Building the Box Dulcimer

Overview:

The handmade dulcimer is a simple first-time “real” musical instrument project. A dulcimer is a long, fretted instrument, designed to be strummed while sitting in your lap or on a table or stand. you play the tune with a small wooden stick pressed against the main string and slid up and down the frets while you strum. You can also pluck and chord the dulcimer with your fingers. Its simple shape and sit-on-top fretboard is easier to build than an instrument with a neck-mounted fretboard like a guitar. The version presented here is a box dulcimer, built in a rectangular shape. It's much easier to build since you don't have to warp the edges to match the traditional hourglass or teardrop shape. If you're a beginner to instrument-making this is your dulcimer.

Materials:

• 3 panels of instrument wood, 1/8’ thick by 18” by 23″
• 1 piece hardwood 1 ¼ inch by 1 1/2 inch by ¼ inch
• 1 piece hardwood, 1 ¼ inch by 2 5/8 inch by 3/8 inch
• 1 piece hardwood, 1/8 inch by 1 ¼ inch by ¼ inch
• Coping Saw
• Hole saw (drill attachment)
• Sabre Saw/Band Saw
• Wood Glue
• Drill and drill bit set
• 1 Very dense hardwood board, 1 ½ inch by ¾ inch by 28 inches for the fretboard
• 4 small screws, 1/8 inch by ¼ inch long
• Set of 4 dulcimer strings
• 4 single peg guitar machine heads (from music store)
• Box of extra large paper clips
• Bastard file
• Pencil
• Carpenter Square
• Electrical tape
• Wood stain and Varnish
• Fine bristle paintbrush
• Paint thinner

Step 1

Cut two pieces of 1/8 inch panel into a rectangle 6-inch wide by 23 inches long. These are the top and bottom pieces. Cut 4 one-inch diameter sound holes in the top piece. They can be any shape, but should be at least a half-inch from the edge and about 7 ½ inches from the heel and front of the top piece. Cut with a hole saw and sand the edges all around on the top.

Step 2
Cut two more strips of 1/8 inch panel 1 ½ inches wide by 23 inches long to make the sides of the rectangular box. Cut two strips of 1/8 panel also 1 ½ inches by 5 ¾ inches for the front and heel ends of the box. Assemble the box by gluing the heel and front strips and the side strips between the top and back panels to create a rectangular box. Set some books on top of the box till the glue cures and sets.

Step 3


This is the full length fretboard described here.

 Take the hardwood fingerboard. Measure five inches from one end. Mark the end of the fingerboard ½ inches from the bottom and draw a line on the side of the fretboard from the mark on the neck to where the half inch line touches the edge of the end of the fingerboard. Trim the end of the fingerboard so it slopes downward from the 5 inch mark to the end of the fretboard. This is where you will install the tuning pegs. This is the headstock.

The headstock can also be extended past the end of the box as shown below to allow you to install standard banjo or guitar tuning pegs. The fretboard wood is 28 inches to allow you to construct a proper headstock if you want.  You can also cut off the fretboard to the length of the box and attach tuning pegs at the end as shown in the short fretboard below.  I like the longer version with banjo or individual machine heads.  They seem to hold their tune better than friction pegs.  Simply drill holes in the headstock for the four tuning pegs you'll need and screw them in place as shown.  If you elect to build a three string dulcimer, you only have to install three tuning pegs.  I prefer the doubled melody string with two single drones.

Step 4

This dulcimer has an extended carved headstock

Measure 1 ½ inches form the heel of the fingerboard. Measure 4 more inches. Use the band saw to cut a shallow 3/8 inch deep dip in the fretboard for a strumming hole.

Step 5
Cut two bridges from hardwood. The one for the heel should be 1 ½ inches wide, 1 ¼ inches tall by ¼ inches thick. The second is 1/8 inch thick by 1 ½ inch by ¼ inch tall.



This is an alternate short fretboard with a gap for strumming

 Step 6
Glue the fretboard to the top of the box in the center so that the heel end is 1 ¼ inches from the heel of the box. You will have to calculate where to glue the bridge before you mark and set it.  The fret calculator link in step 9 should help you figure out how far apart to place the bridge at the lower end.  The nut as the bridge-like structure at the top of the fretboard by the tuner machine heads is properly called is glued to the top of the fretboard and the frets are calculated from the nut (step 9). When the bridge has set (24 hours) glue the heel bridge into place at the end of the box. When that sets, glue the 1 ¼ inch by 2 5/8 inch by 3/8 inch hardwood square to the heel of the fretboard over the bridge and end of the box to create a heel plate for attaching the string holder screws. Cut a 1/8 inch wide groove 1/8 inch deep into the bridge below the headstock where the fingerboard begins to taper toward the end. Glue the second bridge into the groove and let it set.

