Syzygy - Adventures in Woodturning and Woodworking

Bowl depth gauge

Ever made a lampshade out of a bowl? I’ll never admit to it, but I’ve heard of people hollowing right through the bottom of a bowl

I recently turned a bowl and the bottom was a lot thinner than I liked and getting dangerously close to becoming a lampshade. So I decided to make myself a better bowl depth gauge. Something more accurate than my current method of holding my gouge at the center of the bowl, eyeballing along the rim of the bowl and then bringing the gouge up and out of the bowl to eyeball how deep I was with my hollowing. I wanted something that would be accurate, but would still be quick and easy to use.

A visit to the plumbing section of Home Depot and I returned with a couple two foot sections of 3/4″ PVC, two tee sections, a 90 degree elbow and a cap. The wooden morse taper I turned and the rifle laser was purchased off Ebay.

I cut one of the PVC pipes in half and then cut an 8″ section off the other. (The length of the 8″ section was determined by the swing of my lathe, half of 16″. I cut the other pieces to 12″ as with the current tools that I have I’m unlikely to be turning a hollow form any deeper than that.)

Depending on the laser sight you get some adaptions may be needed to one of the PVC tee pieces. In my case the diameter of my laser sight was slightly greater than the internal diameter of the tee piece.

I mounted the tee piece in the pin jaws of my chuck using a 60 degree live center to help mount it true.

Then, with the lathe speed slowed down, I drilled it out with a Forstner bit that matched the diameter of the laser.

A nice snug fit.

I turned a tenon on the wooden morse taper that matched the internal diameter of the PVC pipe and then I pieced all the parts together.

Here is the depth gauge mounted on the lathe. The wooden morse taper is inserted in the tail stock. It is not necessary to jam it into the tail stock.

Side note: With a self ejecting tail stock it is not considered a good idea to use a wooden morse taper. Click here to read a discussion on this subject.

So, throwing caution to the winds, I mount my bowl depth gauge in the tail stock. Once everything is adjusted and the laser is shining on the tip of the cap, a couple of drops of CA glue can be applied to each of the PVC joints. Don’t glue the laser into the tee piece though, at some point you will need to take it out and change the batteries The laser sight I got has a switch to turn the laser on and off, a lot more convenient than the lasers you get from stationary stores which require you to constantly depress a button for the laser to be visible.

I’m still trying to get a good shot of the laser on the outside of the bowl. When I do I’ll update this post with a picture of the depth gauge in action.

Turning a wooden morse taper

For the technically inclined a Morse Taper #2 has a angle of 1° 25′ 50″, as gleaned from the fountain of knowledge, Wikipedia. For the less technically inclined, myself included, turning a wooden morse taper is a quick and easy project that can be done with some simple measurements.

The first step is to mount a piece of hardwood between centers, or as I have done, in a chuck with a live center at the tailstock for support. True the piece and turn it roughly to size.

Take one of your centers and transfer two marks to the piece indicating the two sides of the taper.

Set a pair of calipers to the diameter of the morse taper upper end, and using a parting tool, part into the piece until the calipers slip over the parting cut. Repeat the procedure for the lower end of the morse taper.

Make a relief cut to the tailstock side that is smaller in diameter than the lower end of the morse taper.

Turn a straight line from the larger diameter to the smaller diameter. You’ll need to sneak up on this slowly and check the line often with a straight edge. I cut up one of those plastic discount coupons to use as a straight edge.

With the piece still held in the chuck, remove the live center from the tailstock and slide the tailstock forward to check the fit of your taper. Rotate the headstock by hand while the piece is in the tailstock to identify the high spots to be turned down. Once the fit is good, round off the end of the piece.

Remove the chuck and insert the new morse taper into the headstock. You can now shape and true up the area that will be used to mount a work piece to. Wooden morse tapers are useful for holding small turnings. They can simply be glued to the morse taper. Bear in mind that there are limitations to the size of a turning as a wooden morse taper is nowhere near as strong as a metal dead center!!

Why did I need to turn a morse taper? Stay tuned

Processing a log for bowl blanks

I often hear turners talk about “free wood”. To my mind there is no such thing as “free wood”. Between the time and mileage spent driving to pick up the logs and the time and energy spent processing the logs into blanks, I often feel it would be easier and cheaper to just buy the bowl blanks!

Cutting your own blanks does have some advantages. The primary advantage is that of re-using or recycling wood that would otherwise be destined for the chipper or the burn pile. There is something very satisfying about holding a finished bowl and knowing that you were involved in the complete process from log to bowl, and you created a functional and beautiful object from some timber that could have just ended up in a landfill somewhere.

However, there is a lot of work involved in processing a log for blanks, and it is frustrating when the end results are just a bunch of checked and cracked blanks. Two very important things that will help you avoid this are:

Process the wood as soon as you can. Ideally you will want to process the log the same day as you get it. When this isn’t possible, try and at least get the chainsaw part of the process done as soon as possible, which will remove the pith and then seal the end grain with Anchorseal.
Remove the pith, remove the pith!!

