[Kevin Sevcik]

Originally Posted by ferrari77

I saw those but the reason i didnt go with those is because the McMaster flexible coupling is around $40 so i'm trying to find a lower price.
I am using a flexible beam coupling so that any mis alignment between the motor axle and the lead screw casued by mounting it slightly off.

Good idea on the 1/2 to 1/4 coupling
I didnt realize those would be easier to find than the 8mm to 1/4 coupling
I found one from Michigan that is only $13
http://www.cadcamcadcam.com/shaftcoupling-2-1.aspx

Yeah, but there's lots of misalignment coupling options. I'm curious why you picked the flexible beam option specifically over something like an Oldham or Lovejoy or something. Beam couplings are typically more expensive and less robust than Lovejoys, for instance. If you're using the beam coupling because it's like a flexible version of a rigid coupling, that's no necessarily the best idea for the reasons I outlined above.