Step 7
Drill two 1/16 inch holes ¼ inch in diagonally each of the top corner so of the hardwood heel plate. Drill two more pilot holes ½ inch diagonally toward the center from the lower corners of the heel plate. Screw the four small screws into the 4 holes with enough of the heads protruding to wrap a string loop around.

Step 8
Stain and varnish the box end of the instrument and peg head and allow finish to cure and set. Drill four holes in the head stock the size called for in the instructions for setting the guitar tuner pegs. Set the pegs with the keys down and the wire holes sticking up.

Step 9

Calculate the spacing of the frets. You can use an on-line fret calculator or buy a fret spacing guide from several different sources. To determine where to mark the spaces for the frets on the fretboard, measure from the top bridge down the fretboard toward the heel. Cut a groove just narrower than the width of the paper clip wire you are using along each fret mark. Straighten the paper clip wire and tap the wires into the fret grooves, so that the top of the wire extends slightly above the fretboard where each fret was marked. Clip off and file smooth the ends of the fret wires. You can also buy fret wire from a musical supply store to use instead of paper clips.

Step 10
Cut a set of shallow grooves in the top of the bridges. Measure the spacing with the dulcimer peg head to your left if you are right handed or vice versa if you are left. Mark the first groove at ¼ inch, the second at 3/8 inches. This will pair the first or melody string. The middle drone string groove should be marked at ¾ inch and the bass drone string at 1/1/4 inch from the bottom of the bridge.

Step 11
Loop the strings over the screws on the heel of the fretboard. Run the strings through the grooves on the bridges and affix them to the tuning pegs. Tighten and tune the strings to the tuning you’ve chosen to play. There are many different tunings. Standard D tuning for the Dulcimer is: 1st String (bass) D, 2nd String (middle) A, 3rd String and 4th String (melody strings) A.


Summary:
This type of dulcimer is also called a "church" dulcimer. If you'd rather buy one, check out the Mountain Made Music Website where they have a pretty little church dulcimer for about $250.  You can also buy kits and printed plans for various types of dulcimers.  I borrowed pics from several box dulcimer makers to show what one looks like. As soon as I've built my dulcimer, I'll put step by step construction pictures on here.

Links:

Mountain Made Dulcimer
http://www.mountainmademusic.com/default.asp

Osborne A Telier: Building a Mountain Dulcimer
http://www.osborneatelier.com/Dulcimer_01.htm

Folkcraft Instruments: Mountain Dulcimer Building Supplies - Plans And Instructions
http://www.folkcraft.com/p_1482_cat_7000321_hdr_7000336_sort_cattitle_pg_1.html

Quazen: How to Make a Dulcimer
http://quazen.com/recreation/crafts/how-to-make-a-dulcimer/

Howdy Ya Dewit: How to Tell if A Piece of Wood Will Make a Good Musical Instrument
http://howdyyadewit.blogspot.com/2010/08/how-to-tell-if-piece-of-wood-will-make.html

Doug Sparling: Fret Calculator
http://www.dougsparling.com/software/fretcalc/index.php

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Organize Your Coupon Book

Coupon Book Labels for the Nonfanatic

The wife recycled a picture album yesterday to use as a keeper book for her grocery store coupons.  With her disability keeping her out of the workforce, she's decided to at least take a stab at using coupons to cut our grocery bill.  The Queen of Organization came to me to print some labels for her coupon book.  She brought me a list of labels, one for each page in the book (22 pages total - 11 front and back).

She wondered if I could "...make them up on the computer." Once you earn a reputation for being able to do "anything on the computer", the family sends you all sorts of clerical projects.  Since I'm very busy, I did a quick and dirty job of it with Microsoft Word.

Now, I could have gone more elaborate.  Instead I went with a quick MS Word mailmerge.  I may come back to the project later if she sticks with the coupon thing long term and I'll post the prettified version in its place.  She wants me to fix up a larger ex-dayplanner, but I'll have to buy the plastic storage pages at Office Depot, so that will have to wait.  When we get it, I'll do the whole thing up on PageMaker with borders and little pictures and  make it really nice.


