Introduction: LAP PIANO

About: A retired electronics engineer -motorola. delveing into new craft ideas and contest entries.

Make a small light real Piano placed on your lap.and played like a real piano.It also can function as an exerciser for people who have to exercise their arthritic fingers.It will play 2 octaves with sharps and flats.


   This novel piano uses strings and keys like a real piano. I does have its own sound but is
pleasing to hear and play.It can be used by patients who are bed ridden or arthritic and so the instrument can be used on the bed or lap. Hence the title.It only weighs less than 2 pounds and can be made from standard materials found in local craft stores and hardware stores .
    An earlier Instructable initiated this instrument idea. That release the Mini-Piano was released back in an Instructable November 5,2009 and did not have sharps and flat keys.These were thus added here.
    The piano was made in 40 hours of effort and not including search for the materials. Also any one who is a top craftsman may use up time on the wood and appearance if he wishes.I wish to enter this Instructable for the Health Contest.


All items are listed  but refer to the drawings for the item number.
Some parts can be replaced by an equivalent . Example: wood can be any available wood or purchased wood from a craft store.The main resonator box can be made from scratch or purchased in a Dollar store or Crafts store.Here we used a wood box that fits over a box of tissue paper.It was sanded and painted with varnish.The main thing is to obtain a surface that is thin.The surface is a resonator so it must be less than 1/8 inch thick.[See Item 24}
     The main axle is a knitting needle but any steel rod or wire can be used here.[Item 25]
The 1/4 inch long tubes [item 14 ] can be any tubular metal that will easily fit the axle item 25.
Aluminum sheet .02 in. thick can be same as home siding  material as used here.
Pliers-long nose.
Hemostat clamp pliers.
Shears to cut plastic and metal sheet aluminum [item 15 and 20 ] [Adhesive tape item 12]
Drill press or Dremel to drill holes in the tuner dowel rod and top Item 1]Item  7 Rod]
Drill-bit .093 for the tuner screws.[Item 6]  and screw item 5.
Awl - to mark drill holes .06 dia drill for each string.[19 strings]
Glue-E6000[r].  or equiv.
Saw- or coping saw.


Refer to Drawing B and C
B= side view.

Start by taking dimensions from the drawing and cut and glue all sides , top and ends. as shown in the 1 to 1 scale drawing.
After all wood is in place except the tuning support dowel [3/4Dia.] mark off the 19 hole locations for the strings on the resonator top [item 24].
   The next step is more  involved- attaching the tuner screws.
Mark of the 19 spots and drill the .093 holes about .5 inches apart on the 3/4 in. dowel item 7.
insert the tuning screws full in and then one turn more. this assembly  can now be installed on the  side wood item 22.using item 5 wood screws.
    Drill 19 anchor holes 1/16Dia. at all preset punched spots at the bridge. about 1/.8 inch out.
String  Assembly--Attach  a bead crimp to a string. crimp it with plier. insert  through the above anchor hole and pull it thru. about 10 inches of length to the tuning screw.Attach to screw that  is previously sqyeezed closed loop witha pliers. This can be done with another crimp clamp of the open U-type.Rotate the string clock-wise around the screw base until you sound a note close to the desired note .Later  the tuning is made final.  Perform this operation for all 19 strings.Be sure and stretch the strings until you get the note  for that key.then tie the end to the screw-eye.
      Key Construction-
Key sticks-Cut to length shown [4 in.] using side cutters. clean and sand ends. Mark the centers and place a tube at this point and glue down.Dont let glue enter inside the tubes.[item 25].
Note the sharps keys are shorter so the tubes will be 1-1/4 in. from one end. Be sure the needle axle fitssnugly inside each tube.
     Attaching adhesive-- String the keys  onto the axle and lay axle thru the two end slots . locate  keys . in right place for the note to be used. starting at left  B note.
Locate and glue the side guides item 15 and 20 so the keys will not move side -ways more then 1/32 inch.Lift a key and hold it up to insert the adhesive strip [1/4x1/2 in. precut in their holder and one side of paper removed. Press ont bottom end of stick and over the end 1./16 in. The adhesive is very sticky so use caution here for placement .
    Weights- All weights are about 9grams. position on top end with a little glue.
Add plastic key pads to key ends.[3/4 x 3/4  .Add plastic blocks to Sharps  keys.two per key.
Foam- slip item 18 urethane foam pad under keys and spot glue in place.
Final check of adhesive- Press each key down onto the foam slowly- The string should release from the adhesive Uglu. This completes the main  part of the piano.

Step 4: TUNING

     Using  a piano or a Casio type instrument we use an initial tune-up about 1 note higher than  desired. After 2 hours the string will relax to a lower pitch about one note  down.
     After sitting for 4 hours -retune it to nominal. There will be a drift  of each key note down word about 1/2 note. This is normal for strings of all kinds. 
      After the 3d retuning the drift is zero to -1/.4 note .  and not too noticeable.
Drift after 1 month is about 1/2 note down.  

Play smoothly- some sticking  occurs at first. If adhesive acts up . remove and replace  with a new piece.


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Finalist in the
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    26 Discussions

    Are you able to post a picture of how you attached the keys. Also, a picture of the underside of the piano?

    if i wanted to make this 4 octaves, what would the measurements be?

    3 replies

    It would not be practical due to the limitation of the sstring lengths.
    Three octaves maybe. I have not tried it beyond 2 oct.

    The reason i was asking was because i have to make a musical instrument for my physics project and i'm using your design for the keys but making the body different measurements and im planning on making it 4 or five octaves.

    if i wanted to make this 4 octaves, what would the measurements be?

    Looking at the pictures and description, I don't get what strikes the strings when you press the keys. All I see is that you're removing a damping pad from the string when the key is pressed down. Where's the hammer to strike the string?

    3 replies

    hi- the hammer does not strike the string as in a regular piano apparatus .
    The adhesion at the tip of the lever grabs the string and pulls it upword as you press the arm of the key down.. .
    Then- after x grams of pull the adhesive releases the string and it vibrates freely for a few seconds.It stops when you release the key- arm -going down making contact and muting the string.
    hope this helps visualize the operation.
    I use weights to press the adhesive onto the strings as 20 grams. I could use wire springs but have not found any that will push at a accurate grams push down of the adhesive tip onto the strings.Im open to suggestions.

    Plucking the strings? Then it's an adhesive harpsichord, not a piano.

    Sounds like a novel instrument we developed.. Sure sounds good too.

    yes. but it must be of the hi-tech modern plastic material as used in jewelry stretch string found in craft stores. Neoprene and natural rubber materials appear to deteriorate after a year of use. The New material will withstand at least 10 years of use.

    Yes and No. NYLON string is non-stretching and wont work in our mechanical tuning set-up. It will work if you can get [1] a robust tuning type screw as used in Uku's. and [2] if you make the Frame much more robust so it can withstand the higher stress used in Nylon strings for tuning to a desired note.
    The key advantage to use of stretchable strings or cords is [a] ease of tuning and [b] very low stress used so that the tuner and frame are easy to make and of a lower material cost.
    This is the main reason we used stretchable strings in our mini-instruments
    We have been using stretchable strings since 2001.See instructables.

    Thanks for the comment. After I made it I asked .. can any one do it themselves and the answer from various contacts was it looks easy in its steps but may be tedious to do.
    Now to simplify the steps... I am working on it and will publish it in my web page -- .

    It would be much more worthwhile if you turned those pictures the right side up so you can actually read it without twisting your neck. Or is that intended as exercise?

    It is a wonderful piece of equipment. The writeup and photos are not always easy to follow however. Once I figure out what exactly you did here, will definitely make myself something like this.