I use several machines with wildly different set-ups
a Rollomatic cut back liner, it's a Spaulding Supreme frame with the contact post moved back about an in inch, it has a very short front spring (something like a 19 gauge thickness) and what appears to me to be a piece of strapping iron cut into a spring. It has a Rollo a-bar that is heavily shaved, making it very light (and it has a super annoying looooonnng needle loop post). 8 wrap coils. About a nickel size air gap, and a lil less than a dime on the contact point. and for some reason a 47uf cap.
I just built a Mickey Sharps dial clone, I used 8 1/2 hand wound coils (MY FIRST SET I EVER MADE!) . EIkon springs (both 18) but I cut the front one back quite a bit. I have the contact post moved back,It has about a dime space on the contact point gap, and about a nickel and dimes worth on the air gap. 22uf cap (from Radioshack). I put an EIkon high speed a-bar on it. This machine is my daily liner. In fact I used it for 4 hours straight today.
I have a brass Jonesy that I use to shade (Jonesys are my fav shader) big 10 wrap (er...layer really) coils joined together with a fat iron yoke. Eikon 16 back spring, and 18 front spring. It has a pretty small throw the air gap is just a lil bigger than a dime. Contact point gap is a lil smaller than a nickel. 47uf cap (which was a bitch to find a place to put it) This machine is fast for a shader (zippy) but it works great for shading with a 7 mag
My color packer is a one off frame I made, pretty much the geometry of the Jonesy, but a lil longer. 8 wrap coils, 47uf cap, eikon 16 springs, a long throw with about a nickels air gap. Contact point is a lil bigger than a nickel. It works slow and low, sounds exactly like my electric razor when running.
I have a Forgiven machine, a bulldog frame. I built it as a ghost coil for light work. Eikon 19 front spring, 18 back. 22uf cap. 7 1/2 wrap front coil, rear coil is a bare post (lacquered) very good for 3 liners.........
that's kinda what I use everyday lately, works pretty good for me......I use two rubber bands on every machine, no o-ring on any of them
zombies got my dog.....