Soap box in doing it legit but being kind. It is correct that if you can't use the proper methods and materials you should not do it or find a different way. Given you are going to have to anyway here is some info on how safely.
First all rigging components from your
safety cables to your head blocks should be tracable as to who manufactured the part and what it's safe working load limit is. It should also be inspected for safe condition before use. You should keep this info on file for liability reasons if it is not stamped on the product.
Given standard hardware store equipment, a little extra
leg work should be all that's necessary to use it.
Chances are what equipment they carry is either from National (a sub company of cooper I think but could verify) or Cooper both of which will have catalogs or websites you can get this info from.
www.coopertools.com
Load ratings and appropriate uses of the equipment need to be followed. If say their
wire rope or
wire rope clips from the website catalog say for instance "not for
overhead lifting" it should not be used. If you still have to use it, make sure those in charged of you using it see that note about the gear being used so it's their liability for approving of it's safe use and not yours.
So in getting the
wire rope, note also from the spool the info of who made it or get the info on where the store got it from. Get the lot number
etc. also from the spool.
You now have both manufacturer and tracable elements of it such as lot number.
Most hardware stores will
stock a 1/8" 7x19
GAC or Galvanized Aircraft Cable. This is the same stuff for all intensive purposes as you would get from a rigging supplier - and most of it these days will all come from China no matter who the supplier is. All of it is rated for a 280# Safe Working Load.
The
wire rope clips available will probably be of the Mailiable type and not
drop forged. Again find out who made or supplied them to your store, and get a lot number. The safe working load or deduction for that on the cable for a mailable
wire rope clip is 60% instead of 80% for that of a domestic
Drop Forged one.
Given these type of
wire rope clips, your new safe working load will be 168# per
lineset which is OK. Follow the directions from the website as to proper torque, installation and required number of them. I might even add a third
wire rope clip in the termination for
safety.
You can also step this up to 3/16"
wire rope and clips for more of a
SWL by way of the
wire rope clips.
Otherwise if a very temporary install and you have a real rigger do so, a
circus knot is 80# effective. Short of proper instruction, don't try it however. Much less the rigger might have a stash of proper
wire rope clips.
A further option would be to pre-purchase a spool rope such as a spectrum
braid from Sapsis Rigging amongst many suppliers. Than again in pre-planning, even McMaster Carr sells
drop forged
wire rope clips and
wire rope that is rated. This amongst mail order companies such as Sapsis, Rose Brand,
Stage Technologies/Secoa, Peak, John Sakash, Atlanta Rigging, Reed Rigging, J.R.
Clancy, Fehr Brothers, Fisher Theatrical, Texas Scenic, Design Lab, Grand
Stage, Mainstage Theatrical, LVH, Rockford,
Stage Rigging, Tiffin Scenic, Total Tool, Ver Sales, I Weiss, and Merrill
As for hanging the door
flat from it, and assuming the proper hanging hardware is used, there is some
safety factors already involved in doing so. Standard rigging 4' on center should be sufficient to fly the door
flat given a soft
flat construction no more than 12'. You might need some folding
stage jacks on the
flat to help support the
flat/doorway.
You did not mention thimbles either. Given hanging hardware, you will need a
thimble at least in attaching to the ring.
This is opinion of course but given I am not there your TD or having a real rigger on site is necessary to verify these assumptions and the actual equipment to be flown will be safe.