Drilling Holes for Top Operating Detail

Christopher Zurek

Hello all,

I'm to the point where I need to drill holes in the tops of some couplers for the top operating detail. I need to do some Type E, Type F and Type H for locomotives.

I've done a few Type E by hand and that kind of sucks.

Anyone have some suggestion on how I can drill the holes easier than by hand? And exactly where the holes should be?

I do have a Seig X2 mini mill and drill machine, so I'm thinking I should just be able to put the couplers in a small vise somehow.

Chris Z.



I would spend some time with your mill and make a fixture for holding the couplers.  I would make the fixture so that the coupler would be held in place with a screw through the hole in the shank.  The fixture should precisely locate the coupler each time one is put in place.

The hole in the coupler then would be located by the Z-Y movement of the mill table and no fiddling would be necessary from one coupler to the next.  Use a solid carbide drill because they are stiff and will make a hole where they are pointed, not wander about like a typical twist drill.  A really light touch on the Z movement will be essential to avoid going too deep into the coupler. 

I cannot answer your question about exactly where the hole should be.  It think it would be worth buying a package of couplers with the top operating feature to learn just where and how deep the hole is.

Rex Beistle


Estes Valley Division

Earl Tuson

And exactly where the holes should be?
A quick look through a '31 CBC shows 3" forward of the back of the coupler horn on Sharon and Type D couplers, 3 1/4"
on Type E couplers. There are a few other designs with slightly different dimensions shown.

Earl Tuson

Frank Sergent

Hi Folks,

I clamp a modified assembly fixture in an old Unimat SL to drill the tops on EC87 and EN87 couplers. I just use my finger to push the coupler against the dowel pins in the assembly fixture to make sure I hit the same location each time. The modification of the fixture is basically just some shim material glued to the fixture to support the coupler head while the drill pushes down on it. You can do a bunch this way pretty quickly.

I use #80 carbide drills intended for printed circuit boards at a high speed. You can generally find these on ebay by the pound. Be aware and beware that these are very brittle though. Don't think you can do this without safety glasses. A Seig X2 might be a bit overpowered for this job and vibration might be more than the tiny carbide drills can handle. I think you can buy kits to convert these to belt driven to reduce the vibration. I've got a Seig X2 as well, but I go to the small (really small) Unimat for this job.

I generally just drill in the location that is more or less centered in the raised "D" on top of the coupler horn. Something that should be considered when drilling holes is how you are going the make the loop. I'm not really impressed with the appearance of the commercially available lift rings because they just don't seem to look right on top of the coupler. They are too big. I think you can do better with wire. The process is described somewhere on the website. If you want to go the wire route, you need to offset the hole forward or back of where you want the ring to be.


Frank Sergent

On second thought I don't think a belt drive will help the Sieg X2. You need something with some serious spindle speed like a small drill press from MicroMark, etc.