sure you need the square frame, I was talking just the x-axis
If you want to make stuff dirt cheap you've got to remove as many components as possible and make the remaining components as cheap (often=flimsy) as possible.
A few options:
- Scrap the frame and bolt the MGN9 rails to a cheap & easy to clean laminated kitchen shelf.
- To get away with the flimsiest dimensions possible yo need to reduce the moving weight.
- Only drive first axis on one side and let it follow freely on the far side.
- Put 3 stepper motors on the outside of the near side so the moment of inertia balances out with the cross rail.
- This will be affected by the position of the head on the cross rail, so keep it light and balance the center position.
- On the far side you only have light weight rollers to return the thin 6mm tooth belts.
- One belt will drive the head position on the cross rail (belt in any orientation).
- Another belt will drive the vertical position of the two pic & place heads (belt horizontal).
- When one head goes up the other goes down.
- This belt will have to move synchronously with the head position belt to keep the vertical position stationary.
- The third belt controls the rotation of both heads (belt vertical).
- This belt will also have to move synchronously with the head position belt to keep the rotation stationary.
- All electronic and vaccuum control should be placed with the motors so the only connection is power and vaccuum.
- Maybe a couple of DC supply wires could be placed inside the vaccuum connection tube to reduce the clutter?
- Find the mechanical resonance frequency of the assembled cross rail (this will vary with head position on the cross rail).
- Accelerate and decelerate the cross rail on a cosine curve with the frequency matching the resonance frequency at a given head position.
- This will prevent vibration when the cross rail has reached its end position (just like you do when controlling a gun turret to fire quickly).
- You essentially replace structural rigidity with more complex acceleration and deceleration equations (but math is cheap these days).
The only mass attached to the head should be a linear bearing, belts, belt fittings, the suction heads, vaccuum tubes and a very light camera.
Disclaimer: These are just penny pinching ideas - I have no practical experience with this specific application.