For now, though I'm posting the printable label page as a PDF file here.  Click on the link and the page will open in Adobe Reader.  You can also click on the title of this article and it'll do the same thing.  Then simply insert an AVERY 8460 address label or compatible generic label sheet into your printer and print it.  Then it's just peel and stick.  It leaves a few blank ones if you collect coupons for auto parts or sporting goods or something else we forgot.

Have fun with the coupons. I once saved about $40 on groceries with just an hour invested in coupon hunting, so it does work pretty well.  Unfortunately, I have the attention-span of a jackrabbit on a date, so I'm leaving coupon hunting to the wife.  She's good at stuff that requires organization.

How to Tell if a Piece of Wood Will Make a Good Musical Instrument - Part Dieux

How To Do a Tap Test

Wood that your are looking at for a musical instrument can come in a wide range of colors, grain patterns and hardnesses as we saw in my previous post. Depending on the kind of instrument you’re building, you may choose a wood that produces a bright and brassy tone, a soft and mellow tone or a deep, rich tone. The dulcimer at the right was made with a less expensive wood that absorbs some of the sound and gives it a thin, soft tone than doesn't carry well. It's pretty, but nowhere near performance grade sound-wise. Even if you are not an expert, though, and this is your first attempt at building an instrument, you can get an idea of the sound quality of the wood you select for your musical instrument before you start cutting it up. Here's how....

1. Hold up the piece of wood your will be using by pinching the edge of the wood about a fifth of the way down its length. Don't hold it by the top or from the center. Harmonics for a musical chord are divided into what are called fifths.  Turns out the best place to hold something that you want to tap on to hear its true tone, it's a fifth of the way from either end.

2. Put your ear next to the edge to hear the tone of the piece of wood best. You can hear the tone much better from the edge than if you put your ear at the face.  At the face, the vibrations from the wood get muddled.I like to squint one eye real tight when I'm sounding the wood. It makes the wood salesman think I know what I'm doing and he'll bring me better wood and give me discounts and stuff -- that's my story and I'm sticking to it.


3. Give the wood a sharp tap with your knuckle or a metal object. Try both to get an idea of the two types of sounds generated by a padded tapper like your finger and a hard tapper like something metal or wood. Find a place where you can tap the piece of wood so that it doesn’t wobble when you hit it. When you find that sweet spot, tap just above and below that spot to listen to the difference between the sounds.

 4. The wood will have a pitch to it. It may be pitched higher, mid-range or lower more bass tone. There will be a ringing aftertone that persists after the initial tap dies away. This sound will tell you a lot about what the instrument will sound like. Choose a higher pitched piece of wood if you are looking for a brassier sound for an instrument like a bluegrass banjo or mandolin. If you’re building a larger instrument or one from which you need a deeper tone (a viola or bass for instance), you’ll want a wood that resonates with a deeper tone when you thump it.  If you're really having trouble hearing the difference in tone, you should try skrinching up your mouth on one side. The wood salesman will run screaming in terror to his manager.  Only then will they bring out their secret stash of Madagascar Rosewood, retrieved from the hold of the HMS Dingleberry, which sank in the Thames river in 1832 with a cargo of Madagascar lumber, where it soaked for 180 years.  Recovered in 1994, the freshwater-soaked rosewood sheets were dried in the humidity controlled drying sheds of Fishgill, Thimblequack and Dimbulb, Ltd., wood merchants to the greatest luthiers in the world, then shipped to your local wood merchant where they can be had for the ridiculously low price of $9.99 per sheet.  And yes, "skrinching" is a real world. I made it up, but since you understood the word meant "making a face like the one in the picture above", communication, therefore, took place, which is what you use words for.  Call Webster.  Tell him to stop the presses. We've got a new one for the "S's".

5. Consider the shape of the instrument you are designing. A teardrop shaped dulcimer, for instance, should have a balanced, mellow sort of tone. You’ll need wood for the back, where the sound resonates, that has a higher baritone or tenor tone and a pronounced ringing aftertone. If you use a rich bass/baritone piece of redwood or something similar for the top, you can create a harmonic interplay between the two pieces, especially if you “tune” the pieces beforehand by selecting two pieces of wood that make a nice harmony when tapped. Pair a tenor with a baritone harmonic or baritone and bass for throatier instruments.  An hourglass shaped dulcimer produces a deeper, but more crisp sound. Pair a baritone back with a tenor top and you get that full sound while preserving the crispness of the string sounds in the aftertone.

