the pivot point needs to clear the sled, so at least 9" above the workpiece (figure 12" to allow for real world dimensions)

If the rods are a fixed length, then you have two options (each with their own problems)

**Pivot point at the top**

This requires more clearance around the machines

- The pivot point needs to be high enough that the rods clear the ground when the sled is in the center
- The machine needs enough clearance on the sides for the rods to swing off the end of the sides

9’ rods would mean the machine is 10’ tall and needs 18’ of clearance out the sides

** rods fixed to the sled**

*needs vertical clearance of rod height + workpiece height + a bit

*when the sled is high on the machine, the leverage of the rods above the pivot point could be higher than the leverage of the sled, causing the sled to pivot up

6" bar would let the machine be 8-9’ wide, but would require 10-11’ of height

**telescoping ‘bar’ fixed to the sled and the pivot**

*what is the telescope ratio? even 2:1 could work, but 3:1 or better would be needed to fit in a normal size room comfortably

*how do you apply a pushing force

this avoids any extension of the pivoting mechanism beyond the workpiece (allowing for sled overhang that is), so it seems like it’s worth trying to figure this out.

options I see that are worth looking into

- tape measure material as a pusher
- two geared straight pieces with a gear in between them that gets turned
- a wire/chain zig-zag so that as the chain is pulled, it pulls parts to be longer (think a N with sprockets in the corners, as you pull it tight, the sprockets get closer and it becomes more like a double height I, this could be doubled or tripled with more segments)

one interesting thing about the zig-zag approach is that there is the potential to take up the line with a weight not a motor, providing a constant force outwards from the top center. It would probably need to be a very heavy weight on a pulley system on the back of the machine to work, but this could potentially reduce the weights needed on the sled

hmm, I wonder if you could use drawer sliders to manage the telescoping with just enough between them to attach them together and mount pulleys