The first step is to measure the glass you will use and calculate the scale of wooden wanted for its construction. For this pattern venture, the peak of the glass, not together with the knobs on the ends, is 7-5/8″ (19cm), and its largest diameter is 3-1/4″ (8cm). I prefer to make a scale drawing, or paper template. This course of takes solely about twenty minutes, and it saves lots of frustration and errors down the road.
Design and Materials
For this glass timer, you’ll need two ends, or bases. (Both finish disks are thought-about “bases” as a result of the timer is flipped repeatedly in use.) Each base is 3/4″ (19mm) thick and 6-1/4″ (16cm) in diameter. You may also want three spindles, every 7/8″ (22mm) in diameter and 8-3/8″ (21cm) lengthy.
Don’t minimize your wooden to those remaining sizes firstly. Always permit a fudge issue for truing issues up on the lathe. For the 2 bases, I usually depart 1/8″ (3mm) additional thickness and a 1/4″ (6mm) additional diameter. For the spindles, add 1/8″ to the diameter, however it’s OK to chop them to remaining size — 3/4″ longer than the size of the glass to permit for a 3/8″- (10mm-) lengthy tenon at every finish.
It is essential to decide on wooden that’s totally dry. Even barely inexperienced wooden will shrink over time, and this could doubtless trigger the glass timer to crack. I used to be capable of minimize all of the items from a single slab of dry, properly figured broadleaf maple. By utilizing a single piece of wooden on this method, all the weather of the construction may have comparable shade and grain.
Buying a Glass Timer
When searching for a glass timer on-line, seek for an “unmounted” hourglass to search out the glass solely, and not using a supporting construction. Most of the hourglasses accessible on-line are flat-bottomed and are supposed to stand alone, however a cup or recess may be turned on each bases to simply accept the ends of the timer.
In my expertise, U.Ok.-based Day-Impex, Ltd. and Wisconsin- primarily based T & K Young produce the best hand-blown hourglasses accessible, however they do price extra. The occasions vary from one minute to 3 hours. Best to buy a timer that fits the wants of the proprietor-to-be, or simply persist with the standard one-hour timer. Glass timers additionally are available in a wide range of sand colours, and in all kinds of shapes and sizes.
Given the low price of timed glasses with a construction on the Internet, it might be cheap to buy one, minimize away the wooden construction, and use the glass timer in your personal hourglass design. This method, you’ll be able to select some lovely wooden and flip the picket components to the next customary.
Turn and Drill the Bases
My favourite method to mount the bases on the lathe is with a glueblock connected to a 2″ (5cm) faceplate. I take advantage of two faceplates with glueblocks for added effectivity and ease of evaluating and remounting the 2 bases whereas they’re in progress. I connect the glueblocks to the bases utilizing 5-minute epoxy.
Once the surface edges of each bases are trued to six-1/4″ diameter and the fronts and backs are flattened, evaluate them. When their sizes match up, align the grain and scribe a single pencil line throughout each items.
Using my paper template, I decide that the middle of every spindle is 2-3⁄16″ (6cm) from the middle of the bottom. With the lathe operating, I switch this measurement to the bottom.
There are three spindles on a conventional hourglass. Having marked the space of their holes from the middle of the bottom, I now have to find out their even spacing and actual places.
I do that utilizing the indexing head on my lathe, together with a jig that holds a mechanical pencil at heart peak. Divide the circle into three equal components and apply these marks to one of many bases.
Now align each bases and switch the spindle gap divisions from one base to the opposite. This course of ensures that the grain on each bases will run in the identical course on the finished venture.
Then I take advantage of a pointy axe to indent the situation of all six spindle holes. Make certain these punctures are fairly deep as a result of they should endure by the sanding of the bases.
Next, drill a gap within the heart of every base to simply accept the knob at every finish of the glass timer. (If your glass doesn’t have knobs, flip a cup or recess to simply accept the ends of the timer.) I decide {that a} gap 9⁄16″ (14mm) in diameter and about 3/8″ deep permits the knobs to seat properly within the wooden. Mount a drill chuck within the tailstock of your lathe and use a Forstner bit to drill this gap in every base.
For a easy embellishment on the bases, flip a cove on the outer edges utilizing a small bullnose scraper. To sand this cove, I wrap sandpaper round a small drill bit and apply it to the spinning wooden.
I then sand all of the flat areas utilizing sanding blocks. Start at 100-grit abrasive and progress to 220.
To take away the bottom from the waste block, half midway by the scrap wooden, then, with the lathe off, use a handsaw to chop the bottom free. Do this for each bases, leaving as little scrap wooden as potential.
A chunk of 60-grit sandpaper pulled over a block of wooden shortly removes any signal of the additional wooden and glue from the waste blocks. Use the shopmade sanding blocks to work your method again to a 220-grit floor on the highest of each bases. Always end your sanding by shifting the block again and forth within the course of the grain.
Use the drill press to bore the six spindle holes utilizing a half″ (13mm) bit, drilled 3/8″ deep . Leave the bit within the drill press for now, because it is likely to be essential to make the holes deeper after the spindles are turned.
Shopmade Sanding Blocks
Perhaps the easiest way to sand wooden flat on the lathe is with the help of a sanding block. You could make your personal double sided sanding blocks by adhering sandpaper to reverse sides of a block of medium-density fiberboard (MDF). I made two blocks, one with 100- and 120-grit sandpaper and one other with 150- and 200-grit paper.