It takes something of an ear for music to do this effectively. If you’re like me and have something of a tin ear, get your wife who has perfect pitch to help you do the selection. You’ll be glad for that extra edge that someone with good pitch brings to the process. The beauty of hand made instruments is that you get to select the pieces of wood and mechanical parts that you want. A musical instrument, lovingly made is a joy to play.

Have fun making your dulcimer.  If you want to make one that looks really odd, hang on a couple of days.  I'll be posting a rectangular dulcimer design that's super easy to build and really unusual. How it sounds will depend entirely upon the wood you use, but as big as the box is, you should get guitar level volume from the thing.  I'm assuming you'd want to build this one out of the harder stuff.  Just guessing.  Haven't found the right wood to build my own version yet.  I'm thinking of building an octagon shaped dulcimer and painting a stop sign on the back. 

Tom

Selecting Wood for Your Musical Instrument Project

Thinking of finally putting together that dulcimer you bought the plans for 10 years ago and never got around to building. A crashing economy and the federal unemployment insurance extension bill give you some time on your hands and you’ve cleaned out the shop three times already? One of the first things you’ll need to do is choose the wood you want to use for that lute, guitar, banjo, dulcimer or violin you’re going to tackle.
 
First lets look at what makes a good wood for a musical instrument.  Tomorrow, we'll talk about how to do a tap test for tone quality.

Age:

• The best wood for instruments is something that’s been sitting quietly somewhere for a hundred years or so, preferably at the bottom of a freshwater river or lake. Some of the best instrument wood around these days is being fished out of the rivers of the great north woods where loggers once floated their harvest to the sawmills. Along the way, some of the denser hardwood logs absorbed enough water to sink. And there they have been sitting for the past hundred to a hundred and fifty years curing. Brave scuba divers have been diving down into the tangled wreckage on the bottom of those rivers and fishing out these monsters and carrying them to special mills where they are dried out and carefully cut up into pieces suitable for the luthier’s art. People who make their living playing music pay top dollar for instruments made from this lumber. Another source for wood is old buildings that were built with whatever would was handy including some very expensive (nowadays anyway) lumber. Some farmer’s used to clear out their old nonproductive fruit trees and build chicken coops, barns and wooden fences from the lumber. Antique furniture, too damaged to restore, can provide you with well-aged instrument grade pieces of wood if you keep an eye out for them at flea markets and garage sales. A friend who is a luthier once bought some wood on a trip to Germany. It came out of a shed behind what she recognized as an old luthier’s shop, now abandoned. The wood had been cut from virgin timber in the Black Forest nearly 125 years before. She made a killing fashioning the wood into violins using an Anton Stradivarius pattern she’d wheedled out of a fellow luthier (considerable eye-batting and sweet talk was involved). Anyway, be imaginative. That ancient rock maple credenza of your Aunt Sophie’s might just have a couple of banjo necks in it. You never know.

Types of wood:

• Five common types of wood for handmade and professional musical instruments include maple, rosewood, spruce, mahogany and basswood. Soft maple is prized for its ability to bend, making curved surfaces easier to form and is used in the bodies of guitars, dulcimers and violins. Harder maples are frequently used as necks where rigidity is essential. Spuce is used a lot in guitar tops and orchestral stringed instruments because of it’s tone. Spruce is a hardwood that has a soft core. This duality makes it a wonderful soundboard, but means you have to put a very hard lacquer finish on it to protect it from damage. Electric guitar makers like dense hard woods like mahogany for solid body guitars because its otherwise dark sound reproduces electrically amplified tones particularly well. Though beautiful, mahogany is seldom used in acoustic instruments save possibly in the fretboard where a denser, more durable wood might be important. Basswood isn’t very pretty despite its fine tonal qualities and is used in instruments that are going to be painted or in drums where a consistent frequency throughout the length of a board is important. Rosewood is also popular for use with fingerboards. Like mahogany it has a very dark tone and if used in the body of an acoustic instrument tends to dampen the sound.

