Guitar Building

Tenor Ukulele Side Bending Machine

so i got really frustrated trying to bend uke sides on my bending iron, i dont have the patience for it and i kept cracking them, so i built a Fox style bending machine

for heat it uses 2 100 watt bulbs, wired in series.  they heat up the steel rods that ring the edge of the form and also the aluminum top of the bending surface.  the wood rests between the aluminum top and the copper bending strap.

the bending strap has a whole bunch of holes drilled into it to let the steam from the wood escape so there should be little spring back when the sides are done.

once the wood starts to bend, you cinch down the clamp at the waist by turning the screw, and pull down the sides with the eye-bolts.  the eye-bolts secure into the slots on the stand, and finally the sides are clamped down with the plywood/screw/wingnut clamp

it takes about 25 minutes to reach 190 degrees

after the first test it ran into some issues...
the adjustment screw chewed up the piece it pushes against pretty bad, this will need to be fixed and probably can be with a washer and a couple of nuts so as to have the washer push against the top of the waist clamp.

also, it did really good bending the upper and lower bouts but it cracked the wood at the waist.  i plan to try different options including boiling the wood before bending as opposed to just soaking it, or even giving that bend a head start on the free bending iron before putting it in the bending machine.

more progress updates to come

I finally got around to giving this machine more test runs and found the secret to it working... I now pre-soak the sides for 20 minutes, and pre-bend the waist on the bending iron.  when I put the sides into the bending machine it is warmed to ~200 degrees and that seems to work like a charm.  also, the sides are thinned to .19"

I call that a win.  there will be more updates about these sides in the ukulele page

Thickness Sander

i have been working on a thickness sander for thinning ukulele and guitar tops/backs/sides.  at first i intended to buy one but the cheapest one i could find that would suit my needs was around $1400... way too much.

the motor is a 1/2hp motor i picked up for $100, $15 for bearings, $20 for pulleys and $4 for the V-belt. the hardest part was getting the steel rod that i used as a drive shaft to fit inside the pillow block bearings, they had to be bored open a little wider with a dremmel.

the drum is made from 24 pieces of 3/4" thick MDF which gives me more than enough room to thickness an acoustic guitar body.

the discs of MDF were epoxied to the shaft

the belt is tensioned by the weight of the motor, its mounted to a board which is hinged to the frame

the work table is made from shelving material, chipboard with a nice smooth surface for sliding the wood under the sanding drum.  the table is raised up and down by the adjustment screw under it, and the whole table top is hinged on the out-feed side.

with the motor all wired and working it is time to true the drum with some sandpaper attached to a very flat board

nice and straight and flat

the drum gets coated with some lacquer to protect it from dings and humidity

wrapping the drum with the velcro was much more a pain in the ass than i ever thought it would be, the angle must be perfect so that the strip wraps around the drum and lands perfectly next to itself... you cant really pull it left or right to adjust it or else you wind up with ripples in the velcro which translate to high points on the sandpaper and a poor sanding job.

a quick note about the build, just for anyone who may want to make one of their own... this is not an original idea by any means, there are tons of examples of these on the interwebs, but these are the things i wish i would have known prior to starting...

vibration issues:  
vibration is a huge issue with these sanders.  mine started out on wheels but they only amplified the vibrations to the point where the whole unit skittered across the floor when first plugged in.  dont put it on wheels.  if you are like me and want to cut costs, don't go for the steel rod from the hardware store as the drum's shaft, they arent perfectly round making them a bitch to fit into the pillow block bearings and if they arent perfectly straight they will give you more vibration when sanding... get one off the internet that is meant for an application like this.  if you do decide to get the hardware store steel rod, make sure when you are not using the sander that you always raise the table up so the drum rests on it, this should keep it from sagging and bending from the weight of the drum.

some things i found that help the vibration issues:  

1. ditch the wheels.  just forget them.  i now have felt pads under the legs of the stand to further cut down on vibration.
2. using the weight of the motor to tension the belt is fine, but if things aren't perfectly lined up the motor will bounce and shake the whole unit.  i used a couple of springs to act like shock absorbers for my motor mount
3. the drum, before it is sanded true, will itself produce a ton of vibration-with the drum unbalanced it acts like a huge vibrating cell phone motor.  try to get it sanded nice and perfectly round before trying to troubleshoot any other issues

finished the sander today, yay!  i made it a dust hood (and finger protector) which actually works pretty good... the sander was made to live in the garage and the actual dust collector lives in the basement, so this had to hook up to a shop vac.  the shop van does a much better job than i thought it would, not perfect by any means, but much much better than nothing at all.  i also attached a piece of paneling to the table top; on the out-feed side there was a small ridge where the table hinged, which was just enough to flex the wood being sanded and sand a dip/low spot into the board... with the paneling in place the problem is gone.

the dust hood has a plexiglass front and back so i can watch the drum spin and make sure the sandpaper doesn't start to peel back or anything.  i took it for a test drive and it did everything i expected it would do... actually it works a bit better than i had expected.

done.  cant wait to start on the next stringed instrument.

Fretboard Slotting Jig

Just finished a new jig to slot fretboards

the fretboard rests against the fence, and the whole work surface slides across the blade- which is mounted on an incline which causes it to gradually give a deeper cut as the wood moves over it.

it uses a .5mm Japaneese hand saw blade and the depth of the cut is adjusted by the bolts shown in the picture below.  it gives a real nice fret slot, the same depth every time.

"Pearl" Dots

i now have a setup allowing me to cut my own pearl dots for fretboard inlays.

the dots are not pearl though, not even truly abalone... they are cut from shells collected at a local park's lakeshore, but they are beautiful none the less.  the picture doesn't do them justice, they have a lot of fire.

they look right at home between some frets.  (not centered, i know... relax, it's just a test piece)


i built this guitar in the fall of 2010.  the body is black walnut with a through maple neck.  Bigsby B7 tremolo, Jazzmaster Buzzstop, Seymour Duncan pickups (sh-1 bridge and TB59 neck) with nickel pickup covers, tune-o-matic bridge and Grover locking tuners.  and yes, i realize i installed the tuners upside down