Cut the sandpaper 1/8″ bigger than the block on all sides. Use a sprig adhesive to hitch the sandpaper to the block, one aspect at a time, working in a nicely-ventilated space and following the directions on the adhesive spray can. When the adhesive has dried, use a pair of scissors or a pointy knife to trim away the surplus sandpaper.
Turn the Spindles
Before mounting the spindles on the lathe, I prefer to mark and drill a middle gap in each ends of the clean. These holes assist to precisely information the location of my spur drive and stay heart. Use a drill gauge to search out the best dimension bit for the factors in your drive and stay heart. The heart factors ought to match within the gap however nonetheless depart the spur blades and stay heart cup ever so barely off the wooden.
Mount one of many spindle blanks on the lathe and flip it spherical. Set a caliper to 7/8″ and use a parting device to chop to that depth. Do this about each inch alongside the spindle. Turn away the surplus wooden till you attain the underside of the parting cuts. Repeat this course of on the opposite two spindles, evaluating measurements alongside the best way.
Measure and mark the middle of every spindle, then measure out from this line to both aspect to realize the general size wanted for the glass you’re utilizing (7-5/8″ for this pattern venture). The wooden left on the ends can now be minimize to the tenon diameter, half″.
Cut away any scrap on the finish of the tenons with a pointy knife, and check match the tenons by putting them within the holes drilled within the bases. The tenons needs to be barely unfastened within the holes, and the shoulder of the tenon ought to lay flat on the bottom. It could also be essential to drill the holes deeper or remount the spindle to cut back the tenon diameter.
An easier strategy is to make the spindles tapered on the ends, with out utilizing a tenon and shoulder. This method, you’ll be able to merely trim the ends of the spindles so as to get them to the proper size in your glass.
Adding a tenon and shoulder makes the venture extra technically difficult—you need to make the three spindles precisely the identical size shoulder to shoulder, or there can be gaps the place the shorter spindles meet the bases. But a tenon/shoulder successfully hides the glue gap, is a extra elegant answer, and is my most popular technique.
Once you obtain the proper lengths, remount the spindles and barely undercut the tenon shoulder at each ends. This undercut ensures that solely the surface of the spindle shoulder touches the bottom. This minimize is greatest made with a small skew.
Remounting Tip!
You will doubtless have to remount and tweak these spindles a number of occasions to get the size excellent for the glass timer you’re utilizing. If the spindles are too lengthy, the glass may have a unfastened match; too quick, and you’ll crush the glass throughout meeting.
To make remounting the spindles simpler and extra exact, grind a small nick in one of many blades in your spur drive. This nick leaves a inform-story signal on any clean you mount and compress. If you want to remount a clean, the precise orientation of the spur needs to be apparent.
Dry-fit the Glass Timer
Now you’ll be able to dry-match the glass timer with the wooden items to check the match. I like to put a heavy object (about 5 lbs.) on high to press all the weather collectively and present a great reference for inspection earlier than glue-up. Check which you could simply spin the glass on this compressed setup. Then verify to see if the glass may be moved up and down. If there’s an excessive amount of play vertically, the spindles will must be uniformly shortened. Check that each one six of the tenon shoulders are touching with no gaps the place they meet the bases. Remount the spindles and cut back their size with tiny cuts on the ends till that is achieved. The tip of a small skew does this job nicely.
Considering that wooden strikes with modifications in humidity, it’s at all times higher to have a timer that could be a little unfastened than one that’s too tight.
When you have got a great match of the glass with the wooden, remount the spindles and type small grooves on all of the tenons. I do that utilizing the lengthy level of the skew. These grooves improve the energy of the glue joint of the tenons. This can be a great time to sand the spindles, utilizing a sanding block to keep up flatness.
Apply Finish, Assemble Hourglass
Before gluing the wooden items collectively, apply your end. I desire a hand-rubbed oil akin to Minwax’s Antique Oil.
I desire to attach one base at a time, fairly than all the meeting abruptly. First, I apply some recent oil across the glue holes and on the ends of all three spindles (however not on any gluing surfaces). Then I combine up some 5-minute epoxy and apply a liberal quantity into all three holes and on the three tenons. Once the hourglass is reassembled and the 5-lb. weight is ready on high, the surplus epoxy oozes out of the glue joints. This is the proper time to twist the spindles till the grain course traces up with the bottom.
The undercutting of the tenon shoulders and the appliance of recent oil across the glue joints now come into play. The exterior of the tenon shoulder “cuts,” or separates, the surplus epoxy, and the additional oil creates a floor that the epoxy can’t bond to. It’s only a matter of ready till the epoxy goes from sticky and elastic to the consistency of a rubber eraser. I poke the epoxy regularly to watch its consistency. When the glue resists the choose, I can draw back all the surplus epoxy, leaving three clear joins. Then I do a vigorous rub with a clear rag to take away the recent oil I had simply utilized. I can then insert the glass and repeat this course of for the opposite base. Note that the glass doesn’t obtain any glue; it “floats” between the 2 bases.
Final Thoughts
Understand that most individuals choose up an hourglass by a single spindle to flip it and get the sand operating. Keep this in thoughts as you design your hourglass and determine on the diameter of the spindles.
I now usually make my hourglasses with a detachable finish, in case the glass ought to must be changed.
This is completed with threaded inserts within the ends of the spindles and ornamental toes that serve to cover the screws.
Scott Belway is a woodturner primarily based in British Columbia, Canada.
