Category: Lutherie

In 2015 I started a Musical Instrument Making course at TAFE. This is my record of what I’ve done in that course and since.

Week 8 – Side bending part 2

Posted on by Iain 'Cutty' Carlin

Second side bend

  • Same as first side (couple of notes below)
  • Make sure the waist block on bender is centred correctly to drop into the slot
  • Push down on top as you pull over the blocks – push with left hand while pulling block with right
  • MAKE SURE YOU DON”T LEAVE IT TOO LONG with the heater on – it burns the wood!!!

 First side into guitar mould

  • Put first side into the guitar jig/mould
  • Put in first then tighten up the spreader
  • Cut off excess on ends if spreader won’t fit
  • Tighten spreader and mark sides to centres and cut to centre line

 Cross brace curves

  • Carve curves into the cross brace using a chisel
  • Use thumb planes to taper sides to a point at the top
  • Sand down sided and tops
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Week 7 – Side Bending

Posted on by Iain 'Cutty' Carlin

Side Bending

  • Thickness sides to 2.5mm
  • Cut to 115mm wide
  • Turn on the heating pad to warm up
  • Mark top and bottom and front with white engineers pen
  • Wet side and wrap in alfoil
  • Mark the waist position on the alfoil and insert into bender with bottom to bottom of jig
  • Put springs on clamps and side blocks after inserting wood
  • Heat for 15 minutes – screw down waist till tight then back off 2 turns
  • Pull over spring blocks to bend sides – may need to pull back and repeat
  • Turn off heater after 15 minutes and leave for a week to set bends

Top braces

  • Plane top braces to 15mm high
  • Cut leftover spruce from top to cover top of join in X-braces –  50mm long and as wide as brace
  • Glue and hold down with masking tape

Main brace hole for truss rod adjustment

  • Find centre of top main brace on front, mark 7.75mm up from botom and drill 9.5mm hole(for access to truss rod nut)
  • Chamfer other braces for top so centre is 3mm wide, remember not to go beyond the bottom width
  • Cut small 45 degree angles on ends of small braces to provide slotting into the cross braces
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Week 6 – Cross Brace

Posted on by Iain 'Cutty' Carlin

Notch front X-brace

  • Use sliding bevel to set angles of cuts
  • Use scribe to measure 7.5mm from top and bottom of ‘A’ and ‘B’ braces
  • Notch for smaller braces into bottom of X-braces
    • Mark either side & cut with dovetail saw at 45 degrees then chisel out with 6mm chisel
  • Glue join of x-brace
  • Glue x-brace to front hold down with go-bars
  • Use wood slivers to get excess glue out of smaller brace cut-outs

 Back

  • With block plane chamfer off braces to a slope
  • Sand with 150 till tops are round
  • Clean off excess glue on back by sanding
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Week 5 – Back work and Sound Hole

Posted on by Iain 'Cutty' Carlin

Attaching back braces

  • Use block plane to round off back reinforcing strip, sand to get good finish
  • Cut slots in back reinforcing strip using template to mark distances
  • Saw through slightly and then use 6mm chisel to cut out
  • Plane tops of back braces to an angle so that the top is 4mm wide, but the bottom retains its original width
  • Glue the back braces in between the cut slots and use the go-bars to hold in till dry
    • 2nd from bottom brace goes in first then check it is square with the reinforcing strip
    • Put in the last 3 braces, measuring the distance between left and right sides with the first strip to ensure parallel

 Front work

  • Thicknessed the sound board to 2.5mm on the sander so that inlay is flush with top
  •  Cut sound hole using circle cutting jig.
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Week 4 – More Sound Hole work

Posted on by Iain 'Cutty' Carlin

 Cutting the inlay channel

  1. Block planed the inlays round sound hole till flush with top
  2. With 10mm router bit, but rosette inlay circle to 1.5mm deep. Start nearer neck end in case mistakes are made because these can be covered up by the neck.
  3. Start from the centre of rosette then adjust outwards slowly in micro-steps until the router just starts to cut into the other inlays

Cutting the inlay for the rosette

  1. Cut the inlay to the outside diameter of the channel (can always cut a slot to make it smaller if it doesn’t fit
  2. Then cut the inner side of the inlay based on the width of the channel (not the diameter of the inner edge).
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Week 3 – Reinforcement and Sound Hole Sculpting

Posted on by Iain 'Cutty' Carlin

Back reinforcing strip

  1. Glue reinforcing strip made from cross cut strip taken from guitar top/front.
  2. Burr side up and overlap top and bottom ends on back and glue down. Won’t necessarily be a strip the whole length of back so glue a shorter strip if necessary. Hold down with masking tape.
  3. Clamp down using the clamping/joining jig for 5 minutes. Cover with paper to prevent wood from sticking to clamp bar
  4. Remove clamps and wipe off excess glue and re-clamp for 1 hour

 Cutting circles for centre sound hole decoration and rosette

  1. 1.5mm router bit and special jig on router rotating round a 1/4″ pin.
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Week 1 – Sound board and back

Posted on by Iain 'Cutty' Carlin

So glad I took some of the wood with me, the top and bottom. (AA Sitka Spruce Top Board, Tasmanian Blackwood bottom and sides).

Tonight I joined the top and bottoms together and cut out the back braces. Here’s a summary of what I did:

Making the top and bottom

  1. Michael helped identify the mirror edge of the bottom halves. He lay them on top of each other and looked at the end grain to see that it matched (halves are sawn from the same cross cut piece of timber).
  2. Identify and mark the top side of both halves.
  3. Long plane both top and bottom halves along the join edge.
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