All other types of wood are likely to have one or a combination of the characteristics of the 5 common types above. These basic characteristics include:

1. Strength and durability – Dense hardwoods are good for necks and headstocks, but tend to dampen the sound if used in the body of an acoustic instruments. Electric solid body instruments, however, tend to sound better with heavy hardwood bodies.
2. Flexibility – These woods are used in the sides or in arched backs and tops where the shape of the box creates some special tonal quality the instrument maker is looking for.
3. Tonal Quality—Many woods have, within themselves, special tonal qualities that the instrument maker is looking for that comes from the resonance of the wood itself. Some of these woods are like basswood and don’t have very pretty grain, but with a nice coat of paint, serve well, especially in lower cost instruments.
4.  Beauty--If you can find a wood with an attractive grain pattern, you'll have an instrument that not only sounds beautiful, but looks beautiful as well. 

This list is only a partial list of some of the woods being used by instrument makers worldwide to create beautiful sounding musical instruments ranging from banjos and cellos to tongue drums and bodhrans. The list is broken down by where in the world you can find the wood. This LINK is to a page that shows pictures of the grain pattern of many of these woods.

Argentina and Chile: Angico, Black Mesquite, Rauli Beech
Tropical Africa: Iroko or Afrormosia (African Teak), Panga Panga, Zebrawood, Wenge, Lovoa (African Walnut), Mansonia, Moabi (African Pearwood)
East Africa: Blackwood, Muhuhu, Tambootie
North Africa: Thuya Burl
Central Africa: Wenge
South Africa: African Boxwood, Leadwood, Mopane, Pau Rosa, Pink Ivory, Tambootie
West Africa: Afrormosia, Aniegre, Avodire, Beli, Benge, Bubinga, Doussie, Gaboon Ebony, Ekki, Emeri, Limba, Black Limba, African Mahogany, Makore (African Cherry), Movingui (Nigerian Satinwood), Obeche’, Padouk, Sapele, Shedua,
Asia: Camphorwood, Lebanon Cedar, Merbau, Paulownia, Larch
Southeast Asia: Afzelia Burl, Amboyna Burl, Kwila, Maidou Burl, Narra (New Guinea Rosewood), Thai Rosewood,
East Australia: Blackbean
Australia: Banksia, Bimblebox Burl, Australian Blackwood, Coolibah Burl, Australian Cypress, Jarrah Burl (Eucalyptus), Mulga (Spearwood), Raspberry Jamwood, Sandalwood, Blackbean, Fishtail Oak,
Brazil: Bloodwood, Castella Boxwood, Brauna, Canarywood (Putumuju), Friejo, Gombeira, Imbuya (Brazilian Walnut), Ipe, Jatoba (Brazilian Cherry), Brazilian Kingwood, Lacewood, Marblewood, Partridgewood, Pequia Amarello, Pernambuco (Brazilwood), Peroba Rosa, Brazilian Rosewood, Brazilian Satinwood, Sucupira, Tulipwood, Andiroba (Brazilian Mahogany), Brauna, Gombiera, Pau Ferro, Sucupira
Burma: East Indian Laurel, Burmese Rosewood
Carribean: Blue Mahoe
Celebes Islands: Macassar Ebony
Ecuador: Balsa
England: European Boxwood, English Elm, English Oak, European Walnut, Yew, Bog Oak
Europe: European Boxwood, Lebanon Cedar, European Chestnut, Hornbeam, English Oak, Pearwood, European Plum, European Walnut
Fiji Islands: Yaka
Germany: Acacia, European Beech, Pearwood
Guyana: Kabukalli, Snakewood, Tatabu, Shibadan
Hawaii: Koa, Monkeypod Wood
India and Sri Lanka: Ceylon Ebony, Kokko (E. Indian Walnut), E. Indian Laurel, Palmwood, E. Indian Rosewood, Sisoo Rosewood, Sandalwood, Ceylon Satinwood,
Madagascar: Madagascar Ebony, Madagascar Rosewood,
Maylasia: Jelutong, Damar Minyak
Mediterranean: Spanish Olive (Olivewood),
Mexico and Central America: Balsamo, Bocote, Chakte-kok, Chakte-viga, Cocobolo, Brown Ebony, Fustic, Goncalo Alves, Granadillo, Jabin, Katalox, Mexican Kingwood, Lemonwood, Lignum Vitae, Honduras Mahogany, Mesquite, Prima Vera (Blond Mahogany), Purpleheart (Amaranth), Guatemalan Rosewood, Honduras Rosewood, Mexican Rosewood, Tzalam, Tropical Walnut, , Ziricote, Nargusta
Myanmar: Teak
Polynesia and Pacific Islands: Monkeypod, New Guinea Red Cedar, New Guinea Rosewood, Black Palm
South America: Alerce (Patagonian Cypress) Beefwood or Bulletwood, Spanish Cedar, Fustic, Goncalo Alves, Lemonwood, Honduras Mahogany, Pau Marfim (Ivorywood), Prima Vera (Blond Mahogany), Purpleheart (Amaranth), Rauli (Chilean Beech), Amazon Rosewood, Santos Rosewood, Verawood, Tropical Walnut, Cocobolo (Granadilla), Kabukalli, Nargusta
Spain: Mediterranean Briar, Mesquite,
Surinam: Marblewood
Sweden: Masur Birch
Tasmania: Tasmanian Myrtle, Huon Pine
United States: Buckeye Burl, Mesquite, Red Oak (Spanish Oak), Osage Orange, Larch
Northeastern USA: Basswood, Eastern Hard Maple (Sugar Maple), Eastern Soft Maple
Northwestern USA: Alaskan Yellow Cedar, Port Orford Cedar, Western Soft Maple, Myrtlewood, Oregon Oak, Sitka Spruce, Pacific Yew
Eastern USA: American Ash, American Cherry, American Holly, Eastern White Oak, Eastern Black Walnut
Midwest USA: Eastern Black Walnut
Southern USA: Swamp Ash, Eastern Red cedar
Southwestern USA: Desert Ironwood,
Western USA: Red Alder, Incense Cedar, Western Red Cedar, Douglas Fir, Madrone, Mountain Mahogany, Myrtlewood, California Nutmeg, Ponderosa Pine, Sugar Pine, Redwood, Englemann Spruce, Claro Walnut
Venezuela: Zapatero (Maracaibo Boxwood)
West Indies: Zapatero Boxwood, Cocuswood

