VARI-PITCH STRING MUSIC PLAYER

CONSTRUCT A STRING MUSICAL INSTRUMENT ANYONE CAN PLAY INSTINCTIVELY BY EAR by changing length of strings.
It can be made for children to have fun with also.The music  is similar  to a guitar or ukulele.Make one in 3 nights.

     This concept , variable pitch by stretching a string or flexible rubber band ,is  not new . The idea was used by kids for years.
All  that was necessary was to attach a rubber band to a pan and strum the string as one pulled on it.  The difference here is as follows- The string  is now a high-polymer stretchable cord or string that is extremely strong and  can be stretched  to four times its initial  length.
The  string can be found in any arts and crafts store. In fact it was used in other musical instruments that were made for the Instructables site.See :How to make a Mini-Ukulele" posted Jan.14,2010 .by Mistic." for example.
     Any one with a feel for tone can hum a song. If so he can also play this instrument. That's how easy it is.
     Also another improvement was added. More than one string can be added. Here, we used  two strings tuned to be two notes apart as A and C. This  dual tone stays as a dual tone   but changes in pitch as the strings are simultaniously stretched.See picture of the  slider
at its neutral point.

See the picture for tools  used here. Not shown is a small vise which comes in handy when bending plastics for the slider and holding wood for sawing. 
     Item 3 is a dremel[r]  tool and it is used for drilling and sawing a top vent hole  in the resonator box . Item 2 is the dremel saw.
     Item 8 is a small non locking hemostat. but a locking type is best.These are available  almost anywhere..
     Item 9 is one of two drill sizes.  .063 ]1/16in.]   and. 093 for the 5/8 size tuning hook type screw installation.
     Item 7- gas pliers used for closing the open loops of the cup-hook screws used for tuners.
     Item 6 - pliers used to crimp the eyelets or crimp tubes around the strings  at the tuner screws and at the anchor points  at the bridge.
     Item 10 - wood screws used to attach the box to the 24 in. long stock.Pre-drill holes for the screws using the .093 drill  or what ever screws you may have .

All material  used here were either purchased or found in  our junk  pile. The wood for the stock  of 24 in. long was a pine wood.It was
smooth  after fileing and sanding and coated with lacquer.
Ref. assembly dwg.  for Item 1. stock.
Item 2- Front  guide  bridge- any plastic  gift card or stiff .o15 plastic.Plastic guide tube -any semi-hard plastic tube or rod material.
same for the width control .62 in. wide  shown. It is used to keep the strings in the slots from vibrating out if the slots are too wide.
3- Back bridge -- pine.
4-Box- Purchased at Micheals stores. [Cigar box unfinished ,Darice Inc.Strongville Oh.] approx t $5.00
5-6-7-8 Slider.. Has a low friction  plastic attached to it. This plastic was .o19 thick clear package material . Easy to bend  on an vise .
    Same plastic is used for underside of slider wood. Glue to  slider with E6000 glue.Let cure for 8 hours.
9-Crimps- used at anchor and the 3 tuner screws. Small eyelets are best to use at the tuner screws to tie  on strings..
10 String-  Stretch string or cord as used in making jewelry items. 1millimeter dia. about 15 foot spool. [$2.50} [Stretch Magic].

    Ref. Drawing--
First cut all wood parts- slider  ,stock, handle,
Box- sand and dye it and lacquer at least one coat. [polyurethane].
Attach box to 24 in.stock. using 2 screws..Cut a hole in top of box with dremel saw.
Form the front and back bridges . Attach to box as shown  with dimensions shown.
Drill  tension string anchor holes at back of slider as shown Item 10.  and stock end view.  Strings are attached to the screw tuners at end of the tension side.. then attached last ly to the slider after the 2 strings are in place.
Slider- Cut and form the clear plastic shown. We used a vise and then pounded the bend witha small hammer to retain a 90 degree bend..Glue to slider and  a plastic flat to under side of the slider wood. Slide this assembly  onto the stock while the glue is wet and it will harden in place.
Drill two .093  d. holes on the slider . Attach 2 hook tuner screws. all the way down to the shoulder of the screw then rotate the screw 2 more times with a pair of pliers so the shoulder is down  solid and the torque is now lower.
After  glue sets - we can attach the two strings.
Insert  one string  into box anchor hole.Open the box. and crimp  the string inside of the box. Same for  no.2 string. close box lid.
Extend the string on the slider   tuner and rotate it twise clock-wise. and ancher in the loop of the screw with a crimp.
Place a spacer 6.5 in long on the stock  between the slider and the box. This wil lbe used s a buffer  while tensioning the  string to the key of C[Piano middle C] Second string  is stretched to key of A..When the string is stretched to key [ the key  of C] it is then wrapped around the screw and and crimped. After the strings are attached the spacer can be removed  after the counter string at the top of the stock is attached and stretched till the slider is centered. [ equal tensions  from left and right string assemblies.
Attch the Handle with glue.
Attach velcro or felt to the feet and stock end.
Be sure the crimps in Item 10 do not extend below the surface of the slider.  If this gives trouble then alternately we can place a screw on top of the slider and crimp on the left tensioning string.
White paint can be used on top of the stock to make markings for the keys .We  used C DEFGABC. This is witha felt tip marker.

To use the instrument-
Options A. lay the device on a table. Slide the slider and strum.
B-  Hold in left hand on slider. right hand  press against box and strum. and hum a song.

It can be a Hawaiian steel  guitar.

You can tremolo it.

Kids can make strange sound  on it..

Have fun too.