 Introduction

In the previous chapter, in thinking about the way the tool cuts, three important factors were temporarily ignored. These are :

the question of grain and its direction

the rotation of the work-piece

the fact that the cutting edge is often held at an angle to the direction in which the wood is moving (the slicing cut)

7.2 The concept of grain

The cells of the wood, which take the form of hollow cylinders, join together to form strands of fibres which lie in a uniform direction which is more or less axial either to the trunk or to its offshoots. The lay of the fibres is commonly referred to as the ‘grain’.

Diagram 7.1 Primary forms of cutDiagram 7.1 shows a block of wood in which the grain is running longitudinally. Three tools are shown as if about to make cuts in the directions indicated by the arrows. These illustrate the three primary forms of cut; as defined in the common expressions of:

cutting along the grain (A);

cutting across the grain (B);

cutting end grain (C).

In practice of course, particularly in woodturning, there is an infinite range of variations on these cuts. Not only can any number of intermediate positions between those shown be taken up but the edge of the tool does not necessarily have to be held at 90 degrees to the direction in which the wood is moving. It should be noted that in Diagram 7.1 the wood is assumed to be stationary and the tool to be moving. Often, in woodturning both the wood and the tool are moving, but with the wood moving faster than the tool. For the purposes of analysis, in this particular context, this does not matter; all that we are concerned with here is the movement of the wood and the cutting edge in relation to each other.

7.3 Cutting along the grain

Anybody who has worked wood with a hand plane will know that it is desirable to plane with the grain. Diagram 7.2 illustrates the common situation in which the fibres of the wood lie at an angle to the edges of the wood block.

Diagram 7.2 Planing with and against the grainWhen the wood is planed with the grain any splitting between the fibres takes place above and in front of the cutting edge, which subsequently severs the fibres neatly, so leaving a clean surface, as shown in Diagram 7.3.

Diagram 7.3 Cutting with the grain
Based on: Bruce Hoadley, Understanding Wood, The Taunton Press (1980) – p150

If an attempt is made to plane against the grain the cutting edge picks up the ends of the fibres, lifting them out of the wood, so that they break off in an irregular manner leaving a rough finish. This is illustrated in Diagram 7.4.

Diagram 7.4 Cutting against the grain
Based on: Bruce Hoadley, Understanding Wood, The Taunton Press (1980) – p150

Drilling a pen blank on the lathe

Keith Larrett — Tue, 02 Jun 2009 01:16:37 +0000

I drill all my pen blanks on the lathe. It takes a little bit longer than using a drill press, but I find it to be more accurate, both in terms of the hole size and drilling through the center of the blank. The later is particularly important when drilling a segmented blank, as you need to drill directly through the center of the design.

I’m sure others have slightly different techniques, so feel free to post any comments or tips on something I may not have mentioned.

The pen blanks I show here are cherry. A customer ordered a couple of Perfect Fits and supplied a slab of cherry from which I milled these two blanks.

You can click on any of the images to see a larger version.

The first thing I do is mark the center of each end using a center finder and a marking knife. Once I locate the center I will mark it with a spring loaded automatic punch

I will then mount the blank on the lathe between centers and knock the edges off with a spindle roughing gouge. Then, starting at one end of the blank, I will turn it round to 3/4″. I use a 3/4″ wrench as a gauge. Once the wrench drops over the blank it is at the correct size. Moving the wrench to the side will burnish the wood and show you clearly where the blank still needs to be turned down.

Once the blank has been turned down to 3/4″ diameter, I move the tool rest closer to the blank and rest the tubes on it and the blanks. Looking at the grain, I mark where I plan on cutting the upper and lower barrels. I normally cut my blanks using a crosscut sled on my table saw, so I allow for the kerf of the blade between the upper and lower barrels. I also mark the two barrels and draw a couple witness lines at the center band.

Then I’ll sharpen my drill bits. I use a set of Harbor Freight bits and sharpen them using a Drill Doctor I sharpen them using the 135 degree setting. I’m sure plenty of people will swear by more expensive bits or a different angle, but this is what I use including when I’m drilling blanks segmented with aluminum or brass. So far it seems to be working, so I’ll stick with it.

The shot below shows the tools I use to do the actual drilling on the lathe. From left to right, PSI collet chuck, center bits and 1/2″ drill chuck. I found that when I started using the center bits, my drilling on the lathe really improved. A big thanks to “rherrel” on the IAP for turning me on to that!

When I mount the blank in the collet chuck I will orientate it so that the entry hole is on the center band side. Using a center drill that is slightly smaller than the drill bit I need to use, I will drill a starter hole in the blank. The tail stock is locked down on the lathe bed. As I advance the quill in the tail stock by rotating the handle with my right hand, I will apply pressure to the lock lever with my left hand, to the point where it starts to become a little difficult to rotate the handle. I find that pressure on the quill seems to stabilize things a bit and reduce any possible vibration.

Then I will mount the drill bit in the drill chuck, and applying pressure to the lever, start drilling the blank. I run my lathe between 400 to 500 rpm while drilling. I will typically drill about 1/2 to 1″ at a time. If I see the flutes are clearing the chips then I’ll keep on drilling. The moment I stop seeing chips being ejected, I will stop the lathe, back out the tail stock using the wheel, clear the flutes, advance the whole tail stock forward, lock it down, turn on the lathe and start advancing the drill bit by rotating the wheel. I’ll repeat this until I feel the drill bit exiting the blank.

Before I remove the blank from the collet chuck, I will push the tube into the hole to check the fit and to confirm that I have drilled deep enough. Here are shots of the tube in the blank showing both the entry and exit holes.

Then I’ll repeat the procedure on the other blank. Once done, I’ll mount a 60 degree live and dead center in the lathe and sand the tubes with some 100 grit paper.

Back at my workbench I plug the tubes with dental wax. Then I’ll coat the inside of the blanks with gorilla glue using a q-tip, dip the tubes in some water and then insert them in the blank with a twisting action. Gorilla glue expands as it cures and sometimes will push the tube out of the blank so I use some small clamps until the glue cures.