Cheap and Easy Cartop Canoe Carrier

Have you got a canoe you want to carry to the lake and only have your sedan to carry it on.  No roof rack? So how do you haul your canoe without buying an expensive strap on canoe rack?  Easy Peasy.  Everything you need is down at Wal-Mart and won't cost more than twenty or thirty bucks.

Here's what you need to pick up:

Three Styrofoam swim "noodles" - the kind with the hole in the middle as shown at the right.

Two racheting tie-down Straps

Here are the tools you need:

1 hunting knife or sharp butcher knife
Tape measure

What else you need:

Canoe with a rope loop at the the bow and stern
Your car

Here's how to do this:

This canoe "rack" doesn't attach to your car, won't scratch your paint and hooks up in less than ten minutes.

Here are the steps:

1. Lay the canoe on the grass right side up as shown.

2. Measure the length of the gunwales (the edge of the canoe) between the thwarts.

3. Split the two Styrofoam noodles lengthwise down one side so that you cut halfway through the noodle as shown at the right.

4. Cut the noodles to fit between the stern thwart and the center thwart and between the bow thwart and the center thwart.

5.  Spread the noodle sections apart and slip them over the the gunwales.  This creates a secure Styrofoam padding on the gunwales where they will touch the roof of the car.  Wipe the noodles to make sure there is no sand on them.  Attached, the noodles look like the picture below.

6. Clean any dirt off the top of the car. Sand between the noodles and the cartop can scratch the finish.

7.  Flip the canoe over and set it on top of the car with the bow and stern extending equally over the front and back of the car (not the passenger cabin).

8.  Run the ratchet tie-down through the rope loop and hook the end hooks under the bumper in front. There are two towing loops under the frame in front that are used in the manufacturing process. They are perfect for attaching the ratchet straps.

9.  Tighten the straps lightly Do the same thing in the back of the car with the second ratchet strap as shown at the right.

10.  Split the third Styrofoam noodle and wrap it around the ratchet straps anywhere it touches the car hood or bumpers to protect the car.

11. Tighten each ratchet strap a little at a time till the canoe is pulled down tight on top of the car's cabin and the canoe rides level.

You don't need a center strap. The 4 point tie-down you've created is very secure and gives you pressure from 4 directions that keeps the canoe from sliding.

Now wasn't that fun (and cheap).   See you on the river.

Tom King