The picture below shows how I plan on cutting this small camphor log to yield both bowl blanks and some spindle stock. If the log were bigger the spindle stock could be used for hollow forms. This layout is just one possible scenario, the most important thing is that the pith, marked with a red x, is going to be removed and discarded.

Make two cuts down the length of the log, either side of the pith. Don’t cut all the way through with the first cut. In the picture below I have made the first cut and then paused towards the end of the second cut to take the picture. Normally I would have just cut all the way through the log with the second cut.

Complete the first cut.

For the most part this is all that I will do with the chainsaw. I then take the three pieces of wood inside to my band saw. However, some of the cuts that I make with my bandsaw can be made with the chainsaw. I just find the bandsaw more accurate, less wasteful and it’s in the shade

If the log is fairly straight, I set my fence and then cut off about an inch of the live edge. If the log is not very straight then I will just free hand this cut.

Then using the flat section I just created, I will rotate the log 90 degrees and cut it to the desired thickness. If you do not have the capacity to do this on your bandsaw, then this step can easily be done on the lathe when you first start turning the blank.

I have a set of 1/4″ plywood circular discs in 1″ increments which I use to gauge how large a bowl blank I can get out of the log as well as guide me in the cutting of the blank.

From this section of the log I’ll be able to get two small blanks, one 7″ and one 6″. I draw around the discs with some white chalk and mark the circles to be cut out. I could also just nail the disc to the log and leave it in place while making the cuts.

I would then process the other log half in a similar fashion before moving on to the slab I removed from the center of the log. On this slab I cut off about an inch from both live edges.

Then I would set the fence to the same dimension as the thickness of the slab and cut out as many sets of spindle stock as I can, working towards the center of the slab from either side, being mindful of where the pith is. In the picture below, you can set two pieces of spindle stock either side of the pith section which will be discarded.

Here is the yield from the log. Three bowl blanks, two pieces of spindle stock and a section of questionable orientation that I will probably make a sphere from.

This is the reason why the one log half only yielded one blank and the piece of questionable orientation. The chainsaw cut revealed that I had cut through two nails embedded in the log. This illustrates the importance of inspecting the logs carefully before cutting with either the chainsaw or bandsaw. It also confirms my theory about there being no such thing as “free wood”. My chainsaw blade needs to be resharpened now and if I had not noticed these nails they would have trashed my bandsaw blades. I think I may look into buying a metal detector!

The final step is to coat the blanks with Anchorseal. I cut the entire blank, however many people will just coat the end grain and leave the face grain bare. I’ve found the horizontal section of my new log processing platform to be perfect for this.

Log Processing Platform

For the longest of time I’ve been working on the ground when processing my logs with a chainsaw. I had a wooden pallet and I would position the logs on it and then cut them. It worked OK. Often I had trouble securing the logs so they didn’t move while I was cutting them, especially when they were still round. However with the use of wedges and such I normally could work around that and get the job done. And each time the job was done my back was killing me!

So I started looking for ideas as to how I could raise the logs to a more comfortable working high and hold them securely while cutting them. Finally I saw a solution in the June 2010 edition of the American Woodturner, the AAW journal.

The log processing platform was in the “Tips” section of the journal and I’m really pleased with the one I built. It holds the logs secure and steady, has plenty of room for the chainsaw to travel after the cut is complete so the chain doesn’t end up buried in the the dirt, and it raises the logs to a comfortable working height, which my back is really pleased about!

I built mine from pressure treated pine. It took about ten minutes to cut the timber to size, cut some 45 degree angles on the uprights, and then I shot it together using a framing gun and some galvanized nails. The four tall upright pieces are 32″, the two shorter upright pieces are 26″. The gap between the tall pieces is 7″ and the other gap is 4″.

Processing logs with my chainsaw is a far more enjoyable experience. Quicker, safer and less stress on my back. My thanks to the reader who submitted this tip to the AAW Journal.

Installing Concealed Hinges

Installing concealed hinges can be a pretty simple process, even using a hand held drill, with the help of a jig. The Rockler Concealed Hinge JIG works really well at positioning the Forstner bit, as well as holding it square to the door frame surface and finally controlling the depth of the hole. Of course, if you have a drill press with a good fence and large enough table then that will work just as well.

The first step is to mark the center line of where the hinge will be positioned. Then position the jig using the alignment arrows and clamp it in place. Note: the clamp is on the underside, or show face of the door. You can’t see it in the following picture and I didn’t take a picture showing it. Sorry, my bad.

Set the stop collar on the bit guide so the bit drills to the correct depth. I like to drill a test hole in a scrap piece of wood and make sure the hole is deep enough to allow the hinge to fit in without bottoming out.

The bit guide is then positioned over the alignment plate. The wide circumference of the bit guide ensures that the bit is held square to the work surface, important when drilling with a large Forstner bit. As the bit guide fits over the alignment plate it also stops the bit from wandering.