In article t,
Roger Hull wrote:

Hi, guys & gals. For some time I've been wanting to build a small scissors
lift to raise and lower the seat on my electric wheelchair (with me in it).
I've already obtained a 24v motor and a Acme leadscrew and pretty well have
it planned out. I'm aiming for a total lift of 20" with a load of 250#. But I
wonder if I'm reinventing the wheel here. Has anyone here done anything along
this same line and could share their experience or point me to plans, ect, on
the 'net? Thanks in advance for any help.

Roger in Vegas
Worlds Greatest Impulse Buyer

Here's one approach: Lots of photos and specs, Patented of course.

This design should be easily adaptable for a power base if it has enough
inherent stability. You got a hell of a moment arm to affect stability
when you're up there.

Have been having similar thoughts about making something similar for my
Jazzy 1170. I think I'd be more comfortable with somewhat less lift and
maybe some kind of incorporated outrigger arrangement for lateral
stability. The whole world isn't level, unfortunately, and it might only
take a few degrees for things to get tippy. My Jazzy base's 295 pounds
empty weight might help though. as might the four-point seat mounts.