Kadee couplers

I use ONLY Kadee #805 metal couplers.

I've used 805s, but some of the new offset shank couplers may work better (less shim to use):

http://www.kadee.com/htmbord/coupler.htm#O-Scale

#805 will work fine. I just ordered the new 740 as an alternative. I haven't seen or heard anyone else using them yet.

Ray Marion

Thanks for the help, BTW what size screws are best?

I recently started using #2 Button Head screws from MicroFasteners.  I went ahead and bought lengths of 3/8", 1/2", 3/4", and 1" just to be safe.  A small Allen Wrench will get them in place.  Button head IMO is much better than Hex head.  With small #2 screws the Hex Head seems to round off easily.  I got the black screws, easy to hide!

I have, great coupler with the knuckle spring inside.  Only minus is the plastic box

When I first started up-grading to Kadee couplers I used those #2 button head sheet metal screws. Worst mistake I ever made doing Kadee up-grades!!!! They keep coming loose, and I could NOT get them tight enough with such small button head drivers.

I finally started using #2 stainless steel, standard slot head, sheet metal screws (for a normal flat blade screwdriver), from Micro Fasteners (out of New Jersey). They work MUCH better, and with a top quality, flat blade screw driver, I get them REALLY TIGHT! No more problems.

HW,

The screws I'm using are #2-56.  I drill and tap the holes, never had any back out.  I don't think I've ever used the sheet metal screws, but I wouldn't think the head type would make them back out.  Are the sheet metal screws those tapered-looking screws?  I can see where they may loosen after some use.

Bob, 

Even though you are using #2 machine screws, I still don't think you can get them tight enough with that button head driver. I generally use the #2 stainless steel sheet metal (self tapping threads) for mounting Kadee couplers to plastic under frame cars. Everything I purchase from Micro Fasteners, is ALWAYS slotted head, for use with flat blade screw drivers. 

Superwarp

Kadee 740 comes with a metal box, which one did you use? Any pics?

Ray Marion

I too use Micro Fasteners.  I use the standard cap screws, and in 2-56 size they are bulletproof.  The button head, 0-80, and flat head use a smaller hex key, and the hex broach is oversize.  As soon as we can buy oversize hex drivers to match, these smaller sizes will be really good fasteners.

This is a new problem - production of smaller cap screws in the USA in the olden days gave us screws that would not slip on the hex driver.

I use a lot of 0-80 flat head hex for crankpins,and slippage of the wrench is a big problem.

If your hex heads are rounding off, you are using too much torque.  Put some contact cement on the threads if they back out.  Most hex heads will separate before the hex fails.

I believe it's the miniature hex head socket wrenches I have that are rounding off inside, rather than the hex head of the screws, or it may be a combination of both.

The mini-socket wrenches came from either MicroMark or Micro Fasteners (I haven't been able to find them on either sight for a while now).  It feels like there's a small portion of the wrench right at the end that does not have "teeth" to engage the hex head of the screw.  Most of the time I have to slightly tilt the wrench to get it to engage.  That causes wear on both the wrench and the screw.

I've been using the #2-56 button head screws for 6 months or so now and none of them have backed out or loosened.  I use a bit from my old Chapman tool set to tighten them:

http://www.chapmanmfg.com/

Me bad 745 sorry no pics.  I use Philips head wood screws from Micro fastener.