## Introduction: 3D PRINT 4 Fork Robot Arm ( FULL TUTORIAL )

this instructable will show you how to make 3d print robot arm with 4 forks to design it you need Autodesk 123D Desgin it is free app here link http://www.123dapp.com/design.
you can use Autodesk inventor or Auto CAD too but this instructable is for 123 design
if you want to know how to use it here link :

•  http://www.123dapp.com/howto/design
•  http://autode.sk/19ZcDCo
•  http://autode.sk/19ZcIG0

Warring read this: do not start your design before read the full instructable

i hope you enjoy your time

## Step 1: Get Started

*first thing is to draw this shape then draw rectangle at the end of at as shown on the figure u can use any length you want that does not matter you can use any numbers and change the length but make sure you use the same ratio you can also draw as mine as shown there.

#1_ Extrude the first shape with length 6 mm, (Extrude is from Construct menu ), now Extrude the rectangle 1.5 mm

now as shown on the figure that is the shape of the solid

## Step 2: Forks Inner Side

#3_ now go to online kite you will find it at right side of the screen at the middle then choose "keyhole" from primitives then choose smart primitives.

#4_ move it then rotate it as shown on the figure ( Move is from transform menu ) then place it on the solid as on the figure.

#5_ copy the key hole  ( Ctrl+C ) or snap it then  past it as on figure at the same high

#6_ check the object if it need to increase or decrease on scale

#7_ now draw this cylinder  and mark the center of the key hole and insert the cylinder at the center of the keyhole and don't forget to make it's high more than the high as by one it is 7 mm , this cylinder will allows the fork to move, do the same on the other one or just copy first one and replace with the other as shown

#8_ Optional:you can change the martial as you want you can change it from martial menu shown on the photo.

#9_ now it is time to close the  shape by drawing rectangle as on the figure  and Extrude it with length 1.5 mm

#10_Optional:you can make the cylinder smooth by using fillet tool from modify menu.

#11_don't forget to Extrude the cylinder as shown on the figure

now we are done the fork inner shape.

## Step 3: Gripper

#12_ now draw this shape as length of fork ( 15 mm ) and then zoom to draw this small things and make sure its right measure ( 90 deg ) or u can make it 60 deg and then draw the inner part

#13_ now Extrude it ( inner part 5 mm high, outer part 6 mm high and it's final shape is shown there on the figure

#14_now add this extra part as shown on the figure

#15_ if u make mistake as wrong direction no problem just mirror it ( from Pattern menu ) and site axes point then do it as shown on the figure.

#16_ place this part ( gripper ) on the fork as shown on the figure and insert another cylinder at it's middle

now it's final shape.

## Step 4: Fork Outer Part

#17_ now copy the key hole or mirror it at the other end as shown on the figure, if you want to fillet the other arm u can do this.

#18_ now it is time to insert gears go to online kite then choose gear then 40 degree then  " 40CA 36T Spur " place it at the lower face of the second keyhole as shown on the figure and then insert cylinder at it's middle

#19_draw rectangle as on the figure

#20_ now draw 2 circles 1st one it center (where cylinder will place  )other one will fill occupation of gear to make 2 sides 90 deg now Extrude 2nd circle by same high of your gear my gear is 0.424 mm and insert cylinder on the 1st one.

#21_ now Extrude the rectangle 1 mm and join it with the shape as shown on the figure.

now it 's  finally done the fork

## Step 5: Description

Description on fig 1 show you were will the gear of the motor will be, the gear of the motor will be this cylinder and the gear type is worm gear u will see it on fig 2 so your motor or gear box must have this gear so u have to buy 60 deg worm gear.it is to Difficult to me to design it with 123d i am already made one with Auto cad but 123d is not really perfect for this.

note this photo is from Wikipedia not mine one i just share it to show it to you.

lets come back to the project :

## Step 6: Join Them Together

#22_mirror the fork now on the axis where gear will be and then mirror it again or just copy that and rotate it as on the figure to get the 4 forks

## Step 7: Position on the Gears

there is to option for you to choose fig 1 or figure 2 it's just moving gears , and make sure that you but this at the right place with the same distance between them  and the gears and make sure you are on the same axis and u can also check this all by measuring the distance by using measure tool but at all i choose 2nd one

## Step 8: Finishing It

#23_ copy this  sheet and place it on the other side and do this with all sides.as shown on the 2nd figure

#24_ now join them together with this bars on fig 3 you can also Chamfer from modify menu r=2 as shown on the figure

#25_ now Extrude the sheets and bars more as shown on the figure then close the X sign part as on the figure

#26_ now draw this shape with the same length of the arm  then Extrude it and finally add to arm as shown on the figure and leave some holes for nails
so it;s over now great thanks to see this instruction and waiting all this time and i hop u like it and follow me to :D

## Step 9: More Idea

this is double face fork just mirror it u will get this thing  it is strong but need more force